Workshop on Integrated Water Research and Water Management

Transcrição

Workshop on Integrated Water Research
and Water Management
1
DFG-Senatskommission
für Wasserforschung
Workshop on Integrated Water Research and
Water Management
June 28 th – 29 th 2004
Haydau Monastery
34326 Altmorschen
(close to the city of Kassel)
Germany
2
Modelling of Hydrosystems
3
The German Research Foundation (DFG) in agreement with its Senate Commission on Water
Research invites advanced young researchers working on problems in the fields of economic
tools, water quality, aquatic ecosystems, modelling of hydrosystems and water resources
engineering for efficient watershed management in an integrative approach to participate in the
announced interdisciplinary workshop.
The aim of the workshop is (1) to bring together young postdocs or advanced graduate
students in the final stage of their thesis working in different water-related topics such as
Management of water resources
Aquatic ecology
Water Resources Engineering
Economic tools
and (2) providing a forum for the development of further research approaches.
Scientific and organizing Committee
PD. Dr. Dietrich Borchardt, Institut für Gewässerforschung und Gewässerschutz,
Universität Kassel, Email: [email protected]
Prof. Dr. Rainer Helmig, Institut für Wasserbau, Universität Stuttgart,
email: [email protected]
Prof. Dr. Till Requate, Department of Economics, Universität Kiel,
Dr. Annekatrin Wagner, Institut für Hydrobiologie, Technische Universität Dresden,
Dipl.-Ing. Markus Funke, Institut für Gewässerforschung und Gewässerschutz, Universität
Kassel, Email: [email protected]
4
Program
June 28th 2004
8:30- 8:55
Opening ceremony
A. Roßnagel, Vizepräsident der Universität Kassel;
R. Mäusbacher, Mitglied des Senats der DFG
J. Benndorf, Vorsitzender der DFG-Senatskommission für
Wasserforschung
Chairman: D. Borchardt, Kassel
9:00 - 9:45
Plenary lecture
Aquatic ecology: state of the art and future research
directions
E. Jeppesen, Silkeborg, Denmark
9:45- 10:30
Plenary lecture
Water Resources Engineering: state of the art and
future research directions
J. Londong, Weimar
10:30- 11:00
Refreshments
11:00-13:30
Session:
Aquatic ecology and Water Resources Engineering
Peer reviewed
presentations
by delegates
and discussion
S. Langenheder , E. Lindström, L. J. Tranvik: The interaction
between biodiversity and ecosystem functioning in aquatic
systems from a microbial perspective.
J. Siemens: Merging aquatic and terrestrial perspectives of
carbon ecology.
K.-E. Lindenschmidt: Extended uncertainty analysis of a
hydrodynamic – water quality modeling system embedded in
High Level Architecture.
H. Sewilam: Fuzzy Indicators for Interdisciplinary Performance
Assessment of Water Resources Management.
5
Poster
presentations:
C. Engelhard: The Water Framework Directive and wastewater
management: A pragmatic approach to the assessment of the
ecological status.
R. Hämmerling, J. Rücker, A. Launhardt, H. Behrendt & B. Nixdorf:
Phosphorous input and eutrophication control in a small catchment –
Case study Lake Scharmützelsee.
R. Ibisch: Ecotechnological measures for eutrophication management in
streams.
J. Kail: Influence of large wood on stream morphology.
N. Kirchheim & M. Oberlack: 3D Modelling of a weir to describe the
discharge of a combined sewer overflow.
P. Kulle: Hygienic aspects concerning the quality of receiving waters.
A. Kurtenbach, A. Krein, W. Symader & S. Möller: The analysis of runoff
processes during artificial and natural flood events.
S. Rolinski: Coupled modelling of physical und biological processes in
reservoirs and lakes.
N. Saenger, P. K. Kitanidis & R.L. Street: Hyporheic exchange
processes: Controlling parameters, natural and anthropogenic
influences, and challenges.
B. Tetzlaff & F. Wendland: Area-differentiated modelling of P-fluxes from
diffuse sources in macroscale river basins.
G. Wauer, P.Casper, T. Gonsiorczyk & R. Koschel: A Discussion about
Inlake Restoration with Aluminium.
13:30- 14:30
Lunch
14:30 – 15:00 Presentation +
discussion
Promoting Young Researchers by DFG
B. Scholz, DFG
Chairman: R. Helmig, Stuttgart
15:00 - 15:45
Plenary lecture
Modelling of Hydrosystems: state of the art and future
research directions
A. Bardossy, Stuttgart
15:45 – 16:15 Refreshments
6
16:15- 18:45
Session:
Peer reviewed
presentations
by delegates
and discussion
J. Schaffner, M. Oberlack: Numerical calculation of shear stress
oreated by flushwaves in sewers: Presentation of testsides in
Offenbach and Lyon.
H. Puhlmann: Stochastic modelling approach for deriving
hydrological growth conditions in floodplain forest.
H. Bormann: Hydrological catchment models between process
representation and applicability for water management issues –
case study for Benin (West Africa).
S. Liehr & F. Keil: Integrated water quality management –
development of a socio-ecological approach.
Poster
presentations:
P. Bayer & M. Finkel: Hydraulic groundwater management optimisation
by evolution strategies.
C. Bürger: The design of groundwater treatment systems under
uncertainty: Assessment of funnel-and-gate systems.
J. Dörner & R. Horn: Modelling of the one and two dimensional water
flow in hills lopes.
J. Helmschrot: An integrated approach to model wetland dynamics in a
changing landscape: A case study from South Africas.
H. Holländer: Integrated groundwater management in coastal semi-arid
areas using artifical ?
A. Klawitter: An approach to simultaneously model rainfall-runoff events
in rural and urbanized catchments as well as their interactions, with
help of a GIS.
C. Kohfahl, P. Brown, C. Linklater & A. Pekdeger: Estimating the
Discharge of Sulphate from Dump Sediments into the Surface Water of
an Abandoned Open Pit Lignite Mine.
F. Lindenmaier: Dominating structure and processes in a hydrological
induced mass movement – an interdisciplinary approach.
M. Schirmer & A. Kaschl: Numerical calculation of shear stress oreated
by flushwaves in sewers: Presentation of testsides in Offenbach and
Lyon.
N. Schütze: Meeting the challenges of the blue revolution: increasing
the irrigation efficiency with soft-computing optimisation methods.
M. Seeger, N. Lana-Renault, D. Regüés & J. María García-Ruiz: The
variability of the hydrological response of highly disturbed and forested
catchments in the Spanish Central Pyrenees.
L. Wolf: Developing modelling tools for management of Urban
groundwater resources.
G. Wriedt, H. Geistlinger & M. Rode: Modelling of Nitrate transport and
turnover in a small lowland catchment.
7
18:45 - 19:15
Poster session Forum for presenting posters by delegates
19:30
Banquet
June 29th 2004
Chairman: T. Requate, Kiel
8:30 - 9:15
Plenary lecture
9:15- 10:00
Plenary lecture
10:00- 10:30
Refreshments
10:30- 13:00
Session:
The Economic Analysis in the EU Water Framework
Directive
A. Garrido, Madrid, Spain
Water Use and Water Protection - Control
Mechanisms of Politics
P. Kessler, Wiesbaden
Economic valuation, Economic tools and
J. Meyerhoff & A. Dehnhardt: A benefit-cost analysis of
Peer reviewed
presentations by extending riparian wetlands along the river Elbe.
delegates and
E. Petersson: Multi-criteria decision analysis in sustainability
discussion
assessment: The large dam context.
F. Messner: Integration of Economic Evaluation into the Water
Resources Model WbalMo
L. Breuer, J. A. Huisman, B. Weinmann, T. Wronka, N. Steiner:
Deriving Ecological-Economic Trade Offs for Land Use
Change Simulations with ITE 2M.
8
Poster
presentations:
13:00- 14:00
Lunch break
14:00-15:30
Short statements
and discussion
A. Dehnhardt: The replacement value of riparian wetlands along the
river Elbe as nutrient sinks.
M. Grossmann: Stakeholder involvement and economic assessment
of management strategies for wetlands in a river basin context: Case
study from the Spree-Havel river basin.
K. Hennrich: Interdisciplinary assessment of suitable measures to
minimise P input in the Weiße Elster river.
A. Klaphake: Congested waters: how to conceptualise and measure
recreation benefits and the influence of visitor use levels on peoples'
satisfaction?
H. Koch: Integrated water resources management in the Spree River
catchment in the context of global change.
H. Kreibich: Estimation of flood losses in Germany, Actual Data from
the Elbe and Danube floods in August 2002.
EbroAgua Working Group, E. Petersson:, geosciences and
sustainability – Water from northern to southern Spain?
C. Schleyer: Economics and Ecological transformation processes in
Eastern Germany Water Management Regimes.
H. Tauchmann: Innovativeness in the German Waste Water sector – a
micro-econometric approach.
Chairman: NN.
Presentations of further funding institutions
U. Schaub (Internationales Büro des BMBF)
V. Wachendörfer (DBU)
-
15:30- 16:00
Refreshments
16:00- 17:30
Discussion
H. Hof (Volkswagen-Stiftung)
Perspectives for realization of science plans
Perspectives for proposals
Chairman: J. Benndorf, Dresden
Scientific outcome of the workshop
- Interdisciplinary science plans
- International perspectives of integrated Water
Research and Water Management
- Creation of interdisciplinary networks for water research
17:30- 18:00
Closing ceremony
Final statements
Extended abstracts
9
10
Aquatic ecology and
Aquatic ecology and
C. Engelhard: The Water Framework Directive and wastewater management: A
pragmatic approach to the assessment of the ecological status.
R. Hämmerling, J. Rücker, A. Launhardt, H. Behrendt & B. Nixdorf: Phosphorous input
and eutrophication control in a small catchment – Case study Lake Scharmützelsee.
R. Ibisch: Ecotechnological measures for eutrophication management in streams.
J. Kail: Influence of large wood on stream morphology.
N. Kirchheim & M. Oberlack: 3D Modelling of a weir to describe the discharge of a
combined sewer overflow.
P. Kulle: Hygienic aspects concerning the quality of receiving waters.
A.Kurtenbach, A. Krein, W. Symader & S. Möller: The analysis of runoff processes
during artificial and natural flood events.
S. Langenheder , E. Lindström, L. J. Tranvik: The interaction between biodiversity and
ecosystem functioning in aquatic systems from a microbial perspective.
K.-E. Lindenschmidt: Extended uncertainty analysis of a hydrodynamic – water quality
modeling system embedded in High Level Architecture.
S. Rolinski: Coupled modelling of physical und biological processes in reservoirs and
lakes.
N. Saenger, P. K. Kitanidis & R.L. Street: Hyporheic exchange processes: Controlling
parameters, natural and anthropogenic influences, and challenges.
H. Sewilam: Fuzzy Indicators for Interdisciplinary Performance Assessment of Water
Resources Management.
J. Siemens: Merging aquatic and terrestrial perspectives of carbon ecology.
B. Tetzlaff & F. Wendland: Area-differentiated modelling of P-fluxes from diffuse sources
in macroscale river basins.
G. Wauer, P.Casper, T. Gonsiorczyk & R. Koschel: A Discussion about Inlake
Restoration with Aluminium.
Aquatic ecology and
11
The Water Framework Directive and wastewater management: A
pragmatic approach to the assessment of the ecological status
Carolina Engelhard
Institute of Environmental Engineering
University of Innsbruck, Austria
Email: [email protected].
Keywords: WFD, CD4WC, ecological status, water quality
The EU Water Framework Directive (WFD) (2000/60/EC) introduces integrated river
basin management into European water policy. It is based on an immission-based approach
requiring a “good ecological status” for all water bodies. The European Project CD4WC
aims at developing a method for the cost-effective adaptation of wastewater systems in
agreement with the WFD by considering the integrated wastewater system. First measures
in the subsystems are to be identified and their cost-effectiveness is to be evaluated. On the
basis of the findings the integrated system is to be investigated. Alternative policy
instruments for the control of pollution at a river basin scale are to be compared. The work
is performed by literature studies, simulations and case studies.
In the course of the project CD4WC it became clear how important it is for the evaluation
of the measures to have a link with the biological status, not only for the comparison of
measures applied in different sub-systems but also to determine their cost-effectiveness.
For this purpose a link between the abiotic parameters (hydromorphological, chemical and
physicochemical status) and the biological status is needed. A literature study revealed the
gap of knowledge regarding approved cause-effect relations despite all research performed
in this field. Cause-effect relations are only available for few parameters (e.g. dissolved
oxygen). Complex models like the River Water Quality Model 1 try to predict the fate of
substances in the river. Those models are highly complex but nevertheless a simplification
of the real processes and they do not include predictions of the impact on the aquatic
biocoenosis.
For CD4WC it is necessary to find a way to deal with this problem which is applicable for
the work in the project. Therefore it is necessary to have a closer look at the WFD. The
good status of rivers, chosen as main focus of receiving waters in CD4WC, contains of the
ecological status and the chemical status. The chemical status is described by the
concentrations of priority pollutants as defined in article 16 WFD. The limits consider
chronic and accumulative effects. For the compliance with the immission-based criteria an
12
Aquatic ecology and
integrated view of a river basin is necessary. From the engineer’s viewpoint the
consideration of the chemical status is rather unproblematic.
The major challenge is the consideration of the ecological status. According to the WFD
the ecological status includes biological elements and in support for those
hydromorphological, chemical and physicochemical elements. As far as it can be estimated
from the stage of the implementation process in Austria no limit values for other
substances than the priority pollutants and a few other toxic substances will be set. The
ecological quality will be measured as occurrence and abundance of species in comparison
with a reference biocoenosis. This is not applicable for CD4WC (or for other planning
purposes in the field of wastewater management).
For the handling of the ecological status the following methodology is proposed: The
impacts caused by wastewater depend on the time scale of the discharges. Wastewater
treatment plants cause chronic impacts, while the pressure from combined sewer overflows
mostly is due to acute toxic effects. Accumulation of toxic substances can come from both
sources but also from infiltration of stormwater. Considering the different time scales of
impact it is necessary to differentiate limit values in limits to protect the biocoenosis from
acute toxic effects, limits to avoid long term changes (e.g. caused by eutrophication) and
limits to prevent the accumulation of persistent toxic substances. Beside the time scale the
characteristics of the receiving water have influence on the impact of wastewater;
important is among others the recolonisation potential, the reaeration rate or the status of
adaptation of the biocoenosis to wastewater.
Nutrients released by wastewater treatment plants cause chronic effects. To assess the
influence of plant nutrients on the receiving water a comparison should be drawn with a
reference state. A similar approach is used by the US Environment Protection Agency
(www.epa.gov/ost/standards/nutrient.html). The natural status of a river is low nutrient
conditions in headwaters with increasing concentrations along its course. The effects of
organic loads like BOD depend on the status of the biocoenosis as it can adapt to
degradation of high loads of nutrients if the reaeration rate is sufficient. An increased
supply with nutrients can lead to variations in species composition of biocoenosis in rivers
with naturally low nutrient contents. Up to now no quantified criteria are defined about the
acceptable extinction of species – making it impossible include this effect in nutrient
limits. Limit values can be based on reference conditions, old EU directives like
78/659/EEC (directive on the quality of fresh waters needing protection or improvement in
order to support fish life) or be derived from reference values oriented on the saprobic
system, for example the German water quality system of the LAWA, upgraded with typespecific information on the river.
(example for Germany: www.gdch.de/strukturen/fg/wasser/publikat/vali/vdok_m1.pdf).
Aquatic ecology and
13
The assessment of acute toxicity of wastewater is difficult. The sensitivities of species are
differing and furthermore the toxicity is influenced by many processes. On the one hand
the pollutants react with other components of the wastewater (adsorption, chemical
reactions, adjustment of reaction equilibrium by changes in pH value, conversion and so
on) but also antagonistic and synergistic effects of substances can change the toxicity of a
pollutant. Nowadays the knowledge of these effects is not sufficient to correctly predict the
fate of a substance in the wastewater. Limits are usually based on toxicity data like the
Predicted No Effect Concentration. Those values are obtained under laboratory conditions
with single species and single substances so that their significance in the river is limited.
Thus it is proposed for the work in the project CD4WC to limit the parameter for
simulation to a few selected substances and values only for short duration- low frequency
(e.g. 1 hour once per year). For this it is proposed to stick to parameters, where the causeeffect relations are relatively good known (like dissolved oxygen or un-ionised ammonia)
and update them regularly on the basis new scientific knowledge. Examples for acute
limits can be found in (FOUNDATION FOR WATER RESEARCH, 1998), ORTH et al.
(2003). A similar approach can be applied to the definition of limits for morphological
impacts.
For planning purposes in the field of urban wastewater management further research is
needed to allow the compliance with the European Water Framework Directive.
Acknowledgement
The results presented in this publication have been elaborated in the frame of the EU
project CD4WC, contract no. EVK1-CT-2002-00118. The programme is organised within
the Energy, Environment and Sustainable Development Programme in the 5th Framework
Programme for Science Research and Technological Development of the European
Commission.
FOUNDATION FOR WATER RESEARCH: URBAN POLLUTION MANAGEMENT
MANUAL - A planning guide for the management of urban wastewater discharges
during wet weather. Foundation for Water Research (FWR), Buckinghamshire,
Great Britain. (1998).
ORTH H., LONDONG J., PODRAZA P. and HALLE M.: Ein integriertes Gesamtkonzept
für Entwässerungsgebiet, Kanalnetz, Kläranlage und Gewässer mit dem Ziel eines
nachhaltigen Gewässerschutzes und einer Reduktion der Kosten. Ruhr-Universität
Bochum, Wupperverband, Germany. (2003).
14
Aquatic ecology and
Changes of phosphorus input and Ecological lake response in a small
catchment Basin – Case study OF Lake Scharmützelsee
Hämmerling, Ronny, Rücker, J., 1 Behrendt, H., Nixdorf, B.
University of Cottbus, Chair of Freshwater Conservation, Germany
1
IGB Berlin
Keywords: phosphorus entries, phosphorus release, phytoplankton assessment
Introduction
The region of lake Scharmützelsee (Federal State of Brandenburg, Germany) is
characterized by a chain of eu- to hypertrophic shallow as well as meso- to eutrophic
dimictic lakes. The lake is used as environmental and nature protection zone and for
fishery as well as for water sports and tourism. Until 1990, the lake Scharmützelsee
received up to 18 t a-1 total phosphorus (P) mainly from sewage effluent and, to a smaller
part, from agricultural sources. Although the external P-input decreased since 1990, the
actual ecological state is insufficient according to the EU-Water Framework Directive
based on the phytoplankton assessment approach.
Long term changes and source
apportionment of external P-input for lake Scharmützelsee were quantified for the drainage
basin using the MONERIS model (BEHRENDT et al. 2000). This detailed analysis is the
precondition for the catchment basin management and for phosphorus control. The
implementation of the EU Water Framework Directive (WFD) in Germany is requiring -a
good ecological status for surface waters -by the year 2015.
Area under investigation
Lake Scharmützelsee is situated in the catchment basin of the river Dahme 50 km southeast of Berlin, in the German Federal State of Brandenburg. Table 1 shows the
morphometrical and hydrological characteristics of lake Scharmützelsee.
Table 1 : Morphometrical and hydrological characteristics of lake Scharmützelsee
Lake area [km2 ]
12.1
Volume [Mill. m3 ]
108.23
Maximum depth [m]
29.5
Mean depth [m]
8.8
Average outflow from 1976 to 2003 [m3 s -1 ]
0.31
Water residence time [a]
11
2
Basin area [km ]
127.91
Aquatic ecology and
15
Methods
Limnological investigations of lake Scharmützelsee
The water quality investigations of the Scharmützelsee are carried out at its deepest site
(29.5 m, s. Table 1) near Wendisch Rietz monthly to fortnightly. The analyses include
vertical profiles of water temperature, conductivity O2 , and redox potential using a
multiprobe (H20? , Hydrolab) and chemical parameters (concentration of dissolved and
total phosphorus, nitrogen, silicate) and biological criteria (chlorophyll a, abundance and
composition as well as biomass of phytoplankton). The P-load at the outflow was
calculated with P concentration measured by the Environmental Agency Brandenburg and
water discharge data measured by the ‘Wasser- und Schifffahrtsamt’ Berlin.
Assessment of trophical and ecological status
The trophic status was estimated based on the chlorophyll a concentration, Secchi depth
and total phosphorous concentrations and compared with the potential natural state
according to LAWA (1999). The biological assessment based on phytoplankton biovolume
regarding the approach of MISCHKE et al. (2002).
Estimation of the P input into the lake
The Geografical Information System (GIS)-oriented MONERIS model (Nutrient
Emissions in River Systems) is, in its current version, developed for catchment basins
areas larger than 100 km2 . Various point and diffuse nutrient inputs into rivers and al kes
can be estimated by the MONERIS model.
Results
Characterization of P loads and its changes from the 1990th to 2000
According to estimations of the regional authorities, the Scharmützelsee received up to 18 t
a-1 total phosporous (P) mainly from the sewage effluent of a nearby military hospital and
to a small part from agricultural sources until 1990. Figure 1 shows the average annual P
input of 1.65 t a-1 into the catchment basin of the lake Scharmützelsee between 1996 and
2000.
Urban
systems
12%
Atmosphere
32%
Groundwater
35%
Erosion
6%
Overland flow
10%
Tile drainage
5%
Fig. 1: Annual average phosphorus
entries of 1.65 t a-1 in the lake
Scharmützelsee catchment
basin between 1996 and 2000
estimated by MONERIS
model
16
Aquatic ecology and
The current main P sources in the catchment basin are the groundwater, the atmospheric
deposition and the urban systems.
The P entries into the lakes and rivers proceed in subject to the specific P retention
function of the MONERIS model. The P load of lake Scharmützelsee compared with the P
load between 1980 and 1990 ( 18 t a-1 P) has been reduced approximately by 95 % to
0.8 t a-1 P.
Internal P release and comparison between calculated and measured P export
The internal P-release in lake Scharmützelsee by RÜCKER et al. (2003) with an average
annual rate of 0.56 g m-2 a-1 P, remained relative constant and high up to 6.75 t a-1 P in
comparison with the external P-load.
Provided that the P retention would reaches the value of 78 % (VOLLENWEIDER &
KEREKES 1982), the P export of the P release approximately reach 1.04 t a-1 P.
Trophic and biological assessment
Over a period of 10 years between 1994 and 2003, excluding 2000 and 2003; the trophic
status of the Scharmützelsee was high in comparision to the mesotrophic reference status
in relation to the morphometry and the potential natural P-load.
The ecological assessment based on phytoplankton biovolume (MISCHKE et al. 2002) for
the same timeframe was, excluding 2000 and 2003, between 3 and 5, in average 4, a worse
status with high annual variations. The LAWA assessment showed better results compared
with the ecological approach of lake assessment.
Discussion
From the end of the 60th until 1990 the lake received a high phosphorous load up to 18 t a1
total phosphorus (P) mainly from sewage effluent and, to a smaller part, from agricultural
sources. The eutrophication process accelerated in the 70th showed drastical symptoms:
Mass development and sporadic blooms of cyanobacteria. The lake function as a
phosphorous sink during the “high” eutrophication phase with extremely high phosphorous
loads were established.
The current P concentration of lake Scharmützelsee is mainly influenced by the internal Prelease of 6.75 t a-1 . This is eight times higher than the annual external P load. That means
that the lake was a P source between 1996 and 2003 except for the years 2000 and 2003
(annualised). To reduce the trophic status of lake Scharmützelsee it is necessary to increase
the long-term P-accumulation in the lake sediment by restoration measures. Because of the
dimension and the morphometrical conditions of lake Scharmützel is the phosphorus
precipitation a possible restoration method (SCHAUSER et al. 2003). In the current status
only the P concentration of the groundwater can be reduced slightly by a further reduction
of the agricultural production in the catchment basin.
Additional examinations to determine the development of the future P-release rate are
necessary in order to reach the good ecological status of the Scharmützelsee as required by
the EU-WFD.
Aquatic ecology and
References
BEHRENDT,H., HUBER, P., KORNMILCH, M., OPITZ, D., SCHMOLL, O., SCHOLZ,
G., & R. UEBE (2000): Nutrient balances of German river basins. UBA-Texte,
23/2000, 261 pp.
EU (European Union), (2000): Directive 2000/60/EC of the European Parliament and of
the Council of 23 October 2000 establishing a framework for Community action in
the field of water policy. PE-CONS 3639/1/00, REV 1, ENV 221, CODEC 513: 152
pp.
LAWA (1999): Gewässerbewertung –Stehende Gewässer. Länderarbeitsgemeinschaft
Wasser, Kulturbuch-Verlag, Berlin.
MISCHKE, U., NIXDORF, B., HOEHN, E., & U. RIEDMÜLLER (2002): Möglichkeiten
zur Bewertung von Seen anhand des Phytoplanktons – Aktueller Stand in
Deutschland. In R. Deneke & B. Nixdorf (Hrsg.) Implementierung der EUWasserrahmenrichtlinie in Deutschland. BTU Cottbus Aktuelle Reihe 5/02.
RÜCKER, J., B. NIXDORF, R. DENEKE, A. KLEEBERG & U. MISCHKE (2003):
Reaktionen von Seen im Scharmützelseegebiet auf die Reduzierung der externen
Belastung.
Wasser & Boden 55 (4): 4-10.
SCHAUSER, I., LEWANDOWSKI, J., & M. HUPFER (2003): Seeinterne Maßnahmen
zur Beeinflussung des Phosphor-Haushaltes eutrophierter Seen. Berichte des IGB,
Heft 16 / 2003.
VOLLENWEIDER, R. & J. KEREKES (1982): Eutrophication of waters – Monitoring,
assessment and control. Synthesis Report, OECD Paris: 154 pp.
17
18
Aquatic ecology and
Ecotechnological measures for eutrophication management in streams
Ralf B. Ibisch
Institute of Water Resources Research and Management
University of Kassel, Germany
Email: [email protected]
Keywords: eutrophication, river management, water quality goals
Eutrophication is a fundamental concern in the management of all water bodies throughout
the world and has been one of the key topics of contemporary research in freshwater
systems. Management problems caused by nutrient enrichment and associated growth of
primary producers include degradation of water quality (above all dissolved oxygen and
pH) resulting in detrimental effects on fish, the aesthetic degradation of water bodies, the
loss of invertebrate taxa that are sensitive to water pollution and the colmation of river
sediments. The understanding of interactions in river ecosystems between nutrient loading
and associated excessive algae growth is essential for the establishment of river
management measures. In the last years, several statistical, deterministic and neural
network based models have been developed to predict the effects of nutrient enrichment on
phytoplankton biomass in lakes. Since the publication of the EU Water Framework
directive in december 2000, there is also a considerable interest in the eutrophication of
streams and rivers and the development of classification schemes for lotic water bodies.
Existing criteria for reactive solutes need to be discussed (e.g. Chemische
Gewässergüteklassifikation, LAWA 1998) and european standards have to formulated.
Trophic status was defined in the DIN standard 4049, part 2 (1989) as the intensity of
primary production, while eutrophication has to be understood as the increase of primary
production, caused by increased supply rates or by enhanced utilization of nutrients.
Phosphorus and nitrogen are the two elements that most frequently limit aquatic primary
production and are most commonly implicated in eutrophication from point and nonpoint
source pollution. As phosphorus is an order of magnitude less abundant than nitrogen,
phosphorus will often be the first nutrient to become limiting. However, the rate of primary
production in streams is a function of many factors, including availability of light,
nutrients, temperature, grazing and periodic disturbances of substrates. These factors
interact with one another, and different ones predominate in different situations.
The negative effects of eutrophication have lead to multiple action plans in Germany in
order to restore water bodies and to reduce nutrient enrichment. The most important
measures for the improvement of water quality were the construction of circular sewage
water systems (Ringkanalisation) in Bavaria and Austria, the reduction of phosphorus in
washing agents (Phophathöchstmengen-Verordnung 1980, phosphate-free detergents since
Aquatic ecology and
19
about 1986), improved techniques of phosphorus and nitrogen removal in sewage water
and in recent times the reduction of phosphorus supply rates through nonpoint sources in
agriculture. All these measures have lead to a significant reduction in the concentration of
phosphorus in german water bodies, for example in the lower river Rhine by 80 % between
1972 and 1994 (Hamm 1999). For the year 1995 the annual P load to german surface
waters was estimated to amount 58 t P (Umweltbundesamt 1997), whereas nonpoint
sources accounted for more than 50 % in most of the larger river basins like the river Elbe
and the river Rhine (Behrendt et al. 1998). However, reduced concentrations of phosphorus
in some river systems did not result in a reduction of eutrophication to the same extent. For
example, the long-term mean values of chlorophyll a did not change significantly during
the last decades (e.g. river Ruhr, Nusch 1999). However, the reduction of phosphorus
concentrations has reduced the excessive growth of algae und the frequency of oxygen
deficits occuring in rivers. For the design and development of efficient management
strategies of river basins, it seems to be useful to identify the limiting factors of primary
production. In some cases, the advancement of dynamic bed load leading to significant
biomass loss of benthic algae might be a more powerful tool in river mangament than
further reducing nutrient concentrations alone. There is a need for research in this field.
The characterisation of the trophic state of streams and rivers can be done by means of the
following methods:
-
measurement of nutrient concentrations
-
measurement of biomass of primary producers
-
measurement of physico-chemical variables
-
bioindication (species composition and abundance)
The most important parameter in routine river monitoring programs is the measurement of
nutrient concentrations (phosphorus, nitrogen, silica). In order to limit excessive growth of
algae and to stabilise oxygen budgets, Hamm (1991) formulated the following water
qualitiy goals for plankton-dominated rivers: 160 – 200 µg/l TP are tolerable, 50 – 150 µg/l
TP as an advanced quality goal. The latter concentration values were taken some years
later as a limit for water quality class II in german standard classification schemes
(Chemische Gewässergüteklassifikation, LAWA 1998). The utility of a general application
of these concentration values should be questioned, as it does not represent the variety of
streams and rivers, which might differ significantly in geology, hydromorphology,
hydrology and biology. In our presentation several examples will be shown, where the
determination of nutrient concentration in streams leads to a misinterpretation in the actual
trophic state of water bodies. We will show that there is a significant research need for the
development of water quality goals and management strategies that takes basic
limnological
knowledge
(e.g.
river-continuum-concept,
nutrient-spiraling-concept),
20
Aquatic ecology and
catchment characteristics and ecotechnological measures for eutrophication abatement into
account.
BEHRENDT, H., HUBER, P., LEY, M., OPITZ, D., SCHMOLL, O., SCHOLZ, G. &
UEBE, R. (1998): Die Nährstoffbelastung der Flußgebiete in Deutschland - Ursachen und
Veränderungen. - Jahrestagung der DGL (Klagenfurt), Werder: 74 - 81.
DIN 4049, T. (1989): Hydrologie. Begriffe der Gewässerbeschaffenheit.
HAMM, A., HRSG. (1991): Studie über Wirkungen und Qualitätsziele von Nährstoffen in
Fließgewässern. Hrsg. vom Arbeitskreis "Wirkungsstudie" im Hauptausschuß "Phosphate
und Gewässer" in der Fachgruppe Wasserchemie in der Gesellschaft Deutscher Chemiker
durch den Obmann des Arbeitskreises. - Academia, Sankt Augustin, 830 S.
HAMM, A. (1999): Die Eutrophierungsverminderung - eine Erfolgsstory ? - Jahrestagung
der DGL (Klagenfurt), Werder: 58 - 73.
LAWA (1998): Beurteilung der Wasserbeschaffenheit von Fließgewässern in der
Bundesrepublik Deutschland - Chemische Gewässergüteklassifikation, Berlin.
NUSCH, E. A. (1999): Wann nehmen die Algen endlich unsere Eutrophierungsstudien zur
Kenntnis? - Jahrestagung der DGL (Klagenfurt), Werder: 473-477.
UMWELTBUNDESAMT (1997): Daten zur Umwelt. - E. Schmidt Verlag, Berlin.
Aquatic ecology and
21
Influence of large wood on stream morphology and the potential use of
wood in Central European stream restoration projects.
Jochem Kail
Institute of Ecology, Faculty of Hydrobiology
University of Duisburg-Essen
Keywords: large wood, stream morphology, stream restoration, Water Framework
Directive
The restoration of degraded stream channels has become a widely accepted social objective
in developed nations and the scientific interest in stream restoration has been steadily
increasing over the last two decades. Wood is a key component of ecosystems in temperate
forested ecoregions, which influences stream hydrology, hydraulics, sediment budget,
morphology and biota across a wide range of spatial and temporal scales (see review in
Harmon et al., 1986, Maser and Sedell, 1994, Gurnell et al., 1995, Gregory et al., 2003).
Therefore, it is widely used in stream restoration projects, e.g., for local bank protection, as
grade control, to enhance habitats for fish and benthic macroinvertebrates, to initiate the
development of a meandering channel pattern and to generally increase the structural
complexity of streams. The vast majority of these restoration projects has been carried out
in the northwestern U.S. to restore fish habitats by the placement of artificial instream
structures such as log weirs.
In contrast to North America, the relevance of wood for stream ecosystems has long been
overlooked in Central Europe, presumably because it is rarely found in Central European
streams due to the long term human impact on streams and the adjacent floodplain. Wood
is rarely used in Central European stream restoration projects not only because the
beneficial role of wood is not well-known, but also because wood increases the flood
probability upstream and floating wood is a potential hazard to works downstream (e.g.,
bridges). In North America numerous studies concerning wood in streams have been
carried out, but transferability of the results is limited because land-use pressure is
particular high in Central Europe and the natural setting (e.g., discharge, geology,
vegetation) and restoration objectives differ from those in North America.
The main objective of the PhD thesis is to help develop a European perspective on the
influence of wood on stream morphology and the potential use in stream restoration. The
latter is of special practical importance, because the “European Water Framework
Directive” recently inacted by the EU requires a good ecological status of all European
rivers to be achieved by 2015 and hence there is a strong demand for cost-effective stream
22
Aquatic ecology and
restoration measures. The specific objectives of the study are to (1) describe the amount of
wood present in natural streams, (2) investigate the influence of single large fallen trees on
stream morphology, (3) identify stream reaches which potentially can be restored using
large wood, (4) summarize the experiences that have been gained in Central European
stream restoration projects where wood has already been used. Some general results are
given in the following:
Potential natural wood loadings: My own and other unpublished data on the quantity and
distribution of large wood in near-natural stream sections with currently low human impact
and thus a comparatively high amount of wood were compiled. The objective was to
deduce natural conditions, which can serve as reference and target conditions in stream
restoration projects. The data suggest, that the large wood present in the near-natural
stream sections investigated should be considered as the minimum volume to be obtained
in restoration projects. A potentially natural stream morphology and community would
probably boast a much larger amount of large wood, and therefore, stream restoration
projects should aim to increase the input of large wood even in the most natural stream
sections.
Influence of large wood on stream morphology: The impact of large fallen trees on channel
morphology is described for six short stream sections in Central Europe, five of which are
compared to nearby reference sections free of large wood. Such single trees are often used
in stream restoration projects, because they are usually available in close vicinity to the
stream. A wide range of different parameters was derived from the digital terrain models
and cross sections (e.g., volume and extent of channel features, complexity of streambed,
cross-section area, width, depth and complexity). Differences in channel morphology
between the wood sections and reference sections indicate, that single large fallen trees can
significantly increase the structural complexity of stream reaches within one to several
years and act as a strong morphologic control.
Potential use of large wood in stream restoration: Hydromorphological data of three
federal states (“Gewässerstrukturgütedaten”, total stream length 44,880 km) were used to
identify stream sections, where two different methods of stream restoration can potentially
be applied: (1) “wood placement” (anthropogenic input of large wood) and (2) “wood
recruitment” (restoring natural recruitment of large wood). Differences exist between (1)
the lower-mountainous area, where a large number of channel segments can be restored
yielding an improvement from a moderate/good to a good/excellent morphological status
and (2) the lowlands, where only a small number of channel segments can be restored
yielding an improvement from a bad to a moderate morphological state. The latter
upgrading might be sufficient to reach a “good ecological status” as defined by the EU
Water Framework Directive. The results of this study show the suitability of large wood
Aquatic ecology and
23
recruitment and placement as appropriate measures to restore a large proportion of the
streams in the study area.
Review of restoration projects with wood: A mail survey was carried out to summarize the
experiences that have been gained in Central European stream restoration projects where
wood has already been used. The study documents the project objectives, types and extent
of measures, costs, monitoring efforts, and problems that occurred during planning,
approval, and implementation of the projects. Two aspects appear to be of special
importance with regard to the aim of the workshop: (1) Several respondents pointed out,
that the lack of information on the use of wood in stream restoration was one major
problem in planning of the projects. In accordance with these results, educational events on
stream restoration with wood show, that there is a strong demand for methods to assess the
influence of large wood on channel hydraulics, especially on water level. (2) Perception of
the drawbacks and opportunities of stream restoration with large wood differs markedly
between stream ecologists, stream managers, landowners and residents causing
communication problems. These two aspects show, that interdisciplinary research
programs of stream ecologists, stream morphologists, engineers and sociologists could
make valuable contributions to the knowledge on stream restoration with wood.
Gregory, S. V., Boyer, K. L. and Gurnell, A. M. (Ed.) 2003. The ecology and management
of wood in world rivers. American Fisheries Society, Symposium 37, Bethesda,
Maryland, 431.
Gurnell, A. M., Gregory, K. J. and Petts, G. E. 1995. Case studies and reviews: The role of
coarse woody debris in forest aquatic habitats: implications for management. Aquatic
Conservation: Marine and Freshwater Ecosystems (5), 143-166.
Harmon, M. E., Franklin, J. F., Swanson, F. J., Sollins, P., Gregory, S. V., Lattin, J. D.,
Anderson, N. H., Cline, S. P., Aumen, N. G., Sedell, J. R., Lienkaemper, G. W.,
Cromack, K. and Cummins, K. W. 1986. Ecology of coarse woody debris in temperate
ecosystems. Advances in Ecological Research (15), 133-302.
Maser, C. and Sedell, J. R. 1994. From the forest to the sea - The ecology of wood in
streams, rivers, estuaries, and oceans. Delray Beach, 196.
24
Aquatic ecology and
3D Modelling of a converge side weir to describe the discharge of a
combined sewer overflow
Norma Kirchheim,. Martin Oberlack
Hydromechanics and Hydraulics, Technische Universität Darmstadt,
Petersenstr. 13, 64287 Darmstadt,
[email protected]
Keywords:
numeric modelling, combined sewer overflows (CSO),
water resources, hydromechanics, aquatic pollution
Ecological and water-economical interests require an exact determination of the combined
sewage discharge by storm overflows. The common methods and calculations expressed in
the directives from the ATV [1] implicate losses of accuracy. It is the aim of the 3D
modelling to determine the discharge as a part of the precipitation dependent drainage
system preferably close to reality. In this sense the interdisciplinary investigation at hand
connects numeric modelling with aspects of water management and operating of drainage
systems as well as waters ecology and hydromechanics facets.
To a large extent the water pollution results from combined sewage discharge or external
water entries [3]. Concerning the effects of combined sewage discharges into receiving
waters it is necessary to differentiate between the hydraulic and the substantial load.
Consequences of the hydraulic load are e.g. substrate relocation, clogging of the retreat
area for the macrozoobenthos, drift and the so-called hydraulic stress, which results in a
sudden increase of the flow velocity. The effects of substantial load by combined sewage
are the oxygen deficit due to biological dismantling, acute toxicity by high nitrite and
ammonia concentration, the eutrophication as a consequence of nutrient entry and the
accumulation of heavy metals or other pollutants. To reduce the aquatic pollution, the
water framework guidelines (guideline 2000/60/EG) suggest an approach of emissionoriented observations of point sources and the fixing of imissions-oriented goals [2].
Therefore it is essential to calculate the discharge of a combined sewer overflow as exact
as possible. The requirements of the individual constructions concerning their hydraulic
load are specified to fifty overflow events with a discharge time of 20 h in total [6].
Frequent measurements of the water level are the only technical and economical possibility
to investigate and supervise the discharge of a storm drainage system. However usual
calculation methods cause errors within the range of up to 50% due to the inexact
determination of the water levels. An improvement of the determination of the discharge
by the knowledge of the exact surface profile leads to a decrease of these errors down to
5% referred to the discharge [7].
The monitoring and dimensioning of combined sewer overflows becomes complex because
the design rules are only valid for subcritical flows, which are frequently exceeded in
reality. The most common method to calculate the discharge of combined sewer overflows
Aquatic ecology and
25
is the use of the formula of Poleni [1]. The spatial variability of the flow as well as the
boundary conditions and the influence of the friction (distribution of velocity and pressure
due to streamline curvature) are expressed by a discharge factor. For the determination of
the discharge coefficient the empirical approach of Rehbock is predominantly used. The
computations of overflow quantities are critical to evaluate due to the large variability of
discharge coefficients for different weir forms [4].
The flow within a converging side weir can be described as unsteady (quasi-steady), nonuniform decelerated and turbulent. The flow across the weir is discontinuous and shows a
strong variability in the discharge and the water level along the spillway. The diagonal
inflow of throttled side weirs lead to a complicated, spatially distributed flow inside the
weir. The flow depends on inflow conditions (energy and bottom gradient) and drainage
control (inlet and throttling) as well as on the position of the weir crest. In particular, largescale vortexes and fluctuations of the water level lead to changes of the incoming flow and
intake losses of the pipe flow. The surface profile may be concave or convex depending on
the incoming flow conditions (subcritical and supercritical). The commercial program code
StarCD [6] was used for the numerical computation of the flow. The code solves the
Reynolds averages Navier Stokes equation using the standard k-? model as the turbulence
model. The spatial discretisation is based on the finite volume method using a low order
procedure. For the temporal discretisation a fully implicit procedure was chosen. The
pressure correction is calculated employing the PISO algorithm (Pressure Implicit with
Splitting of Operators) and the free surface is solved with the VOF method (Volume of
Fluid). The computational grid of the 2.5 m long and 0.8 m high overflow chamber consist
of approx. 32,000 cells. The inflow pipe (DN 600) as well as the outflow via the throttle
(DN 200) is modelled as 0.5 m long section in each case. The bottom slope of the main
sewer pipe of 0.48 ‰ was also used for the pipe sections. The height of the crest (wm =
0.357 m) is horizontal. Dr. A. Wetzstein [7] used a physical model (scale 1:1) of a CSO at
the Technical University of Darmstadt to take measurements at different water levels.
A comparison of the measured values with the computed results showed a very good
agreement for a subcritical inflow combined with quasi-steady flow conditions inside the
weir. (Figure 1) The maximum deviation of the surface profiles amounts to 5.8 %. The 3D
modelling of the CSO with StarCD shows the stationary flush above the throttle and its
reflection. The vector field for the calculation indicates this flush above the throttle and the
backflow at the surface.
26
Aquatic ecology and
hWSP [cm]
75
70
65
60
55
50
45
40
35
30
0,0
Measurement
Simulation
Fr0 = 1,4
Fr0 = 0,84
Fr0 = 0,44
0,5
1,0
1,5
2,0
150-90
350-65
480-67
150-90
350-65
480-67
Q 0 –Q thr
[l/s]
2,5 x [m]
Figure 1: Comparison of the measured values with the computed results,
water level in the middle of the converge side weir
These results prove that an advancement of the determination of the discharge
numerical modelling is possible. The next step would be to create a link between
numerical modelling and linear hydrologic models. Therefore it is essential to integrate
solute transport into the numerical models to calculate the solid and substantial load of
discharge of combined sewer overflows.
by
the
the
the
References
[1]
[2]
[3]
[4]
[5]
[6]
[7]
ATV (1994): Arbeitsblatt 111 „Richtlinien für die hydraulische Dimensionierung
und den Leistungsnachweis von Regenwasser-Entlastungen in Abwasserkanälen und
–Leitungen“
Blöch, H. (2001): Europäische Ziele im Gewässerschutz - Auswirkungen der EUWasserrahmenrichtlinien auf Deutschland, KA - Korrespondenz Abwasser, Heft 2, S.
168-172
Krauth, K.H. (1992): Abwassertechnische Strategien für den Gewässerschutz,
Berichte der ATV, ATV-Bundestagung 1992, Berichte der Abwassertechnischen
Vereinigung, Nr. 42, 13-24
Peter, G. (2004): Kritische Betrachtungen zur Berechnung der Überlaufmengen an
Überfallbauwerken, Wasserwirtschaft, Heft 3, S.14-18
Staatsanzeiger für das Land Hessen (1992): Regeln der Technik bei der
Mischwasserentlastung, Ausgabe vom 03.02.1992, Nr. 5, 339
User Manual (2002): USER GUIDE StarCD Version 3.15A, CD adapco Group,
Computational Dynamics Limited
Wetzstein, A. (2003): Berechnung von Entlastungsabflüssen an gedrosselten
Streichwehren auf der Basis von gemessenen Wasserständen, Dissertation an der TU
Darmstadt am Instituts für Wasserbau und Wasserwirtschaft
Aquatic ecology and
27
Hygienic aspects of the quality of receiving waters
E.- Peter Kulle, J. Londong
MFPA at Bauhaus- University, Institute for Materials Research and Testing,
Department of Environment, Amalienstr. 13, 99423 Weimar, Germany
Keywords: antibiotic resistance, bathing water, constructed wetlands, disinfection,
hygienic risks, microfiltration, microorganisms, receiving water, UV treatment,
wastewater separation, wastewater treatment
A tremendous variety of bacteria, but also viruses, microfungi and planctonic organisms
are abundant in receiving water systems. Their counts and the composition of species vary
considerably. Besides autochthonic microorganisms which are members of the natural
ecosystem there are allochthonic organisms coming from different media and trying to
survive within the waters where they can be the source of human illnesses. The hygienic
risk is due to the discharge of purified and non-purified wastewater but also to wash-outs
of agricultural soils after fertilising with liquid manure.
German Water Law is based on the principle of emissions for the discharge of municipal
wastewater. For the discharge of purified wastewater minimum requirements have to be
fulfilled concerning the generally accepted rules of technology. After the immission law
additional demands can be laid down if it is necessary for the receiving waters. This was
and still is taken into account for the European Water Framework Directive and for the
amendment of the Bathing Water Directive in which clear demands for
hygienic
objectives of waters are set.
Water protection zones are areas of high sensitivity, and it is important to avoid
contamination of groundwater there as a consequence of pathogens released in wastewater,
in particular viruses. For the treatment of wastewater in water protected areas in Germany
additional hygienic demands are defined for the quality of treated wastewater. But the
disinfection of raw wastewater is established only for specific hospital wastewater,
wastewater from tanneries, knacker’s yards and genetic engineering plants. Besides that in
Germany there are no limiting values of bacteriological and virological parameters for the
discharge of wastewater into receiving waters.
The biological treatment of wastewater reduces the levels of pathogens whatever treatment
system is used. However, surviving critical microorganisms can still cause a significant
28
Aquatic ecology and
pollution. Conventional activated sludge and trickling filter systems lead to a far-reaching
reduction of hygienic relevant germs, but nevertheless a considerable amount of bacteria
and viruses „survive“. Together with the purified wastewater they reach the water bodies,
sediments and/or soils. The hygienic problem shifts to water bodies mainly which have
become an important source for human infections meanwhile.
To microorganisms “our world” is a single entity without borders. Microorganisms have
more freedom than we do and also more genetic flexibility. Antibiotics which have been a
front-line weapon against diseases for decades are becoming increasingly ineffective. The
alarming progressing spread of bacteriological antibiotic resistance leads to questions
about reasons and effective measures to solve that serious problem. In order to reduce
hygienic risks more attention should be paid to water protected areas, bathing waters, large
centralised sewage treatment plants especially when discharging into small receiving
waters. To improve the hygienic situation two possibilities will be discussed:
1
Separation of yellow, grey and black water and separate use
and/or treatment
2
“End-of-pipe” solution: hygienic treatment steps (microfiltration,
UV treatment, planted soil filters)
After establishing the nitrogen und phosphorus elimination for large sewage treatment
plants a “fourth wastewater treatment step” as disinfection process could be realized as a
further “end-of-pipe” step. It can be done effectively by micro- or membranefiltration, UV
treatment or by using constructed wetlands. The microfiltration reduces the amount of
germs completely but costs are still high and technical problems remaining until now.
Other filtration techniques like reverse osmosis are far too expensive. The treatment of
wastewater with UV waves is the most common technique in Germany. It causes less costs
than the microfiltration. With time its efficiency is dropping because of growing biofilm
formation on the quartz glasses, so that additional cleaning work has to be carried out
regularily. Constructed wetlands can be very efficient. Long retention times of the
wastewater and a very “aggressive” biocoenosis of authochthonic organisms make it
difficult for pathogens to survive. But that technology needs a lot of space and is, therefore,
only useful for small sewage treatment plants in rural areas.
With a strict separation of yellow, grey and black water by using new sanitary systems a
very effective way of disinfection and hygienic safety can be gone. The pathogen content
almost only due to the black water can be reduced completely. The human faeces in which
approximately 1 - 5 ? 1011 microorganisms / g and more than 400 species were detected
can be treated by composting processes or anaerobic digestion. During composting the
Aquatic ecology and
29
hygienic relevant germs are killed because of the development of high temperatures far
above 50 °C. The mesophilic or thermophilic anaerobic digestion leads to a stabilization of
faecal materials with high hygienic safety. Yellow water is of no hygienic relevance except
for cases of specific sicknesses. The content of pathogens in grey water is neglectable.
For the future more research work should be done in the field of wastewater separation as
an intelligent method not just to use our wastewater as a source for nutrients with
fertilising potential like phosphorus but also to minimize hygienic risks coming from
receiving waters.
ENGLERT, R., KULLE, E.-P.:
Wastewater treatment and pathogens in a water protection zone.
Abwasserbehandlung mit Keimreduzierung in einem Wasserschutzgebiet.
Wasser & Boden, 51/3, 13-18, 1999.
KULLE, E.-P.:
Wastewater disinfection in water protected areas.
Lecture, Summer School at Bauhaus- University Weimar, 2001.
LONDONG, J.:
Brauchen wir neue Sanitärkonzepte ?
Schriftenreihe der ATV.
ATV-DVWK Bundestagung Weimar, 18. – 19.09.2002.
LONDONG, J.:
Integrale Konzepte der Wasserrahmenrichtlinie.
ATV-DVWK Seminar „Bewirtschaftungsplanung nach EG-Wasserrahmenrichtlinie“.
Erfurt, 27. – 28.01.2003.
LONDONG, J., OTTERPOHL, R.:
The Lambertsmühle case: Ecologically and economically efficient decentralized
wastewater and resources management.
2nd IWA World Water Congress, Berlin 15. – 19.10.2001.
30
Aquatic ecology and
The analysis of runoff processes during artificial and natural flood events
Andreas Kurtenbach, Andreas Krein, Wolfhard Symader
Department of Hydrology, University of Trier, 54286 Trier, Germany
Steffen Möller
Institute of Geographical Sciences, Physical Geography, Freie Universität Berlin, 12249
Berlin, Germany
Keywords: Runoff generation, storm events, mixing models, kinematic waves
Natural flood events are complex hydrological and chemical responses of the river basin
owing to allochthonous river basin and autochthonous in-channel impacts. The analysis of
hydrographs and chemographs at a gauging station is a promising approach to
understanding the interacting processes within a river basin. It is assumed that the output
signal at a specific gauge can be attributed to an integrated response of the upstream basin
to a precipitation input. This concept was applied to investigations of runoff generation and
solute transport over a wide array of basin sizes (e.g. Buttle 1994).
If a flood response at a gauging station is considered as an integrated output signal of the
basin to a rainfall event, two questions have to be answered. First, which parts of the basin
contribute water as well as dissolved solids during an event? Second, can these parts be
assumed to be invariant during an event? The variable source area concept negates this
assumption (Hewlett and Hibbert, 1967). Therefore, the factors controlling the temporal
and spatial variability must be determined. Against this background, it still has to be
established for which part of a basin at which stage of a flood a gauging station is
representative. This will be crucial for all aspects dealing with river management
strategies, monitoring programmes, land use modifications and spatially distributed runoff
models.
The objective of this study is therefore to assess the spatial representativity of a gauging
station. Three strategies have been adopted: 1) longitudinal profiles of important ions and
electric conductivity have been analysed to characterise the spatial variability within the
river basins, 2) artificial flood events were generated to investigate in-channel related
processes and 3) natural flood events have been analysed at multiple locations to
characterise the temporal dynamics of runoff generation and solute transport. In contrast to
numerous case studies concentrating on small, homogeneous river basins, the aim of our
approach is to extract similarities in low-mountainous, heterogeneous river basins of
different size (Kartelbornsbach: 3 km², Olewiger Bach 35 km², Ruwer basin 238.5 km²) in
order to enable the transferability to other river basins.
Aquatic ecology and
31
The results reveal that near-gauge sources, in-stream processes and the spatial and
temporal activation of contributing source areas have a considerable influence on runoff
processes and solute transport. During dry weather conditions the gauging station was only
representative for a short river segment upstream owing to discharge and solute
concentrations of sources contiguous to the measurement site. During artificial flood
events the kinematic wave velocity was considerably faster than the movement of water
body and solutes, refuting the idea of a simple mixing process of individual runoff
components. The artificial wave in the Ruwer basin (238.5 km²) was entirely composed of
old in channel water after travelling only 3 kilometres. In the smaller Kartelbornsbach
catchment, a disconnection between discharge response and solute transport was identified
already after 80 metres. Generally, there is a decrease in the time lag with an increasing
baseflow (Krein & DeSutter 2001). This decoupling process between water input and wave
arrival results in a crucial reduction in the spatial representativity of a gauge. Natural flood
events were characterised by a superimposition of local overland flow, riparian water and
the kinematic wave process comprising the downstream conveyance of solutes.
Particularly summer floods were marked by a chronological occurrence of distinct
individual runoff components originating only from a few contributing areas adjacent to
the stream and gauge. Thus, the representativity of a gauge for processes in the whole
basin depends on the distance of the nearest significant source to the station. The
consequence of our study is that the assumptions of mixing models are not satisfied in river
basins larger than 3 km².
BUTTLE J.M.:
Isotope hydrograph separations and rapid delivery of pre-event water from drainage
catchments. Progress in Physical Geography 18(1): 16-41, 1994.
HEWLETT JD, HIBBERT AR.:
Factors affecting the response of small watersheds to precipitation in humid areas. In
Forest Hydrology, Sopper WE, Lull HW (eds.). Pergamon: Oxford; 275-290, 1967.
KREIN A, DE SUTTER R.:
Use of artificial flood events to demonstrate the invalidity of simple mixing models.
Hydrological Sciences Journal 46(4): 611-622, 2001.
32
Aquatic ecology and
The interaction between biodiversity and ecosystem functioning in
aquatic systems from a microbial perspective
Silke Langenheder, Eva S. Lindström and Lars J. Tranvik
Department of Limnology, Evolutionary Biology Centre, Uppsala University, Norbyvägen
20, 75236 Uppsala, Sweden
e-mail (presenting author): [email protected]
Keywords: bacterioplankton, community composition, ecosystem functioning,
environmental changes
During the last decade the relation between biodiversity and ecosystem functioning and
stability has attracted considerable attention (Loreau 2000).
Ecosystem functioning is the biogeochemical activity of an ecosystem or the flow of
materials (nutrients, water, atmospheric gases) and processing of energy. Bacteria are of
special interest, because they conduct most of the biogeochemical transformation. Most
studies done so far, however, focused on the interaction between plant diversity and
ecosystem functioning and stability, almost exclusively in terrestrial systems (e.g. Naeem
et al. 1994, Tilman et al. 1996).
To study how microbial and especially bacterial diversity is related to the functioning of
ecosystems is one of the challenges of current ecological research (Loreau et al. 2001). The
major obstacles have been and still are methodological difficulties to study bacterial
diversity. Traditionally microbial ecologists relied on cultivation of bacteria from
environmental samples, a method, that allowed identification of approx 1 % of the existing
bacterial diversity, since most bacteria in the environment are not culturable (Amann et al.
1995). However, huge progress has been made during the last two decades, due to the use
of evolutionary marker genes, like the 16 S ribosomal RNA gene. Since then, knowledge
about bacterial diversity and the dominating types of bacteria in natural system has
increased rapidly (Pace 1997). However, there are still no reliable estimates of the total
number of bacterial species and estimates vary from a couple of thousands to several
millions (Torsvik et al. 2002).
Molecular fingerprinting methods based on the 16 S rRNA approach, provide tools to
follow rapid changes in bacterial community composition. These tools provide the
opportunity to investigate if and how bacterial communities change in composition along
an environmental gradient or in response to a stress factor. We make use of this molecular
approach in experimental studies. Briefly, we performed several culture experiments where
mixed bacterial assemblages (“inocula”) obtained from different Swedish lakes were
exposed to growth media manipulated with regard to one or several factors. Our
Aquatic ecology and
33
experiments focused on changes in salinity, pH, UV-radiation and dissolved organic matter
quantity and quality. Subsequently, we followed the growth patterns of bacterial
communities in the cultures. Functional parameters (i.e. biomass yield, respiration, growth
efficiency) and genetic composition of the enriched communities were measured.
The major aim of our work is to gain some understanding about 1) the relationship
between bacterial community composition and functioning and 2) the influence of
environmental changes and perturbations on the genetic structure and functioning of
bacterial communities.
There is an anecdotal statement concerning the biogeography of bacteria saying that
“everything is everywhere – the environment selects”. Since bacteria are extremely
abundant, have short generation times and a high dispersal ability, it has been concluded
that they must have a cosmopolitan distribution and a high local diversity, since it is
unlikely that geographic isolation – resulting in speciation – occurs (e.g. Pedrós-Alió
1993). This means that all globally occurring bacteria are present in any single habitat on
earth, most of them, however, in dormant and inactive stages, waiting for more favourable
environmental conditions allowing them to “wake up”. We performed a culture experiment
to text this idea. A factorial experimental design was chosen where sterile water from 4
lakes (ranging widely in terms of organic matter quantity and quality) and bacterial
assemblages from the same lakes were set-up in all possible combinations. If the
“everything is everywhere – the environments selects” hypothesis was true, we would
expect the source of the media to be the only selective factor for the structure and
functioning of bacterial communities growing in the cultures – independently of the origin
of the inoculum. We found that the functional performance of bacterial communities
growing in the cultures depended on the type of the medium but not on the origin of the
bacterial assemblage. Functional changes were, however, only partly paralleled by changes
in community composition. Cultures shared bacterial taxa as a result of receiving the same
medium and/or inoculum, indicating that bacterial communities are comprised of
populations of generalists that can grow under most conditions as well as population with
the life strategy of specialists.
When exposing bacterial communities to different substrate pools, like done in the
experiment above, they were able to adapt to the new conditions without any consequences
for the functioning of the system. In other experiments, we found that changes in substrate
quantity (Eiler et al. 2003) and salinity (Langenheder et al. 2003) led to changes in both
bacterial community structure and functioning. However, in these cases, exposing
freshwater bacteria to highly diluted environments or changes in salinity induced a stress
response within the bacterial community resulting in functional and structural instability.
34
Aquatic ecology and
In addition, our unpublished results show that pH and UV-radiation are important
regulating factors of bacterial community composition and functioning.
To summarize, environmental changes induced changes in bacterial community
composition as well as functioning. However, we found indications that environmental
changes have stronger effects on the functioning than on the genetic composition of
bacterial communities. This suggests that there is a loose coupling between bacterial
community composition and ecosystem function – in contrast to what is commonly
believed for plant and animal communities.
References:
Amann RI, Ludwig W, Schleifer KH (1995) Phylogenetic identification and in-situ
detection of individual microbial cells without cultivation. Microbiological
Reviews 59:143-169
Eiler A, Langenheder S, Bertilsson S, Tranvik LJ (2003) Heterotrophic bacterial growth
efficiency and community structure at different natural organic carbon
concentrations. Applied and Environmental Microbiology 69:3701-3709
Langenheder S, Kisand V, Wikner J, Tranvik LJ (2003) Salinity as a structuring factor for
the composition and performance of bacterioplankton degrading riverine DOC.
FEMS Microbiology Ecology 45:189-202
Loreau M (2000) Biodiversity and ecosystem functioning: recent theoretical advances.
Oikos 91:3-17
Loreau M, Naeem S, Inchausti P, Bengtsson J, Grime JP, Hector A, Hooper DU, Huston
MA, Raffaelli D, Schmid B, Tilman D, Wardle DA (2001) Ecology - Biodiversity
and ecosystem functioning: Current knowledge and future challenges. Science
294:804-808
Naeem S, Thompson LJ, Lawler SP, Lawton JH, Woodfin RM (1994) Declining
biodiversity can alter the performance of ecosystems. Nature 368:734-737
Pace NR (1997) A molecular view of microbial diversity and the biosphere. Science
276:734-740
Pedrós-Alió C (1993) Diversity of bacterioplankton. Trends in Ecology and Evolution
8:86-90
Tilman D, Wedin D, Knops J (1996) Productivity and sustainability influenced by
biodiversity in grassland ecosystems. Nature 379:718-720
Torsvik V, Ovreas L, Thingstad F (2002) Prokaryotic diversity - magnitude, dynamics, and
controlling factors. Science 296:1064-1066
Aquatic ecology and
35
Extended uncertainty analysis of a hydrodynamic – water quality
modeling system embedded in High Level Architecture (HLA)
Karl-Erich Lindenschmidt
UFZ – Centre for Environmental Research Leipzig-Halle GmbH,
Department of Hydrological Modelling
Brueckstr. 3a, D-39114 Magdeburg, Germany.
Key words: DYNHYD, EUTRO, HLA, Monte Carlo, TOXI, Uncertainty Analysis
Currently a large project (involving approximately 30 scientists) is underway at the UFZ –
Centre for Environmental Research, Germany to develop a river basin management system
of the Saale river (approximately 24 079 km2 ), which is the largest German tributary of the
Elbe river. The system being developed is based on computer technology and encompasses
integration of models from the natural sciences (hydrology, land surface sediment and
nutrient transport, floodplain habitat, river hydrodynamics and water quality), macroeconomics (input-output models) and social sciences (weighted multi-criteria decision
support) (Rode et al. 2002).
This presentation concentrates on the river hydrodynamics and water quality aspects (see
Lindenschmidt et al. 2004a, 2004b). The Water Quality Analysis Simulation Program
(WASP5) developed by the US Environmental Protection Agency (Ambrose et al. 1993) is
used for the river modeling. The program is divided into three models: DYNHYD
(hydrodynamics), EUTRO (eutrophication) and TOXI (sediment and micro-pollutant
transport). Conventionally, the sequence of simulations is to first run DYNHYD for all the
time steps and store the hydrodynamic results in a file for subsequent simulations with
EUTRO and TOXI. Information flows unidirectinally from DYNHYD to EUTRO or
TOXI. In order to investigate the effects hydrological parameters and input data have on
water quality variables, the flow of information needed to be extended to include data
transfer between all three models and after each consecutive time step. The High Level
Architecture (HLA) was used as a platform to easily couple the three models into one
system and to allow control of information between the models after each time step.
HLA (High Level Architecture) is computer architecture for constructing distributed
simulations. It facilitates interoperability among different simulations and simulation types
and promotes reuse of simulation software modules (Kuhl et al. 1999). HLA can support
virtual, constructive, and live simulations from a variety of application domains.
The core of the HLA is the Run-Time Infrastructure (RTI) which is an implementation
consisting of a set of services having a precise specification of the interoperability-related
36
Aquatic ecology and
actions that a simulation may perform, or be asked to perform, during a simulation
execution. The RTI provides services to start and stop a simulation execution, to transfer
data between interoperating simulations, to control the amount and routing of data that is
passed, and to co-ordinate the passage of simulated time among the simulations. Within the
HLA, a set of collaborating simulations is called a federation, each of the collaborating
simulations is a federate, and a simulation run is called a federation execution. Federates
that adhere to the rules can exchange data defined using an object model template; those
services are provided at run-time by the RTI (Petty 2002). Figure 1 provides a conceptual
view of a HLA federation for the WASP5 modules. Since the WASP5 modeling system is
written in FORTRAN and the HLA is written in C++, a wrapper for each model
DYNHYD, EUTRO and TOXI needed to be implemented in order for the RTI functions to
be transmitted between the models and the RTI.
DYNHYD
EUTRO
TOXI
Fortran
Wrapper
Fortran
Wrapper
Fortran
Wrapper
RTI
Figure 1:
Integration of the WASP5 modules in the HLA
A second goal of this presentation is to explore the effect uncertainty in both the
hydrodynamic parameters and boundary conditions have on the water quality output
variables. Most uncertainty analysis studies are focused only on the effect parameters have
on the variables due to the difficulties in measuring or deriving the parameter values. Only
some studies implement both the parameters and the input data into their uncertainty
analyses. Aalderink et al. (1996) investigated the uncertainty in heavy metal concentrations
in the River Vecht caused by uncertainties in the parameters, boundary conditions and
initial concentrations related to the fate of the heavy metals. They found that the error in
the boundary concentrations can affect the output variability as much as the uncertainty in
the parameter settings. Initial conditions had little effect on output uncertainty. Using a
hydrological precipitation-runoff model, Nandakumar and Mein (1997) also found
significant contributions to output uncertainty from error in both parameters and input data
(precipitation and evaporation).
Aquatic ecology and
37
An important advantage in implementing the HLA modelling platform is the ease of
carrying out uncertainty analysis on several models in a synchronised modelling system.
The analyses are not limited to a certain set of parameters, variables and initial and
boundary conditions of a certain model but are extended to a set consisting of parameters
across numerous models. The error propagating through several models can then be
followed and the error resulting from a particular sequencing of model simulations can be
assessed. This allows us to see how the errors in the input data from the hydrodynamic
model DYNHYD affect the output from the water quality models EUTRO and TOXI.
Aalderink RH, Zoeteman A, Jovin R. 1996: Effect of input uncertainties upon scenario
predictions for the river Vecht. Water Sci. Technol. 33:107-118.
Ambrose RB, Wool TA, Martin JL. 1993. The Water Quality Simulation Program,
WASP5: Model Theory, User’s Manual, and Programmer’s Guide. U.S. Environmental
Protection Agency, Athens, GA, 209 p.
Kuhl F, Weatherly R, Dahmann J. 1999. Creating computer simulation systems. PrenticeHall, Englewood Cliffs, NJ, 212 p.
Lindenschmidt K-E, Poser K, von Saleski M, Warwick JJ. 2004a. Uncertainty analysis of a
hydrodynamic model of a regulated river. River Research and
Applications
(submitted).
Lindenschmidt K-E, Eckhardt S, Wodrich R, Eckert U, Baborowski M, Guhr H. 2004b.
Water quality modelling of a lock-and-weir system of the lower Saale river. Gas- und
Wasserfach (in press) (in German).
Nandakumar N, Mein RG. 1997. Uncertainty in rainfall-runoff model simulations and the
implications for predicting the hydrological effects of land-use change. J. Hydrol.
192:211-232.
Petty D. 2002. Comparing high level architecture data distribution management
specifications 1.3 and 1516. Simulation Practice and Theory 9:95-119.
Rode M, Klauer B, Krause P, Lindenschmidt K-E. 2002. Integrated river basin
management: a new ecologically-based modelling approach. Ecohydrology &
Hydrobiology 2:171-179.
38
Aquatic ecology and
Coupled modelling of physical und biological processes in reservoirs
and lakes
Rolinski, Susanne
Institut für Hydrobiologie, TU Dresden, 01062 Dresden
[email protected]
Modelling aquatic ecosystems in lentic waters can be considered as interface between
various disciplines and water management demands. First of all, the complex web of
biologic organisms and their interactions is to be generalised in order to obtain an
ecological model. Mathematical knowledge enables the implementation of appropriate
equations and algorithms for numerical solutions. Understanding of the main physical
principles structuring the natural environment is necessary to interpret the ecological
development in terms of local or advected signals and with regard to a cause analysis.
Especially in reservoirs, hydrology and water management provide boundary conditions
for the water supply and storage which have a significant effect on the dynamics inside the
water body.
Within the joint project GETAS 1, the integration of all these disciplines is the major aim
in order to establish a coupled physical and biological model for reservoirs and lakes.
Coming from the mathematical and physical side of sciences, my experience lies mostly in
the model development for the transport of suspended substances, including the exchange
with bottom sediments. As having been involved in some projects with biological foci2,
the limitations of the physical modelling of suspended substances became obvious enough
when comparisons with data during the vegetation period were less than satisfactory. On
the other side, my interest in biological processes is longstanding and even in school the
decision in favour of mathematics and against biology as a major course was narrow. Thus,
the combination of modelling experience and becoming acquainted with the aquatic
ecosystem seemed the logical movement to make.
Physical conditions in reservoirs structure the environment mainly by temporal gradients.
For the development of phytoplankton during the vegetation period, the formation of warm
epilimnetic waters itself is of more relevance than its actual temperature. The transition
periods (i.e. during spring when stratification establishes and autumn when the water body
mixes) determine the plankton development in the months following. The coupling of
existing one-dimensional hydrodynamical and ecological models enables us to simulate the
dynamics of nutrient, phytoplankton and zooplankton concentrations on hourly timescales. Model results are compared with data sets from several measuring campaigns in
two reservoirs in Saxony (Germany) comprising physical, chemical and biological
measurements of high temporal resolution.
Aquatic ecology and
1 Gekoppelte hydrodynamisch-ökologische Simulation zur Bewirtschaftung von
Talsperren, BMBF 02 WT 0233
2 SFB 328; F-ECTS, MAS3-CT97-0145
39
40
Aquatic ecology and
Hyporheic exchange processes: Controlling parameters, natural and
anthropogenic influences, and challenges
Nicole Saenger, Peter K. Kitanidis, and Robert L. Street
Civil and Environmental Engineering
Stanford University, U.S.A.
Keywords: hyporheic exchange processes, impact of natural and anthropogenic
influences, stream ecology
Streams and rivers are complex ecosystems that respond to natural and anthropogenic
influences, such as varying flow, sediment transport, manmade structures, and sewage
treatment plant effluents. Natural influences vary in space and time and have an overall
positive effect on the ecosystem. Anthropogenic or external impacts are mostly negative,
so we aim to reduce their influence on the ecosystem. This can be done by such means as
restoring streams, better sewage treatment design, and by enhancing ecological processes
in the stream and its sediments, i.e. eco-technology. The eco-technology approach needs
more research, because the connections between physical stress and the structure and
function of water ecosystems is inadequately understood (Deutsche Forschungsgemeinschaft, 2003).
This paper examines how the exchange processes and modifications that take place in the
saturated near-stream sediment, called hyporheic zone, can provide a basis for an ecotechnological approach. Stream surface water flows through the hyporheic zone, and after
a short distance, returns to the stream channel. This infiltrating water is rich in nutrients
and oxygen. During its relatively long residence time in the subsurface layer, the nutrients
and oxygen are transformed by biofilms, hyporheic fauna and algae, after which, the water
and its metabolized nutrients reenter the stream and change the water quality. Thus, the
hyporheic zone and the hydraulic exchange processes have an important function within
the stream’s ecosystem. Exchange between surface water and subsurface water is
controlled by surface water flow, groundwater aquifer, topography, and sediment
properties of the river bed.
This paper will present results from combined field and numerical studies of exchange
processes at pool-riffle and step-pool sequences in natural river beds. Wroblicky et al.
(1998), Kasahara and Wondzell (2003), Saenger (2002), and Saenger et al. (submitted)
have examined the effects of such factors as scale, surface water flow, sediment properties,
topography and gradients on exchange flows. Numerical modeling has attempted to
reproduce field experiments and predict exchange processes due to varied conditions.
These studies have shown that hydraulic connectivity between stream and hyporheic zone
Aquatic ecology and
41
is so intense that the latter reacts immediately to changes in the stream. The stream changes
may be either natural (e.g. changed stream flow or sediment transport) or anthropogenic
(e.g. new inflows or structures). Gradients in the surface water are altered, thereby
influencing the nature and quantity of the hyporheic exchange, which in turn impacts both
the hyporheic zone and the surface water. A case study will be presented to demonstrate
the influence of natural and river restoration structures on the exchange processes.
Hyporheic zone research provides challenges that can only be met by interdisciplinary
projects. For example, the Deutsche Forschungsgemeinschaft funded several projects that
focused on the hyporheic zone in the River Lahn. These projects brought together experts
in the fields of limnology, microbiology, water quality, hydrology and hydraulics. Even
this wide array of disciplines may not be enough; future efforts may require expertise e.g.
in sediment transport, watershed influences and the economics of amelioration efforts like
sewage treatment. The paper will discuss the obvious and very challenging questions at the
interfaces of the different disciplines that are needed to gain a better understanding of the
impacts of the hyporheic exchange on stream ecology and water quality. The basic and
applied research that is required to provide a basis for decisions taken to enhance the state
of streams and rivers will also be discussed.
Deutsche Forschungsgemeinschaft (2003), Wasserforschung im Spannungsfeld zwischen
Gegenwartsbewältigung
und
Zukunftssicherung.
Denkschrift.
Wiley-VCH,
Weinheim, pp. 175.
Kasahara T. and S. Wondzell (2003), Geomorphic controls on hyporheic exchange flow in
mountain streams, Wat. Resour. Res. 39 (1).
Saenger, N. (2002), Estimation of flow velocities within the hyporheic zone, Verh.
Internat. Verein. Limnol. 28, 1790-1795.
Saenger, N., P.K. Kitanidis and R.L. Street: A numerical study of parameters controlling
hyporheic exchange processes (submitted to Wat. Resour. Res.).
Wroblicky , G.J., M.E. Campana, H.M. Valett and C.N. Dahm (1998), Seasonal variation
in surface-subsurface water exchange and lateral hyporheic area of two streamaquifer systems, Wat. Resour. Res. 34 (3), 317-328.
42
Aquatic ecology and
Fuzzy Indicators for Interdisciplinary Performance Assessment of Water
Resources Management
Hani Sewilam
PhD Staff Scientist, Section of Engineering Hydrology, University of Aachen, Germany
E-mail: [email protected]
Keywords: Fuzzy Logic, Performance Indicators, Water Resources Management,
Interdisciplinary Management.
Interdisciplinary management of water resources involves complicated social,
organizational, legal and economical issues in addition to the undoubtedly important
technical matters and environmental aspects. A sustainable management requires a regular
performance assessment of the system which is a problem of increasing concern among
policy makers. Performance assessment is quantifying the achievement degree of the
management targeted objectives. It is essential to answer questions such as “is our system
improving or deteriorating over time”. Generally, indicators are used for assessing system
performance. However, modeling and/or aggregating them to draw an overall conclusion
about system performance is a threefold problem because of; a) associated uncertainty that
can be summarized in; uncertainties in the estimation of indicators, uncertainties in the
quality of collected data, uncertainties of vaguely expressed indicators (qualitatively rather
than quantitatively e.g. land productivity is “high”) and uncertainty of assessment opinions
of involved decision makers. b) Noncommensurability of indicators which is a problem of
dealing with indicators that have been measured in different interval and ratio scales (e.g.
$/ha and $/m3). c) the involvement of multiple participants (ecologists, economists,
hydrologists and sociologists) who hold distinct interests and unique objectives in the
assessment and aggregation process of indicators. This paper suggests a framework for
using indicators to assess the management performance of water resources projects taking
into consideration multiple objectives (economical, social, environmental and technical).
The framework allows decision makers who represent all parties involved in the
management process (environmentalists, economists, engineers, sociologist, and water
users) to express their opinions in the assessment process.
The assessment concept overcomes the three mentioned problems by using soft computing
technologies (fuzzy logic and artificial neural network) instead of traditional hard
computing ones. The identified indicators (e.g soil productivity/unit water) will be
classified into different classes according to the area they cover (social, economical,
environmental … etc.). To reach an overall performance, the indicators will be organized
in a hierarchical structure. Each indicator will be represented as a fuzzy linguistic variable
instead of classical numerical variable. This will enable to integrate qualitative and
quantitative indicators in one assessment process. The crisp values of the indicators will be
transformed to linguistic terms using fuzzy membership functions (Fuzzification process).
Aquatic ecology and
43
This enables aggregating the indicators using rule-based procedure to reach an overall
indicator. The value of the overall indicator will be transformed to a single crisp value that
reflects the performance of the assessed management situation.
To assess and aggregate the indicators, the opinion of the involved decision makers will be
acquired and used to construct the components of the fuzzy system (membership functions
as well as the aggregation rule-base). To overcome the problem of integrating decision
makers with different backgrounds, education level and experiences, the Analytical
Hierarchical Process (AHP) will be used to allocated different weights for decision makers.
The weights will be considered while formulating the membership functions and the rulebase.
The capability of the Artificial Neural Networks (ANN) will be used to acquire the opinion
of decision makers with respect to their weights and automatically construct the main
components of the fuzzy system. Therefore, this work integrates neural network and fuzzy
logic (FL) in a so called neurofuzzy system. NeuroFuzzy systems can be regarded as a
partnership in which each of the ANN and the FL affords its computational properties to
form a system which exploits the strengths of both systems best while reducing their
weaknesses.
A demonstration model for assessing irrigation scheme management will be presented in
this paper. A set of indicators (12 indicators) that can be measured or calculated as a result
of simulation models is identified. The indicators are classified in four classes (economical,
social, environmental and technical) to assess the performance of irrigation schemes as a
result of implementing certain management strategy. A three level hierarchical structure is
used to aggregate the indicators to a single performance value. Decision makers from
different departments were interviewed to use their opinions as training sets for the
neurfuzzy model. The AHP is used to identify the weights of the decision makers with
respect to five criteria (personal knowledge, past experience, performance measure,
personal interest and represented public). The weights are considered while formulating the
training sets. The training sets are used to construct the components of the fuzzy system
which are required to aggregate and assess the indicators. The model was implemented to
assess ten different management scenarios. The model delivers an overall performance
value or ranking score (from 0 to 10) for each management scenario which enables easily
ranking the scenarios according to their overall performance.
The model can be simply used for assessing the management performance
systems taking into consideration the multiple objectives as well as the
participants. The model can be also coupled with simulation models to assess the
other management scenarios and can be considered as a main component
management decision support systems.
of water
multiple
results of
of water
44
Aquatic ecology and
Merging aquatic and terrestrial perspectives of carbon ecology
Jan Siemens
Department of Soil Science, Institute of Ecology, Berlin University of Technology
Salzufer 12, D-10587 Berlin
Keywords: Global change, carbon sequestration, "missing" C sink, ecological signalling
The German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) has
identified the integrated understanding of aquatic, terrestrial, and atmospheric systems as
one major challenge of future research (Grünwald, 2003). Burning of fossil fuels increases
the partial pressure of carbon dioxide (CO2 ) in the atmosphere which in turn induces
changes of the global climate (IPCC, 2001). However, the increase in CO2 in the
atmosphere during the past decades was smaller than the increase in CO2 emissions
because approximately 50% of the emitted CO2 was absorbed by the hydrosphere and by
terrestrial ecosystems (IPCC, 2001; Houghton, 2003). Understanding the processes of
carbon (C) sequestration in aquatic and terrestrial settings is therefore a prerequisite for
predicting future trends. Estimates of C sequestration revealed a gap of approximately 70
Tg a–1 for C budgets of European terrestrial ecosystems (Fig. 1, Janssens et al., 2003).
Reviewing data of dissolved C fluxes in soils, Siemens (2003, Fig. 1) showed that transfers
of C from terrestrial to aquatic ecosystems might fill this gap. Generally, the analysis of
Siemens (2003) fits well to the results of hydrological research summarized in the
empirical "Global Erosion Model" that describes the export of carbon from land to oceans
(Ludwig et al., 1998, Fig. 1), which points at the relevance of land-water interactions for
landscape to continental C sequestration. There are indications from aquatic research that
transfers of C from land to hydrosystems increased in the past decades (Raymond and
Cole, 2003). Raymond and Cole (2003) hypothesized that land use is the main control of C
export from land to aquatic ecosystems. However, controls of C export from terrestrial
settings are difficult to identify and to quantify from a purely aquatic perspective.
Therefore, controls of C transfer from land to hydrosystems should be a focus of future
integrated water research.
Recent results of aquatic ecosystem research revealed that 22–55% of zooplankton C of
two Michigan lakes are derived from terrestrial sources indicating that there is significant
subsidy of aquatic ecosystems by land-water transfers of C (Pace et al., 2004). Additionally
to its relevance as an important source of energy, there is increasing evidence that organic
compounds of terrestrial origin influence aquatic biocoenoses in a sense of environmental
signalling by exerting direct, hormon-like effects or indirect effects (Steinberg, 2003).
Hence, future aquatic ecosystem resarch might benefit from a focus on the terrestrial origin
of organic and inorganic C.
Aquatic ecology and
45
a
atmosphere
205 Tg a-1 (21 g m -2 a-1)A
(„top-down“ view)
difference: 70 Tg a-1 (7 g m -2 a-1)
terrestrial ecosystems
? C: 135 Tg a-1 (14 g m-2 a-1)A
(„bottom-up“ view)
A
B
C
soils
d
b 114 Tg a-1 (11 g m-2 a-1)B
c
hydrosphere
groundwater
continental
surface waters
67 Tg a-1
(7 g m-2 a -1)C
e
f
sea
Figure 1: Simplified model of European net CO2 -C exchange between atmosphere, terrestrial
ecosystems and hydrosphere (modified from Aumont et al., 2001 and Ittekkott, 2003). a: Topdown estimate of flux from atmosphere into terrestrial ecosystems., b: Export of dissolved
inorganic C (DIC) and dissolved organic C (DOC) from soils into groundwater, c: DIC and
DOC flux from groundwater into surface waters, d: Outgassing of CO2 from surface waters
back into the atmosphere. e: Riverine export of DIC and DOC into the sea, f: Flux of DIC and
DOC into the sea via groundwater; A according to Janssens et al. (2003); B Siemens (2003), C
Ludwig et al. (1998).
Summarizing, my contribution will explore and highlight the potential of merging aquatic
and terrestrial perspectives of C processes in integrated water research to derive a
landscape view of C ecology.
REFERENCES:
AUMONT, O., J.C. ORR, P. MONFRAY, W. LUDWIG, P. AMIOTTE-SUCHET., J.L.
PROBST. Riverine-driven interhemispheric transport of carbon. Global Biogeochem. Cycl.
15, 393-405, 2001.
GRÜNWALD, U. Leitthema 1 "Wasser in der Landschaft". In: DFG: Wasserforschung im
Spannungsfeld zwischen Gegenwartsbewältigung und Zukunftssicherung, Denkschrift.
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Aquatic ecology and
(Senatskommission für Wasserforschung; Eds.: J. BENNDORF, H. KOBUS, K. ROTH, G.
SCHMITZ), Wiley-VCH, Weinheim, 14-36, 2003.
HOUGHTON, R.A. Why are estimates of the terrestrial carbon balance so different?
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third assessment report of the Intergovernmental Panel on Climate Change. (Eds.: J.T.
HOUGHTON, Y. DING, D.J. GRIGGS, M. NOGUER, P.J. VAN DER LINDEN, X. DAI,
K. MASKELL, C.A. JOHNSON). Cambridge University Press, Cambridge, UK and New
York, USA, 881 p., 2001.
ITTEKKOTT, V.: A new story from the Ol‘ Man River. Science 301, 56-58, 2003.
JANSSENS I., A. FREIBAUER, P. CIAIS, P. SMITH, G.-J. NABUURS, G. FOLBERTH,
B. SCHLAMADINGER, R.W.A. HUTJES, R. CEULEMANS, E.D. SCHULZE, R.
VALENTINI, A.J. DOLMAN. Europe’s biosphere absorbs 7 to 12% of European
anthropogenic carbon emissions. Science 300, 1538-1542, 2003.
LUDWIG W., P. AMIOTTE-SUCHET, G. MUNHOVEN, J.-L. PROBST: Atmospheric
CO2 consumption by continental erosion: present-day controls and implications for the last
glacial maximum. Global Planet Change 16-17, 107-120, 1998.
PACE, ML., J.J. COLE, S.R. CARPENTER, J.F. KITCHELL, J.R. HODGSON, M.C.
VAN DE BOGERT, D.L. BADE, E.S. KRITZBERG, D. BASTVIKEN:
Whole lake carbon-13 additions reveal terrestrial support of aquatic food webs. Nature
427, 240-243.
RAYMOND, P.A., J.J. COLE: Increase in the export of alkalinity from North Americas
largest river. Science 301, 88-91, 2003.
SIEMENS, J.: The European carbon budget: A gap. Science 302, 1681, 2003.
STEINBERG, C.: Ecology of humic substances in freshwater. Springer, Berlin, 225-320,
2003.
Aquatic ecology and
47
Area-differentiated modelling of P-fluxes from diffuse sources in
macroscale river basins
Tetzlaff, B. & Wendland, F.
Research Centre Jülich
Programme Group Systems Analysis and Technology Evaluation
D-52425 Jülich, Germany
Email [email protected]
Keywords: Modelling diffuse P-entries, catchment management, political nutrient
reduction measures
The authors are involved in the interdisciplinary research project named "REGFLUD",
which is part of the programme "River Basin Management" funded by the German Federal
Ministry for Education and Research (BMBF). One aim of REGFLUD is the development
of policy options leading to a reduction of phosphate inputs from diffuse sources into
surface waters.
The areas investigated under this project are the basin of the River Ems and parts of the
River Rhine basin (rivers Ruhr, Wupper, Sieg and Erft). Each investigation area is about
12,500 km² in size. The characteristics relevant for P-output and transport differ between
the two areas: The River Ems basin is determined by lowlands, intensive agriculture, partly
animal husbandry and larger parts with soils having a low sorption capacity (sandy soils
and raised bogs). Typical for the parts of the River Rhine basin are highland regions, urban
areas and dammed lakes.
Quantifying P-output from diffuse sources is performed by using the GIS-based model
DiPhos, developed at the Research Centre Jülich (Programme Group Systems Analysis and
Technology Evaluation) within the framework of a Ph.D. thesis (Tetzlaff 2004). DiPhos
works on an area-differentiated emissions approach, using export coefficients for the
calculation of the mean long-term P-output. The model comprises the four pathways
drainage, groundwater, wash-off and soil erosion in order to meet varying natural site
conditions in the mentioned river basins. Its approach is founded on the assumption that Poutput from diffuse sources does not occur evenly on land under agricultural use within a
catchment. But the P-output from a river basin can be traced back to sub-areas having a
potential for P-output as field studies have proved. This potential for the output of P via
one specific pathway is determined by a combination of individual site factors describing
the soil sorption of P, strength of a transport medium (runoff component or erosion) and
the retention in the landscape. For example, the long-term mean P-output by drainage is
48
Aquatic ecology and
influenced mainly by the drainage runoff level, but the soil type, culture type and level of
fertilizer excess additionally play a role. For modelling with DiPhos various site factors are
combined in order to define types of sub-areas with homogenous potential for P-output.
For each pathway several types can be defined and export coefficents assigned.
Digital data sets of soils, erosion potential, relief and land use with high spatial resolution
are needed as input parameters for the modelling process. More input data is obtained by
coupling the P-model to the water balance model GROWA (Kunkel & Wendland 2002)
and to the agro-economic sector model RAUMIS, developed by the Research Association
for Agricultural Policy and Rural Sociology. GROWA calculates the runoff components
surface runoff, drainage runoff and groundwater recharge. The agro-economic model
RAUMIS is used for nutrient balancing and provides data on the P-surplus in the soil.
The calculation of P-output via drainage affords area-covering information on the location
of drained fields within large scale river basins. Due to the lack of data a methodology was
developed for estimating drained agricultural land on the basis of soil properties, land use
information and river networks.
Modelling P-output via the erosion pathway requires that the sub-areas delivering sediment
to surface waters must be known. Using a higly resolved digital terrain model with a cell
size of 10 metres morphometric analysis is performed to derive water flowpaths on the
land surface. If these flowpaths do not end in sinks and are not crossed by roads or buffer
strips on the river bank, they reach the main receiving channels. Intersection points
between flowpaths and receiving channels can be mapped and catchments derived which
act as sediment delivery areas.
The model results are validated with observed data from gauging stations. For the
validation process emissions from point sources like sewage treatment plants and industrial
inputs are taken into account in the same way as stormwater inflow from urban areas.
Retention in the cannel is calculated by a sub-model built up on algorithms developed by
the United States Geological Survey (Smith et al. 1997).
The DiPhos model results for the P-output from diffuse sources in macroscale river basins
are very differentiated in terms of spatial resolution and transport processes leading to
entries into surface waters. This means that geo-referenced sub-areas within the river basin
can be classified or ranked according to their individual contribution to the entire P-output,
enabling comparisons between sub-areas or sub-catchments. Areas with an output above
average can be identified. Furthermore the locations where P-outputs via drainage, erosion
and wash-off enter the river are determined by the model. P-output via groundwater flow
doesn’t play a significant role. These results allow the development of management
options which vary spatially and are adapted to the specific site conditions of sub-areas
releasing P. Due to the information on which pathway the P flux entered the river scenarios
involving interruptions of pathways can be developed, for example measures for the
Aquatic ecology and
49
reduction of erosion potential or blocking drainage installations. Knowing the existence
and location of areas with a P-output above average, management options open up which
lead to a reduction of a high share of P-output within a catchment at relative low expense
(Min-Max-principle).
Regarding the described properties of DiPhos model results chances for inter-disciplinary
systems analyses arise. Overlapping fields of interest, for example with aquatic ecology,
are forecasts how reduced P-entries into surface waters will result in long-term changes of
hydrochemistry and aquatic biocoenoses. There is the possibility of coupling a water
quality model to the DiPhos model.
Couplings with socio-economic models would result in information, how spatially varying
phosphate reduction measures lead to changes in capital investment, labour situation,
stocking densities and income from agricultural activities. Another example for linking
DiPhos model results to socio-economic modelling is the demand for spatially
differentiated information on P fluxes when finding regions evenly affected by
environmental pollution. This leads to the definition of homogenous areas for political
actions (Huchtemann 2004).
Only by linking ecological, economic and social aspects, the development of policy
options which could lead to real sustainable use of water resources seems feasible.
Investigating large scale river basins is of outstanding interest when the focus is on
changes of socio-economic conditions. In this context modelling results with high spatial
resolution are of advantage in order to develop differentiated policy options adapted to area
conditions.
References
Huchtemann, D. (2004): Delegation von Kompetenzen an Entscheidungsträger und
Betroffene in Flusseinzugsgebieten.- In: Möltgen, J. u. Petry, D. (Hrsg., 2004):
Interdisziplinäre Methoden des Flussgebietsmanagements, Workshopbeiträge 15./16.
März 2004, S. 179-186.
Kunkel, R. & Wendland, F. (2002): The GROWA98 model for water balance analysis in
large river basins – the river Elbe case study.- Journal of Hydrology, 259, 152-162.
Smith, R.A., Schwarz, G.E. &Alexander, R.B. (1997): Regional interpretation of waterquality monitoring data.- Water Resources Research, 33, 2781-2798.
Tetzlaff, B. (2004): Entwicklung eines GIS-gestützten Modells zur Analyse der
Phosphatbelastung aus diffusen Quellen in großen Flusseinzugsgebieten.- Ph.D.
thesis, Research Centre Jülich, in preparation.
50
Aquatic ecology and
A Discussion about Inlake Restoration with Aluminium
Gerlinde Wauer, Peter Casper, Thomas Gonsiorczyk, Rainer Koschel
Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Department of Limnology of
Stratified Lakes, Stechlin-Neuglobsow, Germany
Keywords: Inlake restoration, aluminium, phosphorus
The eutrophication of lakes is a pervasive problem and external load reduction has
remained indispensable. In deep and stratified lakes however the accumulation of nutrients
in the sediments may cause an internal fertilising, leading to a delay in the improvement of
water quality. Inlake restoration methods, which use aluminium salts, are highly effective
in regulating the P concentration in the water body and the P release from sediments. But
concerns about the toxicity of aluminium restricted its use. The extent of the real exposure
of aluminium in lake treatment is not well understood. Therefore the pyrocatecholviolet
method for the determination of “labile” aluminium species, which were considered to be
highly bioavailable to aquatic biota, had been further developed. The technique could be
successfully applied for the monitoring of aluminium concentrations during an inlake
restoration measure with combinated addition of aluminat and calcium hydroxide.
The investigations were carried out in Tiefwarensee, a dimictic, eutrophicated lake situated
in Mecklenburg, Germany. After reducing external loading, the phosphorus release from
bottom sediments of Tiefwarensee remained an important source of hypolimnetic nutrient
enrichment during stratification periods. To lower the lake’s P content, mainly by P
inactivation in the sediment, aluminat and calcium hydroxide were injected into the
hypolimnion by deep-water aeration technology . Since 2001 about 100 g m2 Al3+ and 116
g m² Ca2+, related to the sediment surface below 10 m, have been added. The application
was done during two (2001) or three (2002/03) cycles per year, each involving two weeks
for the addition of the chemicals, two weeks for aeration resp. mixing of the deep water
and two weeks for sedimentation. The time span varied between the cycles.
The hypolimnetic addition of aluminat and calcium hydroxide led to an increase in the
sediments surface P-content from 2 g kg-1 of dry weigth (dw) to 7 g kg-1 dw.In particular,
the P fraction bound to metal oxides increased, this means the permanent buried P. The
SRP concentration in the interstitial water of the uppermost sediment layer diminished by
nearly 100 % to 0.05 mg L-1 . The thickness of the P adsorbing sediment cover was
estimated as 6 cm at the end of 2003.
Aquatic ecology and
51
Subsequent TP concentrations in the water decreased since spring 2002 and reached about
30 µg L-1 during spring mixing period 2004. Before the application the TP concentrations
were 170 µg L-1 (average 1998-2001) during spring circulation periods.
The bi-weekly measured concentrations
monomeric aluminium) are shown in Figure 1.
of
“free”
aluminium
(including
inorganic
1800
1600
1400
-1
Alfree [µg L ]
1200
1000
Application cycles:
NaAl(OH)4
Ca(OH)2
0 m
10 m
15 m
22.5 m
800
600
400
200
0
A S O N D J F M A M J
A S O N D J F M A M J
A S O N D
2001
2002
2003
Figure 1. Concentrations of free aluminium in different depths of lake Tiefwarensee during the
addition of aluminate and calcium hydroxide. The sampling was 50 m from the application- and
aeration-system.
The epilimnetic concentrations of aluminium were about 100 µg L-1 and not affected by
the treatment. The WHO guideline value for Al3+ in drinking water is set at 200 µg L-1 .
Maximum aluminium concentrations were determined up to 1,500 µg L-1 in the
hypolimnion in a depth of 15 m during the application periods. At the beginning of
restauration the hypolimnion of Tiefwarensee was anoxic during summer stratification, as
in most eutrophicated lakes. As anoxic region is not inhabited by fish, an hypolimnetic
increase in Al3+ concentration following the aluminat application into the anoxic water
layer, the possible impact on fish is very limited. If the hypolimnetic content of dissolved
oxygen and the volume of usable fish habitat increased as a result of the treatment,
52
Aquatic ecology and
additional applications of aluminium should be performed not until the oxygen is depleted
again during the stratification period.
Inlake restoration with aluminium containing chemicals was very successful in suppressing
P release from sediment. For application techniques it has to be considered, that
concentrations of “labile” aluminium species can increase temporally and locally
connected with the addition of the chemicals.
Further readings:
WAUER, G., HECKEMANN, H.-J., KOSCHEL, R.: Analysis of Toxic Aluminium Species
in Natural Waters, Microchimica Acta 2004 (in press).
WAUER, G., GONSIORCZYK, T., KRETSCHMER, K., CASPER, P., KOSCHEL, R.:
Sediment Treatment with a Nitrate-Storing Compound to Reduce Phosphorus Release,
Water Research (subm. 2004).
WAUER, G., GONSIORCZYK, T., CASPER, P., KOSCHEL, R.:
P-immobilisation and Phosphatase Activities in Lake Sediment Following Treatment with
Nitrate and Iron, Hydrobiologia (subm. 2003).
P. Bayer & M. Finkel: Hydraulic groundwater management optimisation by evolution
strategies.
H. Bormann: Hydrological catchment models between process representation and
applicability for water management issues – case study for Benin (West Africa).
C. Bürger: The design of groundwater treatment systems under uncertainty: Assessment
of funnel-and-gate systems.
J. Dörner & R. Horn: Modelling of the one and two dimensional water flow in hills lopes.
J. Helmschrot: An integrated approach to model wetland dynamics in a changing
landscape: A case study from South Africas.
H. Holländer: Integrated groundwater management in coastal semi-arid areas using
artifical ?
A. Klawitter: An approach to simultaneously model rainfall-runoff events in rural and
urbanized catchments as well as their interactions, with help of a GIS.
C. Kohfahl, P. Brown, C. Linklater & A. Pekdeger: Estimating the Discharge of Sulphate
from Dump Sediments into the Surface Water of an Abandoned Open Pit Lignite
Mine.
S. Liehr & F. Keil: Integrated water quality management – development of a socioecological approach.
F. Lindenmaier: Dominating structure and processes in a hydrological induced mass
movement – an interdisciplinary approach.
H. Puhlmann: Stochastic modelling approach for deriving hydrological growth conditions
in floodplain forest.
J. Schaffner, M. Oberlack: Numerical calculation of shear stress oreated by flushwaves in
sewers: Presentation of testsides in Offenbach and Lyon.
M. Schirmer & A. Kaschl: Numerical calculation of shear stress oreated by flushwaves in
sewers: Presentation of testsides in Offenbach and Lyon.
N. Schütze: Meeting the challenges of the blue revolution: increasing the irrigation
efficiency with soft-computing optimisation methods
M. Seeger, N. Lana-Renault, D. Regüés & J. María García-Ruiz: The variability of the
hydrological response of highly disturbed and forested catchments in the Spanish
Central Pyrenees.
L. Wolf: Developing modelling tools for management of Urban groundwater resources
G. Wriedt, H. Geistlinger & M. Rode: Modelling of Nitrate transport and turnover in a
small lowland catchment.
53
54
Hydraulic groundwater management optimisation by evolution strategies
Peter Bayer, Michael Finkel
Center for Applied Geoscience, University of Tuebingen, Sigwartstrasse 10, 72076
Tuebingen, Germany
[email protected] [email protected]
Keywords: capture zones, derandomized evolution strategies, groundwater management,
groundwater remediation, hydraulic modelling, optimisation
Hydraulic technologies such as wells, drainage systems and physical barriers are common
utilities for the control of groundwater flow. Their effect and efficiency is tested by flow
and transport models, which simulate the relevant subsurface processes. Since natural
aquifers are spatially heterogeneous in their hydraulic as well as chemical and microbial
properties, numerical simulation models are in most instances preferable over analytical
approximations to reveal the relationships between measures and their effect. These
relationships are generally non-linear, illustrated for example by moving one well in an
heterogeneous aquifer, which results in a disproportionate change of the well capture zone
position, its extend and form. If in such a case the objective is to capture part of the aquifer
at minimum extraction rate, then an optimal strategy exists, which is determined by the
well position and the pumping rate. Approaching this ideal technological variant is usually
a difficult task. Numerous model runs of different variants are required to sort out
unsatisfactory solutions and identify the most optimal. Increasing the technological
variability by e. g. raising the acceptable number of wells, well positions or pumping rate
ranges widens the multidimensional decision space which at some point can hardly be
explored by a trial-and-error method alone.
For the past two decades research has been putting forth the use of mathematical
optimisation methods in the context of groundwater management. Gorelick (1993) and
Freeze & Gorelick (1999) delineate the continuous innovation of techniques to assist the
expert in ideally adapting hydraulic control systems, remediation technologies or
monitoring plans. Several approaches are presented, which are primarily classical gradient
based, (non-)linear programming techniques. During the last years, modern heuristic
methods turned out to be more suitable for the generally complex, highly non-linear and
non-convex problems. Especially the evolutionary algorithms are regarded as one of the
most promising techniques to optimise groundwater management issues. They are oriented
on features of natural evolution, which are exploited to intelligently direct the search
through the available decision space. Individuals, representing managerial alternatives, are
created, which are iteratively altered and so undergo a synthetic, partially stochastic
evolution (see Figure 1). Compared to classic optimisation methods, evolution algorithms
are highly unspecific and thus can represent robust techniques. By nature, they are less
55
susceptible to getting trapped into so-called local optima common in this area and
obstacles principally for all optimisation algorithms.
parametric
description of
technological variant
flow model,
transport model
model specific
description of
simulation
model
objective
function
optimisation
algorithm
model results for
site description,
generic model data
evaluation of
Figure 1. Flow chart of the optimisation procedure of groundwater control technologies by external
solvers. Evolutionary algorithms such as CMA-ES make use of iterative model calls with altered
technological variants to attain a continuous improvement of the technology.
Our work focuses on the employment of derandomized evolution strategies (CMA-ES),
which have been presented by Ostermeier & Hansen (2001) and Hansen et al. (2003). We
compare this new species of evolution algorithms to other types of heuristic optimisation
techniques for the adaptation of pumping wells. The objective is to capture a contaminant
plume in an aquifer by downgradient extraction of groundwater within a pump-and-treat
measure. Up to eight wells are positioned to minimise the required total pumping rate
regarded as a proxy for the technological costs. A central aspect, which has to be clarified
before the optimisation procedure can be carried out, is the set-up of the interface between
the modelling suite and solver. In particular, an objective function that incorporates capture
and pumping rate has to be formulated. The objective function interprets the response of
the model to pumping as well as the user-defined valuation of responses to the optimisation
routine. Thus the apt formulation of the objective function is crucial to express the
optimisation goals. Aside from this, the objective function form may also affect the
performance of the optimisation algorithm. Performance issues are to reduce the number of
model calls required to identify optimal solutions and to improve the robustness of the
optimisation algorithm. Since the CMA-ES make use of a stochastic source, not all CMA-
56
ES runs deliver the optimal solution and thus some runs fail. To overcome this, a remedy
could be to repeat the optimisation procedure as a whole.
In our work we investigate strategies to appropriately use evolution algorithms. It is shown
how modifications to the objective function change the performance of the solver and how
optimisation procedure restarts have to be planned. Here, a hypothetical pump-and-treat
scenario modelled on a finite differences grid is considered. The given spatially
heterogeneous transmissivity distribution creates a complex optimisation problem, which is
reflected by a highly non-convex objective function. As is also described in a recent
publication (Bayer & Finkel, 2004), the CMA-ES proves to be very efficient in discovering
the ideal pumping strategies, even when 1000 potential well positions are considered.
Compared to popular evolution algorithms in groundwater management such as the genetic
algorithms, low numbers of simulation model runs are required. So, especially for high
dimensional problems, a method is introduced to reduce the computational burden and
improve reliability as well as robustness of the optimisation.
The application of CMA-ES for the specific pump-and-treat case reveals an initial insight
of the suitability of this algorithm in solving groundwater management problems in
general. Though the step to a broad, straightforward practical use of evolutionary
algorithms in this area is still considerably large, the promising results so far prod us to
form a conceptual basis and framework for CMA-ES application. Current research focuses
on extending the horizon towards the optimisation of barrier-supported pump-and-treat
systems (Bayer et al. 2004) and (permeable) barrier systems. In addition, we work on
general design rules for the formulation of objective functions, which may incorporate
technical as well as economic and ecologic criterions.
References
Bayer, P., Finkel, M. (2004) Evolutionary algorithms for the optimization of advective
control of contaminated aquifer zones, accepted by Water Resources Research.
Bayer, P., Finkel, M., Teutsch, G. (2004) Hydraulic Performance of a Combination of
Pump-and-Treat and Physical Barrier Systems for Contaminant Plume Management,
accepted by Ground Water.
Freeze, R. A., Gorelick, S. M. (1999) Convergence of stochastic optimization and decision
analysis in the engineering design of aquifer remediation, Ground Water, 37, 934-954.
Gorelick, S. M., Freeze, R. A., Donohue, D., Keely, J. F. (1993) Groundwater
Contamination Optimal Capture and Containmen", Lewis Publishers, 385 pp.
Hansen, N., Ostermeier A. (2001) Completely derandomized self-adaptation in evolution
strategies, Evolutionary Computation, 9(2), 159-195.
Hansen, N., Müller, S. D., Koumoutsakos, P. (2003) Reducing the Time Complexity of the
Derandomized Evolution Strategy with Covariance Matrix Adaptation (CMA-ES),
Evolutionary Computation, 11(1), 1-18.
57
Hydrological catchment models between process representation and
applicability for water management issues – case study for Benin (West
Africa)
Helge Bormann
Universität Oldenburg, Institut für Biologie und Umweltwissenschaften,
Uhlhornsweg 84, 26111 Oldenburg, Germany, [email protected]
Keywords: hydrological models, model applicability, water management, data availability,
process representation
Freshwater is scarce in many regions of the earth. In most regions of the earth water is a
valuable good and does not abound. Assuming a global climate change and thus changing
rainfall inputs into the hydrological systems, freshwater availability for various uses will
significantly change on the local, regional and global scale, and drinking water will
become a scare resource in particular in the dry climate regions. Especially in these regions
a competition towards water will take place: there will not be enough freshwater to serve
the demands on drinking water as well as the water use of industry, agriculture, energy
production, recreation, etc. A multidisciplinary water management is required.
To be able to install water management systems on the (regional) catchment scale the
effects of changing climate and precipitation patterns due to global and regional change as
well as the effects of the management itself on hydrological resources and systems need to
be estimated. This can be realised by the use of hydrological models. Models are adequate
tools to analyse the effects of the changing environment on diverse subsystems.
Hydrological models for example can assess the future development of water related issues
if future boundary conditions of hydrological systems (climate change, population
development, land use change, industrial development, world market, etc.) can be
predicted.
For hydrological catchment water balance calculations multiple model types are available.
These model types can be classified into physics based models (white box, process based),
conceptual models (grey box) and black box models. This classification is characterised by
decreasing hydrological process knowledge. Westervelt (2001) furthermore distinguishes
between scientific models, expert models and idea models (fig. 1, right). This classification
is much mode general but very important for model application by the water management
and for an acceptance of models by stakeholders and decision makers.
58
The choice of the adequate model type finally depends on the purpose of the study, the
data availability, the scale and on the uncertainty to be accepted. Pure scientific studies on
the one hand mostly focus on the detailed description of the processes involved in a system
investigated. Applied scientific studies on the other hand often arrive at the best
compromise between scientific results and model applicability in practise. Thereto the
purpose of a study needs to be defined carefully.
The more data are available on the catchment properties (topography, soils, land use, etc.)
the better physics based models can be driven and parameterised. If the data base is scarce,
conceptual and lumped models are preferred. For both types it is decisive to know the
dominant processes as good as possible to optimise the representation of these dominant
processes by the models. Therefore the process scale must be known and reconciled with
the model and data scale (Blöschl, 1996). Last but not least the maximisation of the
predictive performance and therefore the minimisation of the predictive uncertainty of the
data-model-system are of major importance. After Grayson & Blöschl (2001) complex
(=scientific) models can only be applied successful if also data availability is large (fig.1,
left).
Fig. 1: Schematic diagram of the relationship between model complexity, data availability and
predictive performance (left, after Grayson & Blöschl, 2001); role of modelling with respect to
levels of stakeholder interest and scientific uncertainty (right, after Westervelt, 2001).
Aiming on predictions (or scenarios) of a change in catchment hydrological processes due
to changing environmental conditions, normally models are required which represent the
whole hydrological process network and not only the actually dominant processes as the
dominance of processes may change under changing boundary conditions. But these
models can not always be applied due to constraints in data availability leading to
problems with regard to model parameterisation and validation and due to a limited
transparency of most scientific models for stakeholders and decision makers.
59
This presentation presents parts of a case study within the IMPETUS project (Speth et al.
2003) which is faced by the very balancing act to run hydrological models to be used for
scenario analysis in a developing country (Benin, West Africa) limited by scarce data
available. In this case study different model types and their applicability under the given
circumstances have been compared, and the decisive uncertainties have been quantified to
weigh up the usability of different model types for hydrological catchment management
purposes (Bormann & Diekkrüger, 2003 and 2004). Environmental change scenarios have
been run and evaluated towards the applicability of a conceptual model approach for
application oriented scenario analyses in spite of the simplified model approach.
In addition to the analysis of the appropriate hydrological model type with regard to data
availability and predictive uncertainties, this presentation tries to answer the questions on
which scale the decisions of a catchment management are taken and on which scale theses
decisions are implemented. First of all the latter scale should coincide with the modelling
scale to be able to assess the effects of the changing landscape system. Considering these
general conditions hydrological catchment models can significantly contribute to the
decision making process in water related issues.
BLÖSCHL, G.: Scale and scaling in hydrology. Habilitation. Wiener Mitteilungen
Wasser-Abwasser-Gewässer 132, 346p., 1996
BORMANN, H. & DIEKKRÜGER, B.: A conceptual hydrological model for Benin (West
Africa): Validation, uncertainty assessment and assessment of applicability for
environmental change analyses. Physics and Chemistry of the Earth. In Press. 2004
BORMANN, H. & DIEKKRÜGER, B.: Possibilities and limitations of regional
hydrological models applied within an environmental change study in Benin (West Africa).
Physics and Chemistry of the Earth. 28/33-36, S. 1323-1332. 2003
GRAYSON, R., & BLÖSCHL, G.: Spatial patterns in catchment hydrology – observations
and modelling. 404 p. Cambridge. 2001
SPETH, P., DIEKKRÜGER, B. & CHRISTOPH, M.: IMPETUS West Africa - An
integrated approach to the efficient management of scarce water in West Africa - Case
studies for selected river catchments in different climatic zones. In: GSF Forschungszentrum für Umwelt und Gesundheit GmbH (Hrsg.): GLOWA - German
Programme on Global Change in the Hydrological Cycle. Status Report. S. 61-67. 2002
WESTERVELT, J.: Simulation modeling for watershed management. Springer. 190p. 2001
60
The design of groundwater treatment systems under uncertainty:
Assessment of funnel-and-gate systems
Claudius Bürger, Michael Finkel
Center for Applied Geoscience, University of Tuebingen, Sigwartstrasse 10, 72076
Tuebingen, Germany
[email protected], [email protected]
Keywords: groundwater remediation, hydraulic modelling, parameter uncertainty, data
worth analysis
The functionality of groundwater treatment systems for a particular site is inevitably
subject to the prevailing hydrogeological and hydrogeochemical characteristics of the
natural groundwater system. Due to economic and technical constraints, only limited
information can be gathered and made available by site-investigation campaigns. The
knowledge that the predictions of the effect of any particular design are uncertain typically
results in the application of a safety factor i.e. in a certain overdesign of the system in
question. Commonly, the value of the safety factor is based on general experiences rather
than on an actual analysis of the existing parameter uncertainty. The latter, however, may
strongly differ from site to site, depending on the characteristics of the aquifer and the
amount and quality of the available data. Therefore, safety factors may largely over- or
underestimate the actual uncertainty, and associated system designs may be inappropriate.
In order to improve the design process three main questions have to be answered:
-
How can uncertainty be incorporated in the prediction of the effect of a particular
treatment system design while honouring the available data?
-
What is the worth of additional data in this context i.e. how does additional site
investigation reduce the existing uncertainty for a particular design?
-
How will the incorporation of parameter uncertainty change the design process i. e.
the determination of the most cost-efficient design?
The work to be presented addresses the first two questions, taking the design of funneland-gate systems (FGS) as an example. FGS, a variant of permeable reactive barriers,
intercept and passively treat a contaminant plume in-situ either by degradation or sorption
(Starr & Cherry 1994). This energywise advantageous passive approach, though, poses a
disadvantageous dependency on the local groundwater flow system. As a later upgrading
(in case of an unexpected failure) of an already implemented FGS is both, technically
cumbersome and costly, a proposed FGS design should carefully incorporate the
uncertainty of underlying parameters.
61
Figure 1 shows the typical trade-off between cost and reliability of a treatment technology.
Additional data acquisition requires a further investment on the one hand, but may
significantly reduce the uncertainty on the other hand, hereby allowing for less
overdesigned and – likewise - more cost-efficient designs.
In order to gain knowledge about the sensitivity of FGS to parameter uncertainty (here
hydraulic conductivity) studies dealing with FGS’ capture zone reliabilities with respect to
FGS design variables like the number of gates, the gate positions and the funnel width to
gate width ratio were carried out for heterogeneous flow domains. The results show that
FGS’ capture zones are relatively sensitive to the variability of hydraulic conductivity,
when no data is honoured within a modelling study. Yet, multi-gate systems seem to reach
higher capture reliabilities compared to hydraulically equivalent (based on a homogeneous
aquifer) single-gate FGS (Bürger et al. 2003a,b).
total cost [€]
These results motivated additional studies on FGS design and sampling strategies analyses
in heterogeneous aquifers accounting for available conductivity data. The results state that
reliability improvements are highest, when sampling locations, where the sensitivity of the
flux through the gate with respect to a change in Kf-value is highest. Other criteria, such as
simple geometric grid considerations or locations of highest flow field uncertainties (Kfvariance, head-variance) yielded comparatively minor improvements.
current status
CP
additional data
? TC(r)
TC(r)
? CC
CC
0
reliability r [-]
1
CP : crossover point
? CC : additional investment
? TC(r) : potential cost savings
Figure 1. A typical cost-reliability trade-off curve for a remediation technology.
62
In addition to this, a further study showed that a strategy based on the sensitivities of
plume capture with respect to a change in Kf-value allows to discriminate quite effectively
(with only a few additional sampling points) whether a given design will function at a
given level of reliability (e.g. 95%) or not. The effectiveness of the strategy is shown
within a two-dimensional modelling framework honouring head and conductivity data
(Nowak & Cirpka 2004) for two different virtual realities (“true parameter fields”
conditioned to the same initial data set). While in one reality scenario the FGS design
actually captures the plume, the FGS design fails to capture the plume in the other.
In all, the results achieved so far clearly reveal the relevance of parameter uncertainty
inherent to the decisions that are made on the choice and the design of groundwater
remediation systems. There is a strong need for quantitative approaches incorporating both
the parameter uncertainty and the worth of data. These approaches shall be further
improved in order to be capable of answering the third question mentioned above. It will
be discussed how such an improvement could be realized.
References
Bürger, C., Finkel, M. & Teutsch, G. (2003a) Technical and economic evaluation of
multiple gate funnel-and-gate systems under homogeneous and heterogeneous aquifer
conditions. In: Calibration and Reliability in Groundwater Modelling: A Few Steps
Closer to Reality (ed. by K. Kovar & Z. Hrkal) (Proc. ModelCARE'2002, June 2002).
448-455. IAHS Publ. 277.
Bürger, C.M., Finkel, M. & Teutsch, G. (2003b) Reaktionswandsysteme und „Pump-andTreat“ – Ein Kostenvergleich. Grundwasser 8 (3), p. 167-178.
Nowak, W. & Cirpka, O.A. (2004): A modified Levenberg-Marquardt algorithm for quasilinear geostatistical inversing. – Advances in Water Resources (in press).
Starr, R.C. and J.C. Cherry. (1994). In situ remediation of contaminated ground water: The
funnel-and-gate system. Ground Water. v. 32, no. 3, pp. 465-476.
63
Modelling of the water flow in Hillslopes in northern Germany.
José Doerner and Rainer Horn
Institut for Plant Nutrition and Soil Sciences, Christian Albrechts University Kiel
Olshausenstraße 40, D-24118 Kiel
Keywords: water movement, hillslopes, modeling, pore system functions, anisotropy.
Mathematical models are good tools to describe processes like water movement in soils.
There are one and two dimensional models of water flow and transport available, which
are used for different purposes in the literature (infiltration experiments, simulation of
contamination, etc). One dimensional models are restricted to vertical or horizontal flux
analysis. If water flow in hillslopes should be simulated we need at least 2 dimensional
models because the lateral flow and anisotropy of the hydraulic conductivity must be
considered (Tigges, 2000). Greminger et al (1979) mentioned that the knowledge about
water movement in Hillslopes is essential because the water is a medium of transport for
the deposition (Verlagerung) of chemical substances.
Processes like sedimentation, development of structure and compaction of soils results in
anisotropic behaviour of hydraulic condutivity. The effect of anisotropy on water flow was
investigated by different authors (McCord et al, 1991; Tigges, 2000; Ursino, N. 2001).
Assumming isotropic conditions, the water flow vector and the hydraulic conductivity are
parallel, but under anisotropic conditions, the water flow vector will be deviated in the
direcction of the higher hydraulic conductivity. Therefore, the purpose of this work is to
show some results of the modelling of the water flow in a hillslope of a weichselien
moraine in northern Germany. The effect of the anisotropy on the water flow is considered
and some results that try to explain the anisotropy in structured soils will be presented.
Some field measurements were conducted to describe the water flow in the hillslope. The
slope of the soil catena is 7° and the soils are a Stagnic Luvisol at the top (S1) and at the
middle (S2) of the catena and Cumulic Anthrosol at the footslope (S3) of the Catena.
Tensiometers were installed at differents depths (25, 50, 75, 100, 125 and 150 cm depth; 3
repliclates) and were used to measure the development of the matric potential at three sites
(S1, S2, and S3) of the soil catena.
Undisturbed soil samples were taken at an angle of 0°, 45° and 90° from the different soil
horizons and plough pans at the three locations to determine the effect of the anisotropy on
the water flow. The water retention curve (WRC) and saturated hydraulic conductivity
(Ks) were measured. Additionally, undisturbed soil samples at an angle of 0° and 90° were
64
taken at the middle of the catena to measure shear resistance and air permeability. The
purpose of these measurements is to try to explain the anisotropy in structured soils.
The soils samples were saturated slowly by capillarity. From 10 replicates, 4 were used to
determine the soils water retention curve (WRC), and 6 to measure saturated water
conductivity.The soil samples for the determination of the WRC were drained at different
matric potentials (-10, -20, -30 hPa on a sand bed; -60, -150, -300, -500 hPa on ceramic
plates and –15000 hPa in a pot pressure) and the water content of the samples were
measured. The saturated water conductivity was measured under non steady conditions.
The air permeability was measured at the matric potentials of the WRC.
The parameters of van Genuchten were derived with RETC v 6.0 (van Genuchten et al,
1991) for each soil horizon. The one dimensional water flow was modelled with Hydrus
1D v 2.01 (Simunek et al, 1998) and the two dimensional water flow was modelled with
hydrus 2D v 2.07(Simunek et al, 2002). The two dimensional water flow was modelled
with and without consideration of the anisotropy and the r² of the solutions were
determined. Dry and nearly saturated conditions were compared.
A good fitting of the modelled to the measured matric potential data was obtained,
however, the fitting was not so accurate if soil dry out. Hydraulic gradients and water
flows were directed upwards, downwards and parallel to the slope depending on the water
content of the soil. The parallel water flow was higher above the plough pan. The
anisotropy of the water conductivity leads to a higher parallel water flow above the plough
pan under saturated conditions (see fig. 1). With consideration of the anisotropy the
correlation between the modelled and measured matric potential data was improved.
0
5
10
15
20
25
30
35
40
45
Fig. 1. Two dimensional water flow in the Hillslope in nearly saturated conditions.
65
With our results we try to demonstrate that due to the spatial orientation of soil agregates,
which could be verified by shear resistance measurements, we also have to deal with
anisotropy of pore functions. If we furthermore take into consideration that, above the
plough pan we can expect a higher concentration of nutrients due to the fertilization, the
risk of contamination for natural water sources, due lateral fluxes, is higher too. During the
presentation some more data and consequences for the enviroment will be discussed.
References
McCord,J., D. Stephens, J. Wilson. 1991. Toward validating state-dependent macroscopic
anisotropy in unsaturated media: Field experiments and modeling considerations.
In: P.J. Wierenga (Guest Editor), Validation of flow and Transport Models for the
Unsaturated Zone. Journal of Contaminant Hydrology, 7: 147-177.
Simunek, J., M. Th. van Genuchten and M. Sejna. 1998. The Hydrus-1D Code for
Simulating the One-Dimensional Movement of Water, Heat and Multiple Solutes in
Variably Saturated Porous Media.Version 2.01. US Salinity Laboratory, USDA,
ARS. Riverside, California.
Simunek, J., M. Th. van Genuchten and M. Sejna. 1999. The Hydrus-2D Code for
Simulating the Two-Dimensional Movement of Water, Heat and Multiple Solutes
in Variably Saturated Media.Version 2.0. US Salinity Laboratory, USDA, ARS.
Riverside, California.
van Genuchten, M. Th.. 1980. A closed-form equation for predicting the hydraulic
conductivity of unsaturated soils. Soil Sci. Soc. Am. J. 44:892-898.
van Genuchten, M Th., F.J. Leij and S.R. Yates. 1991. The RETC Code for Quantifying
the Hydraulic Functions of Unsaturated Soils. Version 6.0. US Salinity Laboratory,
USDA, ARS. Riverside, California.
Tigges,
U. 2000. Untersuchungen zum mehrdimensionalen Wassertransport unter
besonderer Berücksichtigung der Anisotropie der hydraulischen Leitfähigkeit.
Dissertation. Christian Albrechts Universität, Kiel.
Ursino, N., Th. Gimmi and H. Flühler. 2001. Combined effects of heterogeneity,
anisotropy, and saturation on steady state flow and transport: A laboratory sand
tank experiment. Water Resources Research, Vol. 37, No. 2:201-208.
66
An integrated approach to model wetland dynamics in a changing
landscape: A case study from South Africa.
Jörg Helmschrot
Department of Geoinformatics, Geohydrology
University of Jena, [email protected]
and
Modelling,
Friedrich-Schiller
Keywords: wetlands, classification, hydrological modelling, landscape model
Wetlands have received an unprecedented amount of scientific and public attention during
the last years. This is mainly caused by the worldwide loss and degradation of these highly
sensitive habitats. Their conservation and sustainable development have been considered in
a variety of national and international programmes and activities (Clean Water Act 1977,
National Water Act 1998, RAMSAR 1971, UNDP etc.). As a result of the increasing
awareness, the hydrological, hydro- and biochemical and ecological functions of wetlands
as well as their importance for the water and nutrient cycle have been investigated in a
variety of different studies. The ongoing research can be summarized as following:
i)
The majority of inland wetland studies are focused on the humid regions of the
northern hemisphere (Europe, USA, Canada).
ii)
A variety of different definitions and classification systems for wetlands have
been developed regarding specific topics and research needs.
iii)
The complexity of both the process dynamics within the wetlands and their
correspondence with the surrounding environments is realised; however
insufficiently considered in integrated approaches.
As a consequence, there is a need of detailed wetland studies for semi-arid landscapes as
well as the development and application of multidisciplinary and integrated approaches
regarding the functioning of wetlands within a basin perspective. Therefore, a study was
initiated focused on such an interdisciplinary approach addressing the classification and
characterization of freshwater wetlands as well as their functional dynamics within a semiarid region of the Eastern Cape Province, South Africa. The project integrates methods and
concepts from hydrology, geomorphology, ecology, and geoinformatics and remote
sensing to identify criteria that have relevance for the sustainable functioning of such
inland wetland systems and their response due to noticeable land use changes such as
afforestation.
Since the study is based on a nested catchments approach, two catchments have been
investigated to assess the impact of these afforestation activities on the landscape
hydrology on different temporal and spatial scales. The catchments are the ‘Mooi’ (ca. 300
km²) and the ‘Weatherley’ test catchment (1,2 km²), which represent the headwaters of the
‘Umzimvubu’ basin (ca. 20.000km²). The catchments are located in the south eastern part
of South Africa and mainly determined by triassic sedimentary strata belonging to the
Karoo Sequence. The soil development depends on the muddy or sandy parent material
and the hydrological conditions. The region lies in a summer rainfall area that is
67
characterised by rainfalls from September to April (750-1500 mm/year). However,
temperature and precipitation show a high temporal variability over the years. The
vegetation is characterised by a grassveld type namely Highland Sourveld in the upper
parts and Dohne Sourveld in the warmer and drier lower elevations. Since the
establishment of forest industries in 1989, large scale afforestation have resulted in
significant changes in land use especially in the headwaters of the catchment. During the
last 15 years forest industries owned some 120,000 ha and afforested rather 60,000 ha of
the former range land with various pine and eucalyptus species for timber production in
short time rotation cycles. The effects induced by large plantations are influencing a
variety of both changes in the hydrological system behaviour (runoff reduction,
interception losses, etc.) and ecological changes (dry out of wetlands, destruction of natural
habitats, etc.). Up to now, a quantified description of the effects of these phenomena is not
available.
Based on the integrated approach a variety of parameters have been delineated and
measured for each scale. Field measurements provided data about vegetation
characteristics, soil physics, soil hydrology and hydrological time series at each scale.
Multitemporal remote sensing data have been used to delineate land use patterns and their
changing as well as vegetation parameters such as spatial Leaf Area Indices (LAI) and
cover densities for different land use units. A GIS-based digital terrain analysis has been
developed to provide a set of geomorphometric and geomorphographic parameters such as
different curvatures, the compound topographic index and hillslope position utilizing a
SRTM Digital Terrain Model. These data have been integrated into a wetland classification
scheme and could therefore used to classify and differentiate several wetland types
according to their specific characteristics and functioning within the landscape. Table 1
shows a preliminary model of the different wetland types and a choice of their specific
parameters.
Furthermore detailed field studies and intensive investigation of the hillslope flow
mechanisms have been used to develope a conceptual model to characterize the
hydrological functioning of the Weatherly catchment and its different types of wetlands
which comprise 28 % of the basin. These concepts have been incorporated into the
MMS/PRMS model which have been used to simulate the catchment hydrology under
varying conditions utilizing a refined Hydrological Response Unit approach combined with
a topological routing method developed by STAUDENRAUSCH (2001). Spatial
parameters have been generated using the GIS Weasel. First model results indicate that the
wetland hydrology is much more controlled by the interflow dynamics on the slopes than
by the groundwater processes and direct precipitation input. In further studies the
knowledge of the dominant process dynamics experienced from Weatherley will be used to
develop a hydrological model for the Mooi catchment.
Additionally, the study indicates significant evidence that the wetland extend has been
changed since 1989, but the investigations also revealed that such changes will be different
regarding both the type of the specific wetland and the temporal scale and magnitude.
Finally the project outcome will be fed into an integrated generic landscape model
comprising the different wetland process dynamics and considering the spatial and
68
temporal heterogeneity of their respective scales. The model will be used to assess the
importance of different wetland types for the landscape hydrology and the impact of the
changing land use on their functionality and surveillance by prognostic modelling.
Tab. 1: Conceptual model for different types of wetlands (preliminary) and specific characteristics.
Slope Wetland Type
Valley Bottom Wetland Type
Type
Subtypes
WA
RD
Soils
Vegetation
Hydrodynamics
[ha]
[cm]
floodplain
> 10
45-210
Gleysols
Sedges,
hydrophyte
grass species
permanent,
seasonal
channel
< 10
30-140
Gleysols, gleyic
Planosols
hydrophyte
grass species
seasonal
MainSource
GW, IF, RF, retF
RF, retF
Description: The floodplain wetland type comprises large wetlands in broad valleys controlled by groundw ater
dynamics and partially associated with interflow and rainfall. They show a high retention potential. Rarely these
types are characterized by complex groundwater systems. The channel types are small in extent and mainly
controlled by return flow and interflow.
Surface
inlet/outlet
> 50
25-125
Stagnic
Luvisols,
Stagnic
Cambisols
hydrophyte
grass species
Only Surface
outlet
10-50
40 125
Stagnic
Luvisols,
Stagnic
Cambisols
hydrophyte
grass species
< 10
45 180
Stagnic
Luvisols,
Stagnic
Cambisols
Sedges,
hydrophyte
grass species
No surface
inlet/outlet
temporal
NS
seasonal,
temporal
NS, IF, retF
seasonal,
temporal
IF, GW, RF
Plateau Wetland
TYpe
Description: Slope wetlands are medium-sized wetlands located at downslope areas and mainly controlled by
rapid lateral water flow (surface runoff and/or interflow). They are characterized by permeable soil layers with high
infiltration capacity.
<5
10-50
Stagnic
Luvisols,
Stagnic
Cambisols,
Regosols
hydrophyte
grass species
temporal
pGW, RF
Description: Small wetland patches in plateau situations, which are associated with perched groundwater and/or
precipitation input.
WA..Wetland area
IF..Interflow
RD..Root Depth
RF..Rainfall
GW..Groundwater
pGW..perched Groundwater
retF..Return Flow
References
STAUDENRAUSCH, H. (2001): Untersuchungen zur hydrologischen Topologie von
Landschaftsobjekten für die distributive Flussgebietsmodellierung. PhD-Dissertation,
Friedrich-Schiller-Universität Jena, 158 pp.
69
Integrated groundwater management in coastal semi-arid areas using
artificial recharge
Holländer, H.M.
Institute of Water Resources Management, Hydrology and Agricultural Hydraulic
Engineering, University of Hannover, Germany
Keywords: artificial recharge, coastal areas, semi-arid climate
Groundwater can be utilized for potable water, irrigation and other related purposes. In
areas with distinct rainy seasons, rain water is only available during specific months in the
year. During the rest of the year (dry season) water has to be drawn from reservoirs or from
groundwater. In coastal areas with alluvial plains, the storage of large amounts of water in
reservoirs is difficult since the slope of these plains is often nearly zero so that no large
reservoir can be constructed. The abstraction of groundwater is possible because the
groundwater table is near to the ground surface. Hence, if it is abstracted saltwater
intrusion from the sea side may occur.
The rainfall in the monsoon seasons causes a flooding of the area. Depending on the water
height and on the submerge time of the crops, the yields in harvest time will be lower.
The objective of the study is to develop a water management in semi-arid climates by the
combined use of analytical calculation and numerical groundwater simulation. The study
area gives for this objective two study cases which have to look at:
1. To protect plants in early growing state caused by submerging of the plants.
2. To utilize the rain water which is surplus in quantity but with unequal time
distribution allowing no successful growing of plants through out the year.
For both objectives surplus water has to be stored in the aquifer as storage of water in
surface reservoirs is often not possible in coastal areas. It can be used again in the dry
season. The study area is near the city of Balasore, Orissa, India and is located direct at the
Bay of Bengal.
If the groundwater table reaches the surface, the water is lost by evaporation or flows away
into canals which are normally used for irrigation and into natural ditches. Some of the
water is lost by flowing into the sea (Bay of Bengal). To store this water it can be
infiltrated into the soil if during dry season water would be pumped so that the storage
volume for water in the soil is larger. The stored water can be used in dry season again for
drinking or irrigation purpose depending on the water quality (Mull et al., 2000).
Artificial recharge is necessary to store the water. Highly recommended for a direct
infiltration of surface water into aquifers which are overlain by silt and/or clay soil layers
70
are ASR-wells (Aquifer Storage Recovery Wells) (Pyne, 1995). ASR-wells have the
advantage that they can infiltrate water into the aquifer like a recharge well and later (in
dry season) the same well can be used as a discharge well.
Water can be stored through ASR-wells in different aquifer types. It is possible to infiltrate
water into unconfined, semi-confined and confined groundwater systems. While
infiltrating the surface water, a cone of elevation is build during recharge (Fig. 1). The
cone of elevation is limiting the infiltration rate because the infiltration is done only by
gravity.
During an infiltration into a semi-confined groundwater system, the system behaves like a
confined aquifer if the duration of the infiltrations is short because the conductivity of the
overlaying soil layer is low in relation to the conductivity of the aquifer. If water is
infiltrated for a longer time, the system behaves first like a confined aquifer and with
increasing usage of time like an unconfined system.
A single well is shown in Fig. 1. It can be assumed for the calculation that the
neighbouring wells have no or only a negligible influence on the observed well because the
wells are located in a large distance from each other. The groundwater table shown in Fig.
1 is the large scale groundwater table at a certain time step. This follows that the
calculations can be based on the equations for non-influenced single wells.
Fig. 1
Principal scheme of the usable pore volume in the soil under usage of ASR-well
The field size which can be connected to an ASR-well to protect plants against submerging
depends mainly on the water height which has to be infiltrated, on the time which is
available for infiltration, the natural percolation and on the depth of the groundwater table
71
because the ASR-wells shall work by gravity force. If the field size is calculated for the
water management purpose the most important factors are the natural percolation and the
depth of the groundwater table.
The analytical calculation of the water management is verified by a groundwater model
which also gives the results of the groundwater variation during the management time. The
following cases of the management have been simulated:
1. The situation as it has been found in 1999.
2. One harvest in monsoon (Kharif) and a second harvest in post-monsoon season
(Rabi).
3. Growing crops in Kharif and Rabi and using 50% of the total area for a third
summer crop.
4. Growing crops in Kharif and in Rabi and using the whole area for a third summer
crop.
First results show that the planned groundwater management can raise the agricultural
production by securing the plants during monsoon season and by providing water to
additional crops in post-monsoon and summer time. A full use of all fields over the whole
year is only sustainable in some parts of the study area. The calculated groundwater
recharge value of 188.8 mm/a is according with Bouwer (2002). The potential of artificial
recharge is up to 600 mm/a.
The development of a groundwater management with artificial recharge can help to raise
the agricultural production in coastal areas with distinct rainy seasons. The analytical
calculation of an area which can be connected to one ASR-well and a groundwater model
which calculates the groundwater budget can give answers of the sustainability of the
groundwater use and recharge.
Bouwer, H. (2002): Artificial recharge of groundwater: hydrogeology and engineering.
Hydrogeology Journal, Vol. 10, pp 121-142, Springer Verlag, New York.
Mull, R.; Holländer, H.; Boochs, P.W.; Panda, N.S. (2000): Aspects of water management
in paddy fields in East India. Proceedings of International Workshop on Rainwater and
Groundwater Management for Sustainable Rice Ecosystems, I.I.T. Kharagpur, 25.-26.
September 2000.
Pyne, R.D.G. (1995): Groundwater recharge and wells: A Guide to aquifer storage and
recovery. CRC Press, Florida.
72
An approach to simultaneously model rainfall-runoff events in rural
and urbanized catchments as well as their interactions, with help of a
Geographic Information System
Dipl.-Ing. Arne Klawitter (M.S. USA)
Technische Universität Darmstadt, Fachbereich Bauingenieurwesen und Geodäsie
Fachgebiet Ingenieurhydrologie und Wasserbewirtschaftung,
Petersenstr. 13 – 64287 Darmstadt, Germany
[email protected]
Keywords: integrated hydrologic modelling, Geographical Information System (GIS),
Digital Elevation Model (DEM), sustainable water management
Traditionally, rainfall runoff analyses are looked at from a totally different point of view in
rural and urbanized catchments respectively. Also, they are usually modelled
independently from each other, meaning that there exist numerous models to model either
rural or urban catchments. Only a few models are known that are capable of modelling
both urban and rural catchments simultaneously and in a detailed manner; however
interactions between the systems are hardly taken into account.
This paper shortly discusses an approach to simultaneously model rural and urban
catchments and their interactions, gives some general information about possible
interactions and their effects, and finally presents two model structures which can be used
to model the integrated system.
The natural flow patterns on the soil surface which evolve from natural conditions such as
topography and land use, are altered dramatically in urbanized regions. Here the flow
patterns are mainly predefined by the sewer system; flow paths on the soil surface are short
and are not subject to any significant retention processes. The flow patterns on the surface
do not follow the natural topography any longer, but are influenced by buildings,
sidewalks, ditches etc. Interflow processes are mainly disturbed in urban areas by either
dense sewer systems or deep basements of buildings, or both. Effects of urbanisation are
e.g. that actual evaporation rates are reduced tremendously due to the fast transport of
precipitation water on the soil surface into the sewer system. Due to the increase of
impermeable area, the infiltration rates into the soil are reduced which leads to a lower soil
moisture and in the end to a reduced baseflow. Leaching of waste water from sewer pipes
into the soil matrix can cause soil contamination; or a groundwater table yl ing near the soil
surface can lead to an excessive amount of imported water in the sewer system.
Discharges from sewer overflow structures not only put a strain on the receiving water
body through pollution load, but also due to the resulting hydraulic stress. The fact that
73
temperatures are higher in urban settlements can lead to reduced snow cover periods as
well as higher snow melting rates within the winter months.
There could be more effects listed that an urban area has on the hydrological cycle, and
more interactions between the systems could be named. However, at this point it should be
clear, that for a detailed statement on the water cycle and the effects of urban settlements
on the water cycle in rural catchments, some of the interactions named above should be
considered in an integrated hydrological modelling system. Hence, to better account for
these interactions an approach, that simultaneously couples two existing hydrological
models, is introduced.
The main goal of the work is to find a way of integrating the two existing models, taking
into account the above named interactions of the two modelling systems and to account for
the correct modelling of flow peaks in streams during rainstorm events when sewer
overflows intermittently discharge waste water. Criteria for water quality are neglected in
this discussion.
Considering deterministic hydrological modelling of rural systems, distributed models
based on a geographical information system (GIS) can be called state of the art. Numerous
models based on triangulated irregular networks, stream tubes, hillslopes or regular grids
are known. However in hydrologic urban modelling, the concept of elementary areas or
lumped areas is used rather than highly distributed modelling concepts. Nevertheless,
these simple concepts have proven to adequately represent discharge volumes and
discharge peaks. Hence, in a first step, it is aimed at combining a highly distributed
deterministic GIS-based hydrological grid-model with a deterministic hydrological model
for urban areas, that is based on rather simple concepts.
The grid-model is based on a soil moisture simulation routine that considers non-linear
functions for infiltration, percolation and interflow. Overland flow is routed from grid to
grid with the kinematic wave approach. Channel flow forms according to a threshold
value concept, and can account for up to four different channel types. Channel flow is
routed based on a non-linear reservoir concept. The process of baseflow is modelled by
two parallel linear reservoirs. The model is connected to a GIS, so some results can be
visualized.
The hydrologic model for urban areas uses a simple approach for the formation of effective
rainfall; only surface wetting and losses due to surface dips are considered. The routing of
the effective rainfall on the surface is calculated by a parallel Nash-cascade, each having
three linear reservoirs. Flow routing in the sewer system is carried out using the KalininMiljukov algorithm. Retention basins in the sewer system are modelled using a non-linear
reservoir approach. The model can also account for transport of pollutants in the sewer
system, however this is not further discussed here.
74
The approach of modelling the two combined systems simultaneously can be compared to
a two layer approach. One layer represents the rural system and the second layer
represents the urban system. Within each time step, both layers have to be simulated. This
two-layer-concept is indicated in figure 1. The red areas in figure 1b represent urban
settlements. These areas have to be identified prior to a simulation and can then be
modelled separately. Here, the percentage of impervious area within the urban settlement
plays an important role. It basically controls the partitioning of precipitation on layer 1 and
layer 2.
a)
b)
c)
Figure 1: a) Digital Elevation Model (DEM), b) land use characteristics, red
areas indicate urban settlements, c) system plan for an urban settlement
The red arrows in figure 1c indicate possible points of interaction between the urban and
the rural system. However, only sewer overflows are marked with an arrow here. The
overflow discharges are added to the streamflow in a grid, which means that every
overflow building is assigned to a certain grid cell. Further interactions concern the
modification of surface and subsurface flow patterns, where some assumptions have to be
made. E.g. the interflow process underneath urban areas is “deactivated” in the according
grids in the rural model; hence only vertical flow processes are considered. Overland flow
from rural areas that runs into an urban settlement will then be processed according to the
flow patterns given in the urban system (figure 1c). Leaching of pipes or infiltration of
water into the sewer system can be modelled by an increase or decrease of the soil
moisture.
Taking into account the most important interactions between rural and urban systems, the
model is expected to better represent river discharges in populated mesoscale catchments.
Based on this improved approach, a second step to better model water quality on a more
detailed scale will be envisaged.
75
Estimating the Discharge of Sulphate from Dump Sediments into the
Surface Water of an Abandoned Open Pit Lignite Mine
Claus
Kohfahl*1 , Paul Brown2 , Claire Linklater2 , A. Pekdeger1
1
Inst of Geological Sciences, Free Univ of Berlin, Dept of Geological Sciences, Malteser
Str 74-100, D-12249 Berlin, Germany
2
Australian Nuclear Science & Technology Organization, ANSTO, PMB 1 Menai, NSW
2234, Australia
Claus Kohfahl, Freie Universität Berlin, Inst. für Geologische Wissenschaften, Fachrichtung
Geochemie, Hydrogeologie, Mineralogie, Arbeitsgruppe Hydrogeologie, Malteserstr. 74 - 100,
Haus B, D - 12249 Berlin, Germany
E-Mail: [email protected]
Key words: Lignite mines; Lohsa; pyrite weathering; reactive transport modelling; Spree;
sulphate generation
Large areas in the new federal states of Germany have been subjected to open cast lignite
mining. Acid generation occurs when the iron disulfides oxidize in the dump sediments
due to penetration of oxygen and oxygen-rich waters. Primary oxidation of the sediments
starts during dewatering of the originally layered material prior to mining. The processes of
mining (excavation, mixing, and dumping activities) intensifies aeration. After deposition,
secondary pyrite oxidation continues in the aerated upper part of the spoils, sometimes for
several decades. After decommissioning a mine, standard procedure is to allow the water
table to rise and to convert the pit into a lake for recreational purposes. During the
flooding, which often extends over several years to decades, the acidity and other chemical
contents in the groundwater are flushed into the newly formed lake (Gerke, 1998). To
reduce acid input during inundation, surface water is sometimes used to supplement the
slow natural rise of groundwater.
The study area is the Lohsa lignite mine near Hoyerswerda in Germany. This mine was
exploited from 1970 to 1990, when its groundwater level was lowered artificially to a
maximum depth of 50 m below subsurface. The pumped water was discharged into the
Spree during that period. Pumping of groundwater stopped after the mine was
decommissioned, so the water level of the Spree has declined since 1990, causing water
quality problems for the drinking water supply in the downstream areas. The former lignite
mine is to be flooded, mainly with surface water, by 2005 and will afterwards be used as a
reservoir basin for the river Spree. To equilibrate the hydraulic head of the river, present
management strategies are predicting annual surface water oscillations between 5 and 8 m
((LmbV and Cottbus, 1996).
The ongoing weathering processes in the unsaturated zone of the surrounding 40-m-high
heaps will lead to a continuous release of acidity into the groundwater, which will then
exfiltrate into the newly formed lake and into the Spree. The bank filtrate of the Spree is
76
used for drinking water in urban areas downstream of Lohsa, so the long-term release of
sulphate and acidity from the unsaturated zone of the heaps has to be estimated.
Over the last 15 years, increasingly sophisticated geochemical modelling techniques have
been developed, capable of representing simultaneously many of the chemical and physical
processes taking place in a system of interest. Several models have already been developed
to allow long term predictions of the hydrogeochemical evolution in abandoned and
flooded lignite mine environments (Foos, 1997; Strömberg and Banwart, 1994). These
models usually consider equilibrium reactions and additional kinetic processes. Some
models also include O2 diffusion and transport reactions (Hecht et al., 2003; Prein, 1993;
Wunderly et al., 1996). Mayer incorporated kinetically controlled reactions in variably
saturated porous media in a multi-component reactive transport model (Mayer, 2002). The
code SULFIDOX (Brown et al, 2001) applied in this study, has been developed by the
Australian Nuclear Science and Technology Organisation (ANSTO) for application to
sulphidic mine waste rock dumps.
To provide a first quantitative estimate, the reactive transport code SULFIDOX (Brown et
al, 2001) was calibrated based on in situ measurements in the heap. Using the scaled up
model, a simulations was performed to derive the temporal evolution of sulphate discharge
into the surface water. Scenarios for a period of 80 years were simulated and both, the
mass input of sulphate from the unsaturated zone into the groundwater and the discharge of
acids into the lake were calculated.
SULFIDOX implements a conceptual model of oxidation and transport processes in
sulphidic waste dumps (Pantelis et al., 2002) along with a detailed model of chemical
interactions within the dump.
SULFIDOX is a two-dimensional finite difference code and describes a three phase system
consisting of a rigid solid porous phase through which flow gas and water phases. It
models oxygen transport and depletion, heat transport and production, and reactant
depletion in the solid phase. In summary it represents the following processes in waste
dumps:
-
gas transport via diffusion and/or advection;
-
heat transport via thermal conduction and/or fluid flow;
-
infiltration of water down through the waste dump;
-
speciation and complexation of components within the water;
-
dissolution of minerals in the heap; both slow dissolution subject to kinetic
controls, and rapid ‘instantaneous’ dissolution subject to thermodynamic
equilibrium laws;
-
precipitation of secondary minerals within the dump.
77
Chemical equilibrium reactions can be coupled with the physical transport process by the
inclusion of a geochemical speciation module based on PHREEQE (Parkhurst, 1995).
The aim of this study was to allow quantitative long term estimates concerning the
discharge of weathering products from the surrounding heaps into the surface water.
In my presentation I would like to present the main results of this modelling approach and
discuss the sensitivities of the results for selected parameters.
Foos, A., 1997. Geochemical modelling of coal mine drainage, Summit County, Ohio.
Environmental Geology, 31(3/4): 205 - 210.
Gerke, H., 1998. Modelling the effect of chemical heterogeneity on acidification and solute
leaching in overburden mine spoils. Journal of Hydrology, 209: 166-185.
Hecht, H., Kölling, M. and Geissler, N., 2003. DiffMod7 - modeling oxygen diffusion and
pyrite decomposition in the unsaturated zone based on ground air oxygen distribution.
Geochemical Processes- Concepts for Modeling Reactive Transport in Soils and
Groundwater. Wiley-VCH, Weinheim
LmbV and Cottbus, B., 1996. Wissenschaftlich-technisches Projekt: Erfassung und
Vorhersage der Gewässergüte in Tagebaurestseen der Lausitz als Basis für deren
nachhaltige Steuerung und Nutzung., Cottbus, 56 pp
Mayer, K.U., 2002. Multicomponent reactive transport modeling in variably saturated
porous media using a generalized formulation for kinetically controlled reactions.
Water Resources Research, 38 (9): 1174-1195.
Pantelis, G., Ritchie, A.I.M. and Stepanyants, Y.A., 2002. A conceptual model for the
description of oxidation and tranpsort processes in sulphidic waste dumps. Applied
Mathematical Modelling, 26: 751-770.
Parkhurst, D.L., 1995. PHREEQC - A computerprogram for speciation, reaction-path,
advective-transport and inverse geochemical calculations. 95-4227, U.S. Geological
Survey Water-Resources, Lakewood, Colorado.
Prein, A., 1993. Sauerstoffzufuhr als limitierender Faktor für die Pyritverwitterung in
Abraumkippen, Mitt. des Inst. Wasserwirtsch., Hydrologie und landwirtsch. Wasserbau
Univ. Hannover. Inst. Wasserwirtsch., Hydrologie und landwirtsch. Wasserbau Univ.
Hannover, Hannover, pp. 126.
Strömberg, B. and Banwart, S., 1994. Kinetic modeling of geochemical processes at the
Aitik mining waste rock site in northern Sweden. Applied Geochemistry, 9: 583-595.
Wunderly, M.D., Blowes, D.W., Frind, E.O. and Ptacek, C.J., 1996. Sulfide mineral
oxidation and subsequent reactive transport of oxidation products in mine tailings
impoundments - a numeric model. Water Resources Research, 32: 3173-3187.
78
Integrated water quality management – development of a socio-ecological
approach
Stefan Liehr, Florian Keil
Institute for Social-Ecological Research (ISOE)
Hamburger Allee 45, D - 60486 Frankfurt am Main, Germany
Email: [email protected], [email protected]
Keywords: Integrated Water Resource Management, Decision Support Systems,
Modelling, Water Quality, New Pollutants
Humans and environment – a view at the current debates on problem areas such as climate,
energy and water politics demonstrates the close entanglement of social and natural
processes. Therefore, environmental problems are also social problems and a profound
understanding of the relevant processes requires the analysis of the underlying complex
socio-ecological structures of cause and effect. This circumstance finds its special
expression within the field of water research. Particularly in the integrated water resource
management a multitude of utilization demands and conflicts of interests meet each other.
The economic and social functionality of water – in quality and quantity – stand in
opposition to its meaning for the conservation of the ecosystem. Hence, in the development
of strategies for a sustainable management of water resources the consideration of the
different dimensions of integration is of crucial importance. On the one hand the
knowledge of different natural and social disciplines have to be brought together during a
joint research process, on the other hand scientific results are to be translated in such a way
that they open up the possibility for social action. Inter- and transdisciplinary integration
should be part of this research process from the outset and not at the end.
In order to meet that challenge we will present in the following a future-oriented
methodological approach for the development of an integrated water quality management.
It takes up the problem of the so-called “new pollutants”, which refers e. g. to substances
in the group of persistent organic pollutants (POP). The focus lies on the spectrum of
chemical substances constantly extending by technical and economic progress. Their
exposure into the environment results in a continuously growing and in their forms
strongly varying anthropogenic endangerment of the surface waters and groundwater
bodies. At the same time, the entry paths of most substances into the environment, their
effects on water quality and relevant feedback mechanisms through the hydrological cycle
back to the humans are understood only incomplete. This leads to the central problem of
sustainable water quality management: To investigate the emergence of risk potentials, the
substantial propagation and distribution mechanisms must be identified and estimated in
their relevance. Not only the natural framing conditions play an important role, but also the
79
coupling to socio-economic processes. In addition, specific social processes of negotiation
in handling conflicting interests and behavioural patterns have to be taken into account. All
these aspects form a basis on which policy measures can be compiled and be assessed on
their effectiveness in the context of a complex, multi-criterial decision problem. Also
questions related to the Water Framework Directive (WFD), as the specification of what
good ecological water conditions should be, can be addressed with that approach.
In the centre stands the methodological development of an integrated water quality
management oriented on the sustainability principle and consisting of an interactive
decision support system (DSS) in its core. Thus, the two dimensions of inter- and
transdisciplinary integration are taken into account as central challenges. In the foreground
we do not focus on the in-depth realistic description of individual processes, but first of all
on the identification and analysis of the complex cause-effect-relations between the
interacting components of coupled social, ecological and economic subsystems as well as
secondly the management of the information flow between these components. Special
attention will be given to the development of adequate modelling methods for the formal
description of these interacting processes and on their integration into the context of the
DPSIR concept developed by the European Environment Agency (1999). This is illustrated
in Figure 1. The DPSIR concept with its five environmental indicators structures the
model-based description of the observed complex phenomena and bridges the difficulty of
an policy-oriented reduction of the available information to the most important elements.
It is beyond doubt that models form a crucial gateway to the system examined in each case.
They represent a central link in the combination of different disciplinary and
methodological competences and serve as important instruments for the transformation of
scientific knowledge into socio-political decision-making. Therefore, we will face the
important task of studying methods of implementation of intra- and interdisciplinarily
developed models into the structure of an interactive DSS. Reflecting on the underlying
assumptions in the models (e. g. substantial components and processes, relevant temporal
and spatial scales) and of their limits we will develop criteria, which permit an adequate
handling of uncertainties and ignorance in risk assessment.
Finally, the development of a water quality management which is oriented at the
sustainability principle requires the establishment of new adapted procedures of risk
evaluation in particular in the problem area of “new pollutants”. Our contribution presents
a concept for the development of an integrated, flexible and adaptive water quality
management. It addresses the considerable dynamics of the problem field in a flexible
manner, is open and adapts to varying demands and constantly increasing knowledge and
connects different disciplinary and policy-oriented points of view adequately.
80
References
Becker, E. and Schramm, E. (2002). Gekoppelte Systeme. Zur Modellierung und Prognose
sozial-ökologischer Transformationen. In Balser, I. and Wächter, M., editors, Sozialökologische Forschung. Ergebnisse der Sondierungsprojekte aus dem BMBFFörderschwerpunkt, p. 361–376. ökom Verlag, München.
European Environment Agency (EEA) (1999). Sustainable Water Use in Europe - Part 1:
Sectoral Use of Water. Environmental assessment report 1, EEA, Copenhagen.
Walker, W. E., Harremoes, P., Rotmans, J., van der Sluijs, J. P., van Asselt, M. B. A.,
Janssen, P., and Krayer van Krauss, M. (2003). Defining uncertainty a conceptual
basis for uncertainty management in model-based decision support. Integrated
Assessment, 4(1):5–17.
Figure 1. Integration through the
interaction of models in the framework
of the DPSIR concept. Disciplinary
knowledge as well as policy-oriented
requirements are represented within that
scheme. The way of how models are
implemented and combined as well as
the reflection about their underlying
assumptions and limits play a crucial
role in understanding the significance of
results and in handling uncertainties and
ignorance.
81
Dominating structures and processes in a hydrological induced mass
movement – an interdisciplinary approach
Falk Lindenmaier1 , Erwin Zehe 2 , Jürgen Ihringer1
1
Institute for Water Resources Planning, Hydraulics and Rural Engineering
Universität Karlsruhe, Germany, Kaiserstrasse 12, 76128 Karlsruhe
Email: [email protected], [email protected]
2
Institute for Geoecology
Universität Potsdam, Germany, Karl-Liebknecht-Strasse 24-25, 14476 Golm
Keywords: hydrological induced mass movement, process and structure identification,
hydrological process model
Slope instabilities both in artificial slopes and in mountainous regions are a major concern
for mankind. Not only because of possible human losses but also through a continuously
rising financial threat evolving from a more and more intensive use of our environment.
Major triggers for slope failures can be for example earthquakes or rising water tables
which in turn may be influenced through precipitation and infiltration into the unsaturated
zone. Hydrology plays an important role in triggering mass movements, especially when
its impact is seen in changing climatic frameworks (Delmonaco & Margottini, 2004). More
intensive rainstorms or higher amplitudes of dry and wet climatic periods can possibly lead
to more slope failures as well. Both landslides and slope failures are complex phenomena
which usually show a long enduring time span for the evolution towards failure and a short
event duration after the initiating trigger process. Hence, it is necessary to investigate
slopes which are still prior to failure to better understand the interactions between
hydrological processes and the development of shear zones.
Now the question is, where does the “classical approach” towards a better understanding of
slope instabilities comes from? There are two major scientific groups which are interested
in slope instabilities, namely geoscientists and geotechnical-engineers. Roughly seen, the
first group is rather concerned of large natural landslides and the latter group of failures in
small artificial slopes. If we look to the scale of small slopes or dams, hydrological
influence towards a failure seems to be describable with less difficulty. The pore space in
these systems is rather homogeneous. Subsurface fluid dynamics is dominantly matrix
flow, infiltration as well as changes in the pressure head due to wetting and drying are
processes understood rather well. Here, the focus of research is usually to link subsurface
water dynamics with general stability calculations (e.g. Tsaparas et al., 2002) or continuum
mechanics. On a larger scale, hydrological processes are more difficult to grasp, due to the
sheer size of the landslide body and different processes and scales encountered. Here,
conceptual hydrological models are often too simple to describe the dominating processes
at large. To fully understand landslide triggering mechanisms and their link to climatic
82
patterns, a more detailed look towards hydrological and related processes is of vast
importance (Bogaard et al., 2000; Lindenmaier et al., 2004). We think, as hydrologists, that
we need to intensify our contribution to this already interdisciplinary discussion. The
spatiotemporal distribution of precipitation, which cannot be neglected on this scale,
influences the soil water dynamics not only by matrix infiltration. Fast processes like
preferential flow with soil-moisture dependent thresholds do play a more important role
than they get attention so far in landslide hydrology. These processes are closely linked to
the spatial distribution of fractures, macropores or other large inhomogeneities e.g. woodlogs in chaotic debris material. It is still too difficult to describe and merge all these
processes and structures and their interactions in a single existing method or model.
As we set our goal to improve the understanding of landslide hydrology, we chose a
creeping but not yet failed slope near Bregenz, Austria. The size of the moving body
extends over 1800 x 500 m and has an elevation of about 400 m, the depth is up to
60 meters. A precipitation scheme with high yearly precipitation sums and a high climatic
variability seems to be the trigger for movement rates of the slopes of up to 10 cm a year.
Buildings and roads on top of the slopes are twisted and show cracks, or even had to be
torn down. The research stands in close cooperation with the local authorities whose goal
is to reduce creeping in builded areas, especially to establish a sewage system there. Data
acquisition started in 1998 with geological and geotechnical equipment and observations
and a geodetical observation of surface points with GPS. In addition a hydrological
measurement network has been installed with a meteorological station and several
precipitation and runoff gauges. The system has been enlarged several times with
additional measurement equipment but also suffered data loss through technical failures
and natural restrictions.
In our presentation we want to stress the importance of an interdisciplinary approach
towards landslide behaviour and want to show that process based hydrology needs to have
more attention there. Only through the identification of dominating geological structures
and hydrological processes which also included a close look towards soil-properties and
vegetation and including movement observation, we were led to understand thoroughly the
behaviour of the mass movement. We combined these research disciplines to identify
hydrotopes with characteristic hydrological surface and subsurface behaviour. Data and
also numerical limitations did not allow to grasp the mass movement in total with a single
numerical model so far. We encountered not only a vast span of processes in different time
scales, like fast processes (precipitation and runoff generation) or slower processes
(infiltration and pressure build-up) or even slower reactions like the macroscopic changes
and movements in the slope body. We also needed to look at a high variety of structures in
different scales like the geological setting, the inhomogeneous, post glacial development of
scree material or the soil and vegetation structures like root-holes, shrinking cracks or
wetness patterns. With the hydrological process model CATFLOW (Zehe et al., 2001) we
could describe subsurface water dynamics in the unsaturated zone as well as runoff
83
production and concentration in the creeks on the slope simultaneously so far. With a case
study we could also reproduce the driving factor for the creep which is a pressure
propagation from a hydrological active hydrotope which is not located on the moving slope
body itself.
We cannot give a complete solution towards the triggering process, nor can we apply a
model, which combines all necessary and dominating structures or processes in all scales
encountered here. Our studies still lack some essential data therefore, like more
measurements of pressure heads as well as a more continuously movement observation
which can’t be achieved so easily. But for future research we can provide a detailed study
as useful basis for a coupling of hydrological and soil mechanical processes in large
landslides and can give clues about critical climatic states which could trigger landslides.
The major point of our presentation is to stress the interdisciplinary research approach
without which we would have not come that far.
BOOGARD, T.A., ANTOINE, P., DESVARREUX, P., GIRAUD, A., VAN ASCH,
T.W.J.: The slope movements within the Mondorès graben (Drôme, France): The
interaction between geology, hydrology and typology. Engineering Geology, 55: 297-312,
2000.
DELMONACO, G., MARGOTTINI, C.: Meteorological Factors Influencing Slope
Stability. Natural disasters and sustainable development. Editors: Casale, R., Margottini,
C., Springer Verlag Berlin Heidelberg New York, pages: 397, 2004.
LINDENMAIER, F., ZEHE, E., DITTFURTH, A., IHRINGER, J.: Process identification
at a slow moving landslide in the Vorarlberg Alps. Hydrological Processes, accepted in
January 2004.
TSAPARAS, I., RAHARDJO, H., TOLL, D.G., LEONG, E.C.: Controlling parameters for
rainfall-induced landslides. Computers and Geotechnics, 29: 1-27, 2002.
ZEHE, E., MAURER, T., IHRINGER, J., PLATE, E.: Modelling water flow and mass
transport in a Loess catchment. Physics & Chemistry of the Earth, Part B, 26: 487-507,
2001.
84
Stochastic modelling approach for deriving hydrological growth
conditions in floodplain forests
Heike Puhlmann
Institute of Hydrology and Meteorology, Dresden University of Technology, Würzburger
Str. 46, 01187 Dresden, Germany
Keywords: stochastic modelling, soil water regime, flood plain
Wetland landscapes have been destructed to a great extend particularly during the last
century. Today, most of the flood plains are diked and natural alluvial forests are scarce
due to the cultivation of the flood plains. However, it is now generally recognised that the
narrowing and straightening of the river courses is a major source of the intensification of
flood events in previous years. Dike transfers and the re-establishment of floodplain forests
can increase the retention capacity of flood plains and thereby, reduce flood peaks and
flood related damages. First attempts to put such intentions into practice made clear that
their efficient realisation highly depends on whether we can (i) characterise and quantify
the natural dynamics of flood plains, (ii) frame objectives for a flood plain management
and (iii) predict possible impacts of planned actions on existing ecosystems.
This paper presents a general model system for the characterisation and quantification of
the long-term hydrological conditions in flood plains and their interpretation in terms of
growth conditions for alluvial forests (Puhlmann, 2003). Possible applications of the model
system include the quantification of (i) the actual hydrological state of a flood plain
(indication tool), (ii) objectives for a future flood plain management (planning tool) and
(iii) possible effects of proposed management directives (scenario tool). The hydrological
characterisation of flood plains on the basis of the proposed model system may assist the
management of flood plains and, in particular, reforestation plans e.g. for objectively
selecting sites or tree species best suited for a natural reforestation under the quantified
hydrological conditions. In this way, it may help to minimise costs and effort of
reforestation projects and, last but not least, increase the chance of a project's successful
realisation. The model system links several models for simulating the relevant hydrological
processes in flood plains, i.e. the regimes of the river flow, the groundwater and the soil
water. These models mainly incorporate physically based process descriptions and thus,
allow for a wide range of applications, e.g. predictions and scenario runs or comparative
applications of the model system to different flood plains. The simulation of the soil water
regime which is considered the major growth relevant factor in flood plains constitutes
the central part of the model system. Main feature of the model concept is the numerical
85
one-dimensional unsaturated flow model RFDE1D in which - contrary to common
unsaturated flow models - the model boundary conditions are treated as stochastic time
processes. RFDE1D is based on the so-called Richards Functional Differential Equations
(Liedl, 1991) which derive from the Richards equation for unsaturated flow. Within these
equations, the statistical moments of the initial and boundary conditions - the expectations
and variances - are linked with the corresponding moments of the pressure heads, soil
water contents and water fluxes. In other words, the mean course and the typical variances
of the soil water content are derived directly from the distributions (in time) of the
boundary conditions at a given site. In flood plains, the highly dynamic regimes of the
river and the groundwater have a large impact on the soil water regime. The river levels (or
inundation heights) and the groundwater levels describe the upper and lower hydrological
boundary conditions of the soil water model. The soil water regime also depends on
meteorological processes (precipitation, evaporation), which describe the upper (flux)
boundary conditions in times where the site is not inundated. The model system is applied
in two different simulation modes, which altogether gives a comprehensive
characterisation of both the typical mean soil water regime and its extremes. The
"stochastic simulation" derives the long-term mean annual course (expectations) of the
meteorological and hydrological conditions with its typical fluctuations (variances). In the
"deterministic simulation", long-term deterministic (observed) time series of the
meteorological and hydrological conditions are simulated and subsequently analysed with
respect to extreme events (e.g. deficits below a critical water content, inundations) in terms
of their occurence frequency, duration and height.
A first application of the developed model system focussed on the soil water regime of an
undiked hardwood forest at the Middle Elbe near Dessau. All data required for the model
parametrisation and calibration (e.g. soil characteristics, soil water and pressure head
observations, hydrological/meteorological boundary conditions) were collected at the
investigated site. The calibrated model was finally applied to the years 1947-2000 based on
long records of national observational networks (meteorological data, river levels). The
results of the "deterministic" and "stochastic" simulation altogether give a comprehensive
view of the hydrological regimes at the investigated site. The "stochastic simulation"
shows that soil layering has a significant impact on the soil water availability for plants.
The mean regime of the soil water content in the root zone is characterised by a distinct
annual course. Highly irregular surface inundations, coupled near-surface groundwater
levels and - much less pronounced - the fluctuating precipitation result in highly variable
soil water contents throughout the year. The "deterministic simulation" shows that the
uppermost soil regions frequently undergo short extreme events whilst larger soil depths
are marked by rare, but prolonged extreme events. Whilst precipitation can lessen a water
shortage in the top soil, the saturation of the lower layers is bound to surface inundation or
a near-surface groundwater rise. Surface inundations increase the mean annual saturation
86
level but may not always prevent droughts in summer or autumn. Based on these results,
various sites within the investigated flood plain could be compared with each other with
respect to their suitability for the re-establishment of different tree species.
This paper presents an application of the developed model system to a flood plain in the
sense of an indication tool. For using the concept as a planning tool, other disciplines
(forestry, economics) should be involved, which might help to better evaluate the
feasibility of proposed management strategies (e.g. the selection of tree species) than
stand-alone projects of purely hydrological background. The critical values of extreme
events surely should be defined under consideration of the vegetation, e.g. critical water
contents had to be quantified depending on the drought tolerance of a particular tree
species. Further development of the presented model system aims at its integration in a
broader modelling context in order to better describe the response of the flood plain
vegetation to given hydrological growth conditions. This would require an improved
representation of the interrelation between the soil water regime and the flood plain
vegetation, e.g. by coupling the soil water model with a physiological plant growth model.
References
Liedl, R. 1991: Funktionaldifferentialgleichungen zur Beschreibung von Wasserbewegungen in Böden natürlicher Variabilität. Beiträge zur Theorie and Entwicklung
eines numerischen Lösungsverfahrens. Berichte Versuchsanstalt Obernach and
Lehrstuhl für Wasserbau und Wassermengenwirtschaft der TU München Nr. 67.
Puhlmann,
H.
2003:
Die
Modellierung
des
langfristigen
stochastischen
Boden-
wasserregimes zur Ermittlung hydrologischer Standortbedingungen für Auenwälder
entlang der Mittelelbe. Dresdner Schriften zur Hydrologie, Institut für Hydrologie und
Meteorologie, Heft 1.
87
Numerical calculation of shear stress created by flushwaves in sewers;
Presentation of testsides in Offenbach/Germany and Lyon/France
Jörg Schaffner, Martin Oberlack
Hydromechanics and Hydraulics, Technische Universität Darmstadt,
Petersenstr. 13, 64287 Darmstadt / Germany,
Keywords: Numerical modeling, flush wave, sewer, rotary gate, shear stress
The aim of this abstract is to show the usage of three-dimensional numerical modeling of
the hydraulic description of flush waves in sewer channels. This will be done employing
examples from two different testsides. The first one is a reservoir sewer in
Offenbach/Germany and the second one is a sewer channel in Lyon/France.
The traditional way of cleaning sewer systems in Germany is the use of a high pressured
water jets handheld by workers. This method has drawbacks such as a high demand of
freshwater and energy. It creates large noise levels and the working conditions are
unacceptable. One alternative way of cleaning sewer systems is the flush cleaning with the
aid of various flushing devices which is becoming a common practice in Germany. There
are many different devices on the market available and their design rules depend mostly on
the practical experience by the developer. The gate in Offenbach is build by the company
Liwatech and is a fixed rotary gate of 1.8 m height in a 380m long reservoir sewer. The
project is run by the section of Hydromechanics and Hydraulics at TUD together with the
company Liwatech and includes measurements and the numerical modelling of flushwaves
with different initial conditions.
In Lyon a mobile flush gate (Hydrass gate) was installed in an egg-shaped sewer. The part
of the sewer which was investigated has a length of 590 m. This project was run by Prof.
Jean-Luc Bertrand-Krajewski [BK02]. Within our close collaboration he kindly provided
his data to us so it was possible to calculate this sewer numerically.
To gain a deeper insight into the design rules for flushing devices it is necessary to
understand the hydraulic principles of a flush wave. This can be achieved with
measurements of a flush wave along its way through the sewer channel and the observation
of the effects on the sediments in the sewer. At this point the hydromechanical part, the
numerical modelling, touches other disciplines. There is the urban drainage with the
surface runoff and solute transport which is responsible for the content of the sewer
deposits which should be washed away by the flush wave. Another close discipline is the
sediment transport itself which covers the mechanics of accumulation and remobilisation
88
of the deposits. At a broader view the rotary gate can be regarded as a control element for a
sewer system to detain the storm sewage and to run the sewage plant more efficiently.
After the calibration of a numerical model by measured results it is possible to calculate
many different scenarios in a sewer channel at lower costs compared to a physical model.
The behaviour and the effects of a flush wave can be observed using different boundary
conditions and it is possible to gain more general design rules for the flushing device
creating the wave.
Calculations with one or two dimensional models are easier and less time consuming then
calculations with a three dimensional model. However the initial stages of a flush wave can
be compared with a dam-break wave which has a three dimensional character. Turbulence
in the front wave which playes an important role concerning the cleaning effect of a flush
wave can be described best with three dimensional calculations using a turbulence model
such as the k-? model [LS72].
The discretisation of the reservoir sewer in Offenbach and Lyon was done with the Finite
Volume Method which is used in the most common CFD codes. In our case the StarCD
code was used. The three-dimensional Reynolds-averaged Navier-Stokes equation is
solved by using the k-? turbulence model for high Reynolds numbers. Using high Reynolds
number models requires an algebraic formula called wall function to represent the
distribution of velocity, turbulence, energy etc. at the boundary layers that form adjacent to
walls [NN93].
The calculation of the free water surface is modelled using the Volume of Fluid (VOF)
method which calculates the volumetric content of water and air in each cell of the
numerical grid [HN79].
The most important parameter in these calculations is the shear stress created by the flush
wave at the walls and the bottom of the sewer. The shear stress is the major parameter
which is responsible for the start of the transport of the sewer deposits when it critical
value for a certain sediment is exceeded. Temporal and local fluctuations of the flow
conditions caused by turbulence are also responsible for the start of the particle motion.
When the holding forces are exceeded, first single particles are unhinged and later
complete lumps of deposits are transported with the current. Due to its close link the shear
stress is calculated with the turbulent kinetic energy of the k-? turbulence model [R93].
One major problem when it comes to the boundary conditions of the model is the
estimation of the roughness of the flow domain depending on the sediments in the sewer
channel. A literature search was undertaken to find roughness values for different deposits
in sewers [D03]. To receive more realistic values of the roughness in both sewers it would
be necessary to undertake investigations such as taking samples of the deposits before the
flushing takes places.
89
Another important boundary condition is the rotary gate which swings into a horizontal
position to release the water body. The first estimation was to start off with a free standing
water body which breaks down due to pressure and gravity [SCH2003]. However when the
gate is in horizontal position the water runs above and under it which creates a different
hydraulic situation to the estimated free water body. The first step to overcome this
problem was to model the gate as a boundary condition in the horizontal position when its
rotation has ended. The second step would be to model the gate as a moving grid which is
very close to the real movement.
Using the latter techniques it is possible to calculate the shear stress created by the flush
wave through three-dimensional numerical modeling under different initial conditions and
give estimations about the cleaning effect of the flushing device. It is also possible to give
design rules to avoid an over- or underdimensioning of the flushing device.
References:
[BK02]
Bertrand-Krajewski, J-L. et al, Hydraulics of a sewer
flushing gate,
Proceedings Sewer Processes and Networks, Paris, France, 2002.
[D03]
Darmer, N.. Entstehung und Auswirkungen von Ablagerungen in
Mischwasserkanalisation, Studienarbeit am FG Hydromechanik und
Hydraulik, TU Darmstadt, 2003.
[HN79]
Hirt, C.W., Nichols, B.D., Volume of Fluid (VOF) Mehtod for the
Dynamics of Free Boundaries, Journal of Computational Physics, Vol. 39,
P. 201-225, 1981.
[LS72]
Launder, B.E., Spalding, D.B., Mathematical Models of Turbulence,
Academic Press, London and New York, 1972.
[NN93]
Nezu, I., Nakgawa, H., Turbulence in Open-Channel Flows, IAHR
Monograph series. A.A. Balkema, 1993.
[R93]
Rodi, W., Turbulence Models and Their Application in Hydraulics, A stateof-the-art review, IAHR Monograph series. A.A. Balkema, 1993.
[SCH2003]
Schaffner, J., Numerical simulation of a flush cleaning wave in a reservoir
sewer in Offenbach/Germany, Proccedings 18th European Junior Scientist
Workshop on Sewer Processes and Networks, Almograve, 2003.
90
Contaminated Megasites - a Problem for Water Resources Management?
Mario Schirmer1 and Arno Kaschl2
UFZ - Centre for Environmental Research Leipzig-Halle,
1
Dept. of Hydrogeology, Theodor-Lieser-Str. 4, 06120 Halle/Saale, Germany
2
Dept. of Groundwater Remediation, Permoserstr. 15, 04318 Leipzig, Germany
Keywords: megasites, integrated management, contamination, natural attenuation, socioeconomic considerations
Large-scale contaminated sites like Bitterfeld in Eastern Germany are characterized by a
regional contamination of soil, surface water and groundwater as a result of a long and
varied history of chemical production (Heidrich et al. 2004b; Heidrich et al. 2004a). While
the contaminants in soils and sediments mostly represent a localized problem, pollutants in
groundwater may spread to uncontaminated areas and endanger receptors like surface
water and drinking water wells. In addition to the direct risks for humans and the
ecosystem at the site, a widespread diffuse pollution may result from the transport of
contaminated sediment in surface waters. These megasites therefore constitute a major
problem for water resources management (Kaschl et al. 2002).
The problems for the remediatior may be so extensive that full success cannot be achieved
by conventional technologies for economical and technical reasons, while a complete
remediation of the sources is usually out of the question. Therefore, innovative risk-based
approaches have to be developed to deal with subsurface contamination at this scale. Such
approaches are widely propagated by the avant-garde of scientists and regulators
throughout Europe (CLARINET 2002). From the legislative point of view, the new water
framework directive (WFD) and the groundwater daughter directive (GWDD) have
introduced a new dimension of water resources management at the European level (Steiner
and Willand 2004). The GWDD is currently still under deliberation, but will most probably
allow for a limited tolerance of risk-based approaches for historical contamination such as
megasites.
Under certain circumstances such as quasi steady-state contaminant plumes that pose no
risk to down-gradient receptors, especially water resources, Natural Attenuation (NA) may
be included in the remediation strategy for megasites (Kaschl et al. 2004). This approach
implies accepting the fact that a stretch of the subsurface will remain contaminated and
may have limited future use. However, the magnitude of the problem and the potential
risks associated with megasites require a scientifically sound evaluation of the magnitude
of NA and its sustainability over extended time periods (several decades). Therefore, a
number of novel investigation methods must be applied to assess the temporal and spatial
91
aspects of NA and other remediation strategies (Kaschl et al. 2003). These include direct,
integral measurements of the contaminant mass fluxes at predefined control planes
downstream of contamination sources, involving multiple well pumping tests and a
mathematical inversion of the time-concentration curves measured during pumping. Longterm, time-integrated, multi-level chemical and toxicological monitoring of the
contaminant plume using dosimeters and toximeters are a way to quantify the toxicological
potential in the aquifer and its variation in time and space. Reactive-multitracer tests for
the quantification of the specific interactions between contaminants and aquifer matrix
give insight into the effective redox capacity. Using a lithocomponent-approach, the
natural capacity of the aquifer material to immobilise hydrophobic compounds can be
evaluated. Another powerful tool are stable isotope measurements for the integral
evaluation of natural biodegradation of organic contaminants in the aquifer. In any case,
numerical modelling of the processes has to be an integral part of the decision making
process at these megasites (Schirmer et al. 2004).
Apart from contaminated megasites, tremendous (socio)-economic efforts have been
directed towards the reduction of toxic industrial effluent releases into lakes and rivers,
toward efficient waste water treatment systems, and toward safe drinking and recreational
water supplies. Yet, pressure on water as one of our most vital resources continues to rise.
This requires research and input from numerous disciplines. Research is needed to develop
and introduce innovative investigation, monitoring, modelling and remediation approaches,
which will yield important new insights and cost savings. However, input is also required
regarding economic considerations as well as regulatory and public acceptance through an
iterative and ongoing process. Applying state-of-the-art knowledge and developing new
approaches, the problem of contaminated megasites can and must be vigorously addressed
to protect water resources. Bitterfeld will be used as an example, where modelling,
decision support and management tools are being developed in a hands-on, learning by
doing - process.
CLARINET:
Sustainable management of contaminated land: An overview. Editor: Vegter, J., Lowe, J.,
& H. Kasamas, Austrian Federal Environment Agency, Vienna, Austria, 2002.
HEIDRICH, S., SCHIRMER, M., WEISS, H., WYCISK, P., GROSSMANN, J. KASCHL,
A.:
Toxicological relevance of regional contaminated aquifers and remediaton options
(Bitterfeld case study). Toxicology (In Print), 2004(a).
92
HEIDRICH, S., WEISS, H., KASCHL, A.:
Attenuation reactions in a multiple contaminated aquifer in Bitterfeld (Germany).
Environmental Pollution 129, 277-288. 2004(b).
KASCHL, A., HEIDRICH, S., WEISS, H.:
EU-Projekt WELCOME: Prävention und Sanierung der Grundwasserkontamination an
großflächigen Standorten. altlasten spektrum 3, 111-119. 2002.
KASCHL, A., HEIDRICH, S., WEISS, H., RÜGNER, H., TEUTSCH, G., DEJONGHE,
W., VANBROEKHOVEN, K., DIEHLS, L., ZABOCHNICKA-SWIATEK, M.,
MALINA, G., KOCH, L., KREIMEYER, R.:
Technical Guideline (Catalogue of Methodologies) for the Evaluation and Implementation
of MNA Regarding the Management of Multiple-Contaminated Megasites. EU-Project
WELCOME, Workpackage 6, Deliverable 6.2. Leipzig, Centre for Environmental Science
(UFZ). 121 pages. 2003.
KASCHL, A., RÜGNER, H., WEISS, H.:
Integration von MNA in die Sanierung von großflächig kontaminierten Standorten (am
Beispiel Bitterfeld). altlasten spektrum 2/2004, 79-84. 2004.
SCHIRMER, M, DAHMKE, A., DIETRICH, P., DIETZE, M., GÖDEKE, S., RICHNOW,
H. H., SCHIRMER, K., WEISS, H., TEUTSCH, G.:
Natural Attenuation Research at the Contaminated Megasite Zeitz. Journal of Hydrology
(Submitted), 2004.
STEINER,N., WILLAND,A.:
Rechtliche Rahmenbedingungen für die Altlastensanierung unter dem Einfluß des EUWasserrechts. altlasten spektrum 1/2004, 40-46. 2004.
93
Meeting the challenges of the blue revolution: increasing the irrigation
efficiency with soft-computing optimisation methods
Niels Schütze, Thomas Wöhling, Michael de Paly, Gerd H. Schmitz
Institute of Hydrology and Meteorology
Dresden University of Technology, Germany
Keywords: surface/subsurface flow, irrigation efficiency, artificial neural
networks, genetic algorithm
Water is a limited resource and the dramatically increasing population requires a
significant increase in food production. The enormous challenge to feed in 2030 additional
2 billion people in the world can only be met by an expansion of the irrigated agriculture in
developing countries (WWDR, 2003). Water consumption will increase by 14 percent in
the next thirty years while some developing countries are already using 40 percent of their
renewable freshwater for irrigation. Thus, the FAO (2003) calls for a “blue revolution” in
water management in order to improve the generally low water use efficiency in irrigation
of about 38%.
A number of tools have been developed for managing water supply in irrigation. They
operate with satisfactory results. However, the on-field irrigation efficiency, especially in
surface irrigation, is still low. In this presentation we propose an new strategy for
optimising the water application efficiency in furrow irrigation systems. This strategy
considers the scheduling parameters, i.e. when and how much to irrigate, as well as the
control parameters of each water application, i.e. the inflow and the cutoff time, for
improving both, crop yield and water use efficiency. Due to the fact, that these parameters
are interconnected, their evaluation for attaining an optimal water application efficiency
has to be executed simultaneously. However, up to now, there is no such optimisation
strategy. The current methodologies of classical optimisation encounters two fundamental
problems. Firstly, due to the complexity they only consider parts of the optimisation
problem and/or simplify the latter by linearisation or rough empirical description of the
relevant processes. Secondly, even the remaining simplified algorithms are much too
complicated for a broad application in rural areas.
A reliable determination of the irrigation control parameters requires a coupled physically
based model, which includes interconnected modules describing the processes of
surface/subsurface flow, evaporation, transpiration and plant growth. Thus, for the
development of the furrow irrigation model (FIM) a cooperation of different disciplines
was essential. The presentation demonstrates, that the application of standard softcomputing methods like artificial neural networks (ANN) and genetic algorithms (GA) for
optimisation tasks in irrigation calls for a tailored and customized solution and thus, for an
94
interdisciplinary cooperation between computer scientists, hydrologists, agricultural
engineers and - after a further progress of the project also economists and social scientists.
Standard general-purpose techniques fall short when an optimisation problem is more
complex or restrictions of real-life applications like computer power and availability of
input data are existent.
The considered optimisation problem of finding optimal control parameters in furrow
irrigation is very “hard” in the sense that the target function has many locally optimal
solutions and thus, finding the best global solution is not possible
with classical
deterministic optimisation techniques. For this reason, a stochastic optimisation technique
(GA) is employed for always finding a near-optimal solution of the schedule (when and
how much to irrigate) within reasonable computation time.
In order to reduce the complexity of the complete optimisation problem the determination
of the control parameters of each water application on the field (the inflow and the cutoff
time) is realised by an artificial neural network (ANN) based on self-organized maps
(SOM). A new SOM architecture was developed, which after a unique training, allows
performing simulation tasks as well as solving inverse problems: the Self-Organizing Map
with Multiple Input/Output option (SOM-MIO). This architecture combines the superior
clustering capability of the Standard SOM with a linear interpolation scheme in order to
generate continuous output information. The SOM-MIO approximates the inverse solution
of the coupled numerical surface/subsurface flow model and thus, enormously speeds up
the overall performance of the complete optimisation tool. Furthermore, the robustness and
stability of ANN-based applications could prove to be useful in numerical schemes, such
as nonlinear optimisation or Monte Carlo methods.
The presentation shows an application of the new optimisation strategy to a deficit
irrigation problem in furrow irrigation. The results will compared with those of classical
deterministic optimisation techniques and real-time control systems. Finally, the
presentation discusses the characteristics of both new developed soft-computing
optimisation methods, special developments and problems of the application. In addition,
an outlook of the underlying research project is given which needs a further development
in the issues of economic and social aspects of rural systems towards a sustainable
agricultural water management.
95
References:
WWDR, 2003
World
Water
Assessment
Programme: THE
WATER DEVELOPMENT REPORT: Water for
for Life, UNESCO Publishing, 2003
UN
WORLD
People, Water
FAO, 2003
Jacques Diouf: Agriculture, food security and water : Towards a
blue revolution, OECD Observer (http://www.oecdobserver.org), 2003
96
The variability of the hydrological response of highly disturbed and
forested catchments in the Spanish Central Pyrenees
Manuel Seeger1 , Noemí Lana-Renault2 , David Regüés2 , José María García-Ruiz2
1
2
Physical Geography, University of Trier, D-54286 Trier, Germany
Instituto Pirenaico de Ecología (CSIC), Campus de Aula Dei, Avda. de Montañana 1005,
E-50080 Zaragoza, Spain
Mountains are in Mediterranean environments the most important areas for generating
water resources. They behave as "islands" of humidity in comparison with the plains,
yielding most of runoff drained by the rivers (Thornes, 1999), which is commonly used for
irrigation. These areas have been intensively used and transformed by man for long
periods, but during the last decades, severe changes in society have lead to an
extensification of land use, and thus the characteristics of the headwater areas are changing
substantially. Most of the former farmland, occupying even steep slopes, has been
abandonned during the 20th century and the landscape is affected now by plant
recolonisation processes (Molinillo et al., 1997), depending on the intensity of the actual
land-use (Ries et al., 2000). The soils of these former fields are strongly degraded, showing
low to very low infiltration capacities and drainage, especially near the streams, but on
predominantly undisturbed areas they show clear evidences of regradation of their physical
properties (Seeger, 2001). Such an evolution introduces necessarily changes in many
hydrological parameters (Gallart et al., 1994). Recent studies (García-Ruiz et al., 2001,
Beguería et al., 2003) indicate that, on a long term, water ressources are decreasing more
rapidly than the annual precipitation amounts. This decrease has to be attributed to the
changes in the land use, and is reflected also in changed stream morphology or recurrence
of flood events (López-Moreno et al., 2002)
The comparision of the hydrological behaviour of two experimental catchments in the
Central Spanish Pyrenees, which have been historically managed under different land uses,
allows us to understand the effect of land use changes and the consequences of land
management on runoff: 1. the Arnás catchment has been cultivated for centuries and
abandoned about four decades ago; 2. the San Salvador catchment keeps a dense forest
cover, without evidence of intense land uses in the last centuries. For this, the data of the
period between 1999 and 2002 is analysed 1. based on single events and 2. reagarding the
summarised runoff generation during complete hydrological cycles.
The analysis of the rainfall characteristics shows good coincidence between the catchments
at an event and long term basis. The first third of the investigated period can be considered
as normal, with a total precipitation amount of about 1000 mm a-1 , the second third has to
be considered during a period of about 200 days as very humid, summarising more than
1200 mm a-1 . The third period is, with a precipitation lower than 850 mm clearly dryer.
As expected, the runoff generation characteristics are very different in the formerly intensive used Arnás catchment and the forested San Salvador catchment. The highly disturbed
97
Arnás catchment shows, a relatively simple response scheme, reproducing in its
hydrograph the patterns of rainfall structure. This can be explained with the predominance
of superficial runoff processes in areas near the stream. This limitation of runoff generating
areas is supported by the extreme fast response of the catchment to precipitation. Runoff is
generated in general by saturation excess overland flow, but under certain conditions
Hortonian overland-flow may also produce fast runoff peaks (Seeger et al., 2004). This
behaviour is supported by the negative correlation between the antecedent rainfall and the
discharge parameters and the low hydraulic conductivity of the soils in the catchment
(Seeger, 2001)
The up to 4 times slower reaction of San Salvador to precipitation is directly related to the
dense vegetation cover and the interception processes related to it – water retention in the
vegetation cover, attenuation of the rainfall intensity and distortion of the rainfall structure
and duration. The soil characteristics, its well developed water storage capacity and high
infiltration capacity, contribute as well to the retarded output of the rainfall. But this water
retention capacity is limited, and with very moist conditions, which are reflected by events
with a high antecedent runoff, and linked to high antecedent precipitation the catchment
may respond as fast as the catchment with shrub-cover.
The differences between both catchments can be observed also during whole hydrological
cycles. The runoff in the Arnas catchent follows the seasonal as well as the interannual
variability of precipitation. It maintains a predominantly constant runoff coefficient. The
San Salvador catchment shows a very low runoff coefficient during the first third of the
studied period and no runoff during almost all the last third. It scarcely reflects the
variability of precipitations. But during 2001, the second period, the runoff increases
exceeding the values of the disturbed Arnas catchment. This can be observed at every
rainfall runoff event, where the recession curve of the hydrograph stays at superior levels
than at the beginning of the event for days.
Despite of the landscape heterogeneity of the Arnás catchment (with very different plant
covers and soils) the runoff generation processes are here much more homogenous than in
the forested catchment. The stormflow discharges are linearly dependent on the
precipitation and the hydrographs suggest no complicated interactions between different
ambients inside the catchment. Nevertheless, the antecedent soil moisture conditions seem
to have an influence on runoff generation processes. The homogenous forested San
Salvador catchment is ruled by more complicated runoff generating processes, caused by
the interaction of different compartments with different water storage and response
characteristics. Especially the hysteretic behaviour of water storage and outflow of the
soils inside the catchment are responsible for the strong differing runoff under changing
climatic conditions.
This implies consequences for the water resources management in these areas. Highly
disturbed catchments reflect even some decades after agriculture abandonment the
degradation of soils and plant cover. Forested catchments tend to decrease water ressources
with decreasing precipitations, like they are observed during the the last decades. Minor
floods are damped or even completely absorbed. But during high precipitation periods the
98
forested catchment produces high runoff yields, and it has to be expected, that under these
conditions, major flood events may not be damped.
References
Beguería, S., López-Moreno, J.I., Lorente, A., Seeger, M. & García-Ruiz, J.M. (2003):
Assessing the effects of climate oscillations and land-use changes on streamflow in the
Central Spanish Pyrenees. Ambio, 32(4): 283-286.
Gallart, F., Llorens, P. & Latron, J. (1994). Studying the role of old agricultural terraces on
runoff generation in a small Mediterranean mountainous basin. Journal of Hydrology,
159: 291-303.
García Ruiz, J.M., Beguería Portugués, S., López Moreno, J. I., Lorente Grima, A. &
Seeger, M. (2001): Los recursos hídricos superficiales del Pirineo aragonés y su
evolución reciente. Geoforma Ediciones, Logroño, 192 pp.
López-Moreno, J.I., Beguería, S. & García-Ruiz, J.M. (2002): Influence of the Yesa
reservoir on floods of the Aragón River, Central Spanish Pyrenees. Hydrology and
Earth System Sciences, 6(4): 753-762.
Molinillo, M., Lasanta, T. & García-Ruiz, J.M. (1997). Managing mountainous degraded
landscapes after farmland abandonment in the Central Spanish Pyrenees. Environmental
Management, 21: 587-598.
Ries, J.B., Marzolff, I. & Seeger, M. (2000). Der Einfluss von Beweidung auf die
Vegetationsbedeckung und Bodenerosion in der Flyschzone der spanischen Pyrenäen.
In: G. Zollinger (Editor), Aktuelle Beiträge zur angewandten physischen Geographie
der Tropen, Subtropen und der Regio Trirhena. Freiburger Geographische Hefte. Institut
für Physische Geographie, Albert-Ludwigs-Universität Freiburg i. Br., Freiburg i. Br.,
pp. 167-194.
Seeger, M. (2001). Boden und Bodenwasserhaushalt als Indikatoren der Landdegradierung
auf extensivierten Nutzflächen in Aragón, Spanien. Freiburger Geographische Hefte,
63: 184 p.
Seeger M., Errea , M. -P., Beguería, S., Arnáez, J., Martí, C. & García-Ruiz, J. M. (2004).
Catchment soil moisture and rainfall characteristics as determinant factors for
discharge/suspended sediment hysteretic loops in a small headwater catchment in the
Spanish Pyrenees. Journal of Hydrology, 288, 3-4, 299-311.
Thornes, J. (1999). The hydrological cycle and the role of water in Mediterranean
environments. In: Rural planning from an environmental systems perspective (F.B.
Golley & J. Bellot, eds.), Springer, New York pp. 85-107.
99
Developing MODELLING tools for management of urban
groundwater resources
Leif Wolf
Department of Applied Geology, Karlsruhe University, Germany,
E-mail: [email protected],
Keywords: Urban groundwater, integrated model, sewer system, marker species, urban
water balance
The management of urban groundwater resources is often neglected as the water quality is
presumed to be objectionable or endangered. However, also the quantitative aspects of
urban groundwater management can be of significane to the urban community. Especially
the coupling between urban water supply and drainage systems on one hand and the urban
groundwater has led to several problems in many cities world-wide. The most common
problems are:
-
rising groundwater levels (example effects: cellar flooding, increased infiltration of
water into the sewer systems)
-
declining groundwater levels (example effects: land subsidence, damage to
buildings, drying of groundwater dependent aquatic habitats)
-
water quality deterioration (example effects: health risks, use restrictions)
A primary goal of the studies undertaken in the EU-funded AISWURS project (Assessing
and Improving the Sustainability of Urban Water Resources and Systems) is to combine
models for urban water infrastructure and groundwater models. By applying a chain of
separate models (surface runoff, drainage systems, unsaturated zone, saturated zone) it is
tried to estimate the urban groundwater recharge and all associated mass fluxes in the
urban environment.
The uppermost model applied in the AISUWRS system is the Urban Volume and Quantity
model (UVQ) developed by CSIRO, Australia. Its main input parameters are climate,
urban sealing coefficients and water consumption characteristics. Based on these
parameters the volumes of wastewater and stormwater flows in the sewers as well as the
water content of the unsaturated zone are calculated. This information is later fed into a
specially constructed Pipe Leakage Model (PLM) which estimates the amount of
exfiltration or infiltration for the sewers based on defect distributions observed with CCTV
cameras. The information is then passed to unsaturated zone models which calculate travel
times to the groundwater table. The last recipients are then numerical groundwater
transport models which try to predict the distribution of selected trace substances in the
100
urban aquifer. The cities of Rastatt (SW-Germany), Doncaster (UK), Ljubljana (Slovenia)
and MtGambier (Australia) have been selcted as case study sites.
The protection of urban groundwater ressources is strongly supported by a DFG-research
group project running in Karlsruhe on the risk potential of leaky sewers for soil and
groundwater. For this impact assessment the city of Rastatt (SW-Germany) has been
chosen as case study site. In Rastatt it has been attempted to use a known spatial
distribution of sewer defects together with the hydrogeological boundary conditions for the
estimation of the sewer-groundwater interaction. In a first step groundwater levels were
compared with the sewer depth in order to mark sewers that are prone to infiltration and
sewers prone to exfiltration. Most of the sewers in the Rastatt city centre are permanent
above the groundwater table and therefore prone to exfiltration. Numerical groundwater
models have been constructed using the finite element code FEFLOW. In order to validate
the simulations, several marker species screenings have been performed at up to 45 wells
in the aquifer underlying the city area. High concentrations of iodated x-ray contrast
media, which can be considered as highly specific for sewage, have been found in the
urban aquifer.
101
Modelling of nitrate transport and turnover in a small lowland
catchment
Gunter Wriedt, Helmut Geistlinger, Michael Rode
UFZ Environmental Research Center Leipzig-Halle GmbH, Department Hydrological
Modelling, Brückstr. 3a, 39114 Magdeburg,
[email protected]
Keywords: Catchment, Diffuse Pollution, Denitrification, Groundwater, Modelling,
Nitrate, Nitrogen, Reactive Transport
Diffuse nitrogen pollution is a threat for ground and surface waters. Observed nitrogen
loads in surface waters often do not reflect the actual input situation. This apparent
retention of nitrogen can be explained by various chemical transformations and
hydrological processes in soil and groundwater. The quantification of these processes in
the field is difficult and models are needed to evaluate the interaction of these processes in
space and time. The objectives of this work (Wriedt 2003, 2004), which was funded by the
German Research Foundation (DFG), are
-
to develop a specific modelling approach by combining selected modelling tools
allowing for simulation of N-transport and turnover in soils and groundwater of
lowland catchments on various spatial scales (lysimeter, transect and catchment).
-
to study interactions between catchment characteristics (such as landuse
distribution, geochemistry, channel and river system) and nitrogen transport.
Special attention is paid to potential N-loads to surface waters.
The modelling approach combines various submodels for water flow and solute transport
in soil and groundwater: The soil model mRISK-N combines a soil water model based on
the storage approach SIMPEL (Hörmann 1998) with the analystical soil nitrogen model
RISK-N (Gusman, Marino 1999). The soil model is used to calculate groundwater recharge
and nitrate leaching as input data for subsequent groundwater modelling. Groundwater
flow is simulated using MODFLOW (McDonald, Harbaugh 1988), groundwater solute
transport is simulated using RT3D (Clement 1997). A reaction-module was developed to
simulate various chemical processes in groundwater, such as degradation of organic matter
by oxygen, nitrate, sulphate or pyrite oxidation by oxygen and nitrate. The reaction-module
is implemented as a user-defined reaction-module of the RT3D code.
We present a modelling study focussing on nitrate transport in a lowland catchment. The
study was based on data from the Schaugraben catchment, which is located close to
Osterburg, Altmark in the north of Saxony Anhalt. The study catchment is a pleistocene
102
lowland catchment of 20 km², with mainly agricultural use. A distributed soil simulation
was carried out for the study area to provide groundwater recharge and nitrate leaching as
input data for subsequent groundwater simulations on catchment and subcatchment scale.
Distributed input from the soil and conservative as well as reactive groundwater nitrogen
transport simulations were combined at this scale, focussing on interactions between
spatial distribution of N-sources and N-discharge into the surface water system.
The 3-dimensional catchment and subcatchment simulations show the spatial and temporal
development of substance concentrations in the model domain and allow the identification
of impact-relevant areas. Basic results taken from the simulation runs are i) the distribution
and turnover of solutes (e.g. nitrate, sulphate, DOM) and immobile components (pyrite,
SOM) in space and time, ii) the development of average seepage concentrations as a
measure for baseflow contribution to surface water loads, and iii) the spatial distribution of
seepage fluxes and seepage concentrations within the channel system. The distribution of
nitrate in the catchment is strongly related to the distribution of inputs, transport properties
of the aquifer (and the resulting flow paths and travel times), and the distribution of
reactive substances involved in nitrogen turnover. Seepage loads into the surface water
system are spatially distributed and depend on the spatial arrangement of spurce areas
related to transport paths and the drain system. A comparison to observed nitrate
concentrations in the Schaugraben drain channel suggests that groundwater contribution
can not be the only source of nitrate to the surface water system, even for the conservative
transport case. A significant contribution of other sources, such as drain flow and direct
inputs of nitrate through fertilization, needs to be taken into account in order to explain
elevated nitrate concentrations during winter.
The modelling approach is capable of simulating the fate of nitrogen compounds in
lowland catchment systems. The distributed approach and the implementation of a full
reactive groundwater transport model facilitated the study of spatial and geochemical
interactions. The modelling system is well suited for a variety of tasks, for example i) the
identification of source and sink areas of nitrate pollution, allowing targeted measures for
ground- and surface water protection and design of experimental studies, ii) investigation
of system response to management measures or landuse changes using scenario
simulations and iii) it is an aid in interpretation of observed data, as it allows to integrate
local observations into a spatial and temporal framework.
The prognostic value of the model strongly depends on the possible spatial resolution and
the quality of input data. In this study it was shown how various processes interact at
different scales, but uncertainties of input data need to be taken into account when
interpreting model results for the specific study area.
However, model results allow to improve and to target field studies and monitoring, which
in turn allow improvement of input data and enhance the prognostic value of the model.
Not all potential sources of nitrate relevant for surface water pollution are yet included in
103
the modelling system. Suggested model extensions are the consideration of drain flow and
of surface water and hyporheic zone processes. Further simulations should focus more
closely on the investigation of interactions between the spatial distribution of N-loads,
reactive compounds and flow paths. More research is necessary to quantify the various
chemical processes in the field. These investigations can not be confined to nitrogen
species, but all elements and compounds taking part in turnover reactions have to be taken
into account as well.
References
CLEMENT, T.P. (1997): A modular Computer Code for Simulating Reactive Multispecies
Transport in 3-Dimensional Groundwater Systems, Richland, WA.
GUSMAN, A.J., MARINO, M.A. (1999): Analytical Modelling of Nitrogen Dynamics in
Soils and Groundwater. Journal of Irrigation and Drainage Engineering 1999(11/12),
330-337.
HÖRMANN, G. (1998): Simpel - Speichermodelle zum Bodenwasserhaushalt.
Dokumentation zu Simpel 2, http://www.pz-oekosys.unikiel.de/~schorsch/simpel/index.htm.
MCDONALD, M.G., HARBAUGH, A.W. (1998): A modular three-dimensional finitedifference ground-water flow model. Washington, USA.
WRIEDT, G. (2003): Integrated Modelling of Nitrogen Transport and Turnover in
Lowland Catchments of Northern Germany, In: Institute Groundwater Management
TU Dresden (2003): Diffuse Input of Chemicals into Soil and Groundwater Assessment and Management, Workshop 26-28.02.2003 in Dresden, Proceedings
Institute for Groundwater Management 3, p89.
WRIEDT, G. (2004): Modelling of nitrogen transport and turnover during soil and
groundwater passage in a small lowland catchment of Northern Germany. Dissertation,
University of Potsdam.
104
Economic valuation,
Economic tools and Management of water resources
Economic valuation,
Economic tools and
L. Breuer, J. A. Huisman, B. Weinmann, T. Wronka, N. Steiner: Deriving EcologicalEconomic Trade Offs for Land Use Change Simulations with ITE2 M.
A. Dehnhardt: The replacement value of riparian wetlands along the river Elbe as nutrient
sinks.
EbroAgua Working Group, E. Petersson: Ebro Water, geosciences and sustainability –
Water from northern to southern Spain?
M. Grossmann: Stakeholder involvement and economic assessment of management
strategies for wetlands in a river basin context: Case study from the Spree-Havel river
basin.
K. Hennrich: Interdisciplinary assessment of suitable measures to minimise P input in the
Weiße Elster river.
A. Klaphake: Congested waters: how to conceptualise and measure recreation benefits and
the influence of visitor use levels on peoples' satisfaction?
H. Koch: Integrated water resources management in the Spree River catchment in the
context of global change.
H. Kreibich: Estimation of flood losses in Germany, Actual Data from the Elbe and
Danube floods in August 2002.
F. Messner: Integration of Economic Evaluation into the Water Resources Model
WbalMo.
J. Meyerhoff & A. Dehnhardt: A benefit-cost analysis of extending riparian wetlands
along the river Elbe.
E. Petersson: Multi-criteria decision analysis in sustainability assessment: The large dam
context.
C. Schleyer: Economics and Ecological transformation processes in Eastern Germany
Water Management Regimes.
H. Tauchmann: Innovativeness in the German Waste Water sector – a micro-econometric
approach.
Economic valuation,
105
Deriving Ecological-Economic Trade Offs for Land Use Change
Simulations with ITE2M
Lutz Breuer1 , Johan A. Huisman1 , Bernd Weinmann2 , Tobias Wronka3 ,
Nathalie Steiner4
1
ILR, Institute for Landscape Ecology and Resources Management; 2 Institute of
Agricultural and Food Systems Management; 3 Institute of Agricultural Policy and Market
Research; 4 Biometry and Population Genetics
Justus-Liebig-University Gießen, Germany
E-Mail: [email protected].
Keywords: integrated assessment, model network, ecological-economic trade offs
European agricultural regions are subject to land use transformation mainly due to changes
in economic and political conditions. Besides agricultural production, landscapes provide
other services, such as biodiversity, water supply or nutrient cycling (Costanza et al. 1997);
a fact that is tackled within the European Agenda 2000. Hence, changes in land use have to
be looked at with a multi-functional view of landscapes. The multi-functionality of
landscapes plays the key role in the Cooperative Research Centre SFB 299. Within the
SFB 299, land use concepts for peripheral regions are developed. It is hypothesized that
land use and management – if spatially adapted to site conditions – can lead to an optimal
benefit, both from an economic and ecological point of view. Detailed knowledge of the
underlying processes is necessary to estimate the reactions and consequences of land use
changes. Owing to its size, field investigations cannot be conducted on the landscape scale.
Models are used to overcome that problem, defined as simplified descriptions of the
complex processes found in reality. Calibrated and validated models can be used to
investigate land use changes. The model network ITE2 M (Integrated Tools for Ecological
& Economic Modelling) has been developed in the SFB 299. The general frame of ITE2 M
as well as examples of applications are described in the following.
ITE2 M is an integrated model approach combining agro-economic, eco-hydrological,
biodiversity and socio-political models. The aim of ITE2 M is to provide a tool to analyse
regional land use and management concepts and their effects on economic and ecological
objectives.
Within the integrated model network the agro-economic model ProLand (Prognosis of
Land Use) predicts the spatial allocation of agricultural and forestal land use systems on
the basis of natural, economic, political and social conditions. Land rent is used as a
measure of the potential economic performance, defined as the sum of monetary yields
including all subsidies minus input costs. Land rent maximizing behaviour by land users
for any parcel of land is assumed. Land rent is calculated based on the spatially distributed
106
Economic valuation,
biogeophysical characteristics in a region. Estimated yield is based on Liebigs law and
further site conditions (slope, field size). ProLand yields two types of model output: (i) a
map displaying the spatial distribution of land use systems, (ii) aggregated key indicators
to characterise the economic performance of the estimated land use.
The Soil Water and Assessment Tool (SWAT) is used to quantify changes in water fluxes
and water quality as a result of land use and management changes. Based on a DEM the
catchment is divided into spatially located sub-catchments. Water is routed between them.
Each sub-catchment consists of a set of non-localized Hydrological Response Units
(HRU). Each HRU is defined by a certain combination of soil type and land use. Multiobjective automatic calibration techniques are applied to calibrate the model, taking into
account available information on discharge of the main river and tributaries. Various
model components to describe N- and P-fluxes, erosion and sediment yields are included in
SWAT, which will in future be used in the framework of ITE2 M.
Effects of land use changes on biodiversity are studied with the cellular automaton
ANIMO. The model assumes that each habitat type has its own species inventory
depending on land use type as well as environmental, regional and historical constraints.
Habitat generalists and specialists are taken into account. Species number per habitat are
derived from field investigations. Cells of the cellular automaton interact with
neighbouring cells in the way that all habitat generalists of the central cell disperse into the
four next surrounding cells. Hence, the number of species in a cell (? -diversity) is affected
by the species inventory surrounding the cell. This in turn is influenced by the dissimilarity
between cells (? -diversity). The product of both is the overall landscape diversity (?diversity).
The socio-economic valuation framework CHOICE is finally applied to conduct extended
cost-benefit analyses of multi-functional landscapes. The extension of traditional costbenefit analyses is necessary as the benefits of environmental services are often ignored
due to their public goods properties. In CHOICE stated preferences methods like the
contingent valuation method and the choice experiments are used to determine the benefits
of the various landscape services (e.g. biodiversity, landscape aesthetics or water quality)
for the regional population. In addition with the cost and benefit components of the private
goods an improved assessment of different land use options becomes possible.
The low mountainous Dill catchment (692 km2 ) in Germany is used in a case study. It is a
peripheral region characterised by low agricultural potential. As a result, the fraction of
fallow land is already larger than anywhere else in Germany, and more abandonment of
agricultural land is predicted for the near future. Different land use scenarios have been
developed within the SFB 299 (Table 1).
Economic valuation,
107
Table 1: Land use scenarios investigated in the SFB 299
Land use scenario
Description
Grassland bonus
Support of pastoralism to counteract
land abandonment
Field size
Larger field sizes promote low
machinery costs
Outwintering suckler
All-year round extensive rangeland
cow
farming to reduce investment costs
Further description
Weber et al. 2001
Fohrer et al. 2002
Breuer et al. 2003
All scenarios have in common, that land use compositions vary extremely. One can find
heterogeneous landscape patterns which are composed of a well-balanced mixture of
cropland, pasture and forest. Nearly monocultural structures are also predicted, either
dominated by forests or pastures. In general, agro-economic measures such as grain
equivalent production, added value or employment rate increase with an increase of
extensive pastoralism in the region. Faunistic and floristic biodiversity tend to decrease
with more homogenous landscape patterns. Water fluxes are also affected by land use
changes. Discharge for example is reduced with an increasing share of pasture and
decreasing share of cropland, as annual evapotranspiration of grassland species is higher as
compared to crops. As the different land use scenarios are the basis for all calculated
economic and ecological objectives, one can compile trade-off and win-win situations.
Finally, the public response to the predicted changes in the economic, biological and
hydrological objectives are evaluated. It can be shown, that the environmental landscape
services provide important benefits for the regional population. The society‘s willingness
to pay for high water quality and the prevention of a forest dominated landscape are
especially high. Estimated cost-benefit relations and preferences of land users could be
used to support decision makers.
BREUER, L., et al.: Eco-hydrologic and economic trade-off functions in watershed
management. Proceedings 2. SWAT Conference, 6 pp, 2003.
COSTANZA, R. et al.: The value of the world´s ecosystem services and natural capital.
Nature 387: 253-260, 1997.
FOHRER, N., MÖLLER, D., STEINER, N.: An interdisciplinary modelling approach to
evaluate the effects of land use. Phys Chem Earth B 27: 655-662, 2002.
WEBER, A., FOHRER, N., MÖLLER, D.: Long-term land use changes in a mesoscale
watershed due to socio-economic factors - effects on landscape and functions. Ecol
Model 140: 125-140.
108
Economic valuation,
The replacement value of riparian wetlands as nutrient sinks
– A case study of the river Elbe –
Alexandra Dehnhardt
Institute for Ecological Economic Research (IOEW), Potsdamer Str. 105, D-10785 Berlin,
[email protected]
Keywords:
river basin management, replacement cost approach, nutrient retention,
benefit-cost analysis
Flood plains are considered as highly-productive sites with a high ecological value. The
different services provided by wetlands, derived from their hydrological, biogeochemical
and ecological functions, contribute to the welfare of society. The increasing loss of
wetlands (local as well as world-wide) is recognised more and more as a serious problem
in the public perception. Thus, there is a growing interest and necessity for the
quantification and evaluation of these services. Furthermore, assessing the (monetary)
benefits of restoration measures can help meet the requirements of an integrated,
ecosystem approach to the management of land and water resources as it is applied by the
European Water Framework Directive (WFD) (MEYERHOFF & DEHNHARDT 2004).
Within a benefit-cost analysis of extending riparian wetlands along the river Elbe the
indirect use value of floodplains as nutrient sinks, which refers to the biochemical function
of wetlands, was estimated in addition to a Contingent Valuation which was used to
determine the value that would arise from the ecological function ‘biodiversity protection’.
Indirect use values as well as use and non-use values people may derive from restored
floodplains are different elements of the Total Economic Value (TEV) which is a
conceptual framework widely used for valuing natural resources. The main part of the
restoration program regarded within the benefit-cost analysis comprises the regaining of
15,000 ha flood plains by dike relocations at different sites along the Elbe (DEHNHARDT &
MEYERHOFF 2002).
Many studies which aim to assess the nutrient retention capacity of wetlands have shown
that wetlands in general as well as river systems and flood plains in particular have a
substantial potential for the improvement of water quality. To assess these benefits, the
indirect use values derived from the nutrient removal in floodplains, the Replacement Cost
Approach (RCA) was used. In general, using the RCA the monetary value of a natural
resource is assessed by how much it will cost to replace or restore it after it has been
damaged. As a reference condition usually an environmental quality level is considered,
e.g. a defined water quality. If the ecosystem is damaged and therefore could not provide
this quality, suitable alternative measures have to be taken into account, e.g. the building of
Economic valuation,
109
sewage treatment plants. Thus, if specific functions of an ecosystem can alternatively be
achieved by a technical substitute, then the costs of this substitute to replace this function
can be regarded as the economic value of the ecosystem’s service.
The nutrient retention function refers to the self purification potential of streams, which
depends on the river’s structure and its buffer strips. Due to the enlargement and the
restoration of flood plains the stream velocity is affected and thus, as a result of a higher
water residence time, the denitrification rate increases. The amount of the nitrogen
retention of restored flood plains is mainly affected by the additional flooded area as well
as the denitrification rate. Hence, one of the assumed benefits of dike relocation is an
increase of nitrogen retention in the river system.
The RCA generally requires the three following steps:
1. Identification and quantification of the nitrogen reduction effects
(estimating the ecosystem function),
2. Definition of the reference scenario (i.e. the substitute and costs), and
3. Economic valuation (assessing the ecosystem service).
The amount of the nitrogen retention of restored flood plains is mainly affected by the
additional flooded area as well as the denitrification rate. In the case of flood plains, the
surface area available for nitrogen reduction is primarily determined by the inundation
dynamic of the river, i.e. the duration and frequency of flooding, as well as the morphology
of the flood plain surface. As a result of the enlarged area with its typical structure, the
running velocity decreases as an important parameter known to influence the
denitrification. Accordingly, the results vary substantially, depending on site-specific
conditions that have to be taken into account. Therefore the nitrogen reduction effect was
quantified for two defined relocation sites at the Elbe, in Sandau and Rogätz, in an initial
step because of the availability of site-specific data. The results show that the total
available surface area as a result of dike relocation would be only inundated with a HQ
100. For a mean annual flood discharge the retention area is smaller – depending on the
site conditions. To quantify the nitrogen retention within the flooded area resulting from
the decreased running velocity, a statistical model from BEHRENDT & OPITZ (2000) was
used. Within this model the nitrogen retention rate is determined according to the increased
hydraulic load as a result of structural changes in the regarded areas. The total effects for
the additional retention area in Sandau adds up to a total nitrogen retention of 650 t/a and
for Rogätz, 40 t/a. Subsequently, the effects for the remaining locations were estimated on
the basis of different denitrification rates found in the literature.
In the next step, the substitute and its marginal costs were determined. Two different
alternatives for the service ‘improvement of water quality’ were considered: the building of
sewage treatment plants (with assumend marginal costs of waste water treatment of
110
Economic valuation,
7,7 €/kg N) and measures to reduce nitrogen emissions from agriculture (with 2,5 €/kg N
as a mean of the marginal costs of avoidance of nitrogen loads by agricultural measures).
Finally, the monetary value of regained floodplains was estimated by assessing the
replacement costs to provide the same service (in kg N retention) for the different
scenarios. The results are given for both the project areas analysed in detail and the
remaining area.
Table 2: value of the nitrogen retention of the restored flood plains (2000)
Scenario
Retention area (totally 15,000 ha.)
Sewage treatment plant
Agricultural measures
(a) Sewage treatment plant
(b) Agricultural measures
[ha]
[1000 €]
[1000 €]
[€/ha]
[€/ha]
Sandau
830
5,136
1,734
6,188
2,089
Rogätz
860
293
99
340
115
Other sites
13,310
20,497
6,921
1,540
529
As Table 1 shows, the results considerably differ according to the site conditions and the
scenario considered. Thus, the replacement value varies between approx. € 100,000 and €
290,000 for adverse site conditions and € 1,7 mill and € 5,1 mill for appropriate conditions.
For the total amount of 15,000 ha additional flood plain area, the value ranges von 8,7 to
26 mill. €.
These values are considered as annual benefits concerning the indirect use value of
restored flood plains within the benefit-cost analysis (MEYERHOFF & DEHNHARDT 2004).
BEHRENDT, H. & OPITZ, D. (2000): Retention of nutrients in river systems: dependence on
specific runoff and hydraulic load. Hydrobiologia 410 (1): 111-122.
DEHNHARDT, A. & MEYERHOFF, J. (HRSG.) (2002): Nachhaltige Entwicklung der
Stromlandschaft Elbe – Nutzen und Kosten der Wiedergewinnung und Renaturierung
von Überschwemmungsauen. Vauk: Kiel.
MEYERHOFF, J. & DEHNHARDT, A. (2004): The European Water Framework Directive and
economic valuation of wetlands: The restoration of floodplains along the river Elbe.
Working Paper on Management in Environmental Planning. TU Berlin. Forthcoming.
Economic valuation,
111
Ebro water, geosciences and sustainability – Water from northern to
southern Spain?
The EbroAgua Working Group*, Elke Petersson
Zentrum für Interdisziplinäre Technikforschung, TU Darmstadt, Hochschulstrasse 1,
64289 Darmstadt
E-mail: [email protected], [email protected]
Keywords: National water plan Spain, interdisciplinary research
The Plan and its natural constraints
Spain has a wide variety of climatic zones. They range from humid regions in the north to
subhumid, semiarid and even small arid zones in south-eastern Spain. Mainly along the
south-eastern coastline the water demand triggered by agriculture and tourism exceeds
natural water availability at least seasonally. To satisfy the existing water demand, the
National Hydrological Plan (Plan Hidrológico Nacional 2001),. passed by the Spanish
government in 2001, makes arrangements to transfer 1050 hm3 /a of the Ebro Rivers
average annual run-off to south-eastern Spain.
The Ebro Basin is the southern foreland basin of the Pyrenees, with an asymmetrical (in its
western parts a symmetrical) fill of Tertiary sediments thickening to the north. It is
bounded by the Iberian Ranges to the south and the Catalan Coastal Ranges to the east.
Both, the Pyrenees and the Iberian Ranges have produced thrust sheets at its margins
reducing mainly during the late Oligocene the basin width by about 70%. Pre-Oligocene
successions include shelf carbonates and marls, coastal and deltaic detrital facies, and
evaporites. Post-Oligocene sediments of the Ebro Basin sediments are continental and
reach thicknesses of more than 1.000 m. They include a wide variety of alluvial deposits,
fresh-water lacustrine carbonates and saline playa lake deposits. The alluvial sediments
were deposited in relatively localized alluvial fans (<15 km long) as well as in larger
systems up to 100 km long.
With Quaternary times, the basin changed from a closed interior basin to one drained by
the Ebro River to the Mediterranean Sea. The respective incision and sedimentation of the
river dominates the present geomorphology. Quaternary deposits, like pediments and
fluvial terraces commonly crowned by calcretes, cover about one-third of the depression.
Subsurface dissolution of evaporates caused local thickening in some places.
112
Economic valuation,
The EbroAgua Working Group and its questions
The EbroAgua Working Group consist of Spanish and German scientists from the
University of Zaragoza, from authorities of the Province of Aragón, from other Spanish
institutions, and from the Darmstadt University of Technology with partners at the
universities of Frankfurt am Main, Trier and Magdeburg. It will concentrate its
investigations on the Central Ebro Basin in the Province of Aragón.
Although sustainability is a term frequently used in debates on the future of society and its
needs (e.g. European Water Frame Directive), many questions seem to be open with
respect to a sustainable management of the Ebro River system. For instance, its geology is
well known, but more data are still necessary to reconstruct the geologic “architecture” of
the area in order to answer questions on its natural resources and hazards involved with the
use of these recources. Such questions are e.g.: How much groundwater is available and
what is its quality? What is the value of thickened alluvial deposits as rich sources of
aggregates needed for construction in urban areas and what is its value as groundwater
reservoirs? Is it possible to elaborate risk maps with respect to subrosion of Tertiary
evaporates which may result in sagging as well as collapse features? How will changes in
land use or irrigation techniques applied in agriculture effect erosion? What will be the
amount of sediment trapped in the water reservoirs that were originally mobilised by
erosion on agricultural areas? How will the transfer of Ebro water to southern Spain affect
the state of the environment in the Ebro River Basin and directly or indirectly the needs of
agriculture, cities and other communities in northern Spain? How will possible changes in
climate affect present water management and the water management provisioned in the
National Hydrological Plan? What will be the economic impacts? Is it possible to elaborate
a dynamic geographic information system which will allow the modelling of different land
use scenarios?
As it can be seen easily, the current working group concentrates on geologic and economic
questions as well as on water management. However, the EbroAgua Working Group is
open for other scientists with other questions – they are welcome!
References and data sources:
[1] Ministério de Medioambiente, Secretária de Aguas y Costas, Dirección General de
Obras Hidraulicas y calidad de las agues (2000), Libro Blanco del Agua en España. *
[2] Ley 10/2001, de 5 julio, del Plan Hidrológico Nacional. * [3] Alonso Zarza, A.M.
(2002): Tertiary. – In. W. Gibbons & T. Moreno, The Geology of Spain, Geol. Soc.
London.
Economic valuation,
* José Albiaca, Carmen Castañeda del Alamo a, Juan de la Riva Fernándezb, Götz Ebhardtc,
Maite Echeverria Arnedob, Miguel A. García Verad, Matthias Hindererc, Andreas
Hoppec, Teresa Lamelas Garcia c, Oswald Marinonic, Irene Marzolffe, Manfred
Ostrowskic, Elke Peterssonc, Johannes B. Riesf, Tilman Sauerf, Petra Schweizer-Riesg,
Manfred Seegerf, Crisanto Silvac, Asunción Soriano Jimenezb, Kathy Unger
Shayestehc, Axel Winterscheidc.
a
Diputación General de Aragón, Zaragoza, bUniversidad de Zaragoza, cTechnische
Universität Darmstadt, dConfederación Hidrográfica del Ebro, Zaragoza, eWolfgang
Goethe-Universität Frankfurt, fUniversität Trier, gUniversität Magdeburg
113
114
Economic valuation,
Stakeholder involvement and economic assessment of management
strategies for regulated wetlands in a river basin context: Case study
from the Spree-Havel River Basin.
Malte Grossmann
TU Berlin, Institute of Landscape and Environmental Planning, Dept. Landscape
Economics, FR 2-7, Franklinstr. 28/29, 10587 Berlin,
[email protected].
Key words: wetland, Spree-Havel River Basin, global change, water management, total
economic value, stakeholder involvement
Introduction
In this paper I will report on the integrative approach to water basin modeling adopted
within the GLOWA Elbe project from an economic perspective. GLOWA Elbe is part of
the BMBF funded Programme “Global Change of the Hydrological Cycle”. I will
particularly focus on taking account of multifunctional water uses by wetlands within a
river basin context, when assessing water management strategies. In this context I will
further comment on the experiences with inter - and transdisciplinary modeling and
assessment of water resource systems made in the GLOWA Elbe project.
The primary objective of the Spreewald wetlands subproject was to assess scenarios of
regional effects of global change on current and planed wetland water management
practices in the context of river basin management. The aggravated summer water deficit
with related water management conflicts and policy responses outlined for the Spreewald
are typical for regulated fens and floodplains in many of the north eastern German
lowlands. The more general objective of the project is therefore, to develop methods and
tools, with which effects of management and policy options on the environmental and
economic functions of wetlands can be assessed at the sub-basin scale in the context of
climate change and water availability within a river basin.
Conceptual and methodological framework
The GLOWA-Elbe impact assessment methodology is the basis for the actor-oriented,
ecosystem approach to watershed modeling adopted in the Spreewald subproject. Key
features are: (1) participation of stakeholders in identification of core issues for modeling
and scenario formulation (2) data transfer and scaling up of ecosystem process models to a
watershed scale using hydrological response units derived by a GIS analysis of available
data (3) aggregation of hydrologic response units to larger water regulation entities for the
implementation of a wetland water management and water balance model in direct
coupling with a river basin model (4) economic assessment based on a conceptual
differentiation of wetland functions, uses and values. For this purpose economic
Economic valuation,
115
assessment routines are implemented within the hydrological model. These benefit
functions are used to calculate changes in total economic value of wetlands (5) stakeholder
involvement in scenario formulation and options assessment.
The basic type of model of the water resource systems for basin scale analyses is the water
management model ArcGRM Spree which simulates stochastic water resource behavior in
accordance with a predefined set of rules governing water allocations and infrastructure
operations. It is developed in a node-link network, which is an abstracted representation of
the spatial relationship between the physical entities in the river basin. The ArcGRM
Spreewald model is implemented as a sub-module of the larger scale basin wide ArcGRM
Spree model. For the wetland sub basin, each water regulation entity is implemented as a
node. For these nodes the water balance and corresponding water level is calculated on the
basis of the weighted sum of the evapotranspiration of the hydrological response units
contained in the water regulation entities and externally defined water management
regimes.
Basis for the economic assessment modules are production functions / activities for
different wetland uses that include water as an input to estimate the use and value of water
by sector. Currently, a pasture fodder crop biomass and quality model on the basis of a
relative biomass production function for different combinations of water management
regimes, soil types and cropping practices is included. Further fish production and tourism
boating activities are also included. Value of recreational water use is estimated by travel
cost method, monetary value of biodiversity conservation using benefit-transfer
methodology and CO2 sink potential is valued by replacement cost methodology. Net
economic effects are assessed in terms of net benefit from water use and water use
efficiency is calculated for different water management regimes and water availability
scenarios.
Stakeholder participation in formulation of wetland management scenarios
Water management options are developed and assessed with involvement of stakeholders
of basin water management. Stakeholders from the Spreewald are motivated to participate
in watershed modeling on two accounts: (1) quantification of water demand and associated
benefit of the Spreewald sub-basin for consideration in basin level water management (2)
assessment of impacts of likely changes in water availability on current and intended land
uses in the Spreewald.
Water management at a basin scale is regulated by state water authorities, who utilize the
ArcGRM Spree model as a decision tool for allocations based on a ranking of water use
priorities. Within the Spreewald sub-basin, short term decisions on water levels and water
distribution are made in watershed advisory committees on the basis of existing formal and
informal water use rights. Plans for major changes in land use and water management
116
Economic valuation,
aiming to partially restore floodplain dynamics, retain water at the landscape level and
increase the area dedicated to nature protection are highly contested at the local level, as
changes in land and water use rights will become necessary. Together with key
stakeholders, existing use rights pertaining to land use, water level regulation and water
allocation and their possible future changes are identified and mapped.
The results of stakeholder participation in different parts of the Spree basin are
summarized as scenarios of water management strategies and are assessed in the context of
relevant regional effects of global change quantified in other GLOWA- Elbe subprojects.
Effects of global change on total economic value of wetlands
The Spreewald is a wetland area within the middle reaches of the Spree River, which splits
up into several branches that meander through a wide floodplain. Because of the negative
climatic water balance during the summer months, current land use patterns are reliant on
additional water from the Spree River. Ample supplies of surplus water were until recently
provided from drainage of opencast coal mines in the headwaters. With the demise of coal
mining, water has become an increasingly contested resource – both within the Spree River
Basin as a whole and amongst the water users within the Spreewald. Compounded with
climate change, the current summer water deficit is likely to become more aggravated. At
the same time, changes in land use policy are driving changes in land use patterns and
associated water management regimes. With the gazettement of the Spreewald as a
UNESCO Biosphere Reserve, the restoration of natural floodplain dynamics has become a
major development goal, while shifts in agricultural policy are reducing the incentives for
intensive agriculture production on wetland sites. As can be seen from the figure below,
the water use efficiency of wetland water withdrawl from the Spree River will decline.
Decisions concerning the distribution of water both within the basin and within the wetland
sub-basin will have to be made. Economic assessment of wetland values and stakeholder
participation can assist formulation of water allocation policy and priorities.
117
Economic valuation,
Wateruse efficiency (€ net benefit / hm³
effective water use)
350.000
300.000
250.000
200.000
150.000
current water managemnt without climate change
100.000
current water management with climate change
climate change with adapted water management
50.000
0
0307
0812
1317
1822
2327
2832
3337
3842
4347
4752
Years
Figure1: Changes in water use efficiency (total economic value / water withdrawl from river) of the
Spreewald wetland for different water availability and management scenarios.
Important References
Joint UNDP/World Bank Energy Sector Management Assistance Programme (ESMAP),
2003, Stakeholder Involvement in Options Assessment: Promoting Dialogue in Meeting
Water and Energy Needs - A Sourcebook, World Bank: Washington
Molden, D., 1997, Accounting for water use and productivity. SWIM Paper 1. Colombo,
Sri Lanka: International Water Management Institute.
Turner, R.K., J. van den Bergh & R. Brouwer (ed.), 2003, Managing Wetlands, An
Ecological Economics Approach: Edward Elgar.
McKinney, D.C., X. Cai, M.W. Rosegrant, C. Ringler, and C. A. Scott, 1999. Modeling
Water Resources Management at the Basin Level: Review and Future Directions.
SWIM Report 6. Colombo, Sri Lanka: International Water Management Institute.
118
Economic valuation,
Interdisciplinary assessment of suitable measures to minimise P input in
the Weiße Elster river
Hennrich, Kirsten; Bräuer, Ingo; Rode, Michael
UFZ Centre for Environmental Research, Department Hydrologic Modelling, Brückstr. 3a,
39114 Magdeburg, Germany
Keywords: surface runoff, phosphorus transport, water framework directive, costeffectivity, spatially targeted measures
The purpose of the EU water framework directive is to establish a good ecological status
for inland surface waters, transition waters, groundwater and coastal waters until 2009. To
achieve this goal a program of measures has to be defined in a management plan for each
river basin considering cost-effectivity (s. article 11). To date, methodological gaps exist
regarding the scientific, economic and legal instruments available to implement the
directive in Germany.
The present study is embedded in a BMBF project on the Weiße Elster river in Germany.
The main aim of the project is to develop a decision support system for integrated river
basin management based on a computer modelling system. Study area is the meso-scale
river basin of the Weiße Elster river, flowing through three states, Thuringia, Saxony and
Saxony-Anhalt. Currently, river basins in Germany are managed on an (state)
administrative level. Research is carried out in close cooperation with local authorities. In
the context of the EU water framework directive scientific, economic, and legal methods
and approaches will be coupled and developed further.
The Weiße Elster project focuses on pollution from non point sources, which means
excessive nutrients in rivers mainly resulting from agriculture. Whereas nitrate is most
often leaching into the soil, percolating down towards the groundwater and being
transported to the river by the groundwater, phosphorus takes another pathway. Most
phosphorus in rivers originating from agriculture is present as particulate P, that is, the
phosphorus is attached to particles leaving the field through soil erosion. Therefore, most P
is transported in overland flow loaded with sediments and the amount of P lost from fields
is highly depended on the rainfall intensity as well as the timing of the rainstorm with
respect to the last fertiliser application.
The WFD requires the assessment of the effect of measures on a catchment scale.
However, most measures are rather localised and affect a small scale only. Whereas
coupled hydrology – erosion models provide useful tools for modelling e.g. dissolved P
loss for small scale catchments (Rode and Frede 1997, Lindenschmidt et al. 2004), to date,
no model exists which is able to simulate small scale processes and their effects in a meso-
Economic valuation,
119
to large scale catchment. However, this is a pre-condition for a sensible management plan
for an entire river basin.
Therefore, one task in the project is to develop a method to determine the catchment-wide
effect of measures preventing soil erosion and P export from agricultural areas. The
approach developed is based on the findings of previous studies that P loss from fields only
occurs on very few days in a year (days with surface runoff) and only concerns 10-25% of
the whole catchment area (Voges 1999). Analyses are based on the erosion model
EROSION2D/3D (Schmidt et al. 1997) and on the factor E used in the model to distinguish
erosion events from non-erosion events.
Furthermore based on probability distributions of slope angles, land use, crops, soil
properties and agricultural practices a method has been developed allowing to assign an
erosion probability to each grid cell for given rainstorms. Contributing areas with regard to
sediment (and P) loss are determined. The total area of the contributing areas in a
catchment changes with the seasons, the rainfall intensity and total amount of rain as well
as agricultural practices. The advantage of this approach is that the effects of measures
such as soil cultivation practices, changes in crop rotation or land use can assessed in terms
of changing erosion probability.
In a further step, surface water is routed from the grid cells contributing to erosion and P
loss to the receiving water. All cells not contributing to erosion are considered ultimate
sediment sinks. In that way, it is not only possible to establish a link between the fields and
the rivers and streams (hillslope channel coupling) but also to pinpoint the most effective
spots for establishing riparian buffer strips.
So far, classical agri-environmental programmes implemented under EU directive No.
2078/92 are non-spatially targeted measures (NSTM). This means, every farmer is allowed
to apply and gets a fixed compensation, if he takes previously defined measures. In this
paper, we will show how with spatially targeted measures (STM) cost savings in the
management of river basin can be achieved. In the case of STM public money is spent in a
targeted way, such as the construction of riparian buffer strips is only subsidised in
effective spots, or compensation is only paid for land use changes (field to pasture) in
erosion prone areas. Those areas have to be well defined, by prior modelling or through
field mapping. The above presented method allows the identification of these areas and
hence the design of spatially targeted measures.
As preliminary result, this study shows the different effectiveness of STM and NSTM in
terms of lowering P levels in a river.
Overall, this approach tries to combine the scale of the measure (grid cell), the scale of the
decision making process (catchment) as well as the scale of socio-economic models and
analyses (individual farmer or percentage of a change in a given area).
120
Economic valuation,
The method as well as its advantages and disadvantages will be presented in this paper.
LINDENSCHMIDT, K.-E., OLLESCH, G. AND RODE, M.: Implementing more physically-based
hydrological modelling to improve the simulation of non-point dissolved phosphorus transport in
small and medium-sized river basins. Hydrological Sciences Journal (accepted), 2004.
RODE, M. AND H.-G. FREDE,: Modification of AGNPS for agricultural land and climate
condition in central Germany. J. of Environmental Quality 26(1), 165-172, 1997.
SCHMIDT, J., WERNER, M.V., MICHAEL, A., AND W. SCHMIDT: EROSION2D/3D –
Ein Computermodell zur Simulation der Bodenerosion durch Wasser. Sächsisches
Landesamt für Umwelt und Geologe, Sächsische Landesanstalt für Landwirtschaft, 1997.
VOGES, J.: Empirisches Modell für die mittlere Maßstabsebene zur GIS – gestützten
Bestimmung der Anbindung erosionsgefährdeter Ackerflächen an Fließgewässer.
Dissertation Universität Hannover, 1999.
Economic valuation,
121
Congested waters: how to conceptualize and measure recreation benefits
and the influence of visitor use levels on peoples’ satisfaction?
Axel Klaphake
Department on Landscape Economics, Technical University Berlin, Sekr. FR 2-7,
Franklinstraße 28/29, 10587 Berlin, Germany.
Key words:
water-based recreation, economic valuation, congestion costs,
heterogeneous preferences, integrated modelling
While in former times the direct economic value of many rivers mostly stemmed from
fisheries and navigation, nowadays the importance of recreation and leisure activities like
boating or angling is on the increase. Many German regions are developing water-based
recreation facilities and boating trails because water tourism is perceived an important base
for regional development, in particular in structurally weak rural regions. Consequently,
well-founded knowledge of the economic dimension of water-based recreation is of pivotal
importance for water management. In this context, economic valuation of recreation
services and the modelling of peoples’ behaviour (e.g., trip decisions, preferences for
specific attributes of riverscapes) bridge the gap between, on the one hand, a somewhat
abstract debate on the economic value of freshwater ecosystems in economic literature and
the concrete information needs of water and tourism planners on the other. But while this
strand of economic research appear more developed in the international economic
literature, the German research on the recreation dimension of waters has been limited
hitherto and the empirical knowledge is, if any, weak.
In principle, economic valuation methods which are based on stated and/or revealed
preferences can supply crucial information about the societal dimension of freshwater
ecosystems’ protection. These methods measure directly or indirectly the economic value
of certain attributes of waters (e.g., water quality, aesthetics of watersides) and their
influence on individual recreation behaviour and benefits. However, peoples’ enjoyment of
rivers and their trip decisions are not only influenced by the water quality, the physical
characteristics of a river section or the aesthetic quality of a riverscape but also by
congestion respectively congestion-related impacts. For instance, high visitor use levels on
a river (e.g., boating) may interfere with a quite enjoyment of the nature or the perception
of wilderness. Equally, congestion on rivers may cause additional queue time at locks or
portaging sites. Therefore, congestion can significantly influence the benefits stemming
from water-based recreation and, consequently, will show an impact on individual trip
decisions and the probability of repeated visits to a given site. In other words, the
122
Economic valuation,
widespread policy approach to accommodate an increasing demand for recreational days
can cause – beside from negative ecological impacts – significant welfare reducing
congestion costs. Against this background, the presentation will be structured as follows:
First, we introduce the economic perspective on water-based recreation and the
possibilities to measure the economic value of recreation services provided by freshwater
ecosystems (boating, angling, swimming etc.). Subsequently, various possibilities to
conceptualize congestion of waters in the frame of an empirical research design will be
discussed. In particular, we will distinguish the social science debate on the “social
carrying capacity” of riverscapes and the relevant welfare economic concept on congestion
costs. In this context, we will demonstrate how congestion can principally influence
individual behaviour and why it is a highly relevant dimension for water planners. We will
also discuss different forms of congestion which might be caused either by a high number
of similar users (e.g., canoeists) or because of distinguishable user groups each with
different objectives and claims (e.g., anglers vs. boaters).
Second, we present recent advantages in modelling and empirically measuring congestion
costs in water and environmental economics. We discuss the importance of congestion in
the presence of heterogeneous preferences – obviously, some people perceive congestion
as a problem while others do not – and present a simple approach to model the effects of
different visitor use levels on visitors’ satisfaction in a given riverscape. In particular, we
will differentiate between ex post and ex ante measures of congestion and show the
interdependence of these measures because of self-selecting decisions of the visitors.
Third, we present the key results of an own empirical investigation in the lakes region
Mueritz. Here, we studied the economic importance of recreation activities on the Upper
Havel. Inter alia, canoeists’ perception of congestion on a highly frequented paddling trail
was assessed by applying survey-based economic valuation tools (CVM, travel cost
method) in combination with data from long-term visitor monitoring (count data). We used
linear and logistic regression to determine the main factors influencing visitors’ perception
of congestion as well as the acceptance of different management instruments (fees, quotas).
Furthermore, the travel cost method was employed to assess the effects of different user
fee levels. In this context, it will be generally shown how survey-based economic data can
be used to inform water and management decision-making.
Finally, we will not only sketch some uncertainties relating to the results of the empirical
application but also the room for future collaboration between different scientific
disciplines dealing with water-based recreation issues. For example, integrated ecological
and economic research would be desirable to analyze the impacts of the increasing use of
rivers for recreation and leisure purposes. The rapid increase of activities such as angling
Economic valuation,
123
or boating in the last decades do not only show enormous consequences in terms of use
intensities and the economic value of rivers but also in terms of aquatic ecology and water
infrastructure. Finally, it will be demonstrated how these kind of economic data can be
integrated in the development of integrated decision-support tools for river basin
management. In principle, the ‘congestion topic’ might be a good starting point for a
fruitful collaboration between various disciplines from social and natural sciences.
References:
Grossmann, M.; Klaphake, A.; Meyerhoff, J. (2004): Canoes vs. birds or canoeists vs.
canoeists? Combining interview survey and visitor monitoring to inform visitor
management in the Mecklenburg lakes region, in: Virtanen, Eija et al. (eds.): The
Second International Conference on Monitoring and Management of Visitor Flows in
Recreational and Protected Areas – Conference Proceedings, pages 100-170,
Rovaniemi.
Grossmann, M.; Klaphake, A. (2004): Measuring congestion on waters with economic
valuation tools: some methodological notes and an empirical application, in: Journal
of Leisure Research (under review).
Grossmann, M.; Klaphake, A. (2004): Visitor management in protected areas: The
relevance of congestion costs for the management of highly frequented boating routes.
Working Paper on Management in Environmental Planning, Technical University
Berlin.
124
Economic valuation,
Integrated water resources management in the Spree River catchment in
the context of global change
Hagen Koch
Brandenburg University of Technology Cottbus, Chair of Hydrology and Water Resources
Management, P. O. Box: 101 344, D-03013 Cottbus, Germany
[email protected]; http://www.hydrologie.tu-cottbus.de
Keywords: water resources management, stochastic long-term simulation, global change,
scenario analysis, economic functions, integrated assessment
The management of water resources is closely linked to questions concerning economic
development, social wealth as well as the environment (KALTOFEN et al., 2004). This
linking-up exacerbates the evaluation of water resources management activities. However,
by taking this linking-up into consideration, it is possible to take a step towards a
sustainable water resources management. Inter alia, sustainable development has to include
uncertainties, e.g. regarding the socio-economic development or water availability
(PLATE, 1993). Scenario analysis is one way of dealing with this uncertainties (IPCC,
2001).
Scenarios of water resources management are assessed in the context of global change
within the German Research Programme on Global Change in the Hydrological Cycle
(q.v. www.glowa-elbe.de). The instationary water yield and water demand balancing
model “ArcGRM GLOWA” (planning period 2003-2052), based on the long-term water
management simulation system ArcGRM1 , was developed and embedded in a special
integrated assessment procedure named Integrative Methodological Approach (IMA). This
procedure consists of four steps (HORSCH et al., 2001):
(1) problem analysis and development of scenarios,
(2) derivation of indicators and criteria,
(3) impact analysis via modeling,
(4) evaluation of the results of the impact analysis with respect to the special indicators
and criteria.
Especially in steps (1), (2) and (4) the participation of stakeholders is of relevance
(MESSNER & KALTOFEN, 2004). Results from a casy study in the Upper Spree region,
including the Spree River catchment upstream of Berlin and Schwarze Elster River
catchment, are presented. Parts of these catchments form the so-called Lower Lusatian
mining district. Resulting from more than 100 years of excessive open pit lignite mining a
strong influence on water quality and quantity becomes evident. This mining activities
1
ArcGRM is a registered trademark of WASY Ltd.
Economic valuation,
125
resulted in a significant cone of groundwater depression, reaching a deficit about 13 bn m3
in 1989. In the past the infiltration losses through the river beds were overcompensated by
the amount of groundwater (1989: 1,200 mill m³) pumped out of the mining areas into the
rivers (GRÜNEWALD, 2001). The rapid decline of mining activities after the German
reunification in 1999, only 5 out of formerly 16 mines are still in operation, caused
problems of water quantity and quality. Since the region is relatively dry (precipitation is
about 550 to 600 mm/year), the cone of groundwater depression and the related effects of
missing surface runoff and infiltration can only be reduced during a time span of several
decades. The water demand of traditional users and uses, established by formerly stable
and sufficient water yield due to mining, persists. Moreover, a new, heavily increasing
need to fill up the mining pits has appeared. Mining pits filled up solely by rising
groundwater will be characterised by pH-values down to 2.5 and low acid binding capacity
(GRÜNEWALD 2001; GRÖSCHKE et al., 2002). The extent of these problems pose a
threat to the whole river systems in the mining area and to other users located downstream
(e.g. UNESCO biosphere reserve Spreewald, the German capital Berlin). One of the
socioecomonic effects of the decline of mining activities is the loss of more than 70 000
jobs in the mining sector from 1989 to 2001 (KOCH et al., 2004). For the most of the
emerging mining lakes a touristic utilisation is planned, whereby the creation of new jobs
is desired.
Within the scenarios two effects of global change affecting water resources management
were considered. The first is the phasing out of all mining activities until 2040, the second
the inclusion of a climate change scenario with a warming of 1.4 K until 2050. The
derivation of the data for the climate change scenario is described in GERTSENGARBE et
al. (2003). Using the rainfall-runoff model EGMOD (PFÜTZNER & GLOS, 1986)
stochastic input series for the water resources management model (100 realisations of
monthly values of natural water yield) were generated from the synthetic climate samples.
In order to determine the effects of climate change, also 100 realisations of stochastic input
series without climate change were generated as reference.
Furthermore two socio-economic trends were used. They were chosen according to the
IPCC-storylines A 1 and B2 (IPCC, 2001). These storylines can be described briefly as a
world with globalisation and liberalisation (A 1), and regionalisation and actions taken
according to the precautionary principle (B 2). Both socio-economic trends are only
represented by differences in economic values (costs, benefits).
126
Economic valuation,
100
Ecological criteria [Points]
99
Economy(A1)-Ecology
reference scenario
climate scenario
alternative scenario
98
97
96
Economy(B2)-Ecology
reference scenario
climate scenario
alternative scenario
95
94
93
-600000
-400000
-200000
Net benefit [1000 €]
0
200000
Fig. 1: Ecological criteria and net benefit [1000 €, not discounted] for 3 scenarios and 2
socio-economic trends, 100 realisations for each scenario
The scenarios can be summarised as:
(1) reference-scenario (basic strategy without climate change)
(2) climate-scenario (basic strategy with climate change)
(3) alternative scenarios (alternative management strategies with climate change),
where the basic strategy corresponds to the planning of the federal states of Saxony,
Brandenburg and Berlin. To mitigate the effects of climate change, several alternative
scenarios were developed (in Fig. 1 only the results of one of these scenarios are
displayed).
Regarding the economic effects of water resources management strategies, water
utilisations as tourism and fish farming, and costs for the operation of water resources
management utilities (transfers etc.) and for conditioning of mining lakes (neutralisation),
were analysed. The functions are integrated into the water resources management model by
means of so-called dynamic elements, programmed in FORTRAN. The single economic
indicators are summarised to the criteria net benefit (Fig. 1). Until now only the ecological
indicator ecological required minimum discharge is used. It is measured for 28 separate
locations on a scale ranging from zero to one hundred. For the reason of better evaluation,
all monthly values for the ecological indicator are summarised for each realisation and
divided by the number of months and locations (thereby the comparison with the objective
value of 100 is possible, Fig. 1).
Some of the single indicators, e.g. costs for conditioning or tourism at mining lakes, are
conditional to the cost for the operation of water resources management utilities (e.g.
Economic valuation,
127
transferred water quantities). Therefore the summation of the single indicators for the net
benefit criteria must be executed for each realisation separately. Thus 100 values for each
scenario are the result for the aggregated criteria net benefit. Since the values concerning
the ecological required minimum discharge are also connected to the operation of water
resources management utilities, even this indicator must be assigned to the corresponding
realisation. 100 vectors with two columns, one containing the criteria net benefit, the other
containing the ecological criteria, are the result of this summation (Fig. 1).
References:
GERSTENGARBE, F.W., BADECK, F., HATTERMANN, F., KRYSANOVA, V.,
LAHMER, W., LASCH, P., STOCK, M., SUCKOW, F., WECHSUNG, F.,
WERNER, P.C.: Studie zur klimatischen Entwicklung im Land Brandenburg bis 2055
und deren Auswirkungen auf den Wasserhaushalt, die Forst- und Landwirtschaft
sowie die Ableitung erster Perspektiven. PIK Report 83, Potsdam, 2003.
HORSCH, H., RING, I., HERZOG, F.: Nachhaltige Wasserbewirtschaftung und
Landnutzung - Methoden und Instrumente zur Entscheidungsfindung.
Metropolisverlag, Marburg, 2001.
IPCC (Intergovernmental Panel on Climate Change): Climate Change 2001, Summary for
policy makers. Cambridge University Press, Cambridge, 2001.
KALTOFEN, M., KOCH, H., SCHRAMM, M., GRÜNEWALD, U., KADEN, S.:
Anwendung eines Langfristbewirtschaftungsmodells für multikriterielle
Bewertungsverfahren – Szenarien des globalen Wandels im bergbaugeprägten
Spreegebiet. Hydrologie und Wasserbewirtschaftung,48 (2), 2004.
KOCH, H., KALTOFEN, M., GRÜNEWALD, U., MESSNER, F., KARKUSCHKE, M.,
ZWIRNER, O., SCHRAMM, M.: Scenarios of Water Resources Management in the
Lower Lusatian Mining District, Germany. Ecological Modelling, Special Issue
(submitted), 2004.
GRÖSCHKE, A., UHLMANN, W., ROLLAND, W., GRÜNEWALD, U.:
Hydrochemische Entwicklung Lausitzer Tagebauseen während der Flutung - Beispiel
Gräbendorfer See. Hydrologie und Wasserbewirtschaftung, 46 (6), 256-267, 2002.
GRÜNEWALD, U.: Water management in river catchments influenced by lingite mining.
Ecological Engineering, 17, 143-152, 2001.
MESSNER, F., KALTOFEN, M. (eds): Nachhaltige Wasserbewirtschaftung und regionale
Entwicklung im bergbaubeeinflussten Einzeugsgebiet der Spree. Endbericht des
GLOWA-Teilgebietsprojektes Obere Spree. UFZ-Bericht 01/2004. Leipzig, 2004.
PLATE, E.J.: Sustainable Development of Water Resources: A Challenge to Science and
Engineering. Water International., 18, 84-94, 1993.
PFÜTZNER, B., GLOS, E.: Das Einzugsgebietsmodell EGMOD für wasserwirtschaftliche
Planung und Durchflußvorhersagen im Flachland der DDR. Wasserwirtschaft –
Wassertechnik, 7, 1986.
128
Economic valuation,
Estimation of flood losses in Germany
Actual data from the Elbe and Danube floods in August 2002
Heidi Kreibich
Section Engineering Hydrology, GeoForschungsZentrum Potsdam, Germany
Keywords: natural disasters, floods, vulnerability, damage assessment, loss mitigation
The trend of increasing damages due to natural disasters and especially due to floods was
unfortunately again confirmed to an unexpected extent in the year 2002. Flash floods in
Bavaria and catastrophic inundations in the catchment of the river Elbe and its tributaries
showed the high risk we have to consider today and in the future. The quantification of risk
is determined by the occurrence probability of flood events and by the consequences i.e.
damages, resulting from these events. Therefore, besides hydrologic and hydraulic studies,
also vulnerability assessments for different flood events are needed.
But damage estimation is extremely difficult, even when constricted to quantifiable direct
property losses. So far, in Germany these appraisals are based on HOWAS, a data set held
at the Bavarian Water Management Agency, Munich. HOWAS contains information about
the flood damage of approximately 4 000 buildings caused by nine floods between 1978
and 1994. It is the most comprehensive flood damage data base in Germany. But only
inundation depth and building use as damage-determining factors are contained in the data
set. Since losses are influenced by many more factors, damage estimates are quite
uncertain (Merz et al. 2004). For the development of better tools for damage estimation,
more knowledge about the connections between actual flood losses and damage
determining factors is needed.
Therefore, during April and May 2003 approximately 1700 affected private households
along the Elbe, the Danube and their tributaries were interviewed about the flood damages
to their buildings and inventory as well as about flood characteristics, precautionary
measures, warning time, social-economic variables, regional- and use-specific factors. In
the affected areas, a building specific random sample of households was generated, and
always the person with the best knowledge about the flood damages in a family was
questioned. The standardised questionnaire comprised around 180 questions. An average
interview lasted about 30 minutes. The computer aided telephone interviews were
undertaken by the SOKO-Institute, Bielefeld.
129
Economic valuation,
The damage determining factors can be divided into impact factors like water depth,
contamination, flood duration, flow velocity and resistance factors like type of building,
preventive measures, preparedness, early warning. The most important flood-damage
determining factor is the water depth, but to reduce the uncertainty in damage estimation,
other factors need to be taken into consideration (Kreibich et al., 2004). For instance, the
more impact parameters of a flood are specified, the lower is the coefficient of variation
within the data (Fig. 1). Contamination with oil for example leads on average to a three
times higher damage to buildings, in particular cases even to total loss.
increasing no. of specifying factors
120
Water depth > 10 cm
+ Contamination
+ Flood duration > 48 h
1
2
3
4
15
10
5
0
subsets
coefficient of variation [%]
100
20
All
degree of damage to building [%]
25
80
60
40
20
0
1
2
3
4
subsets
1: all private houses (n = 946)
2: private houses, water depth > 10 cm (n = 622)
3: private houses, water depth > 10 cm, contamination (n = 428)
4: private houses, water depth > 10 cm, contamination, flood duration > 48 h (n = 263)
Fig. 1 Mean degree of damage to building and respective coefficients of variation of
different, more and more specified subsets
On the resistance side, precautionary measures reduce the flood loss significantly even
during extreme floods. One factorial analysis showed for example, that adapted use and
interior reduced the degrees of damage to inventory by 12% and 19%, respectively.
Although, precautionary measures are more effective than emergency measures, early
warning and preparedness are also important for damage mitigation (Thieken et al., 2003).
In August 2002 for example, emergency measures like the erection of water barriers or
carrying the inventory upstairs reduced the degree of damage to inventory by 7% and 9%,
respectively. Thus people can do a lot to protect themselves and their property, but they
need to be aware of the flood risk.
Reliable methods for risk assessment are urgently needed, since they contribute
substantially to flood damage mitigation and an effective flood management.
130
Economic valuation,
MERZ, B., KREIBICH, H., THIEKEN, A., SCHMIDTKE, R.:
Estimation uncertainty of direct monetary flood damage to buildings. NHESS - Natural
Hazards and Earth System Sciences, 2004. -Vol.: 4: 153-163
KREIBICH, H., MÜLLER, M., THIEKEN, A., AXER, T., MERZ, B. (solicited):Flood losses in
private households – lessons learned from the Elbe and Danube floods in August 2002.
European Geosciences Union, 1st General Assembly, Nice, April 25-30, 2004
Thieken, A., Kreibich, H., Müller, M., Axer, T., Merz, B.:
Early warning and people’s reaction during the August 2002 flood – Results from a survey
of private households in the Elbe and Danube region. Second International Conference on
Early Warning (EWCII), Bonn, October 16-18, 2003
Economic valuation,
131
Integration of Economic Evaluation into the
Water Management Simulation System WBalMo
Frank Messner
UFZ – Centre for Environmental Research
Department Economics, Sociology and Law
Keywords: Water management modeling, benefit-cost analysis, integrated assessment,
decision support, global change, economic analysis of water usage
Sustainable watershed management has the higher goal to identify appropriate water
management schemes to meet the needs of present and future generations with respect to
the ecological, social, and economic functions of the water cycle. The scientific
foundations of watershed management are hydrological and water management models and
simulation systems to estimate water availability in the watershed over space and time.
However, in the European tradition, the economic, social and ecological impacts of
different levels of surface water availability have rarely been evaluated explicitly to
support water management decisions. Rather, expected water availabilities for different
water users were evaluated implicitly according to political priorities and to water
allocation principles deemed to ensure a “reasonable” water supply for all water users. This
practice comes to an end with the implementation of the European Water Framework
Directive (WFD), which requires an explicit economic analysis of water usage. In this
contribution I want to present an interdisciplinary approach to integrate economic
evaluation into water management modeling in order to create an improved scientific basis
for watershed management decision making.
No doubt, the evaluation of economic impacts of surface and ground water use and
changes in water availability in river basins depends in many cases on hydrological and
water management modeling results. In most cases economic evaluation of non-market
goods related to water – e.g., wetland areas and the existence of marine species – is
practiced separately from natural science modeling efforts. However, if water management
strategies for a whole watershed are to be evaluated on economic grounds, many water
users are to be included into the evaluation analysis to estimate the marginal benefits and
costs of varying surface water availability. What is more, the spatial and temporal
interdependencies of upstream and downstream water users must be taken into account as
well. This makes the economic evaluation analysis very complex. Therefore, it is sensible
to develop an interdisciplinary approach to link hydrological or water simulation models to
standardized economic evaluation approaches. Such an approach was developed in the
context of the GLOWA Elbe project ni order to evaluate water management strategies in
the context of global change for the surface water conflict in the Spree River Basin.
132
Economic valuation,
The presentation is structured as follows. In the introduction the surface water conflict in
the Spree River Basin, its historical roots and potential water management strategies to
resolve this conflict are portrayed. After that the Water Management Simulation System
WBalMo, which is used for years to support decision making in the Spree River Basin,
will be presented regarding its structure and the form of its results. The main part of the
presentation will then explore the possibilities to integrate standardized economic
evaluation functions into this simulation system. Using the examples of fish farming and
water quality in pit lakes it will be shown what kind of difficulties arise and how the
integration can be done. The major challenge is to adjust the economic evaluation approach
to the form of the simulation results and to identify transfer functions which serve as points
of intersection between WBalMO and economic evaluation. However, it is also
emphasized that some economic evaluations are not possible due to the current structure of
WBalMo. Therefore, based on the experiences made in the interdisciplinary endeavor to
integrate economic evaluation into this simulation system, a restructuring and an extension
of WBalMo is planned to be done in the second part of the GLOWA Elbe project.
In the subsequent part of the presentation selected economic evaluation results are
displayed for different water management strategies in the context of various potential
future circumstances of global change in the Spree River Basin. It will become clear that
this approach makes it possible to take the complexities of spatial and temporal surface
water distribution into account and to quickly calculate the economic results for many
hundred water users over a time horizon of 50 years. This is only achievable through the
direct link to the model which enables to calculate surface water availabilities and their
economic effects simultaneously.
Eventually, some concluding remarks will summary the potentials and problems of this
approach as well as the future plans to apply it in order to support decision making in river
basin management and to assist the process of implementing the WFD.
M ESSNER, F., KALTOFEN, M. (2004):
Nachhaltige Wasserbewirtschaftung und regionale Entwicklung – Analyse und Bewertung
von Szenarien zum Wassernutzungskonflikt im bergbaubeinflussten Einzugsgebiet der
Oberen Spree, UFZ-Bericht 1/2004, Leipzig, Dresden und Cottbus, 95 S.
M ESSNER, F., KOCH, H., KALTOFEN, M. (2004):
Elbe – Integration of Economic Evaluation into the Water Management Simulation System
WBalMo. In: Erickson, J., Messner, F., Ring, I. (Eds.), Sustainable Watershed
Management in Theory and Practice, (ch. 6), Elsevier Science (in Bearbeitung, erscheint
2004).
Economic valuation,
133
A benefit-cost analysis of extending riparian wetlands along the
river Elbe
Jürgen Meyerhoff and Alexandra Dehnhardt
Jürgen Meyerhoff, TU Berlin, Institut für Landschaftsarchitektur und Umweltplanung, FR
2-7, Franklinstr. 28/29, 10587 Berlin, [email protected]
Alexandra Dehnhardt, Institut für ökologische Wirtschaftsforschung (IÖW), Potsdamer
Straße 105, D-10785 Berlin, [email protected]
Keywords: European Water Framework Directive, biodiversity, river basin management,
contingent valuation method, replacement cost approach, benefit-cost-analysis,
sensitivity analysis
By creating the Water Framework Directive (WFD) the European Union applies a holistic
approach in the management of aquatic resources, integrating ecological, societal and
economic aspects at the river basin scale. To meet the requirements of an integrated river
basin management, the valuation of cost as well as benefits of different management
alternatives becomes necessary in order to guide the decision making process.
Accordingly, the benefit-cost analysis presented seeks to contribute to the discussion about
suitable approaches for economic valuation applicable within this context of the WFD and
river basin management.
Wetlands provide many important services to society. In general, a distinction is made
between hydrological (e.g., groundwater recharge), biogeochemical (e.g., nutrient
retention) and ecological functions (e.g. maintenance of habitats). However, the socioeconomic benefits of these functions are often not acknowledged when decisions about the
development of river basins are taken. One reason for this is that these benefits, in contrast
to the costs associated with the conservation and creation of wetlands, are not priced in
monetary terms. As there is no market for many goods and services provided by wetlands,
no market price reflecting their economic value is available. Accordingly, the objective of
the research project was to determine the non-market benefits of certain services arising
from newly created floodplains along the River Elbe. Furthermore, a comparison of the
benefits and costs was conducted.
Although today over 80 % of the original inundation areas are cut off from the river by
dykes, the Elbe riverscape still has many reaches in near-natural state. For example, the
recognition of the Biosphere Reserve "Elbe riverscape" by UNESCO in December 1997
highlights the importance of the Elbe basin as a natural landscape and its significance for
biodiversity protection in Germany as well as in Europe as a whole. A major reason for
this is that there is only one dam on the Elbe in Germany in Geesthacht. Therefore, the
134
Economic valuation,
Elbe is one of the last large rivers in Central Europe that flows freely along several
hundred kilometres. Accordingly, one of the few remaining continuous expanses of largely
still original floodplain forests can be found on the floodplains of the Elbe.
In order to assess the economic value of two services provided by regained floodplains,
two economic valuation methods were employed within the project “Economic valuation
of measures toward sustainable development in the Elbe river basin”: first, the contingent
valuation (CV) was used to determine the value that would arise from the ecological
function ‘biodiversity protection’. The CV is survey-based and creates a hypothetical
market for people to state their preferences for the public good in question. Therefore, it
has the potential to value not only use-related benefits, but also to include non-use values
not associated with any observable behaviour. Secondly, the replacement cost approach
(RCA) was used to determine the value that would arise from the biogeochemical function
‘nutrient retention’. The RCA is an indirect valuation method of estimating costs as a
proxy for benefits. Costs are proposed as a reasonable approximation of the benefits that
society attributes to the resource in question. For example, the costs of technical substitutes
such as a sewage treatment plant are used in order to value the biogeochemical functions.
On the basis of data provided by the International Commission for the Protection of the
Elbe (ICPE) and other projects of the research initiative Elbe Ecology, it was assumed that
15,000 ha of floodplains could be regained along the Elbe between the Czech/German
border and Geesthacht. This corresponds to an increase of roughly 10 percent of the
current floodplain area. According to the ecological targets set for these floodplains, a
mixture of future land uses comprising riparian forests, succession and grazing land was
assumed.
The CV survey was based on a random sample of the population of the catchment areas of
the three rivers Elbe, Weser and Rhine. Of the total sample of 1,304 households, 22 per
cent responded positively to the payment principle question. The mean willingness to pay
for the total sample was EUR 11.9 per household per year. The results of both a logistic
and a linear regression indicate that the principle willingness to pay and the stated amount
can be explained by various expected relationships. Economic, attitudinal and landscape
related variables were all statistically significant. Overall, the goodness of fit of the models
was high. The aggregation of the mean willingness to pay over all households within the
three catchment areas resulted in a total willingness to pay of EUR 153 million in the first
year and EUR 108 million in the following years. The difference is due to the fact that
some people were only willing to pay once while others were willing to pay for a longer
period.
The second economic valuation method employed was the Replacement Cost Approach
(RCA). A relocation of dykes is supposed to have an effect on water quality. The stream
velocity is affected by the enlargement of floodplains and thus, as a result of a higher
residence time of the water, the denitrification rate increases. Assessment of this benefit
Economic valuation,
135
using the RCA first requires the nitrogen reduction effect to be quantified. A statistical
model was used to estimate the amount of nitrogen retention. In a second step, the
replacement and its marginal costs were determined. Two different alternatives were
considered: sewage treatment plants and political strategies to reduce nitrogen emissions
from agriculture. Finally, the monetary value of regained floodplains was estimated by
assessing the replacement costs to provide the same service in kg N retention for the
different scenarios. Accordingly, the value of the additional floodplains due to nutrient
removal is EUR 8.8 million per annum (EUR 585 per ha on average) for the lower value.
Subsequently, a benefit-cost-analysis (BCA) was conducted to determine whether the
benefits would outweigh the cost or vice versa. It was assumed that the project lifespan is
20 years and that the discount rate is 3 percent. In addition, several scenarios were
developed in order to cover the range of possible developments. For example, the size of
the floodplain area regained was varied (10,000 ha / 15,000 ha) and different costs of dyke
relocation were assumed. The BCA indicates that the net present value is between EUR
850 million and EUR 1,080 million depending on the scenario. Even when 15,000 ha of
new floodplains are regained and costs for dyke relocations and land use changes are high,
the net present value is positive. Furthermore, the results show that even the scenario with
the highest costs and the lowest benefits results in a cost-benefit ratio of 2.5:1. Each euro
invested will bring a benefit of EUR 2.5. In contrast, the scenario with 10,000 ha
floodplains and low costs for dyke relocation and land use change showed the highest
benefit-cost ratio (4.2:1). Finally, a sensitivity analysis was conducted to illustrate the
implications of uncertainty. Benefits and costs were each doubled and halved. The analysis
indicates that the results of the BCA are stable and the benefit-cost ratio remains above
one.
In conclusion, the results of the economic analysis show that regaining floodplains by
relocating dykes along the River Elbe is justified from an economic point of view. To
relocate dykes would produce higher benefits than costs to society.
The research project was funded by the German Ministry of Research and Education (Reference
No. 0339594/1). It was part of the Elbe Ecology research initiative (http://elise.bafg.de/).
136
Economic valuation,
Dynamics of change in the Ebro river system – analysis, modeling and
perspectives of a complex resource use system
Elke Petersson
Zentrum für interdisziplinäre Technikforschung, TU Darmstadt, Hochschulstrasse 1, 64289
Darmstadt
Keywords: integrated water management, interdisciplinarity, research structure
Availability and quality of water have been crucial for the development of all human
societies. Water is also an integral part of the natural environment. Human activities,
arising from these developments, such as energy consumption, agriculture or spatial
development, cause negative effects on the environment, including the hydrological cycle.
Climate and land use changes as well as population growth and rising living standards lead
to urgent and challenging problems. Due to the complexity of these effects disciplinary
scientific analysis of the occurring difficulties alone will not be successful anymore. An
integrated management of water-related questions and a corresponding interdisciplinary
scientific approach have to be introduced to achieve a continuous social process aiming at
a sustainable development of water resources as demanded in the European Water
Framework Directive (WFD).
The present paper introduces the activities of the EbroAgua Working Group. Using the
Ebro catchment as case study the research group, comprising Spanish and German
researchers, developed a conceptual project structure, that is intended to support the
achievement of truly integrated water resources management. Activities are based on the
following specific objectives:
-
To understand the complex interactions of the key factors determining water
availability and demand as well as the boundary conditions and requirements of the
water regime in semiarid environments.
-
To promote disciplinary knowledge within the thematic clusters of modeling water
resources systems, soils and land use change, geogenic resources , actors and
decision-making, that is enabled by the interdisciplinary approach.
-
To combine, interpret and compute knowledge of the disciplines in the project
work packages to have added value compared to single disciplinary assessment
-
To verify and improve the research methodology suggested, that is the structural
spine of the project but at the same time is a research object itself.
-
To develop integrated water resources management strategies and corresponding
formal and informal implementation tools to secure water supply for both humans
and nature.
Economic valuation,
137
To reach the given objectives, existing computer models will be advanced and linked. In a
single model they will reproduce the physical processes determining water availability and
water demand, using time and space scales appropriate for the different factors.
Disciplinary research will be carried out for local case studies. As part of the integrated
work packages these results will be assembled and upscaled to gain information on basin
or sub-basin scale. The impact of possible future scenarios, covering e.g. climate change,
land use change, migration, changes in supply and demand management, will then be
modeled and discussed with key players. Special emphasis will be placed on the interfaces
between computer models and investigations in the social sciences, i.e. political science,
economy and spatial planning. To identify possible future conflicts evaluation will take
place in accordance with sustainability criteria that will be adjusted to the local conditions.
Based on these research results integrated policy options for water management as well as
measures how to implement them will be developed in close contact with key players.
D 1.x
D 2.x
D 3.x
D 4.x
+
Iterative Process
Integrated Central Modeling
WP1 Inventory +
Model Building
WP2 Scenarios
of Change
+
WP3 Impact
Analysis
?
WP4 Integrative
Policy Options
Disciplinary
Research Results
Disciplinary
research
Contributions to
interdisciplinary
workpackages
Interfaces between
interdisciplinary
and disciplinary
research
WP
Interdisciplinary
workpackage
D1.x
Disciplines
organised in four
clusters
The project idea is based on a research matrix where the disciplinary research of natural,
engineering and social sciences is represented in columns and the rows represent
interdisciplinary work packages. Disciplinary research is organised in four clusters:
modeling water resources systems, soils and land use change, geogenic resources, actors
138
Economic valuation,
and decision-making. The four interdisciplinary work packages
consecutively, each intending to create an integrated basis for the next.
are
carried
out
Currently activities are limited to disciplinary research on the modeling of the water
resources systems and on the geogenic resources. Remodeling the planned enlargement of
the Yesa dam under consideration of possible climate change impacts has shown that the
project is probably oversized. It seems that the project has not been adapted to the longer
time series available since the original project planning in the 1970s. In addition a water
balance for the Gallego subcatchment under consideration of reservoirs and irrigation
projects has been established.
This is essential for modeling groundwater flow and transport in the alluvial aquifer
confined to the thickened Quaternary terraces of the Gallego River that flows towards the
Ebro River from the North. The model will investigate natural and human impacts on
groundwater resources and chemistry with the aim of establishing sustainability criteria for
water management in this subcatchment.
To reconstruct soil erosion rates in historical time and to compare it with modern land
degradation (e.g. gullying) the sediment volume of Roman and modern dams will be
determined by sounding techniques (e.g. georadar) and GIS. These activities focus on the
rivers Huerva and Aguasvivas, south of the Ebro River.
Land use decisions, which are sustainable from the geoscientific point of view, can only be
made if the local/regional geology is fully taken into account. This does not only imply a
geological model but also models which are derived from the geological conditions such as
exploitable georesources, soils etc. To be able to better specify ‘optimal’ locations for
various use scenarios, all recognised geoscientific aspects will finally be brought together
in a GIS and will be evaluated in a comprehensive Spatial Decision Support System
(SDSS) implying sophisticated decision support methodologies.
The EbroAgua Working Group is presently focusing on water management as well as
geologic and economic questions. To be able to implement the introduced project structure
we would like to welcome new group members.
Economic valuation,
139
Economic and Ecological Transformation Processes in East German
Water Management Regimes2
Christian Schleyer
Chair of Resource Economics; Department of Agricultural Economics and Social Sciences;
Faculty of Agriculture and Horticulture; Humboldt University of Berlin
Luisenstr. 56; D-10099 Berlin; Germany
Keywords:
Water Management Regimes; Institutional Change; East Germany;
Collective Action; Participation; Externalities
Like in many fen land regions in East Germany, long-standing intensive arable farming enabled by reclamation - has caused soil deterioration and high water runoff in the socalled Schraden, a fen land area in the south of the state Brandenburg. More than ten years
of economic and political transformation that followed the unification of both German
countries in 1990 has worsened the situation and even added new problems. The visible
consequences are droughts in the summer, waterlogged plots in the spring, and dilapidated
water management facilities operating in an uncoordinated or even unauthorised way.
This paper is based on empirical material collected within the context of the GRANO
project between July 2000 and February 2002. The GRANO project was a cooperative
project of research institutions from Berlin and Brandenburg. Its objective was to develop
and implement approaches for sustainable agricultural production in Northeast Germany,
taking into account economic, socio-cultural, ecological, and environmental concerns.
Therefore, the project team consisted of scientists from various disciplines, such as natural
science, social science, agricultural economics, etc. (Müller et al 2002). The activities
focused on two research regions – one of them was the fen region Schraden. In this region,
twelve qualitative, semi-structured interviews were conducted with farmers, local
environmentalists, and the regional Water Association as well as with representatives of
the agricultural, environmental, and water administration at the district and at the state
level. Furthermore, notes taken during seven meetings of the regional Agri-Environmental
Forum (AEF) between November 2000 and February 2002 were analysed. The AEF had
been initiated by the GRANO project and regularly assembles 19 regional actors to discuss
options in overcoming the problematic situation of water management (Arzt et al. 2002).
2
The author gratefully acknowledges the financial support received from the GRANO project under a grant
from the German Federal Ministry of Education and Research (BMBF) and from the DFG within a Research
Unit (Forschergruppe 497) on ‘Structural Change and Transformation in the Agricultural Sector’ (Duration:
2003-2006).
140
Economic valuation,
Moreover, available planning materials, regional statistics, and other local information
available for the region were consulted.
This paper aims to explore the reasons for the physical and institutional3 failure of the
present water management system in the Schraden. More precisely, I will investigate the
process of change that has lead to an institutional structure that has been unable to
successfully deal with the problems. In order to analyse institutional change, to structure
the empirical material, and to reveal causalities Hagedorn et al. (2002) suggest an
explorative concept focusing on four groups of determinants: The first group consists of
the features and implications of the transactions – such as excludability, rivalry, and
complexity related to nature and the ecosystem. The second group comprises the
characteristics and objectives of actors – such as the values, attitudes, and social
embeddedness involved in those transactions. These two groups of determinants in turn
affect the third group – namely, the design and distribution of property rights on nature
attributes – as well as the fourth, which pertains to the corresponding governance structures
necessary in guaranteeing the rights and duties and their use in coordinating transactions.
In this paper, I will illustrate that intensive arable farming and reclamation measures
undertaken decades ago have led to the soil’s deterioration and its increasing inability to
hold water. Existing weirs, however, cannot prevent the resulting high water runoff; more
often than not they are degraded and operated in an uncoordinated manner. Given the local
public good character of some features of the fen land, the common-pool character of the
intermittently scarce resource water within the ecosystem, and the conflicting interests of
regional stakeholders, it will be argued that the reallocation of property rights over
reclamation systems, together with ineffective coordination mechanisms, have caused the
physical and institutional failure of the water management system and thus impeded
appropriate use of land and water. More precisely, the combination of legal insecurities
accompanied by enforcement problems, fragmented land ownership structure, and a high
number of short-term lease contracts have reduced the incentives for the majority of
farmers to maintain the reclamation works. Due to limited statutory rights in conjunction
with limited financials, the present water association appears to be an inadequate local
coordination mechanism. Furthermore, the complete and time-intensive restructuring
process at all levels of water administration has resulted in cumbersome or even
nonexistent interrelations between various governmental layers as well as in rare
transboundary contacts. A lack of water management plans and the organisational
subordination of the Lower Water Authority also impede effective administrative work.
The analysis will clearly show that the regional socio-economic system, the ecosystem, and
the hydrological system in the Schraden are highly complex and dynamic in nature and
3
Following Douglas North, institutions are the man-made constraints that structure political, economic, and
social interactions. These consist of both informal constraints (sanctions, taboos, customs, traditions, and
codes of conduct), and formal rules (constitutions, laws, property rights). (North 1991: 7) In other words,
institutions are the rules of the game or the rule of conduct within which human actions take place.
Economic valuation,
141
strongly related to each other. Thus, any research that aims to develop sustainable solutions
in order to overcome the problems of water management must not be restricted to
disciplinary aspects. Furthermore, in view of the characteristics of transactions and actors,
there is extensive literature suggesting that those governance structures could be preferable
solutions that include some form of local cooperation and participation (e.g., Ostrom
1998). Indeed, the aforementioned AEF – essentially a ‘round table’ initiated by the
GRANO project in the Schraden – can be seen as a step in this direction with encouraging
initial results. So far, the interdisciplinary research team together with the participating
regional stakeholders have developed and agreed on a broad concept, which includes
concrete measures such as weir repairs or changes in land use, to improve the water
retention in the region (Arzt et al. 2002). Hence, this paper will also give a brief overview
of the activities and results of this forum.
Arzt, K., E. Baranek, C. Berg, K. Hagedorn, J. Lepinat, K. Müller, U. Peters, T. Schatz, R.
Schmidt, J. Schuler, and I. Volkmann (2002). Dezentrale Bewertungs- und
Koordinationsmechanismen. In: K. Müller, V. Toussaint, H.-R. Bork, K. Hagedorn, J.
Kern, U.J. Nagel, J. Peters, R. Schmidt, T. Weith, A. Werner, A. Dosch and A. Piorr
(eds.). Nachhaltigkeit und Landschaftsnutzung: Neue Wege kooperativen Handelns.
Margraf-Verlag, Weikersheim: 29-96.
Hagedorn, K., K. Arzt, and U. Peters (2002). Institutional Arrangements for Environmental
Co-operatives: a Conceptual Framework. In: K. Hagedorn (ed.) Co-operative
Arrangements to Cope with Agri-environmental Problems. Edward Elgar, Cheltenham:
3-25.
Müller, K., V. Toussaint, H.-R. Bork, K. Hagedorn, J. Kern, U.J. Nagel, J. Peters, R.
Schmidt, T. Weith, A. Werner, A. Dosch, and A. Piorr (eds.). (2002). Nachhaltigkeit
und Landschaftsnutzung - Neue Wege kooperativen Handelns. Margraf-Verlag,
Weikersheim, 410 pp.
North, D. C. (1991). Institutions. Journal of Economic Perspective 5: 97-112.
Ostrom, E. (1998). The Institutional Analysis and Development Approach. In: E. TusakLoehman, and D.M. Kilgour (eds.) Designing Institutions for Environmental and
Resource Management. Eward Elgar, Cheltenham UK and Northampton ME, USA: 6890.
142
Economic valuation,
Innovativeness in the German Waste Water sector
- a micro-econometric approach
Harald Tauchmann & Hartmut Clausen
RWI-Essen
Key words: waste water services, innovativeness, ordered probability model
JEL Classification: C31, L95, O31
It is a common assessment that German water services are of high technical standard.
Nevertheless, the sector faces severe problems which are not solved yet: For instance the
grid-type network is partly outdated requiring enormous future investments. Hormones and
synthetic substances akin to them, nowadays are filtered neither from sewage nor from
drinking water, even though they are considered as potentially harmful to the environment
and even to human health. Finally, in the light of increasing waste water charges, the
economic efficiency of service provision has increasingly been disputed in recent years. In
fact, in order to improve economic efficiency the liberalization German waste water
services has intensely been discussed. But no political decision has been made yet to
substantially open the sector to market forces, raising the question how the sector's
performance could alternatively be improved.
In fact, innovations are often considered as a possible means to solve these problems.
While technical innovations may be the clue for solving environmental and health
problems, and moreover may reduce the average costs of corresponding investments,
organizational ones may improve the economic performance in general. In line with this
argument the State ministers of economics' for instance argue in favour of "modernisation
rather than liberalisation". However, it is far from clear, whether innovations can in fact be
regarded as substitutes to liberalization or privatization, rather than complements. I.e.
privatized firms may well exhibit more innovative activities than the traditional, local
authority operated ones do. Moreover, it is not clear what factors do drive the adaptation
and diffusion of innovations and how innovativeness can be fostered by policy measures.
Against this background, this paper tries to assess empirically which external variables
determine the innovativeness of firms operating waste water services. Our main focus is on
the question whether firms less directly controlled by municipalities are more innovative
than those directly controlled by the authorities. First of all we are interested in the
innovative performance of privately run firms compared with public ones, since allowing
for more private engagement and vice versa reducing the municipalities influence might be
a possible instrument to improve the sector’s performance.
Economic valuation,
143
Innovation surveys often provide only information about the input side of a firm’s
innovative activities. In contrast, this analysis is based on the output side of innovations.
Moreover, our analysis is interested in innovativeness in general rather than single
innovations. Innovativeness may be defined as a firm's general affinity and capability to
carry out innovative activities. However, innovativeness cannot be observed directly.
Nevertheless firms reveal their innovativeness through the adaptation of single
innovations, which is observed in the survey data employed. In order to exploit the
information about single innovations for explaining general innovativeness, a structural
model is constructed. The key assumption of the model is that - beside several exogenous
firm specific characteristics - the unobservable latent variable innovativeness drives the
attitude towards each individual innovation. In turn this latent variable is assumed to be
determined by exogenous variables too. A series of ordered probability models is estimated
that explain firms' attitude towards several specific novelties. However, certain cross
equation parameter restrictions that are imposed by the structural model allow for
identifying effects of the explanatory variables on the latent variable innovativeness.
Our empirical analysis rests on a survey conducted among German firms providing waste
water services. As sample of 683 firms were randomly drawn, whereas 237 firms out of
them returned completed questionnaires. Besides few firm specific characteristics, the
survey contains several innovation related questions. While the questionnaire did not
directly address technical novelties directly, firms were directly asked about several
organizational innovations. In particular with respect to a specific set of organizational
innovations firms had to state whether they have already adapted them, plan to adapt them
or whether they do not consider their adaptation at all. These answers enter the model as
dependent variables.
Since we first of interested in the question whether relaxing the influence local authorities
has an positive effect on the firms' innovativeness, dummies indicating the organizational
arrangement, that defines the legal relationship of municipality and utility, are the key
regressors in our analysis. For instance operating a utility under private law characterizes
one possible organizational arrangement. Additionally we control for firm size, measured
by the population within the disposal area, and the region's density of population.
Alternative specifications include additional controls.
Estimation results display no effect of organizational arrangements on firms'
innovativeness. In contrast the coefficients attached to the population within the disposal
area, i.e. the size of the firm, and the population density, are both positive and significant.
That is, larger firms and those operating in highly populated areas are significantly more
innovative than smaller ones and those operating in rural areas.
Therefore we cannot support the hypothesis that a change in organizational arrangement
and in particular a reduced influence of municipal councils will almost automatically
144
Economic valuation,
improve the innovation related performance of service providers. So, organizational
reforms directed towards increased legal autonomy cannot be recommended as first choice
policy instrument in order to foster innovativeness. However, with respect to question of
privatization this conclusion needs to be interpreted cautiously. The German waste water
sector displays just early signs of privatization. Correspondingly, our sample comprises
just a few private firms which often do not even exhibit actual private ownership. For this
reason effects of private engagement cannot be expected to be easily identified.
Nevertheless, they could still be substantial if a higher level of private engagement were
actually realized.
In contrast, the density of population within the firms' areas of supply strongly determines
the firms' innovativeness. This might rather be a "big city effect" than one of population
density itself, resting upon integration into innovation enhancing networks and access to
human capital which is located in centers rather than at the periphery. Even though, neither
population density nor location can directly be controlled by policy, this finding might
offer a starting-point for pushing innovativeness. Firms apparently benefit from a socioeconomic environment offering access to sources of innovations. Therefore general
investments in research and education are at least likely to have positive effects on waste
water services, too.
Finally large firms proved to be more innovative than small ones. Therefore, even a
moderate restructuring within the existing legal framework leading to larger units may help
to foster innovations and improve the efficiency of the German waste water sector. From
this point of view a process of mergers and acquisitions that has already started in drinking
water supply services could potentially improve efficiency and innovativeness in the waste
water sector, too.
Clausen, H., K. Körkemeyer, J. Lohaus, M. Schroll, H. Tauchmann & M. Willms (2003):
Innovationen in der Abwasserentsorgung - Ergebnisse einer Umfrage, KA-Abwasser
Abfall 50(12), 1563-1570.
Clausen, H.& M. Rothgang (2003), Innovations, Sustainability, and Efficiency in the
German Water Sector: How to Push the Tanker into the Right Direction? In: C. v.
Hirschhausen, T. Beckers & K. Mitusch (eds.), Current Topics in Applied Infrastructure
Research. Regulations, Financing, Institutions, Cheltenham: Edward Elgar, forthcoming

Workshop on Integrated Water Research and Water Management

Transcrição

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Extended Conclusions