Vulnerability of water bodies to diffuse pollution in small

Vulnerability of water bodies to diffuse pollution in small islands:
a hydrological perspective
M.I.P. de Lima
(1)
(1,2)
and J.L.M.P. de Lima
COST Action 869, Working Group 4:
Evaluation of projects in example areas:
The Swiss Midland Lakes.
June 24 - 26, 2009, Nottwil (CH)
Action 869
(1,3)
Institute of Marine Research, (2) Forestry Dep., ESAC/Polytechnic Institute of Coimbra, Portugal ([email protected]), (3) Dep. Civil Engineering, Univ. of Coimbra, Portugal ([email protected])
FCTUC
Study area
Eutrophication of water bodies,
resulting from anthropogenic activities,
is one of the most serious problems of
degradation of their physical, chemical
and biological quality. The complexity
of the processes involved includes the
strong effect caused by climatic,
orographic and hydrological
characteristics of the regions affected.
The vulnerability of the natural
resources in small islands increases
our concern about the extent of the
eutrophication problem in their water
bodies.
The Archipelago of Azores is located in the North Atlantic Ocean. This archipelago is included in the Macaronesian region together with Madeira
(Portugal), Canary (Spain) and Cape Verde archipelagos. The Azores archipelago is formed by 9 small islands, with areas ranging from 17 to 747 km2.
These islands are of volcanic origin and are characterized by very steep landscapes. In general, orography is responsible for significant climatic
variations among and within the islands. The Azores is strongly influenced by its oceanic location; it is characterized by high precipitation and high
humidity. Precipitation shows a prominent east-west gradient with substantially higher annual rainfall in the westerly islands. The freshwater (surface and
aquifers) systems in the Macaronesian islands are unique due to their volcanic origin and oceanic setting, catchment morphology, storage processes,
and the presence of distinct freshwater communities.
The water bodies
In the Azores some of the water bodies have or are suffering a process of eutrophication boosted by the existence of intensive agriculture practices, in particular those that result
from increased livestock in recent years. Tourism industry is also increasing; in same cases, natural lagoons are the pole of attraction. The degradation of the water quality and
subsequent changes in the aquatic ecosystems are of concern to the population and to the regional governmental agencies. To follow the evolution of this problem periodic
monitoring campaigns are sought.
Flores
Annual rain
1800
1600
1400
1200
1000
800
600
400
200
0
1860
Corvo
2500
Hypsometric Curves
2000
Altitude (m)
AnnualRainfall
Precipitation
(mm) (mm)
Introduction
Flores
Azores Islands
Corv o
Flores
Pic o
S. Jor ge
Terc eira
Faial
Gracios a
Sta Maria
S. Miguel
1500
1000
(9 islands)
Graciosa
Faial
Terceira
Horta
Pico
500
Angra do Heroísmo (Terceira)
Horta (Faial)
Ponta Delgada (S. Miguel)
1960
S. JorgeHorta
0
0
10
20
30
40
50
60
70
80
90
S. Miguel
100
Ar e a ( %)
1910
S. Miguel
AZORES ISLANDS
Lagoa das Sete Cidades
Ponta delgada
2010
Year
Mean monthly rain
140
Ponta Delgada (S. Miguel)
Angra do Heroismo (Terceira)
Horta (Faial)
Precipitation (mm)
120
0
Dominant wind direction:
Occidental and Central groups – S and SW
Oriental group – N and NE
km
200
Santa Maria
100
80
60
40
20
0
5
6
7
8
9
Lagoa das Sete Cidades
10 11 12
Chlorophyll a
month
Lagoa do Fogo
(
4
Total Phosphuros
3
Lagoa do Caiado
Pico
Lagoa do Capitão
Transperancy
2
Total inorganic nitrogen
1
S. Miguel
Santos et al., 2004 (7º Congr. Água, APRH)
Concluding remarks
Effects of climate change will probably lead to adjustments in the global hydrological cycle, which could affect the distribution, availability and sustainability of regional water resources. Climate variability on seasonal to
interannual time scales can cause changes in e.g. precipitation and air temperature. Characteristics of small islands that increase their vulnerability to these changes are, for example: their small physical size; limited
natural resources (particularly freshwater resources); highly sensitive small economies; rapidly growing populations with high densities. These characteristics often limit the capacity of small islands to mitigate and adapt
to future climate change and sea-level rise. With respect to eutrophication of fresh water bodies, all these issues have to be carefully taken into account when planning mitigation and remediation measures towards the
sustainability of the lagoons in these islands.resolution. This study contributes to the clarification of the small-scale behaviour and statistics of this process.