Coastal erosion and sea level changes on Rio Grande do

Departamento de Geologia – Geologia e Geofisica Marinha e
Monitoramento Ambiental
Coastal Erosion and Sea Level
Changes on the Rio Grande do Norte
State, NE Brazil
Helenice Vital1 & Karl Stattegger2
Christian-Albrechts-University of Kiel,
Institute of Geosciences,
Sedimentology,
Coastal and Continental
Shelf Research
Results evolved from differents projects
funded by DAAD/CAPES, CNPq, DFG, FINEP:
PROBRAL 21-98 from 1999 to 2001
PROBRAL 150-02 from 2002 to 2003
PROBRAL 337-10 from 2010 to 2012
UNIBRAL 24-04 from 2004-2007
CAPES CIENCIAS DO MAR 207-10
Germany Brazil
31 undergraduated students (12 + 19)
25 pos-graduated students (13 + 12)
Coastal Erosion
Coastal erosion is a natural process along the world’s
coastlines that occurs through the actions of currents
and waves and results in the loss of sediment in some
places and accretion in others.
 dramatic increase in
coastal erosion over the last
two decades and this is
expected to continue as sea
level rises and storm frequency and severity increase.
200 cm
Predicted global rise in sea level
140 cm
Wigley and Raper, 1992, WBGU, 2006, Rahmstorf 2007,
IPCC 2007, Pfeffer et al., 2008;
measured global sea-level rise 1993-2010, Cazenave 2010
88 cm
79 cm
60 cm
59 cm
48 cm
18 cm
15 cm
LOCATION
Narrow and
shallow shelf
Location: 04°50‘S – 05°00‘S; 36°30‘W – 36°50‘W
Environment: open shelf, tide and wave dominated, SE and NE winds,
Mesotidal ( 3.3 m spring tide);
Location: 04°50‘S – 05°00‘S; 36°30‘W – 36°50‘W
38°
37°
36°
Mossoró
Touros
Macau
Açu
Lajes
BRASIL
East Coast
North Coast
5°
NATAL
6°
North Coast
Caatinga
East Coast
Atlantic Forest
East Coast
North Coast
A
5.0S
B
5.1S
5.2S
A
5.3S
5.4S
5.5S
37.0W
FAB
FC
36.9W
36.8W
36.7W
36.6W
36.5W
B
36.4W
36.3W
36.2W
36.1W
36.0W
A
B
38°
Barragem Armando
Ribeiro
37°
36°
5°
Mossoró
BRASIL
Macau Galinhos
Pendências B
R-4
06
Açu
BR-304
Lajes
Touros
NATAL
6°
3600
years
5900
calcal
years
BP BP
Maximo da Transgressão
Holocenica
Evidence of mid-Holocene sea-level highstand
Bezerra (2003), Martin et al. (2003), Caldas et al. (2006)
and prediction of Peltier (1998)
Martin et al. (2003)
Bezerra‘s (2003)
envelope
mssl
msl
Caldas et al. (2006)
causes of coastal erosion
on RN coast:
i) coastal circulation dynamics – the
presence of beachrocks aligned parallel and
intermittent to the beach, change the wave
energy causing accentuated erosion and
embayment on the beach
ii) Holocene evolution of the coastal plain
– the intense longshore drift (from south to
north on the Oriental sector and from east to
west on the Setentrional sector) associated
to a negative sedimentary budget and losses
of sediments towards the land with dune field
and spit formation.
Iii) naturally inefficient sediment supply –
the river of the study area are small and do
not contributed with significant sediment
amounts. Moreover, the most expressive
rivers (e.g. Açu river) are dammed, prevent
the sediments to reach the ocean.
Barragem Armando
Ribeiro
iv) Construction of hard interface
structures, placed parallel to the shoreline
– these structures are built without
background knowledge of the most important
aspects of coastal erosion aggravating the
coastal erosion.
v) Tectonic factors –played an important hole
On the Oriental sector the graben and horst
structural architecture, resulting from intense
tectonic movimentation, origins the embayment
configuration, while on the Setentrional sector the
shelf bottom morphology, strongly conditioned by
the tectonic configuration, also contribute to
coastal erosion by the sediment trapped on
specific places and wave refraction.
The results showed
erosion areas are
linked to large scale
bottom morphology.
The changes are
mainly due to
longshore drift
contributions and
negative sediment
budget.
Ponta Negra (Natal Antiga, Jaeci, inicio século passado)
1919
2001
Ponta Negra, Natal-RN
We are in the wrong
place
2007
Obrigada pela atenção !
Danke fuer Ihre Aufmerksamkeit!