Environmental characteristics,landscape history and pressures on three coastal lagoons in the Southern Mediterranean Region: Merja Zerga (Morocco), Ghar El Melh (Tunisia) and Lake Manzala (Egypt) |
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Authors: | F Ayache J R Thompson R J Flower A Boujarra F Rouatbi H Makina |
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Institution: | (1) Faculté des Lettres et Sciences Humaines de Sousse, Département de Géographie, Université de Sousse, Cité Erryad, B.P. 547, 4029 Sousse, Tunisia;(2) UCL Department of Geography, Wetland Research Unit/Environment Change Research Centre, University College London, Gower Street, London, WC1E 6BT, UK |
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Abstract: | Three North African coastal lagoons were selected as primary sites for integrated ecological and hydrological monitoring and
modelling as part of the MELMARINA Project (see Flower & Thompson, 2009). The three sites, Merja Zerga (13.2 km2, Morocco), Ghar El Melh (35.6 km2, Tunisia) and Lake Manzala (c. 700 km2, Egypt), are permanent water bodies with at least one well-defined connection with the sea. This article provides an account
of each lagoon’s physical characteristics and recent development including the impacts of human activities. The two sites
on the Mediterranean (Ghar El Melh and Lake Manzala) are characterised by small tidally driven variations in water level whilst
Merga Zerga, on the Atlantic coast, experiences large tidally induced water level variations and so contains large inter-tidal
environments. All the three lagoons receive freshwater inflows from their landward margins, varying in magnitude, seasonality
and ecological significance. Freshwater inflows from drains strongly influence ecological conditions within Lake Manzala.
All the three lagoons have significant biodiversity interest, especially for resident and migratory birds as well as fish,
and support local human populations. Each lagoon experienced significant changes during the twentieth century possibly affecting
declines in biodiversity value. These largely resulted from agricultural expansion and intensification and include reclamation
and hydrological modifications which have both decreased freshwater inflows due to upstream diversions (Merja Zerga and Ghar
El Melh) and increased the influx of freshwater through the return of irrigation drainage (Merja Zerga and Lake Manzala).
All three sites experienced nutrient enrichment due to agricultural runoff and discharge of domestic wastewater. Industrial
waste discharge is a particular, but not exclusive, problem for Lake Manzala. Problems of water quantity and quality will
increase through the twenty-first century with increasing demands for water while effects of climate change will enhance freshwater
scarcity. Conflicts between human and environmental uses of water will increase and unless improvements in water use efficiency
and wastewater treatment can be brought about wetlands including coastal lagoons are likely to suffer further loss and degradation.
These problems will be compounded by sea level rise.
Guest editors: J. R. Thompson & R. J. Flower
Hydro-ecological Monitoring and Modelling of North African Coastal Lagoons |
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Keywords: | Climate change Environmental change Irrigation Landscape history MELMARINA North Africa Sea level rise |
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