Morphology and current dynamics of the coast of Togo
1993
Blivi, A. (Universite du Benin, Lome (Togo). Dept. de Geographie)
The Togolese coast, 50 km long and absolutely flat, is made of two generations of beach ridges, separated from the sedimentary coastal basin, of the Tertiary age, by a continuous system of lagoons. For the last two decades, it has been submitted to violent erosion subsequent to the construction of the deep water port of Lome. This construction was executed without any consideration of the potential environment impact. The jetty of the port, 1200 m long, blocking the West-East offshore drift (1.2 to 1.5 million cubic meter per year), has caused an accumulation of sand on the west side over approximately 10 km and is causing the gradual erosion along 45 km of the coast towards the east; the average speed of the retreat is between 5 and 10 m per year. Thus, the sea has devasted several hundred hectares of coconut fields, cut in several places the international coast road, which has been reconstructed further inland, and threatened infrastructures: such as the phosphate factory and the town of Aneho. The importance of the damages let quickly to the development of geomorphological studies, laboratory researches (i.e. modelisation) and significant fields works involving 15 km of coastline protected by breakwaters and groynes. Regular monitoring of the sedimentological evolution carried out by the 'Erosion Cotiere' project of the University of Benin (Togo) allowed, on the one hand the comparison between the model's forecasts and the effective evolution, and on the other hand, the measurement of the speed of retreat along unprotected segment of coast.
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