Coastal accretion as a result of erosion of farmed watersheds: example of the Gallon Bay

The progradation of the shores of the Gallon Bay (Martinique) has been meas ured based on diachronic mapping analysis. The sedimentary volume which acc umulates along the coast and in the bay (under the water surface) is unknow n. Erodibility has been surveyed on a square meter scale and extrapolated t o the watersheds. The results show that most sediments originate from the f armed surfaces, they are then entrained by the runoff and the Gallon river and deposited along the coast, where the bathymetry and currentology of the bay facilitate sediment retention. The harmful effects of anthropogenic in fluence in the area are discussed. (C) 2000 Ifremer / CNRS/IRD/Editions sci entifiques et medicales Elsevier SAS.