Utilisation de données multidates SPOT-XS pour l'évaluation de l'impact d'une ferme aquacole sur la dynamique écologique d'un delta tropical. Un exemple dans le Nord-Ouest de Madagascar

The article describes current changes in the Mahajamba delta, the site of the first industrial prawn production unit in Madagascar. The study of the evolution of this environment, the majority of which is occupied by mangrove, has been carried out by means of SPOT multispectral data from August 1986 and April 1993 (the period immediately preceding the flooding of the prawn farming basins) and May 1999 (in the period of full production). The spread of data over almost 13 years clearly shows the changes, at times spectacular, in the morphology of the delta and its vegetation cover. However, although some of the mangrove has been cleared along certain channels so as to connect the prawn farms to the hydrological network (about 100 hectares, or 0.3 % of the area covered by mangrove), these changes do seem to have been independent of the development of aquaculture.