Unité de Formation en Sciences et Gestion de l'Environnement, Laboratoire Géosciences et Environnement, Université Nangui Abroguoua 02 BP 800, Abidjan, Côte d'Ivoire
This study aims to explain the dynamics of the local climate in southwestern of Côte d'Ivoire in a context of strong human pressure and climate variability. The methodological approach, based on the use of climate data an opportunity to discuss the impact of environmental change on natural resources. Southwestern Côte d'Ivoire has suffered a sharp change in vegetation cover. Since the climate out of 1970, the region observed spatiotemporal variation of rainfall regularly changing down. She sees an emphasis on the occurrence of extreme weather events, especially in terms of temperatures. These changes have resulted in a reduction of consecutive wet months and threatening storm agriculture practice in this area.
This work aims to test the polygons' method of Thiessen, initially used to evaluate the average rainfall for assessing a groundwater recharge. The study concerns the groundwater of Terminal Continental, the main source of water alimentation of Abidjan population. The database is constituted by rainfall (three stations) and piezometric data (ten piezometers). This method has been tested on both cases: in surface for calculating the total recharge and in saturated zone for assessing the true recharge. The results showed that the ground water of Abidjan total recharge is estimated to 252 mm.year-1; the one estimated in saturated zone is equivalent to 158 mm.year-1 in 2006, that is to say 12 pc of the total infiltration. The taking account of "land use" factor in the approach underlined the fact that the quick ongoing urbanization of Abidjan city is reducing the infiltration zones.