Evaluation de la recharge naturelle des aquifères en climat soudano-sahelien par modelisation hydrologique globale: Application a dix sites au burkina faso

Abstract

The considerable effort made to exploit groundwater in the Sudan-Sahel region made necessary the evaluation of the natural aquifer flow due to rainfall. Research by an international group of organisations was performed at ten sites within three regions of Burkina-Faso. Each site was equipped with a climate station and a continuous groundwater-level recorder during 1985 and 1986 in order to make pumping tests. The piezometric measurements at each site have been separately analysed using lumped hydrological models simulating the processes of rainfall, evapotranspiration, streamflow and recharge. The operation of the models showed that, in the absence of surface flow measurements, it is not possible to resolve uniquely the difficulties of estimating the storage coefficient of aquifers. An analysis of surface flow measurements in neighbouring basins associated via a hypothesis of model parameter homogeneity within a given region has allowed a conclusion to be reached which constitutes the best possible compromise between all the data A simulation of piezometric levels and recharge in the period 1954-1986, from available piezometric abstracts at four synoptic stations, permitted the evaluation of the variability of recharge and a statistical assessment of the 1985–1986 period of observation. The calculated annual recharge varies from year to year in the ratio of one to two or one to three according to the site. The simulation indicated that the recharge calculated for 1985 is near the minimum of the period 1954–1986 in the regions of Katchari, Silmissin and Barogo, and near the mean in the region of Sideradougou. © 1990 Taylor and Francis Group, LLC.