Geostatistical analysis of hydrogeology and agricultural land reclamation in Senegal River Delta

Abstract

The Diama dam is a dike that prevents the upstream intrusion of salt water into the lower part of the Senegal River during the low flow season. It is possible that a fraction of the salty lands from the delta region of the Senegal River will be eventually rendered fit for irrigated agriculture as a consequence of the building of this dam. A hydrogeologic survey, based on stratigraphic and piezometric data from a large monitoring well network, was conducted to describe the hydrogeologic setting of the delta alluvial aquifer and to predict the surface of reclaimable land. Geostatistical analysis, in particular kriging techniques, enables a better description of the spatial relationships of the diverse hydrogeologic variables. Since anterior studies demonstrated that the area of reclaimable lands depends mainly on the thickness of the surface clay layer, the geostatistical analysis of this variable indicates that from 40 percent to 80 percent of the lands of the delta region will eventually be cultivatable. The imprecision of this assessment is a result of the difficulty in defining a threshold for the appropriate thickness of the clay layer.