Impact d’un barrage sur la qualité des eaux souterraine en aval, Nord Algérie (Barrage Béni Haroun)

Abstract

This present work aims to study the Impact of a dam on the quality of groundwater downstream, the case of the Beni Haroun dam located in the North-Eastern of Algeria, in a sub-humid to semi-arid region with precipitation of 088 mm and evapotranspiration of 0880 mm. The Beni Haroun watershed occupies a strategic location from a geological and hydrogeological point of view with a surface area of 5320 km3, characterized by a high potentialities of surface water (Oued Rhumel, Oued Endja…) and groundwater (alluvial aquifers of Oued Endja, karst aquifer and Constantinian neritic). The result of the piezometric monitoring at the level of the piezometers installed in the dam site gives an overview of the infiltration of the dam water towards the karst representing the seal of the dike. The last dry years have allowed the filling of the dam and thereby the increasing of the piezometric level in the aquifers located directly below the dam and the inferoflux of Oued Endja The chemical study of water has shown that the alluvial aquifer and the water of the dam are characterized by a sulphate facies while the karst aquifer has been infuenced by the carbonated ormations (calcic carbonated facies).