Etude de la coherence entre la vulnérabilité à la pollution at la qualité des eaux souterraines de la nappe alluviale de l'oued El Hachem (w. Tipaza)

Abstract

The small alluvial aquifer of El Hachem wadi, located in the wilaya of Tipaza midway between the capital of the wilaya and the city of Cherchell, is currently overexploited and at the same time exposed to a serious pollution problem that is caused by wastewater discharges and particularly the misuse of fertilizers in agriculture. According to this situation, the establishment of a rigorous management and protection program for the water table must be given all due attention. It is in this perspective that the present study, whose objective is to develop a tool to characterize in a simple but precise way, the areas where the water table is particularly vulnerable, to circumscribe high-risk areas contamination and to be able to act preventively. In this perspective, the technique used is based on the automatic mapping method known as "DRASTIC", which takes into account the main hydrogeological parameters governing underground flows. The cartographic documents obtained by the DRASTIC method show that a large part of the plain of El Hachem wadi is characterized by a low to medium degree of vulnerability and a high vulnerability just at the El Hachem riverbed. Finally, for better management of this water table, protective measures must be taken for any activity concerned on the plain, such as regular hydrochemical and bacteriological monitoring, the implementation of a policy of protection of vulnerable areas and the regulation of agricultural activities, around the catchment fields.