Étude comparative de deux modèles (DRASTIC et SI) pour l'évaluation de la sensibilité de la nappe phréatique de Mnasra (Maroc nord-occidental) à la pollution d'origine agricole

Abstract

The groundwater of Mnasra, situated on the coast of Gharb in the Northwest of Morocco, constitutes an important reservoir of fresh water. During the last two decades, it has become the basis of the development of intensively-irrigated crops. These are characterized by the intense use of artificial fertilizers which represent, along with pesticides, a major risk for the subterranean durability of water resources.To measure the impact of the intensification of the use of the soil on the quality of subterranean water, the present study aims at evaluating and locating the sensibility of the underground water of Mnasra in terms of the agriculture-induced pollution by means of modeling coupled with the SIG. The application of two models, the DRASTIC model (L. ALLER et al. 1987), and the SI model (L. RIBEIRO, 2000), has made it possible to compare the results of the two methods and to assess them according to facts. The map of the susceptibility obtained by the SI model turns out to be closer to real conditions. It may be considered as an fairly effective tool, although perfectible, to estimate the risks of the degradation of the quality of subterranean water.

Keywords

• Morocco
• pollution
• nitrate
• underground water
• coast of Gharb