Application of drastic method for determining the vulnerability of an alluvial aquifer: Morsott - El Aouinet north east of Algeria: using arcgis environment

Abstract This study aims at the vulnerability assessment of an alluvial aquifer in a semi-arid environment, Morsott, Boukhadra and El-Aouinet region, N.E of Algeria, an alluvial area that has suffered of increasing salinity toward the northern part of the basin. A vulnerability map has been developed using DRASTIC model based on a geographic information system (GIS), this method accounts for the aquifer parameters like depth to water, net recharge, aquifer media, soil media, impact of Vadose zone and hydraulic conductivity. The DRASTIC Vulnerability index (DVI) is calculated as the sum of product of ratings and weights assigned to each of the parameter. Examination of the vulnerability map allowed us to determine three classes ranging from very low to very high. The northern part of the plain show the highest vulnerability class, indicating that it is the most vulnerable to external contamination. The moderate class is scattered in the southern and east also the northwest area, the low class vulnerability occupies the most part of the plain which will guarantee a satisfactory sanitation in space and time, in the case of accidental pollution.