<scp>GIS</scp> ‐Based Groundwater Vulnerability Assessment Using <scp>DRASTIC</scp> Method and Fuzzy Logic: Case Study of Mostaganem Plateau in Algeria

ABSTRACT GIS‐based groundwater vulnerability assessment was conducted on the Mostaganem plateau (700 km 2 ) in north‐western Algeria using an integrated DRASTIC and fuzzy logic approach. The plateau's groundwater, vital for agriculture, industry, and drinking water, faces contamination threats from overexploitation and intensive agrochemical use. Traditional DRASTIC method limitations include abrupt transitions between vulnerability zones due to fixed thresholds. This study integrates fuzzy logic into the conventional DRASTIC model within a GIS environment, enabling gradual vulnerability factor ratings through fuzzy numbers to better represent continuous transitions. GIS‐based comparison between traditional DRASTIC and Fuzzy‐DRASTIC methods shows significant improvement: the traditional method identifies two vulnerability classes (65% low, 35% moderate), while the GIS‐implemented fuzzy version provides enhanced classification with three levels (21% low, 61% moderate, 18% high). The most vulnerable areas are located in the western and southwestern regions. Validation using nitrate concentrations from 52 wells confirms that the GIS‐based Fuzzy‐DRASTIC method delivers superior classification accuracy and better correlation with field data.