Methodology used A combination of the AHP, modified DRASTIC, and DRASTIC models were used to identify the assessment of groundwater vulnerability. Fig. 2 indicates the overall methodology adopted in this study. The following steps were employed. (1) The DRASTIC method was applied. (2) The rates of the DRASTIC model were ascertained through the Wilcoxon rank-sum nonparametric statistical test (Wilcoxon, 1945).