Data collection Table 1 presents the data used for the groundwater vulnerability assessment. The features in the GIS data sets were created and the relationships among the features were defined. The features used in the spatial analysis were represented by each layer on the maps.
2.3. 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).