Groundwater pollution vulnerability assessment using a new GIS-based DRASTIC method

Protection of groundwater from pollution is generally a global political decision. These decisions are essentially supported by DRASTIC analysis-being the most popular method of evaluating the intrinsic pollution vulnerability of groundwater. However, because of the spatial variability around the world, the model has been exposed to various transformations. Especially the weights assigned to the parameters constituting the model, for their enormous effect towards achieving final vulnerability result. Popular among the DRASTIC weights transformation technique are the single parameter sensitivity analysis (SPSA) and analytic hierarchy process (AHP). While these methods are proven effective in some studies, they are contrarily ineffective in others. In this study a new approach was developed using Pearson’s product moving correlation (PPMC). The weight assigned to a parameter is directly proportional its level of input on attaining nitrate contamination. Hence it is likely to be most suitable for virtually all areas as the groundwater vulnerability map is generated based on the pollution pattern of the area under study. Seven models were compared to determine the best option for the study area. The nitrate validation result indicated that DRASTIC was 0.73, FRASTIC 0.65, DRASIC-SPSA 0.75, FRASTIC-SPSA 0.75, DRASTIC-AHP 0.74, FRASTIC-AHP 0.63 and FRASTIC-PPMC which is developed in this study was 0.77. As far as the study area used is concerned the new developed DRASTIC-PPMC had proven to be the most effective groundwater pollution vulnerability assessment approach.