Assessment and Modification of DRASTIC Model for Groundwater Vulnerability – Shahrekord Case Study

DRASTIC model is the most widely used method for aquifer vulnerability mapping which consists of seven hydrogeological parameters. Despite of its popularity, this technique disregards the effect of regional characteristics and there is no specific validation method to demonstrate the accuracy of this method. The main goal of this research was to develop an integrated GIS-based DRASTIC model, to assess its performance, and to modify it in order to obtain a more reliable and accurate model. The original DRASTIC model was not able to predict the extent of nitrate pollution and vulnerability of Shahrekord aquifer. The rates and weights of original DRASTIC were modified using Wilcoxon rank sum non-parametric statistical test and Single Parameter Sensitivity Analysis (SPSA). The validation results obtained from Pearson’s correlation revealed that the modified rate/weight (MRW) DRASTIC model is more efficient than original DRASTIC showing significant improvements (r = 0.88) compared to the original DRASTIC model (r = -0.30).

Keywords:

DRASTIC model , Groundwater vulnerability , Nitrate , GIS