An Assessment of Vulnerability Using DRASTIC Model and a Single- Parameter Sensivity Analysis: A Case Study of Kashan Plain Aquifer, Iran

Assessment of groundwater vulnerability to determine the vulnerability potential factor is deemed to be a basic step in water resources management. In this regard and for the purpose of current study, the DRASTIC model is applied to critically assess the vulnerability of Kashan plain aquifer. In this method, seven hydrogeological parameters, effective in aquifer vulnerability, were prepared based on Raster maps and combined thereafter. Following that, Zone vulnerability to nitrate pollution measured for Kashan plain aquifer were determined. The influence of given parameters was also investigated by implying the Single-Parameter sensitive analysis as well as Wilcoxon Rank-Sum Non parametric statistical test. The result of sensitive analysis indicates that in most of the cases, the effective and theoretical weight of parameters not only lacks any coincidence in the current model but surprisingly some cases have considerable differences. Moreover, the result of various vulnerability zones demonstrates that the study area for three categories of Low, Average and High which were 59.29, 17.82 and 22.89 percent before the correction of model are eventually converted to 48.37, 28.05 and 23.56 after the model correction.