Optimization of DRASTICA vulnerability assessment model by Wilcoxon rank sum non parametrical statistical test

Abstract

DRASTIC is one among the most popular model to assess vulnerability of groundwater to pollution. This is because the model is relatively simple, less time consuming and more economical. The model can be modified to suit each geographical area better by either adding more parameters to it or removing some parameters from it. Modification of the model can also be accomplished by revising the ratings and weights of the parameters used in the model. This paper deals with groundwater vulnerability assessment of the basin of River Kodoor using DRASTIC model. In this paper, Wilcoxon rank sum nonparametric statistical test is used to revise the rates of the parameters of the DRASTICA model which is obtained by adding an anthropogenic factor known as land use and /or land cover to the original DRASTIC model. The vulnerability index of the Wilcoxon-DRASTICA model was correlated with the nitrate concentration data obtained from the study area. The coefficient of correlation between the vulnerability index and nitrate concentration data is obtained as 0.4. The coefficient of correlation between nitrate concentration data and vulnerability index of unmodified DRASTICA model is 0.38 which indicates that Wilcoxon test can be used for modification of rates of the parameters of DRASTICA model in the study area.