Evaluation of Vulnerability to Nitrate Pollution in Aleshtar Aquifer using DRASTIC and SINTACS Models

Protecting and preventing pollution of groundwater resources is an essential element. In this research, two methods of DRASTIC and SINTACS were used to identify vulnerable areas of Aleshtar aquifer. In this research, the sensitivity map of the plain was developed for each of these models in a GIS environment. The correlation coefficient was calculated by Pearson method. By comparing this coefficient and the inherent vulnerability index of the above models, the DRASTIC model was chosen due to having a greater correlation coefficient (0.67) compared to the SINTACS model (0.50) and modify of the weight of its parameters performed. To ensure the performance of the models, the Pearson method was calculated based on the nitrate layer of the wells and vulnerability maps. Due to the high correlation coefficient between the model of the DRASTIC and nitrate layers and because of the non-matching of the parameters assigned to the parameters in the model with the results of the sensitivity analysis, the AHP ranking method was used. According to the results, the weight of the topographic parameter was 1 to 2 and the unsaturated vadoze zone parameters weight was changed from 5 to 2.8, and net recharge parameters and soil environment due to negative correlation with the zoning map nitrate were omitted. The modified model (DATIC) categorized the area into three different vulnerability classes, of which 67 percent were negligible, 24 percent were very vulnerable and 9 percent were classified as vulnerable, Based on the results, the Pearson correlation coefficient jumped to 79 percent in the revised version that can be verified by definition Drastic modification is in the Aleshtar Aquifer.