Determination of Aquifer Vulnerability in Lordegan Aquifer Using DRASTIC, AVI and GODS Models

Background and purpose: In this study, the vulnerability of Lordegan Plain Aquifer to pollution has been evaluated using DRASTIC, GODS, AVI and ArcGIS 10.5 software. The Modified DRASTIC model containing eight parameters, is a model to study the hydrogeological properties affecting groundwater pollution. By weighting and combining these parameters in the ArcGIS 10.5, vulnerable areas of the aquifer to pollution were identified. AVI method measured groundwater vulnerability using two physical parameters containing the thickness of each sedimentary rock above the uppermost saturated aquifer surface and estimated hydraulic conductivity. GODS model assessed aquifer vulnerability based on four layers of aquifer type, unsaturated area, surface depth and soil type. Sensitivity analysis was used to to show the effectiveness of the parameters used to evaluate the vulnerability index. The results of this study showed that based on modified DRASTIC model, 14, 76 and 10% of the study area had a moderate, high and very high potential vulnerability to pollution, respectively. The results of AVI model showed that more than 95% of the aquifers had high sensitivity to pollution. The results of the GODS model indicated that 45.3 percent of the region was in low vulnerability class and the rest in the middle vulnerability class. Results indicated that vulnerability assessment models provides valuable tools for authorities and decision makers to manage the Lordegan aquifer.