Analysis of vulnerability of groundwater resources and analysis of the sensitivity of drastic model using map removal and single-element mapping methods using Monte Carlo technique

Applying a proper management on water resources by identifying vulnerable areas as the first solution can be useful. The purpose of this study was to assess the vulnerability in the central plain of Guilan with drastic model. To identify the vulnerable areas of the central plain of the Guilan plain to pollution, drastic model was used and an aquifer vulnerability map was developed. The principles of the drastic model are based on the combination of seven components, depth to static level, net nutrition, aquifer environment, soil environment, topography, unsaturated environment, and hydraulic conductivity, which after ranking and applying weight impact on each component and algebraic composition of seven components, the final result will indicate the aquifer vulnerability. For this purpose, first, the information of the seven components in the central aquifer of Guilan was collected, and after entering in the GIS software, the layers needed for the model were finally prepared. Then, by using overlapping techniques after applying the required weight coefficients for each layer, a final vulnerability map was prepared. The profile of the drastic model varied from 82 to 182 for the vulnerability of the central aquifer of Guilan. The final drastic model map showed that 48.64% of the area had a high vulnerability and 50.55% had moderate vulnerability and only a small area of the plain (0.81%) had a low vulnerability. Based on the sensitivity method of map removal and single component and using the Monte Carlo technique, the depth distance to the station level was identified as the most effective component and saturation zone as the second most effective component in the central plain of Guilan.