Aquifer vulnerability identification using DRASTIC-LU model modification by fuzzy analytic hierarchy process

Groundwater is one of the most important sources of freshwater supply, which is threatened by unplanned human activities and climate patterns. Identifying areas vulnerable to pollution is essential to protecting these precious resources. DRASTIC model is one of the models that prepares a vulnerability map according to the conditions and characteristics of the study area. In this study, three new vulnerability mapping models were applied to the Birjand aquifer by changing and modifying the original DRASTIC model. By adding the land-use (LU) parameter to the original DRASTIC model, the DRASTIC-LU model was prepared. Analytic hierarchy process (AHP) and fuzzy analytic hierarchy process (FAHP) methods were used to assign new weights and rates to each model parameter. After preparing the required data and thematic maps of DRASTIC parameters, the vulnerability map of each model was generated in the GIS environment. The results were categorized into four classes: low, medium, high, and very high. Using simple linear regression, Pearson's and Spearman's methods, each model was validated with nitrate concentration values. By calculating the accuracy of each model, as expected, it was observed that the DRASTIC-LU FAHP model had the highest accuracy among the models (R-2 = 0.87), followed by the DRASTIC-LU AHP (R-2 = 0.82), DRASTIC-LU (R-2 = 0.77), and DRASTIC (R-2 = 0.69) models, respectively. According to the validation results, the DRASTIC-LU FAHP model was selected as the most suitable model in this region.

Automated summary

Groundwater is a vital freshwater source threatened by human activities and climate patterns. This study developed and validated three new vulnerability mapping models for the Birjand aquifer. The DRASTIC-LU FAHP model was found to be the most accurate and suitable for the region.