Development of a land management model for evaluating the effect of point pollutants on well water quality using mathematical modeling and GIS

ABSTRACT A novel and integrated well capture and point pollution index (WCPPI) model was developed to evaluate the effect of point pollutants on groundwater within wellhead protection buffer zones in the Meshgin-Shahr plain aquifer (Iran), an important horticultural plain. The WCPPI combines point-source pollutant density in river and well riparian buffer zones (derived using kernel density estimation in GIS) with well capture areas (simulated by MODFLOW and MODPATH). The mathematical model was calibrated and validated in steady and unsteady states according to 10-year statistical data (2011–2020). Statistical data were divided into two categories, the first 8 years for calibration and the last 2 years for model validation. Then, sensitivity analysis was performed for hydraulic conductivity, recharge and anisotropy parameters to carry out a more accurate calibration. The WCPPI results were validated by groundwater nitrate and chloride concentrations. The findings put the entire plain area within the low-risk range. A positive and almost linear correlation was found between hazard index and pollution indicators, with the Pearson correlation coefficient of 0.58 and 0.49 for nitrate and chloride, respectively. To conclude, industrial development programs in this plain should give priority to areas with lower risk to prevent groundwater pollution.