Geospatial assessment of groundwater vulnerability to pollution using the DRASTIC and AHP model in flood-affected area, Nowshera, Pakistan

The frequency and intensity of disastrous floods are increasing globally due to climate change. Floodwaters can infiltrate open-dug wells, boreholes, and aquifers, contaminating groundwater. Additionally, anthropogenic activities such as agriculture and industrial processes significantly contribute to groundwater pollution. District Nowshera, located downstream in the Kabul River Basin, faced severe impacts from catastrophic floods in 2010 and 2022, highlighting the serious threat to groundwater vulnerability in the region. The current research is attributed to assessing the aquifer vulnerability to pollution using the DRASTIC and analytical hierarchy process (AHP) models in Nowshera. Several parameters, such as depth to groundwater, Net recharge rate, aquifer media, soil media, topography, the impact of the vadose zone, and conductivity of the aquifer, have been evaluated. Weights and rating analysis for these parameters have been done using the standard methodology of the DRASTIC and AHP approach. The final vulnerability maps produced for the study area were divided into five groundwater-vulnerable zones. The DRASTIC results categorized the study area as very low, which covers an area of 278 km², low 460 km², moderate 543 km², high 355 km^2, and very high 90 km². In AHP results, a very highly vulnerable zone covers an area of 233 km², more than the DRASTIC results. The results have been validated with the concentration of nitrate, sulfate, and total dissolved solvent water quality parameters. This study presents a straightforward method to assess groundwater pollution vulnerability, provides valuable insights for policy and decision-makers in managing groundwater pollution, and identifies suitable sites for landfill disposal.