Utilizing the DRASTIC Framework and GIS Techniques to Identify Groundwater Vulnerability to Pollution

Abstract

Assessing the susceptibility of groundwater is a crucial first step in the effective management of groundwater resources, particularly in regions where groundwater pollution and anthropogenic activity are prevalent. This study evaluates the intrinsic vulnerability of groundwater to contamination in the Qara-Hanjeer sub-basin, northeast of Kirkuk, Iraq, using the DRASTIC model. This model represents Depth to water, Recharge, Aquifer media, Soil media, Topography, Impact of the vadose zone, and Hydraulic Conductivity, integrated with Geographic Information System techniques. Seven hydrogeological parameters, including depth to groundwater, net recharge, aquifer media, soil media, topography, impact of vadose zone, and hydraulic conductivity, were collected from field surveys, borehole logs, and spatial data. These parameters were analyzed using GIS software, standardized, and assigned weights according to their relative importance. The sum of these weighted layers produced a DRASTIC index map highlighting zones of varying groundwater vulnerability. The final map was classified into five zones: very low, low, moderate, high, and very high. These risk zones cover around 26.3%, 26.4%, 13.5%, 9.7%, and 24.1% of the area, respectively. The DRASTIC index ranged from 44 to 98, indicating varied vulnerability across the basin. Results show that the southwestern parts of the sub-basin exhibit high to very high vulnerability due to shallow water tables and steep slopes. In contrast, areas in the center show low vulnerability. The vulnerability map serves as a valuable tool for guiding land-use decisions and prioritizing groundwater protection. Future research may include nitrate validation and sensitivity analysis to enhance model reliability.