ASSESSMENT OF GROUNDWATER INTRINSIC VULNERABILITY USING GIS BASED DRASTIC METHOD IN SOUTHERN PART OF DISTRICT KARAK, KHYBER PAKHTUNKHWA, PAKISTAN

Abstract

The Study area lies in the Eastern part of the southern Kohat deformed fold and thrust belt. This part of the Kohat plateau, borders the southern extension of the Himalayan deformation, with the Salt range to the south most. The research is based on the DRASTIC model. Groundwater is vulnerable to contamination by anthropological activities. Vulnerability mapping is considered as a fundamental aspect of groundwater management. The aim of this study was to estimate aquifer vulnerability by applying the DRASTIC in southern part of district karak, Khyber Pakhtunkhwa, Pakistan. The DRASTIC model uses seven environmental parameters (depth to water, net recharge, aquifer media, soil media, topography, impact of vadose zone, and hydraulic conductivity) to characterize the hydrogeological setting and evaluate aquifer vulnerability, The information layers for models were provided via geographic information system. The results showed that the DRASTIC model. For DRASTIC model, the correlation coefficient between vulnerability index concentrations was 100% which is is highest vulnerability, 66% show medium vulnerability and 33% show low vulnerability, The Low vulnerable zone cover 1019.51 square km area, Medium vulnerable zone cover 375.12 square Km while High vulnerable zone cover 160.35 square Km area. The highest Nitrate concentration recorded in the area is 13.57 ppm and the lowest is 0 ppm. Around 45% of the samples surpassed the approved limit of PSQWA and NSQWQ standard. The concentration of Nitrate >10 ppm represent that some human action has contributed toward the highest concentration.