ASSESSMENT OF GROUNDWATER INTRINSIC VULNERABILTY USING GIS BASED DRASTIC MODEL IN HARIPUR AREA, KHYBER PAKHTUNKHWA, PAKISTAN

Abstract

Study was conducted to assess the intrinsic susceptibility of the groundwater system using a weighted overlay – index approach known as GIS based DRASTIC model in GIS setting in District Haripur. Haripur is a major district of Pakistan’s Hazara division, which is famous for its agriculture. The district Haripur has a major industrial state i.e. Hattar Industrial State which contributes to needs of whole country. Due to the increasing population, rapid industrial growth and other human activities the groundwater is under risk of contamination. Therefore, study was designed to avoid the exposure of population to contaminated water by identifying areas vulnerable to groundwater pollution. For this purpose, GIS based DRASTIC model was applied because of its efficiency, accuracy and easy execution. The data and information needed for assessing the vulnerability of the area was gathered from numerous organizations and from literature survey. Using GIS, seven thematic map layers were generated from the data gathered which are Depth to water, Net Aquifer Recharge, Aquifer Media, Soil Media, Slope/Topography, Vadose zone and Conductivity (Hydraulic). A weighted overlay- index analysis was carried out using these seven layer to obtain a susceptibility map of the study area. Results of the Weighted overlay analysis indicates a range (88-190) of DRASTIC Indices. Which was further classified into five smaller classes i.e. Low vulnerable zone (88 - 109), Medium vulnerable zone (110 - 129), Moderate vulnerable zone (130 - 149), high vulnerable zone (150 - 169) and very high vulnerable zone (170 - 190). Each zone was allotted a distinctive color on the map for easy identification. A dominant area of 965 kilometers square was covered by moderate vulnerable zone. Both medium and high vulnerable zone covers an area of 506 kilometers square. Low vulnerable zone covers an area of 118 kilometers square. Lastly very high vulnerable encompass the least area i.e. 66 kilometers square. The study recommends that the susceptibility map and assessment should be incorporated while making policies regarding land use.