Delineation of regional groundwater vulnerability using DRASTIC model for agricultural application in Pakistan

Abstract

In recent years, one of the major concerns is groundwater contamination by industrial wastewater. Consecutive monitoring/mapping of aquifer water quality is an expensive and hectic job in relatively large areas. Therefore, groundwater vulnerability maps are becoming more crucial to identify regional aquifer contamination potential. The present study area is focused to the largest industrial and metropolitan city of Pakistan, i.e. Faisalabad. The study is aimed to explore groundwater vulnerability potential zones and to identify most influencing hydrogeological characteristics. In this regard, a GIS-based DRASTIC model is used to delineate vulnerability to agricultural applications. Inputs of the model are based on seven different layers and the model is compared with groundwater samples. Results showed that the model accurately identifies the vulnerability with the prediction efficiency of ~ 73%. The results revealed that more than 30% of the study area has high vulnerability potential, located in the middle and upper part of district Faisalabad. It has been found that the causation of high vulnerability in the surrounding of various cities is due to shallow groundwater table, high recharge, gradual slope, sandy aquifer media, and soil media that consist of medium sand. In some of the cities, dominating factors are shallow groundwater table, gradual slope, vadose zone that consists of course sand and high hydraulic conductivity. Therefore, it is recommended that the site-specific solutions according to their influencing hydrogeological features to pollution must be adopted. In this aspect, rainwater harvesting, aquifer storage, and recovery wells (ASR) could be adopted to reduce water salinity in medium and high vulnerability areas.