A GIS based DRASTIC model for assessing groundwater vulnerability in shallow aquifer in Aligarh, India

Abstract Surface water quality can be determined by hydrological responses that vary geographically. The sub-surface hydrologic environment, however, has a primary influence on groundwater movement and hence pollutant migration to the sub-surface water. Maps of aquifer vulnerability to pollution are becoming more in demand because on the one hand groundwater represents the main source of drinking water, and on the other hand high concentrations of human/economic activities, e.g. industrial, agricultural, and household represent real or potential sources of groundwater contamination. There is a need to conduct studies on groundwater pollution. The main objective of this paper is to find out the groundwater vulnerable zones in shallow aquifers in Aligarh and its surrounding areas, which is one of the fastest growing big cities of north India, using the DRASTIC model in a Geographical Information System (GIS) environment. This model is based on the seven data layers that provide the input to the modeling. It corresponds to the initials of seven layers i.e. Depth of water, net Recharge, Aquifer media, Soil media, Topography, Impact of vadose zone and hydraulic Conductivity. ILWIS 3.0 (Integrated Land and Water Information System) and Arcview 3.2a GIS software were used to find out the water vulnerable zones in shallow aquifers. The study shows that more than 80% of the city's groundwater is under medium to high vulnerability to water pollution which is the main cause of concern for nearly 0.8 million people living in Aligarh. The GIS technique has provided an efficient tool for assessing and analyzing the vulnerability to groundwater pollution. The study suggests that this model can be an effective tool for local authorities who are responsible for managing groundwater resources.