Application of GIS based drastic model for groundwater vulnerability assessment in north 24 parganas district

Abstract

Surface water quality is determined by hydrological responses that vary spatially. However, the sub-surface hydrologic environment has a primary influence on groundwater movement and hence pollutant migration to the subsurface water. Maps of aquifer vulnerability to pollution are becoming more in demand because, on the one hand, groundwater represents the primary source of drinking water. On the other hand, high concentrations of human/economic activities, e.g., industrial, agricultural, and household, represent actual or potential sources of groundwater contamination. There is a need to conduct studies on groundwater pollution. The main objective is to determine the vulnerable groundwater zones in North 24 Parganas district by DRASTIC Model in a Geographical Information System (GIS), Arc GIS10.5 was used to create a map by overlaying the available hydro-geological data. This Model is based on the seven data layers that provide the input to the modelling. It corresponds to the initials of seven layers, i.e., Depth of water, Net Recharge, Aquifer media, Soil media, Topography, Impact of the vadose zone, and hydraulic Conductivity. The output map shows that the entire district has been classified into three different groundwater vulnerability zones — high, moderate, and low. The more significant portion of the study area falls within the intermediate vulnerability zone, Blocks name are Amdanga, Barrackpore-II, Rajarhat, Habra-I, Gaighata, Bongaon, Bagdah, Baduria, Swarupnagar, Haroa with an index number of 97-111. Barasat-I, Barrackpore-I, Bashirhat- I, Bashirhat-II, Minakahan, Hingalganj, Sandeshkhali-I, Sandeshkhali-II blocks are in low vulnerability with an index number of 83-97, Barasat-II, Habra-II, Deganga are in high vulnerability zone of 111-125 index number. The GIS technique has proved as an efficient tool for assessing and analysing the vulnerability to groundwater pollution. The study suggests that this can be an effective tool for local authorities responsible for managing groundwater resources. Keywords: Groundwater Pollution, ArcGIS Software, Drastic Model, Groundwater Vulnerability Zones, Raster Calculator, Weighted Sum Analysis