A GIS based DRASTIC model for assessing groundwater vulnerability of Katri Watershed, Dhanbad, India

Groundwater vulnerability assessment could be defined as the degree of assimilation capacity of the area to the contaminant from surrounding surface above the aquifer. It has become an important element for sustainable natural resource management and proper landuse planning. This study aims at estimating shallow aquifer vulnerability by applying the GIS based DRASTIC model in Katri watershed, Dhanbad, Jharkhand. The probable groundwater quality decline due to various anthropogenic activities within the Katri watershed has necessitated this study using a combination of DRASTIC and GIS method as an effective method for groundwater pollution risk assessment. This model is based on the seven hydrogeological 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 vadose zone and hydraulic Conductivity. The mapping of the DRASTIC index allows us to delineate zones with various degrees of pollution vulnerability. The study reveals that about 16.91 % of the watershed area is exposed to high-risk, 30.69 % exposed to medium-risk, and 52.4 % exposed to low risk. The south eastern and south western parts of the watershed are dominated by high vulnerability classes while the south, north western and lower middle portions are characterized by moderate vulnerability classes. The elevated northern, north eastern, and middle part of the study area displayed low aquifer vulnerability.