Application of DRASTIC model for assessing groundwater vulnerability: a study on Birbhum district, West Bengal, India

Abstract

Groundwater is one of the important necessary renewable resources of the world. Without water, no life can be possible on this earth. It is not only sustaining all biotic elements of the earth but also it helps to fulfill the requirement of various sectors like agriculture, industries, and other domestic purposes. Not all types of water but the mineral added purified water is safe for the human being. Unfortunately, in this age of development, it's very difficult to get naturally purified water because of the application of chemical fertilizer to get more production from agriculture, extensive industrialization pollutes groundwater resources badly. So, it’s high time to think about this most valuable resource. In this context, current research aims to identify the most polluted or vulnerable zones of groundwater in the Birbhum district. From several studies, it has been found that Birbhum district is one of the fluoride contaminated districts. Except, fluoride, another chemical component i.e. iron is also another harmful component in this district. Therefore, to assess the most vulnerable groundwater zones DRASTIC model has been applied here. DRASTIC is a widely used model for this purpose. This study deals with how the application of the DRASTIC model can help to extract the vulnerable zones of groundwater. To run the DRASTIC model various parameters viz. Depth to water level, Net recharge, Aquifer media, Soil media, Topography, Impact of the vadose zone, and Hydraulic conductivity have been used here. The final vulnerable map shows that the western part is more vulnerable than the eastern part because the western part consists of the plateau fringe area with basalt and granite and more weathering prone that’s why contamination of harmful minerals dissolve with groundwater most quickly. Moreover, the groundwater level is near to surface in the western part due to the presence of hard rocks near the surface than the eastern part. The applied DRASTIC model has been validated using the receiver operating characteristic curve (ROC) and this curve has been prepared based on some random points composed of various harmful chemical components. The result of the receiver operating characteristic curve depicts that this model is 73% valid in this concerned region.