A GIS-based modified DRASTIC approach for geospatial modeling of groundwater vulnerability and pollution risk mapping in Korba district, Central India

Intensive use of fertilizers in the agricultural lands and a swift-flying of coal and allied industries in Korba district, India in an unprecedented manner has led to groundwater contamination. Accordingly, an integrated modified DRASTIC and risk index model combined with other statistical techniques are applied to evaluate groundwater susceptibility and pollution risk in the region. The ArcGIS based spatial distribution map of the DRASTIC vulnerability index (DVI) reveals that the high (63%) and very high (23.61%) vulnerable zones identified in DVI map are reduced to that of 57.86% and 17.74%, respectively, when compared with pollution risk map. Results of sensitivity analysis, i.e., map removal sensitivity analysis and single parameter sensitivity analysis confirms that amongst seven DRASTIC parameters the net recharge parameter is the most influencing parameter in view of the groundwater contamination. The linear correlation coefficient (r = 0.89) obtained between risk index values and NO3 concentrations alongside nearly 75% of the study area comprises of agricultural lands and forest/tree clad area corresponds to high to very high risk contamination zones reveal the model validation in the light of the influence of anthropogenic contamination factor in these zones. Furthermore, elevated iron concentration also supports the certain influence of geogenic contamination within the study area. In essence, this study can be effectively utilized in the planning and management of precious groundwater resources in high to very high vulnerable and risk zones of the study area, for its overall sustainable development.