GIS modeling approach for assessment of groundwater vulnerability in parts of Tawa river catchment area, Hoshangabad, Madhya Pradesh, India

Assessment of the groundwater contamination vulnerability was carried using a GIS based DRASTIC model in Tawa river catchment, Hoshangabad, Madhya Pradesh, India. The study aimed at demarcation of the susceptible zones of groundwater contamination by integration of the various hydrogeological layers of the model in GIS environment. The input model variables i.e. depth of water table, net recharge, aquifer media, soil type, topography, impact of vadose zone and hydraulic conductivity were evaluated from different sources incorporated in the model and groundwater contamination vulnerability map was prepared. The output groundwater vulnerability map shows that 34.84% of the area is in high risk zone of groundwater contamination. The high probability of contamination in the zone is due to rigorous farming and encouraging recharge facilities along the river valleys. An extensive part covering 54.84% area towards the eastern and western side of Tawa River is falling in moderate zone of groundwater contamination. A small area covering 10.32% towards southern Satpura hill slopes with low contamination chances lies in low risk zone of groundwater contamination. Further, for validation of the model results 30 groundwater samples were collected from the delineated groundwater vulnerability zones. These samples were processed for evaluation of nitrate concentration. In low vulnerable zone, nitrate was present in < 5 ppm, in moderate vulnerable zone nitrate varies from 5-20 ppm, whereas in high contamination zone nitrate varies from 20-76 ppm. Thus, the applied model approach has been found effective for the prevailing hydrogeological settings of the area. The model can be used as an efficient tool for the assessment and management of groundwater resources.