A GIS-based Modified DRASTIC (ANP) method for assessment of groundwater vulnerability: a case study of Nagpur city, India

Quality of groundwater is as important as quantity. For effective planning and management of groundwater resources, groundwater vulnerability assessment is most significant. The objective of the present study was to evaluate the groundwater vulnerable zones of Nagpur city, using Modified DRASTIC methods within a Geographical Information System (GIS) environment. DRASTIC method has been modified using land use/land cover parameter; weight of the parameters was modified using Analytical Hierarchy Process (AHP) and Analytical Network Process (ANP). Sensitivity analysis has been carried out to consider the most sensitive parameters. A new approach ANP was applied on DRASTIC for the first time to modify the weight of the parameters. Groundwater vulnerable zones obtained from the DRASTIC, Modified DRASTIC, Modified DRASTIC AHP and Modified DRASTIC ANP were compared and validated using field data of nitrate concentration. Results obtained from the Modified DRASTIC ANP are found to be well correlated with the nitrate concentration of the city and it is appropriate for assessment of groundwater vulnerable zones of Nagpur city. From this study it was found that the necessary remedial measures should be taken in the highly vulnerable zones of Nagpur city for further prevention of groundwater pollution.