AN INTEGRATED APPROACH OF AHP AND WOA FOR GROUNDWATER IN HARD ROCK TERRAINS – A CASE STUDY OF MAREDUMILLI MANDAL, EAST GODAVARI DISTRICT, ANDHRA PRADESH, INDIA

The present study area comprises hard crystalline rocks of the Eastern Ghats Mobile Belt. For a long period, residents in this area have been suffering from severe water crises. To overcome this problem, an innovative attempt for the first time to integrate both remote sensing and hydro-geological data has been made to identify the groundwater potential zones in the study area. Seven thematic layers like geology, geomorphology, lineament density, land use/land cover, soil, drainage density, and slope were used in this study through GIS analysis. The weights of all the thematic layers as well as ranks of the relevant sub-classes within each layer were determined using Saaty's Analytical Hierarchy Process (AHP) based on their relative importance in influencing factors for groundwater recharge. The final Groundwater Potential Zonation map for the research area was then prepared by combining all of the thematic layers using Weighted Overlay Analysis (WOA). The generated map exhibits four distinct groundwater categories viz., 'good', 'moderate', 'poor,' and 'very poor.' In the study region, these zones cover 14.95 sqkm (1.58%), 405.85 sqkm (42.64%), 518.80 sqkm (54.50%), and 12.10 sqkm (1.28%) respectively. Cross-validation was done using the Receiver Operating Characteristic (ROC) curve and the results revealed a good prediction accuracy of 83.33%. This Integrated approach yields a satisfactory result in terms of delineating groundwater potential zones in the area which may help the people living in this area to drill bore wells for their needs.