Groundwater exploration in hard rock terrains of East Godavari district, Andhra Pradesh, India using AHP and WIO analyses together with geoelectrical surveys

The need for groundwater exploration in India has been increasing enormously, due to the non-judicial use of available water resources. The present study area is located between longitudes from 81°52′20.293′′ to 82°29′32.058′′ E and latitudes from 17°01′6.71′′ to 17°38′ 12.906′′ N in the Eastern Ghats mobile belt region of East Godavari district. The study area is characterized by a wide range of geological settings and high and irregular topographic features. The area is identified by Government as highly backward and Tribal people dwell here. For exploring good aquifer in the study area, the information of ten parameters together with geoelectrical resistivity data has been collected. Analytical Hierarchy Process (AHP) is used as the decision-making technique which uses the weights of different thematic layers (parameters) favorable for groundwater recharge, storage and location. Various thematic layers (parameters) of geology, geomorphology, soil, slope, lineament density, drainage density, groundwater level, Land use/Land cover, rainfall and coefficient of electrical anisotropy were considered in this analysis. A comprehensive groundwater prospect map has been prepared and validated with aquifer thickness map derived from the analysis of geoelectrical data. The entire study area has been classified into different potential zones of good, moderate and poor for groundwater exploration. The good groundwater potential zone is covering an area of 750.91 sqkm (28.4%) with aquifer thickness varying in the range 40–140 m, moderate potential zone encompasses 46.1% of the study area with an areal extent of 1220.33 sqkm and aquifer thickness is about 20–40 m. The remaining area of 24.5% is poor aquifer zone with thickness less than 20 m.