Application of multi-criteria decision making (MCDM) and electrical resistivity tomography (ERT) techniques for identification of groundwater recharge zone(s) in granitic hard rock aquifer

摘要

Groundwater recharge is a hydrological process where water flows from sub-surface layers to the water table of the aquifer and is the backbone of the hydrogeological system. The present study is carried out in a granitic hard rock aquifer region within and surroundings of the CSIR-NGRI campus, Hyderabad. The aim of this study to identify the potential groundwater recharge zone(s) using GIS based multi-criteria decision making (MCDM) along with sub-surface mapping from Electrical Resistivity Tomography (ERT) technique. The assigned weight of the different thematic layers of surface and sub-surface parameters and their specific characteristics was determined based on their relative contribution to the groundwater recharge and thus the normalized weight was computed using MCDM technique. These thematic layers were integrated with the help of ArcGIS to accurately identify the recharge zones within the study region. The resulting recharge map has been categorized into five classes viz., very poor, poor, moderate, good and very good. Numerically 23.11% of the study area is in a moderate zone of recharge, 4.97% in good and very good zone, while 71.92% falls under the poor and very poor zone, i.e., unsuitable for groundwater recharge. The recharge zone map of the study area is found to be in agreement with 2D inverted resistivity models for two different time periods, which revealed distinct geological features and thus identified the near surface recharge property, where recharge zone resistivity values lie between ${sim}$20 and 70 $Omega$.m up to 11 m depth. Thus, the integrated results from the present study delineated groundwater recharge zone(s) for sustainable groundwater resources in the granitic hard rock system.