An Integrated Approach for Delineating and Characterizing Groundwater Depletion Hotspots in a Coastal State of India

Abstract

Abstract Visualization of present state of aquifers and identification of groundwater depletion hotspots are important tools in preparing an effective groundwater management plan. Therefore, this study developed an integrated framework by bridging a number of relevant factors to characterize and visualize groundwater depletion hotspots in Andhra Pradesh, India. Firstly, the groundwater status was assessed by detecting spatio-temporal trends in groundwater levels of 429 dug well sites from 2004 to 2018 using Mann-Kendall (MK)/modified Mann-Kendal (mMK), Spearman’s Rho test, and the magnitude of the slope was determined by Sen’s slope estimator. Subsequently, multiple decision factors were considered in the analytical hierarchy process (AHP) method for producing the groundwater stress zone map. A multicollinearity test was performed prior to the incorporation of these factors in order to improve the decision-making power of the AHP method. The results of the groundwater stress zoning map showed that 19.99%, 16.93%, 24.63%, 18.86% and 19.59 % of areas were classified as low, moderate, high and very high stress zones, respectively. Results also identified the south-western parts as groundwater depletion hotspots. Furthermore, validation results using Sen’s slope map, evaluation metrics of ROC (receiver operating characteristics) and AUC (area under curve) showed that AHP method had exhibited a reliable performance with an accuracy of 76.7%. Thus, the applied integrated approach can be used to explicitly characterize groundwater status by integrating different factors. The findings of our study also would be helpful for water resources managers and planners who need to design proper and sustainable management of groundwater resources.