Quantitative groundwater recharge estimation using water balance and water table fluctuation method over Krishna River Basin, India

Depletion of groundwater resources poses a serious challenge to society around the globe and threatening water quality and quantity; which makes it essential to access groundwater for sustainable development & management. In this study; assessment of groundwater changes is done over the Krishna river basin using the water balance method (WBM) & water table fluctuation method (WTFM) using IMERG-GPM, GLDAS2.1, WRIS, & APSDMA data for the year 2018-2019. Rainfall data from IMERG-GPM & WRIS have a close relationship as indicated by R² of 0.91. Evapotranspiration & runoff derived from GLDAS2.1 shows a close relationship with WRIS & APSDMA data with R² as 0.9 and 0.56, respectively. This shows the good reliability of evapotranspiration & runoff data from GLDAS 2.1 datasets over an entire region. The estimated recharge using WTFM using WRIS data is compared with recharge estimated using IMERG-GPM & GLDAS2.1 data to check the reliability of WBM during monsoon months of 2018-2019, which shows a close relationship indicated by R² as 0.52. The estimated average groundwater recharge over the monsoon months for WTFM and WBM was 127.1 mm, 40.41 mm respectively with an average rainfall of 138 mm. The percentage of rainwater recharge over the Krishna river basin is 32.8, 39.17, 30.25, and 6.9% for June, July, August, and September 2018 respectively. Results show that the basin having a positive water balance of 14692.3 MCM yr−1 during the year 2018-2019. Overall these types of studies will improve the accuracy of assessment of groundwater using different satellite data sources, for the sustainable development & management of groundwater in the future.