Quantification of groundwater storage variations and stressed areas using multi-temporal GRACE data: A case study of upper Indus plains, Pakistan

Abstract

Groundwater is depleting at a more rapid rate than its replenishment in Indus Basin due to increased demand attributed to urbanization, inefficient water management practices especially in the agricultural sector and increase in impervious area in the name of development that can expose the country to severe challenge in the future. Through an unregulated groundwater exploitation now farmers often meet inadequacy in surface water supplies. The concurrent use of surface water and groundwater water now takes place on more than 70% of irrigated lands. Therefore, water resources should be monitored on frequent intervals to sensitize policy makers to formulate an optimal framework for water management practices. This study assessed the competence of Gravity Recovery and Climate Experiment Satellite (GRACE)—based estimation of changes in Ground Water Storage (GWS) as a substitute approach for groundwater quantitative approximation for management of groundwater resources in the Indus basin. The GRACE satellite Total Water Storage (TWS) data from 2011 to 2015 was used to calculate GWS. A common reduction trend was seen in the Upper Indus Plain (UIP) where the average net loss of groundwater was observed to be 1701.39 km3 of water amid 2011-2015. A net loss of around 0.34 km3/year groundwater storage was deduced for the UIP where flooding in 2014 assumed a fundamental part in natural replenishment of groundwater aquifer of the UIP. In view of TWS varieties three out of four doabs Bari, Rachna, Thal demonstrated a decrease in groundwater capacity though Chaj doab brought about increment of 0.09 km3. Based on this study, GRACE-Tellus satellite data is competent enough to hint for groundwater storage variations, however there is a vibrant need to calibrate GRACE-Tellus data with hydrological stations data periodically in order to take a maximum advantage for utility of GRACE to monitor groundwater variations on regional scale. Future studies should focus on this aspect.