Lost Terrestrial Water and Groundwater from Ganga River Basin

Ganga River basin is among the groundwater hotspots basins with a high population count. The drivers and mechanisms for terrestrial water and groundwater decline in the basin are not well understood. We used the groundwater wells observations and Gravity Recovery and Climate Experiment data along with hydrological model simulations. Monsoon precipitation (June - September) has declined significantly (~11%, p-value < 0.05) during 1951-2016. Groundwater withdrawal for irrigation during recent severe droughts in 2009, 2014, 2015 years has contributed to terrestrial and groundwater depletion. We showed that the Ganga River basin had lost 237.2±24.14 km3 terrestrial water storage and 226.57±25.22 km3 groundwater storage during 2002-2016. The most significant contributor is the non-renewable groundwater abstraction, with a relative contribution of 63% to the terrestrial water and 80% to the groundwater depletion in the basin. Frequent droughts of severe intensity in the recent decade adversely impact groundwater recharge with an increase in groundwater abstraction. The non-renewable groundwater abstraction for irrigation needs to be diminished for the basins terrestrial water and groundwater sustainability.