Spatiotemporal evolution of water storage changes in India from the updated GRACE‐derived gravity records

Abstract

Investigating changes in terrestrial water storage (TWS) is important for understanding response of the hydrological cycle to recent climate variability worldwide. This is particularly critical in India where the current economic development and food security greatly depend on its water resources. We use 129 monthly gravity solutions from NASA's Gravity Recovery and Climate Experiment (GRACE) satellites for the period of January 2003 to May 2014 to characterize spatiotemporal variations of TWS and groundwater storage (GWS). The spatiotemporal evolution of GRACE data reflects consistent patterns with that of several hydroclimatic variables and also shows that most of the water loss has occurred in the northern parts of India. Substantial GWS depletion at the rate of 1.25 and 2.1 cm yr 21 has taken place, respectively in the Ganges Basin and Punjab state, which are known as the India's grain bowl. Of particular concern is the Ganges Basin's storage loss in drought years, primarily due to anthropogenic groundwater withdrawals that sustain rice and wheat cultivation. We estimate these losses to be approximately 41, 44, and 42 km 3 in 2004, 2009, and 2012, respectively. The GWS depletions that constitute about 90% of the observed TWS loss are also influenced by a marked rise in temperatures since 2008. A high degree of correspondence between GRACE-derived GWS and in situ groundwater levels from observation well validates the results. This validation increases confidence level in the application of GRACE observations in monitoring large-scale storage changes in intensely irrigated areas in India and other regions around the world. Key Points:Spatiotemporal changes in water storage of India are characterized GRACE records are validated using in situ groundwater levels from observation wells Significant water storage loss from the indirect effect of climate variabilitySupporting Information: Supporting Information S1

Remotely sensed high resolution irrigated area mapping in India for 2000 to 2015

“…3c. In addition, Panda and Wahr 43 reported during 2012 year that the GRACE-derived negative water storage anomaly for the post monsoon and monsoon were less compared to previous years. In addition to that post monsoon of 2012 (October to December) and pre monsoon (January to May) of 2013 having a consistent temporal behaviour of groundwater level anomaly was noticed by in situ data for the years 2011 and 2012.…”

State of the Climate in 2016

“…Severe drought reduced TWS and caused food shortages in Madagascar, Mozambique, Zimbabwe, and neighboring countries. A region centered on Nepal was similarly afflicted, although continuing groundwater withdrawals for irrigation in northern India (Rodell et al 2009;Panda and Wahr 2016) contributed to the observed signal. TWS also decreased in Mexico and northwest Australia.…”

Climate change impact assessments on the water resources of India under extensive human interventions

“…It has been reported that climate change exacerbates the already reduced natural streamflow due to dams and water withdrawals in most parts of the country (Döll et al 2012). The recent acute groundwater depletion in the Indo-gangetic plains primarily due to irrigation water withdrawals was also found to be influenced by the marked rise in temperature since 2008 (Panda and Wahr 2016). The increase in water demands and reduced water availability due to climate change is projected to decrease the area under irrigation substantially by 2030 (Taheripour et al 2015).…”