Dileep K. Pandahas completed his Ph.D. from Indian Agricultural Research Institute, New Delhi in 2000. He is now the senior scientist of the Directorate of Water Management, one of the premium institutes for water management under the Indian Council of Agricultural Research (ICAR). He has published more than 20 papers in international and national journal, and has reviewed papers of Journal of Hydrology, Global and Planetary change, and many others. He has undertaken many prestigious projects, including the ICAR Challenge Project, that ensured training at University of Colorado, Boulder, and this research is a part of that investigation of GRACE records.
Investigating the terrestrial water storage changes (TWS) changes is important to understand the hydrological cycle in response to the recent climate variability in India, a country whose economy and food security depend on its water resources. We use the monthly gravity solutions from NASA’s Gravity Recovery and Climate Experiment (GRACE) satellites to delineate the spatial-temporal evolution of TWS and groundwater storage (GWS) employing robust statistical tools during 2003 to 2012. Results show large-scale water storage losses, particularly driven by the significant GWS depletion in the intensely irrigated Indo-Gangetic north India in the pre-monsoon (JFMAM), monsoon (JJAS) and post-monsoon (OND) seasons, respectively. Comparison with the rainfall, the Global Land Data Assimilation System (GLDAS) modeled soil moisture and the Palmer Drought Severity Index (PDSI) indicates that a little deficit in monsoon rainfall leads to significant water storage losses. In particular, the indirect effect of climate variability in terms of increases in irrigation demands due to the dry spell in India since 2008, as also observed in the adjacent counties and other overexploited aquifers of the world, has resulted in a marked drop in GWS over the northern parts, suggesting the persistence of droughts on the subsurface component.