Regional groundwater storage changes in the Indian subcontinent: The role of anthropogenic activities

Tuesday, 16 December 2014
Soumendra Nath Bhanja, Indian Institute of Technology Kharagpur, Kharagpur, India, Abhijit Mukherjee, Indian Institute of Technology Kharagpur, Department of Geology and Geophysics, Kharagpur, India, Matthew Rodell, NASA/GSFC, Greenbelt, MD, United States, Isabella Velicogna, University of California Irvine, Department of Earth System Science, Irvine, CA, United States, Kishore Pangaluru, University of California, Irvine, CA, United States and James S Famiglietti, Univ California Irvine, Irvine, CA, United States
A large number of people around the globe depend on groundwater as a source of fresh water. Groundwater dependence will be further intensified by the world’s exponentially increasing population and climate change. Therefore, quantification of groundwater storage (GWS) changes is a critical issue in the densely populated regions of the world. Approximately, 90% of groundwater withdrawals are associated with irrigational activities in the Indian subcontinent. We used a combination of Gravity Recovery and Climate Experiment (GRACE) observations, hydrological data from the Global Land Data Assimilation System (GLDAS) together with groundwater level measurements and ERA-Interim precipitation, for the period 2003-2012 to estimate regional GWS changes and to regionally evaluate the anthropogenic and climatic forcing control on the observed changes. Rapid GWS depletion (>10 mm/year) has been observed in the northern and eastern parts of the Indian subcontinent. Most of the groundwater depleted regions coincide with the highly fertile alluvial aquifers of Ganges-Brahmaputra basin, which is subjected to intense groundwater withdrawals associated with crop irrigation. Our GWS change estimates are consistent with ground-based water level measurements (n> 13,000) from the region. Over this ten year period, GWS data show little to moderate replenishments in southern and western regions of Indian subcontinent, probably because of advanced water resource management in these areas. Precipitation is the key factor controlling the renewability of groundwater resources, however, precipitation during the period was generally near normal to historical levels, suggesting strong anthropogenic influence on GWS change in the northern and eastern parts of India during the study period.