Abstract
In summer (pre-monsoon) of recent years, low water level among the last few decades, has been observed in several lower Indian reaches of the Ganges (or Ganga) river (with estimated river water level depletion rates at the range of −0.5 to −38.1 cm/year between summers of 1999 and 2013 in the studied reaches). Here, we show this Ganges river depletion is related to groundwater baseflow reduction caused by ongoing observed groundwater storage depletion in the adjoining Gangetic aquifers (Ganges basin, −0.30 ± 0.07 cm/year or −2.39 ± 0.56 km3/year). Our estimates show, 2016-baseflow amount (~1.0 × 106 m3/d) has reduced by ~59%, from the beginning of the irrigation-pumping age of 1970s (2.4 × 106 m3/d) in some of the lower reaches. The net Ganges river water reduction could jeopardize domestic water supply, irrigation water requirements, river transport, ecology etc. of densely populated northern Indian plains. River water reduction has direct impact on food production indicating vulnerability to more than 100 million of the population residing in the region. The results of this study could be used to decipher the groundwater-linked river water depletion as well as the regional water security in other densely populated parts of the globe.
| Original language | English |
|---|---|
| Article number | 12049 |
| Journal | Scientific Reports |
| Volume | 8 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 1 2018 |
Funding
The ideas, results and conclusions presented in this article are solely of the authors, and have not been endorsed by any other person or organization. The authors are not responsible for any inference or conclusion drawn other than those mentioned in the article. S.N.B. acknowledges CSIR (India) for their support for providing SPM fellowship for Ph.D. research. We acknowledge India Meteorological Department (IMD), National Climatic Data Center (NCDC) and Central Ground Water Board (CGWB, Minisitry of Water Resources, RD&GR, Government of India) for availability of precipitation, open-source GHCN precipitation and water level measurement data, respectively. GRACE data are available at http://grace.jpl.nasa.gov, supported by the NASA MEaSUREs Program. The GLDAS data used in this study were acquired as part of the mission of NASA’s Earth Science Division and archived and distributed by the Goddard Earth Sciences (GES) Data and Information Services Center (DISC). River water level and runoff/discharge data are available from http://hydroweb.theia-land. fr/ and http://floodobservatory.colorado.edu, respectively. The authors wish to acknowledge use of the Ferret program for analysis and graphics in this paper. Ferret is a product of NOAA’s Pacific Marine Environmental Laboratory (Information is available at http://ferret.pmel.noaa.gov/Ferret/). Chemical and isotopic analyses and groundwater flow modeling were done at the laboratories of Hydrogeology group of IIT Kharagpur. The authors also acknowledge the QGIS software (http://www.qgis.org/en/site/), version 2.12, for some of the graphics used in this paper. Dipankar Saha (former Member of CGWB, India), Alan Fryar (University of Kentucky, USA) and Aditi Mukherjee (ICIMOD, Nepal) are acknowledged for knowledge, insights and/or informal review. Koushik Das, Prerona Das, Pragnaditya Malakar, Madhumita Chakraborty and Srimanti Duttagupta at IIT Kharagpur are also acknowledged for their help with data processing and images. The authors acknowledge the IIT Kharagpur SANDHI initiative for data availability.