Groundwater depletion causing reduction of baseflow triggering Ganges river summer drying

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 basefow reduction caused by ongoing observed groundwater storage depletion in the adjoining Gangetic aquifers (Ganges basin, −0.30±0.07cm/year or −2.39±0.56 km3/year). Our estimates show, 2016-basefow amount (~1.0×106 m3/d) has reduced by ~59%, from the beginning of the irrigationpumping age of 1970s (2.4×106 m3/d) in some of the lower reaches.

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