Groundwater depletion dries up the Ganges in summers
doi:10.1038/nindia.2018.121 Published online 20 September 2018
Analysing satellite-based data, researchers have found that extensive groundwater withdrawal through pumping depletes the Gangetic aquifers of north India1. This, in turn, dries up the river in summers.
The Ganges is one of the most polluted mega-rivers of the world. However, water depletion in the recent summers is a bigger threat. It could seriously affect surface drinking water plants, power generation units, irrigation systems and navigation along the river.
To pinpoint the reasons of summer drying of the Ganges, an international research team including researchers from the Indian Institute of Technology in Kharagpur, India, estimated the water levels of the river during the summers from 1999 to 2013 using satellite data and numerical models.
The researchers say that decrease of groundwater baseflow has had a severe impact on the health of the river. They say that the present baseflow to the Ganges from the adjoining aquifers may be a third or more of total river water volume during pre-monsoon months.
The baseflow might have decreased by more than 50% from the beginning of irrigation-pumping age in the 1970s.
If groundwater continues to be extracted at the current unsustainable rate, it would adversely affect the agriculture in the Indo-Gangetic basin, eventually reducing food production. The researchers estimate that, by 2050, carbohydrate-based food would be unavailable for almost one-fifth of the 500 million living in this region.
According to the researchers, measures such as growing lower-water-consuming crops, reducing groundwater extraction and recharging aquifers can help check the drying of the river in summers.
1. Mukherjee, A. et al. Groundwater depletion causing reduction of baseflow triggering Ganges river summer drying. Sci. Rep.8, 12409 (2018)