Close to 30 lakes in India are drying, says study

Close to 30 lakes in India are drying according to an analysis based on satellite data from 1992 to 2020 and published in the journal Science. This has been chiefly attributed to climate change, intensifying concerns about water for agriculture, hydropower and human consumption.

A team of international researchers assessed almost 2,000 large lakes around the world using satellite measurements combined with climate and hydrological models and they found that excessive water consumption, changes in rainfall climate warming, and sedimentation have driven lake levels down globally, with 53% of lakes showing a decline from 1992 to 2020.

Between 1984 and 2015, a loss of 90,000 square kilometres of permanent water area was observed by satellites. Lakes, which cover three per cent of the world’s land surface, are key components of biogeochemical processes and regulate climate through cycling of carbon.

In arid regions, roughly one-quarter of the significant water losses in natural lakes were dominated by changes in temperature and PET or human activities, and another 37% of the water losses were primarily attributable to reduced natural flows. Most of the global lakes in humid regions gained water storage, whereas lakes in arid regions with high human water stress were generally in decline over 2003–2020, revealed the study.

In India, 16 of these lakes are in south India and these include Mettur, Krishnarajasagar, Nagarjuna Sagar and Idamalayar. Nine of these lakes are in north and east India. The study implies that recent droughts may have contributed to declining reservoir storage in southern India.

More than half of the net loss in natural lake volume is attributable to human activities and increasing temperature indicating that any recovery of water storage in these lakes could require substantial management efforts.

The study also revealed that lakes such as the Aral Sea (between Kazakhstan and Uzbekistan) and the Dead Sea have been shrinking due to unsustainable human consumption. Lakes in Egypt, Mongolia and Afghanistan have shrunk due to rising temperatures.