Water

Drying trends recorded in more than 30 Indian lakes: Study

In about 100 large lakes, climate change and human water consumption were identified as the main drivers of water losses and a decline in lake volume

 
By Rohini Krishnamurthy
Published: Friday 19 May 2023
While rivers get all the attention rightfully, lakes have and continue to provide more of the water supply and sustain societies, across the world and, are often not well managed. Representative photo: iStock._

More than 30 large lakes in India have recorded a drying trend from 1992 to 2020, a new analysis published in journal Science revealed.

Of them,16 are the major lakes of southern India. Some of these include Mettur, Krishnarajasagar, Nagarjuna Sagar and Idamalayar. Recent droughts may have contributed to reservoir storage declines in southern India, noted the research published on May 18, 2023.

“Except for few lakes, most of the peninsular India lakes are declining in lake levels and storage,” Balaji Rajagopalan, professor of engineering at the University of Colorado Boulder and co-author of the study, told Down To Earth.

Lakes, which cover three per cent of the global land area, play a key role in regulating climate through carbon cycling.

“While rivers get all the attention rightfully, lakes have and continue to provide more of the water supply and sustain societies, across the world and, are often not well managed,” Rajagopalan added.

Satellite observations have recorded a loss of 90,000 square kilometres (km2) of permanent water area across the world. However, the factors driving such losses are not clear.

Red dots indicate lakes that are drying. Source: Yao et al / Science.

Rajagopalan and his colleagues used satellite observation from 1992-2020 to create a global database of lake water storage. They covered 2,000 of the world’s biggest lakes and reservoirs that contribute to 95 per cent of the total lake water storage on Earth.

They then used models to quantify and attribute trends in lake storage globally to natural changes, climate change and human consumption.

Overall, 53 per cent of the world’s largest lakes have been losing water and 24 per cent have seen an increase. Nearly 33 per cent of the global population resides in a basin with a large, drying lake. 

“The analysis also reveals a declining trend in reservoir water storage in both arid and humid regions,” Sarah W Cooley from the University of Oregon wrote in a related article. She was not involved in the study.


Also read: Earth has lost one-fifth of its wetlands since 1700 — but most could still be saved


The drying trend in Arctic lakes is also more pronounced than previously thought, the researchers highlighted. Climate change has some role to play in driving these changes, they said. “The contributions from temperature, precipitation and runoff indirectly indicate the potential role of climate change,” the author explained.

In about 100 large lakes, climate change and human water consumption were identified as the main drivers of water losses and a decline in lake volume.

The climate is linked to factors contributing to the decline of lakes, such as temperature and potential evapotranspiration (combined loss of water through the plant’s process of transpiration and evaporation of water from the Earth’s surface), precipitation and runoff, and human consumption.

The researchers hope to further understand the role of climate in these factors. They also plan to model the variability of paleo-lakes [old lakes] over the Indian subcontinent and how they potentially impact human migration.

Rajagopalan said it is important to understand the approaches to managing lakes in an integrated manner. “This will elevate the status of lakes to their rightful place,” he said.

Subscribe to Daily Newsletter :

Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.