Nasa satellites reveal freshwater decline in India

Washington, May 18: India is among the hotspots where overuse of water resources has caused a serious decline in the availability of freshwater, according to a first- of- its- kind study using an array

of NASA satellite observations of Earth.

Scientists led by NASA’s Goddard Space Flight Center in the US used data on human activities to map locations where freshwater is changing around the globe and why.

The study, published in the journal Nature, found that Earth’s wet land areas are getting wetter and dry areas are getting drier due to a variety of factors, including human water management, climate change and natural cycles.

Areas in northern and eastern India, the Middle East, California and Australia are among the hotspots where overuse of water resources has caused a serious decline in the availability of freshwater that

is already causing problems.

In northern India, groundwater extraction for irrigation of crops such as wheat and rice have caused a rapid decline in available water, despite rainfall being normal throughout the period studied, the report said.

“The fact that extractions already exceed recharge during normal precipitation does not bode well for the availability of groundwater during future droughts,” researchers said.

The team used 14 years of observations from the US/ German- led Gravity Recovery and Climate Experiment ( GRACE) spacecraft mission to track global trends in freshwater in 34 regions around the world.

“This is the first time that we have used observations from multiple satellites in a thorough assessment of how freshwater availability is changing everywhere on Earth,” said Matt Rodell of NASA’s Goddard

Space Flight Center. On land, freshwater is one of the most essential of Earth’s resources, for drinking water and agriculture. While some regions’ water supplies are relatively stable, others experienced increases or decreases.

“What we are witnessing is major hydrologic change,” said Jay Famiglietti of NASA’s Jet Propulsion Laboratory ( JPL).

“We see a distinctive pattern of the wet land areas of the world getting wetter — those are the high latitudes and the tropics — and the dry areas in between getting dryer. Embedded within the dry

areas we see multiple hotspots resulting from groundwater depletion,” said Mr Famiglietti.

He noted that while water loss in some regions, like the melting ice sheets and alpine glaciers, is clearly driven by warming climate, it will require more time and data to determine the driving forces behind other patterns of freshwater change.