Satellite-observed lake size trends around Asian Water Tower under a
warming climate
Abstract
Recent studies suggest Asian Water Tower (AWT) is vulnerable to climate
change with a detrimental effect on water and food security.
Comprehensive information about the spatio-temporal variability of
lakes, an important freshwater resource, is lacking. Therefore, we
analyzed 89,480 Landsat images to examine the change in the lakes size
around AWT between 1977±2 and 2020±2. Sequentially, the trends of
precipitation, snow water equivalent, glacier mass, and permafrost were
analyzed to understand what caused the lake’s alteration. According to
our findings, from 1977±2 to 2020±2, 84% of mapped lakes grew during
the wet season, whereas 81% of the lakes grew during the dry season.
Lakes in the Inner TP and Tarim Interior basins expanded dramatically.
The Helmand, Amu Darya, and Yangtze basins are the primary locations of
shrinking lakes. The Aral Sea shrunk by 90%. From the region as a
whole, the alpine lakes showed a shrinking trend and the plain lakes
showed an expanding trend from 1977±2 to 1990±2, and vice versa from
1990±2 to 2020±2. Glacial loss and permafrost thawing were corresponding
to lake expansion in the Inner TP, Tarim Interior, Syr Darya, and Mekong
basins. Permafrost discontinuities may cause Indus and Ganges to not
grow significantly in lakes with increased recharge to the basin.
Extreme droughts depleted the lake in Helmand. Human intervention have
caused the shrinking of the Aral Sea and the lakes in the lower Yangtze
River. As AWT retreats and feeds lakes, we need to take immediate action
for managing risks and adaption.