Transition in the glacial bodies indicates possible threats of floods in the downstream of th state, a study by the state centre on climate change, Himachal Pradesh has found.
“An alarming increase” in the number of moraine dammed lakes could cause catastrophic flooding in downstream areas, it adds. A moraine is the accumulation of rock debris carried or deposited by a glacier, and sometimes, it can act as a dam to form a glacial lake.
A sudden release of meltwater due to failure of this dam can result in large downstream river discharges ? an event called a glacial lake outburst flood (GLOF). Using satellite imagery, researchers at the centre have created an inventory of all such lakes in the river basins of Sutlej, Beas, Chenab and Ravi.
The report, authored by Nishtha Gautam, Pooja Rana and SS Randhawa, has called for greater attention to disaster preparedness and management due to projected increase in the frequency and intensity of extreme weather events.
“Scientific insight gained from the analysis of multi-spectral satellite images suggests that spatial extent of a majority of glaciers is changing very fast leading to the formation of moraine dammed lakes.
Formation of such lakes poses potential threat to the infrastructure and human life thriving in the downstream areas of many drainage systems originating in the snow-clad mountain ranges of the state,” said the study.
Of the four river basins, Sutlej was studied right from its origin in the Tibetan Himalaya, and researchers were able to map 562 lakes in its catchment area. Total 81 per cent of these lakes are smaller than five hectares, nine per cent have an area between five to ten hectares, and the remaining nine per cent are big lakes having an area more than 10 hectares, the study said.
The study warned of water accumulation in some isolated pockets in the upper catchment of the Tibetan Himalayan region and within the Spiti basin, which is part of the Sutlej basin.
Some lakes near the village Chicham upstream of Kaza need monitoring as they lie along the river and can cause major damage upon bursting, the report said.
In the Chenab basin, a total of 242 glacial lakes were identified, including some vulnerable areas such as the Miyar sub-basin, where a high frequency of lake formation at the glacier snouts indicates the effects of climatic changes, said the study. In another instance, the area of a lake at Geepang Gath glacier snout in the Chandra sub-basin increased from 93 hectares to nearly 99 hectares within a year.
The authors said that the tragic flooding in Uttarakhand in 2013 has been correlated with the bursting of a 8-hectare lake next to the snout of the Chorabari glaciers which caused widespread damage in the downstream areas.
“A proper monitoring of all such lakes is essential in the Himalayan region to avoid any such eventuality in the future,” the study suggested. (UNI)
