A new glacial inventory in Bhutan reveals two lakes as potentially dangerous, instead of 25 as reported earlier by the ICIMOD. The new finding dismisses the 2001 report of ICIMOD. The finding under the Glacial Lake Outburst Flood (GLOF) project makes a special mention on Thorthormi and Raphstreng lakes that need immediate attention.
The three-year field implementation project by the Japanese experts and geology and mines officials found most of these lakes safe except for Thorthormi and Raphstreng.
According to Dr. Jiro Komori, Physical Geographer, with the JICA the bottom of Thorthormi Lake is very thin and the height difference of riverbed and lake water level is very big. He added that Thorthormi glacial lake is just next to Raphstreng Lake and their barrier part is also very thin. “So if in future the barrier gives a way, the water body from Thorthormi might overflow to Raphstreng and this will be threatening.”
The studies were done using remote sensing data sets and verified with bathymetry, an underwater measurement. According to the experts, Thorthormi expands at a rate of around 10 meters every year towards Raphstreng, which is separated by 30 metres today.
The combined volume of water from these two lakes are projected to produce about 53 million cubic metres; and if it ever creates glacial lake outburst flood, degree of damage is estimated three times more powerful than the one of 1994 flood in Punakha through Luggye lake.
