HT Correspondent
DIBRUGARH, March 4: There is no possibility of Glacial Lake Outburst Flood (GLOF) induced flood disaster for mega hydel projects in Arunachal Pradesh and those living in downstream areas, claimed NHPC officials.
There is a growing concern amongst the masses and intellectuals over the safety of construction of mega dams in India and particularly in Arunachal Pradesh after the recent incident of the Glacial Lake Outburst Flood (GLOF) scenario in Teesta Valley in Oct 2023.
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“The technical facts corroborating the Glacial Lake Outburst Flood (GLOF) scenario in Teesta Valley are entirely different than the prevailing glacial lakes and their likely impact on proposed Dams in Arunachal Pradesh constructed by NHPC. There are several glacial lakes in Teesta Basin, upstream of Teesta III dam (Chungtham Dam), which have been studied periodically due to their potential impact on dams resulting from GLOFs,” stated A.N Mohammed, consultant of NHPC.
In 2015, the Central Water Commission (CWC) conducted a study titled ‘Status of Glacial Lakes and Water Bodies in the Himalayan Region of Indian River Basins’ in collaboration with the National Remote Sensing Centre (NRSC), ISRO.
“A GLOF event originating from South Lhonak lake (located approximately 70 km upstream of Teesta III Dam) could have been triggered by various factors, such as an earthquake, flash flood, glacier calving or breaches due to the detachment of moraine sidewalls or a combination of these events. Most of the glacial lakes present in Subansiri, Siang and Dibang river catchments are present in the Chinese portion of these river catchments, which are far away from NHPC projects. Hence they pose insignificant threat of GLOF induced flood,” Mohammed said.
The topography, catchment characteristic, glacial lake locations in river basins in Arunachal Pradesh are different in following aspects, which indicated there are no chance of GLOF induced flood disaster for projects in Subansiri, Siang and Dibang Basins as it was in Teesta Basin GLOF case.
The glacial lakes are located far away from NHPC dams as a result of this GLOF get attenuated to a very low flood values.
The slopes of rivers are mild. Hence, flow velocities of flood water is lower, also leads to higher travel time and more time to take action to mitigate the effect of flood.
Due to presence of huge reservoir storage volume the GLOF volume will be completely absorbed into reservoirs and hence, there is no threat to any dam or to the downstream population.
As per existing studies the peaks of GLOF at dam sites are even much lower than average monsoon floods for Subansiri, Siang and Dibang basin projects of NHPC.
