This calls for hazard mapping, early warning systems through SMS or radio, as well as mitigation efforts like those carried out to reduce water levels on Imja and Tso Rolpa. The microhydro scheme on the Langtang Lirung Glacier that reduces the water level on a recently-formed glacial lake, and also generates electricity could be a model for other remote valleys in Nepal.
Because glacial lakes are located at such high altitudes in remote roadless areas, lowering their water level can be expensive. Most of the equipment has to be flown in by helicopter, and work is often hampered by altitude and weather. The question is: who should pay for these risk-reduction measures?
“Even if the water level is reduced they can burst and come down like tsunamis, we have to keep monitoring the lakes, and install effective early warning systems in Tso Rolpa and Imja to at least save lives if we cannot save the infrastructure,” says Sarju Baidya of the Department of Hydrology and Meteorology.
There are no feasible methods to prevent a glacial lake from bursting, and it is not in our power to stop the lakes expanding. So the only thing Nepal can do is to reduce the level of the most dangerous lakes, design downstream infrastructure taking the dangers into account, and to have an early warning system.
Says Pradeep Mool: “What we can do immediately is to install measurement stations and monitor them by satellite, prioritise the high-risk lakes for site inspections to gauge the strength of the moraines, and make a short list of the most dangerous ones for early warning, and mitigation measures.”
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