After Tsho Rolpa, Imja Lake will be lowered by three meters


KATHMANDU, Sept 20: Fearing massive destruction from a potential Glacial Lake Outburst Flood (GLOF) in the Khumbu region, government authorities, assisted by a United Nations agency, are now accelerating efforts to lower the water level in Imja glacial lake by three meters.

This is the second time that water level of a glacial lake is being lowered in Nepal — more than a decade after the volume of water in Tsho Rolpa, risk of outburst of which led to a hue and cry among the local people in the late 1990s, was reduced. In 2000, water level of Tsho Rolpa was reduced by three meters through a 70-meter-long water canal, which has been channeled into the Rolwaling River.

After signing an agreement with the United Nationals Development Program (UNDP) in July this year, the Department of Hydrology and Meteorology (DoHM) has now begun a feasibility study to lower the water level of Imja, located at the altitude of 5,000 meters in the Khumbu region, about 160 km from Kathmandu.

As in Tsho Rolpa, water level of Imja, which could possibly affect thousands of people in Solukhumbu district in the event of a GLOF, will be lowered through a water canal. The 70-meter-long canal will be channeled into Imja khola, which originates from Imja Lake itself and gets bigger and wider after receiving glacier melting from other mountains, including Ama Dablam.

The feasibility study for reducing water volume in Imja will be followed by preparation of a detailed engineering design, which will decide what type of canal would be the most cost-effective. “If everything unfolds as planned, Imja Lake will be lowered by 2017,” said Rajendra Sharma, Senior Divisional Hydrologist at the DoHM. “Water level lowering will reduce the risk of a GLOF in Imja Lake.”

Lowering of water level in Imja is a part of a US$ 7.2 million project, funded by the Least Developed Countries Fund (LDCF) of the Global Environment Facility. As part of the project, which will run until 2017 from 2013, early warning system will be developed in four districts in the Tarai — Siraha, Saptari, Udayapur and Mahottari — to protect people and their properties from GLOFs and flash floods in the future.

Experts say Imja Lake, which is believed to have been formed just about half a century ago, is vulnerable due to rapid expansion of its area combined with degradation of its moraine dam. According to a 2009 report prepared by the International Center for Integrated Mountain Development (ICIMOD), Imja has developed into a 1.01 square kilometer lake over the last 50 years. In 1956-1963, according to the same report, Imja was just a 0.03 square kilometer lake.

“The rate at which Imja Lake has been expanding is alarming,” says Kamal Budhathoki, former Deputy Director General of the DoHM. “Along with the area, the depth and water storage capacity of the lake is also increasing, which has posed threats of imminent devastation.” Budhathoki says glacier around Imja is receding much faster, which has made reduction of water volume in this glacial lake a much-needed measure.

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