Imja glacial lake in Everest Region

The climate change during the first half of the twentieth century has brought a tremendous impact on the high mountainous glacial environment. Many of the big glaciers melted rapidly and gave birth to the origin of a large number of glacier lakes. Out of 20 potentially dangerous glacial lakes in Nepal, 12 lie in this Khumbu, Mt. Everest Region. Ima Glacial Lake is in most danger lake for Glacial Lake Outburst Flood (GLOF).

Imja Tsho (or Imja Lake) is a glacial lake created after melt water began collecting at the foot of the Imja Glacier on the lower part of the glacier in the 1950s. The Imja glacial lake is the fastest growing lake in the Himalaya and has been identified as one of the potentially dangerous glacial lakes in the Nepal Himalaya.

The lake was first mapped in the form of a few ponds from the satellite image taken in 1962. The total area of the ponds was approximately 0.03 km2 then (27916 sq m). With the melting of glaciers, the ponds merged into a supra-glacial lake in the 1970s and it has grown continuously ever since. The lake area increased to approximately 0.8 km2 (796600 sq m) in 2000 with an average growth rate of 0.02 km2 per year.

Experts have warned that Imja Tsho, which lies just south of Everest, poses a danger to tens of thousands of people living downstream and threatens to damage the teahouses, settlements, and trekking trails that are key to attracting tourists. Until 1960, the lake, one of 21 lakes in the Nepali Himalayas at risk of bursting, was small in size, but since then, it has expanded rapidly: now it covers an area of 1.28 square kilometers and is 150 meters deep.

The lake is of concern since the moraine that dams it is not stable. It can melt down and erode slowly or it can lose height more quickly resulting in a glacier dammed lake outburst. The level of the lake has been relatively constant in recent years, but is monitored to forecast this potential hazard. ICIMOD has collected satellite images of the lake expansion from 1962-2008.