Imja Tsho - Fastest growing glacial lake of the HKH region

Introduction

The Lake Imja Tsho is located in Everest region at latitude 27°59’17” N and longitude 86°55’31” E at an altitude of 5010 msl in eastern Nepal (Figure 1). The lake is fed by the Imja and Lhotse Shar Glaciers. The Lhotse Shar Glacier flows in a south-westerly direction; its highest altitude is 7590m .



Explore the map 		Imja Tsho

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.

Development of Imja Glacial Lake from 1992 to 2009

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About - Development of Imja Tsho
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Development of Imja Tsho

The Imja Glacier is seen full of glacier mass and no lake had developed in the Imja Glacier till 1956.
  1. The Imja Tsho did not exist till late 1950s and appeared as a group of small supraglacial ponds at the snout of Imja/Lhotse glacier(Figure 2a).
  2. The lake appeared distinctly as a moraine dammed lake after it attained the area 0.3 sq km in 1975.
  3. The lake area attained 0.56, 0.63, 0.77 and 0.97 sq km in 1983, 1989, 2000 and 2009 respectively.
  4. The lake area was 0.83 sq km from the field survey in 2001 (Yamada et al. 2003) and 0.86 sq km in 2002 (GEN, CREH, NU and DHM 2006).
  5. The lake growth rate was found at an average rate of 42m per year between 1962 and 2001; from 2001 onwards, the rate was increased to about 74m per year (Bajracharya et al. 2007).
  6. The length increased from 1647 to 2030m from 2000 to 2009.

As the area increased, the average depth of the lake diminished from 47m in 1992 (Yamada 1998) to 41.6m in 2002 (GEN, CREH, NU and DHM 2006) (note that this same study reported a maximum depth of 90.5m in 2002). The volume of water stored in the lake was estimated about 28 million cubic meters in 1992 and 35.8 million cubic meters in 2002. The lake is in contact with the glacier snout; hence continuous expansion of the lake is anticipated due to calving and melting of the glacier snout as a result of global warming, however the depth of the lake is lowering (Fujita et al 2009). thickness of the ice core is about 150m near the glacier snout and disappears at the edge of the end moraine (GEN and CREH 2006).


The melting pattern of the Imja Glacier snout as seen in the satellite image of 2007 January and from the field observation indicates that the growth rate is accelerating towards east of southern edge of the lake as shown in the circle.The northern part of the glacier snout melted faster till 2000 (Figure 2 b, c and d) and 2001 onward southern part of the glacier snout is melting faster and as a result the south-eastern edge of the lake is protruding (Figure 2f).

From the analysis of remote sensing satellite images it is found that the northern part of the glacier snout is melting and subsiding. It is expected that the north-eastern edge of the lake will expand and attains same level as of south-eastern edge after couple of years. The glacier snout is melting and disappears either southern or northern edge periodically.


For more study: GLOF Report
Data Providers:
  • Samjwal Ratna Bajracharya, Remote Sensing Specialist,ICIMOD
  • Sudan Bikash Maharjan, Research Associate Remote Sensing and GIS,ICIMOD
Web Developers:
  • Bikash Dangol, Research Associate GIS Web Programming,ICIMOD
  • Sameer Bajracharya, Research Associate GIS,ICIMOD
  • Eliza Shrestha,ICIMOD

For further information contact: menris@icimod.org
Mountain Environment and Natural Resources’ Information System
International Centre for Integrated Mountain Development
http://www.icimod.org, http://geoportal.icimod.org

 
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