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Decadal Glacial Lake Changes in the Koshi Basin, Central Himalaya, from 1977 to 2010, Derived from Landsat Satellite Images

  • Shrestha, F.
  • Gao, X.
  • Khanal, N. R.
  • Maharjan, S. B.
  • Shrestha, R. B.
  • Wu, L.-z.
  • Mool, P. K.
  • Bajracharya, S. R.

Changes in glacial lakes and the consequences of these changes, particularly on the development of water resources and management of glacial lake outburst flood (GLOF) risk, has become one of the challenges in the sustainable development of high mountain areas in the context of global warming. This paper presents the findings of a study on the distribution of, and area changes in, glacial lakes in the Koshi basin in the central Himalayas. Data on the number of glacial lakes and their area was generated for the years 1977, 1990, 2000, and 2010 using Landsat satellite images. According to the glacial lake inventory in 2010, there were a total of 2168 glacial lakes with a total area of 127.61 km2 and average size of 0.06 km2 in the Koshi basin. Of these, 47% were moraine dammed lakes, 34.8% bedrock dammed lakes and 17.7% ice dammed lakes. The number of glacial lakes increased consistently over the study period from 1160 in 1977 to 2168 in 2010, an overall growth rate of 86.9%. The area of glacial lakes also increased from 94.44 km2 in 1977 to 127.61 km2 in 2010, a growth rate of 35.1%. A large number of glacial lakes in the inventory are small in size (≤ 0.1 km2). End moraine dammed lakes with area greater than 0.1 km2 were selected to analyze the change characteristics of glacial lakes in the basin. The results show that, in 2010, there were 129 lakes greater than 0.1 km2 in area; these lakes had a total area of 42.92 km2 in 1997, increasing to 63.28 km2 in 2010. The distribution of lakes on the north side of the Himalayas (in China) was three times higher than on the south side of the Himalayas (in Nepal). Comparing the mean growth rate in area for the 33 year study period (1977-2010), the growth rate on the north side was found to be a little slower than that on the south side. A total of 42 glacial lakes with an area greater than 0.2 km2 are rapidly growing between 1977 and 2010 in the Koshi basin, which need to be paid more attention to monitoring in the future and to identify how critical they are in terms of GLOF.

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  • Journal:
    Journal of Mountain Science, 14(10)
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