Some data:

                              CLIMATOLOGY

  • The mean annual temperature at 5500m is -2.4°C (Pyramid weather station data at 5050m). Between 1977 and 1994, the increase in temperature was 0.06°C/year. According to E. BRUN, expert in meteorology and climate change, it is reasonable to expect an increase of 1.7 to 3°C for high altitudes (over 4000 m) between now and 2050.
  • The mean yearly precipitations in Nepal are estimated at 1768 mm/year. Looking at the data, it appears that the monsoon (between june and september) represents between 75 and 87% of the annual precipitations. It is during this period that most of the GLOFs occur.
  • The surface of the himalayan glaciers make up 17% of the mountains' surface. Between 19670 and 2000, 6% of the glacial surface has disappeared.
  • The increase in altitude of the rain-snow limit is estimated between 300 and 500 meters.

The loss of mass of the himalayan glaciers is one of the principal causes of the creation of proglacial and periglacial lakes contained in loose moraine dams which are likely to break.

                                  HYDROLOGY

Himalayan torrent
Himalayan torrent
  • The water volume resulting from glacier melting is estimated between 230 000 and 290 000 m3/year. It tends to increase with global warming.
  • The local population have observed and increased river flow over the last ten years.
  • The mean data does not evolve much however, the floods last longer and have higher flows than previously.