Effect of Supra-Glacial Debris layer on the Surface Melting of Hunder Glacier
By Javed Hassan (2014)
Abstract
Debris covered glacier of the high mountains received
considerable attention due to their unusual behavior. The debris covers
function as insulator. Therefore field survey observations were made and
perform empirical approaches to predict glacier reaction to climate change of
Hunder Glacier. Hunder Glacier (36˚54651˚N and 73˚35448˚E) with elevation
4383.33 m a.s.l. is one of the debris
covered glacier situated on the mountains of Hunder valley in north-west of
Gilgit-Baltistan. The Catchment area of Hunder Glacier is 12.242 km sq. Total
area covered by the Glacier ice is 7.232 km sq with North to South flow. The two
main tributaries which are mainly a part of accumulation zone with cover area
about 4.673 km2 (64.615%) of the Glacier feed the main body of glacier. The accumulation
zone is free of debris. While ablation zone of Hunder Glacier is 2.559 km2,
which is about 35.38% of the total glacier area and saturated with
supra-glacial debris with average thickness about 1.1 meters. Thickness of
Debris increases towards the terminus of Glacier. Thickness of debris gradually
decreases towards accumulation zone. The source of debris is number of
avalanches from different rock slopes. The avalanches contribute to a positive
mass balance of a glacier as well as provide plenty of debris loads to the
glacier body. These avalanches on the glacier reduce melting rate and also take
part in moraine formation. By comparing debris thickness throughout the surface
of glacier it is estimated that; thick layer of supra-glacial debris made it
less sensitive to climate change by reducing ablation rate approximately (30%)
because of insulation effect in comparison with that of thin debris layer
(thickness >2mm) and the white ice. The debris having thickness less then
critical thickness i.e, ≈2mm accelerate malting of glacier. Thickness of debris
is controlled by many factors; glacier flow is one of them which contribute in
stability of debris on surface. Debris on the glacier surface composed of
silica rich minerals which are not a good conductor of heat. This leads to
decrease the rate of energy flow to the glacier surface.
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| Effect of debris layer thickness greater then 2 cm on the surface of Hunder glacier compare to that of clean white ice. |
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| Graph shows comparison of Thermal resistance of the debris layer on the surface of different glacier of world of having several thicknesses. |
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