The Change Of Glacial Lake And Its Influence In Tianshan Mountains

Based the Landsat Thematic Mapper/Enhanced Thematic Mapper Plus images, high-resolution Google Earth GeoEye-1images, scientific expedition carried out on KoxkarGlacier, we first investigated glacial lakes and analyzedtheir changing caracteristics. Then thedistribution characters and their interannual and seasonal changes of supraglacial lakes werethoroughly analyzed in Tuomuer regions. In the end, on the basis of scientific expeditioncarried out on Koxkar Glacier, the temperature variation characteristics of supraglacial lake,debris, and debris-free ice in different depth were analyzed and the thermal regime of thesupraglacial lake were discussed.The mianly results are as following.1667glacial lakes in the Tian Shan Mountains were inventoried, with total area96.5km2in2010. The lakes are largely in central and eastern Tian Shan, representing40.5%and29.8%of total glacial lake area, respectively. The total area of glacial lakes has expanded greatlyover the last20years, at an average rate0.69km2a-1or0.89%a-1. Eastern Tian Shancontributed nearly half that rate (≈0.34km2a-1), followed by northern Tian Shan at0.17km2a-1. The lake area increases in most100-elevation bands except altitude <2900m and>4100m.The fastest growth bands are in the elevation between3500m and3900m with an average rateof1.6%a-1. Both widespread climate warming and glacier shrinking led to glacial lake arealexpansion, while small-to medium-sized (<0.6km2) lakes responded most sensitively toglacier retreat.The closer the hydrologic connection of lakes to glaciers, the greater the areal expansionrate. An average≈0.007Gt a-1of glacier meltwater has been temporarily held in lakes over thepast two decades. In the last decade, the increase rate of total lake water volume was≈0.016Gt a-1, representing≈2‰of annual glacier mass lost in Tian Shan. The increasingquantity of melt available for lake formation and growth may simultaneously increase thefrequency and damage of glacial lake outburst floods or debris flows in this region. Sixtypotentially dangerous glacial lakes are identified, among which12have an outburstprobability status of “high”,25“medium”, and23“low”.