Characteristics And Spatial Differences Of Teminus For Representative Glaciers In Different Areas Of The Tianshan Mountains, China

Glacier terminus plays an important parameter in the glacier variation and is oneof the significant indicator of climate change. So studies of glacier terminus changescan provide a strong basis for the prediction for future glacier and water resourceschanges. Based on the terminus data of the Urumqi Glacier No.1(abbreviated asUG1, henceforth) from1962to2009, the terminus change was analyzed systemically.On the basis of the understanding of individual glaciers and based on field survey,located observation, topography and remote sensing information, five othermonitoring glaciers were selected, including the Qingbingtan Glacier No.72at TomurPeak (QG72), the Haxilegen Glacier No.51at Kuytun River (HG51), the Glacier No.4at Sigong River (SG4), the Heigou Glacier No.8(HG8), the Miaoergou Flat-toppedGlacier in Hami (MG3), from west to east, thus analyzing spatial difference of glacierterminus in the Tianshan Mountains, China. Comprehensive study of thecharacteristics of the glacier terminus changes, plays an important basic role for theunderstanding of the response of glaciers to climate change, and comparative analysisof glaciers terminus changes of the entire Chinese Tianshan benefit for assessing thebasin water resources and provide a scientific basis on economic sustainabledevelopment policy in western China. There are some main conclusions below.(1) Urumqi Glacier No.1from1962to2009showed a continuous shrinkingstate, retreating by the rate of4.22m/a, and the glacier was divided into twoindependent ones in1993. The west branch lasted degenerating momentum, thedegeneration rate accelerating significantly, and was faster than the eastern branch,which was probably caused by the glacier snout covered by the superglacial moraineon the eastern branch to inhibit the degeneration (besides the steep slope and effect ofice crack of the west branch terminus). At the same time, the Glacier No.1terminusaltitude got higher and the area reduced obviously. In addition, the study found thatthe relationship between the accumulated mass balance and the east and west branchterminus retreat rate was better than the annual mass balance with that. But therelationship between the ELA and the west branch terminus retreat rate was greaterthan that with the east branch, in other words, as the increasing of the ELA, the westbranch terminus decreased faster than that of the east branch. (2) Commonly, the glaciers in the Tianshan Mountains, China, presenteddecreasing trend, and showed significant periodical characteristics. Retreating ra te ofUG1was5.96m/a during1962-1973, decreased to3.28m/a during1973-1980, andincreased slightly (3.93m/a) during1980-1993, and the glacier was divided into twoindependent ones in1993. Retreating rate of QG72was40.1m/a during1964-2003,and increased by48m/a during2003-2009. Retreating rate of HG51was1.40m/aduring1964-1999, and increased by5.07m/a during1999-2006. Retreating rate ofSG4was6m/a during1962-1981, increased by8.9m/a during1981-2006, and addedto13.3m/a. Retreating rate of MG3was2.3m/a during1972-2005, and increased by2.7m/a during2005-2007.(3) According to the comparative research, there are obvious spatial differencesof retreating rate about the six representative glacier terminuses in the TianshanMountains, China. The order of terminus retreat rate is HG51<MG3<UG1<SG4<HG8<QG72, and gradually reduced from west to east. This is the result of thecombined effects of climate environment, geographic location, glacier scale andglacier stytle and so on. Summer temperature and annual precipitation are the rootedcause of the glacier changes. As the summer temperature rising, rich precipitation isinsufficient to recover enormous mass losses because of the glacier ablation, the risingsummer temperatures is the main climatic factor of decreasing in the glacier region.Changes in glacier terminus are well related to glacier the length, namely, the greaterthe glacier length, the faster the retreat of glaciers, and the small glacier is moresensitive to climate change. The surface morphology (superglacial moraine) is anothercause resulting in the difference of glacier change. In addition, the glacier terminusaltitude make a difference on glacier change. At the same time, the glacier type, icetemperature, orientations and slope and so on, all result the different change of theglaciers.