Study On Glacier Changes Of The Heihe River Basin In The Middle Of Qilian Mountains Over The Past50Years

The glacier is a solid reservoir and a profound impact on climate changes. It canalso affect the local micro-climate and ecological environment. Mountain glaciers arethe headstream of many large rivers. Especially, as water resources, it is veryimportant to maintain production and living in arid areas. Glaciers are sensitiveindicator of climate change. Under the global warming, it is true that glaciers inWestern China with varying degrees of retreat. The study of glacier changes over thepast50years in Heihe River Basin not only can master information of size anddistribution characteristics, but also understand the rate of glacier change and theresponse to climate. And then it would provide this basin for an evaluative basis ofusing and protecting glacial freshwater resources.Multi-temporal satellite remote sensed data and images are analyzed by usingGIS and RS technology in this study. The thesis mainly studies information andvariation of quantity, area, length, terminal elevation and terminal aspect over the past50years in Heihe River Basin, besides, analysises temporal and apatial characteristicsof temperature and precipitation and their trends from1957to2010in the region.Finally discusses response of glacier change to climate change.From1957to2010, the mountains of the Heihe River Basin has been warming ata rate from0.27to0.48℃percent ten years. It is much higher than the global averagewarming rate which is0.148degrees per ten years, and therefore the climate of themountains is in a rapid warming trend. This is the primary reason for rapid glacierretreat and disappearance. The precipitation increased at a rate from0.6to1.6mmpercent year, but it can not prevent the trend of turning glaciers into smaller and less.In this region, the annual precipitation and the summer precipitation are markedlyincreased, but summer precipitation often takes the form of rainfall. It is not only badfor accumulation of glaciers, but also good for ablation. Under the influence of thetemperature rise, the effect of power-accumulation of the precipitation on the glacieris weakened.In the Heihe River Basin, the quantity of glaciers is428and the total area is164.454km2in1956.The quantity of glaciers is421and the total area is135.156km2in1990.The quantity of glaciers is404and the total area is98.935km2in2010.Thequantity of glaciers during the past50years decreased by24, and the area of glaciersdecreased by65.519km2. Especially, the speed of glacier ablation became faster from1990to2010. From1956to2010, the terminal elevation of glaciers retreated by 164m at a rate of1.06m/a. And the length of glaciers retreated by164m at a rate of21.4%. As far as quantity is concerned, glaciers are mainly distributed in the upstreamof Heihe River, Liyuan River, Maying River, Kekeli River and Dahe River. The totalnumber of their glaciers account for about73%of the whole basin. As far as area isconcerned, glaciers are mainly distributed in the upstream of Heihe River, LiyuanRiver, Maying River, Kekeli River, Dahe River and Bailang River.The area of allthese rivers’ glaciers account for84%of the whole basin.There are not large glaciers, but lots of minor ones in the Heihe River. Accordingto statistics, the major glacier scale grades include less than0.1km2,0.1～0.5km2,0.5～1km2and1～2km2. Take glacier data in2010for example, the sum of glacierquantity, scale grades include less than0.1km2and0.1～0.5km2, account for89.4%ofthe whole basin. The sum of glacier area, scale grades include0.1～0.5km2,0.5～1km2and1～2km2, account for90.0%of the whole basin. From1956to2010, theretreat rate of the glacier area, less than0.1km2,0.1～0.5km2,0.5～1km2,1～2km2and1～2km2, are62.8%,47.8%,35.6%,28.7%and9.1%respectively in the HeiheRiver. This indicates that smaller glaciers are more sensitive to climate change. Thusit can be seen glaciers themselves size are an important factor for the amount andspeed of the retreat in addition to temperature and precipitation.Compared with otherglaciers in western China, glaciers in Heihe River Basin in the middle of QilianMountains have the same trends: melting, reducing and becoming smaller. However,glaciers in the Heihe River Basin appeared to be decreasing more rapidly comparedwith other glaciers in western China. The reason is that most of the glaciers are small.