Yamzhog Glacier - Lake Spatial And Temporal Pattern Of Changes In Its Climate Change Response

Nowadays, global change has drawn world attention of scientists and governments. As the unique natural region unit. The Tibetan Plateau has become the essential area and the hot spot of studying climate change because of its unique nature in the global environmental variation. Glaciers and lakes on the Tibetan Plateau are very sensitive to climate change as one of the important components in environment. In the last decades, climate change over the Tibetan Plateau is obvious. More and more scientists pay attention to its modern climate change and its impact.The thesis studies tempo-spatial variation of glaciers and lakes in Yamzhog Yumco Basin during 1980-2000 by spatial and temporal integration using Remote Sensing and GIS technologies, and analyzes the relationship between climatic change and glacier and lake covariations in the last twenty years.Taking the topographic map (1:50,000) in 1980 as the common base, the series of Landsat TM/ETM+ images that we used in the research are reprojected to the same coordinate system. Then all data sets were orthorectifed based on the 1:50,000 scale DEM, and were accurately co-registered to the topographic map with an accuracy of 1.0 pixel. All data sets were resample to 28.5 m in GRID format. Glaciers and lakes in the basin were compiled by unsupervised classifications and on-screen digitizing by manual delineation from the digital images and the topographic map. In ARC/INFO, tempo-spatial integrated data of glacier and lake is generated. This paper studies the spatial and temporal variation of glaciers and lakes in Yamzhog Yumco Basin, and analyzes the relationship between variations of glacier and lake and climatic change in the last twenty years.Our results indicate that both glacier and lake changed in the Yamzhog Yumco Basin. Lakes present the tendency of shrink at first, and then enlarged later. In 1980, lake area amounted to 1,072km~2, and decreased to 1,005.78km~2 in 1990, but then 1,037.52km~2 in 2000. During 1980-2000. lakes in the basin lost 34.48km~2 in total. Glacier was retreating continually. Glacier area was 218.46km~2 in 1980, 216.68 km~2 in 1990, and 215.18 km~2 in 2000. During 1980-2000, glacier retreated 3.28 km~2 in total.According to the meteorological data from Langkazi Observatory during 1961-2000,annual mean temperature fluctuates and presents a trend of increase, which is consistent with the global change. Especially, the average temperature of colder season increases obviously. The precipitation fluctuates annually during 1980-2000, presents a decrease earlier, and then increases later. Evaporation presents a gentle drop tendency during 1980-2000 period. According to the integrated impacts of temperature, precipitation and evaporation on glacier and lake change, increase in temperature is the major factor that leads to negative matter balance and glacier retreat. Precipitation is the major factor which affects variation of lake area.