Variation Of Lakes Areas And Its Responses To Climate Change In The Tibetan Plateau From 1975 To 2010

The change of lake areas on the Tibetan Plateau is a very sensitive indicator of climate change, especially for inland lakes. Because of good remains of natural conditions, lakes can truly reflect the change of regional climate change on sparsely-populated Tibetan Plateau(TP). Compared with the traditional lakes observation method, remote sensing technology has obvious advantages in areas which are lack of ground observation with bad environmentLandsat data in 1975,1990,2000,2010 years are used to extract lakes on TP.A iterative interpolation method for automatic identification of frozen-lakes was put forward in this study. This method can reduce the influence of frozen lake, hill shadows, ice and snow cover. Some frozen lakes which area are less than 0.1km2 are not extracted. However, The Kappa coefficient of the method is 0.9, which showed better classification accuracy.The result indicated that, the total area of lakes with area greater than 0.0027 km2 in 1975,1990,2000,2010 years on TP are 38537.28km2、41601.21km2、43585.86km2、48208.27km2,respectively. The lake numbers in these four years are 66382、127737、129400、110953, respectively. Lake areas with areas of 0.1-1km2, 1-10km2 or greater than 1000km2 are increased in this four years. Lake areas with areas of 0.0027-0.1 km2, 10-100km2,100-1000km2 are increased in wave. The number of lakes with areas of 0.0027-0.1km2 is firstly increases and then decreases; The number of lakes in other intervals increased only a little.In different river basin, lake areas have been increased in Qiangtang, Huanghe and Yangtze river basin. Lake areas in north foot of Kunlun Shan-Hexi Corridor river basin firstly decrease and then increase. In Southwest rivers basin, lake area and number firstly increases and then decreases, and area decreases obviously.In the past 35 years, the annual average wind speed、annual average air temperature have been increased in TP,annual average precipitation and relative humidity have been increased in north foot of Kunlun Shan-Hexi Corridor and Qiangtang river basin, and decreased in other river basin. According to the analysis,the main cause of lake areas increase is evaporation decreases which is caused by increased wind speed in north foot of Kunlun Shan-Hexi Corridor, Yangtze,Qiangtang river basin. Rising annual average air temperature leads glaciers to melt which make lake areas grow in Huanghe river basin. The main impact factor of lake areas change is the change of annual average relative humidity in southwest river basin. A significant reduction in the humidity enhance evaporation results in lake area reduction especially after 2000 years.