Characteristics Of Lake Changes In The Source Region Of The Yangtze River Based On MODIS Data

The source area of the Yangtze River is located in the southern part of Qinghai Province,in the hinterland of the Qinghai-Tibet Plateau.As one of the most important components of the natural ecosystem,lakes are of great significance to the natural evolution and ecological stability of a region,and studying the changes of lakes in the source basin of the Yangtze River is of great value for analyzing the evolution of the ecosystem in the entire region.Based on the remote sensing image data of MODIS09 satellite,this paper interprets the lake area of the Yangtze River source for 18 consecutive summers from 2001 to 2018.Combined with the temperature and precipitation,glacier area and soil moisture during the same period,the factors affecting the lake area change are analyzed one by one.Conclusion as below:(1)From 2001 to 2018,the lake area in the source region of the Yangtze River roughly experienced a change of “increasing first,then decreasing and then rising”.From 2001 to 2013,fluctuations in the area of lakes in the region increased.From 2013 to 2018,the area of lakes in the region first decreased and then rebounded.(2)Lakes with an area greater than 10km~2 account for the largest proportion and the number is relatively stable.The number of lakes with an area less than 1km~2 fluctuates greatly,and the formation and disappearance of small lakes occurs very frequently.(3)The lakes in the study area are mainly distributed in the high altitude area of 4000-5000 meters.(4)There is a significant positive correlation between temperature and lake area,thus,the lake area increases with the temperature increasing and decreases with the temperature decreasing.(5)The contribution of precipitation to the lake recharge is not large,and it is not the main impact factor for the lake area change.(6)Using MODIS09 data,the annual glacier area is extracted,Based on the Pearson correlation coefficient test,the correlation coefficient between glacier areas and lake areas change is-0.539,and the t value is 0.021 which is smaller than 0.05,indicating that there is a significant negative correlation between the glacier area and the lake area.Thus,the glacier melts Water is an important source of supply for lakes.(7)The distribution of the lake area in the study area will affect the soil moisture near the lake,making it higher than other areas under the same conditions,but soil moisture has little effect on lake area changes.The overall change of soil moisture in the western part of the study area is mainly controlled by air temperature.