Variation Of Lake Area And Its Impact Factors In Three-River Headwaters Region Based On Remote Sensing

Sanjiangyuan is located in the hinterland of the Qinghai-Tibet Plateau and is the source of the Yangtze,Yellow and Lancang Rivers.Lakes are one of the most important indicators of ecosystem changes.It is of instructive value to study the change of lakes in the Sanjiangyuan River Basin to analyze the changes of ecosystems in the entire region.Based on MODIS09 satellite remote sensing image data,this paper carries out a remote interpretation of the lake area of Three-River Headwaters Region(TRHR)for the 15th consecutive year from 2001 to 2015.Based on the local soil moisture,meteorological data,and the area of glaciers,various factors affecting the lake area change in the area of influence Analysis.The results show changes:(1)From 2001 to 2015,the total area of lakes in the TRHR region as a whole increased firstly and then decreased slightly.The area of lakes gradually increased from 2001 to2012,and in 2009 there was a maximum of 5792.14 km~2 of lake area in the whole region;after 2012,it decreased.In 2001,the smallest lake area was 4564.89km~2.(2)The lakes are mainly distributed in the elevation of 4500-5000m.The area of lakes in the source region of the Yangtze River is found to be 73%,and the source area of the Yellow River is 35%,and the lake area in the Lancang River is almost negligible.(3)The small-scale lakes in the TRHR area have a wide range of changes.New lakes and lakes are often shrinked or disappeared.Lakes with large areas are relatively stable.The lake with the largest lake area is 631 km~2 in Erling Lake and the smallest lake is0.25 km~2.(4)From 2001 to 2015,the temperature fluctuates slowly and increases slowly,and the effect of temperature on the change of lake area is indirect.From 2001to 2015,the evaporation fluctuates slowly,and the annual evaporation in TRHR has a greater impact on the change of lake area.small.(5)The annual precipitation change is an overall upward trend of“increasing and then decreasing”,which is in good agreement with the change in lake area.Among them,the annual precipitation in 2009was the largest.The correlation analysis between annual precipitation changes and lake area changes results in R~2 of 0.54 and correlation coefficient R of 0.73,indicating that precipitation is an important factor affecting the change of lake area.(6)The glaciers areas from 2001 to 2015 showed an decrease trend.The glacier change rate from 2001 to 2015 was relatively large.Regression analysis of the area of glaciers and lakes shows that the correlation coefficient R is 0.65,which proves that the area of glaciers is negatively related to the area of the lake.The increase in temperature leading to glacial melting is an important reason for the increase of lake area.(7)Analyze the average water content of four layers of soil in the source area of the Three Rivers,and explore the relationship between soil moisture and changes in lake area.The results show that the soil moisture in TRHR has little effect on the lake area.