Time Series Clustering And Influencing Factors Analysis Of Lake Area Change In Qinghai Tibet Plateau

The Qinghai-Tibet Plateau has the highest altitude,the largest area of plateau,the earliest geological age and the most unique natural environment in the world.It is the largest freshwater reserve outside the Antarctic and Arctic.The scattered lakes have created the largest and densest large lake group and lake belt in China.Because of its special geographical location,it has become an important research object of global climate change and regional response.Taking 149 typical lakes in the Qinghai-Tibet Plateau as the research object,this paper uses Google Earth Engine platform to extract the relevant features of lake area and climate in JRC and ERA5 reanalysis image data from 1985 to 2020,and discusses the correlation between lakes in the Qinghai-Tibet Plateau,the chronological division of climate change,the importance of features and the impact of climate features on the growth rate of lake area.The main conclusions are as follows:（1）The time series clustering algorithm is used to cluster the area time series of141 lakes.The area changes of 141 lakes can be divided into three categories: In the C1 model,the lake has a slow growth trend,in the C2 model lake area has strong volatility,and in the C3 model lake area has a significant growth trend.（2）Cluster analysis is carried out on the climate of 141 lakes to find out the time division points of the climate of each lake area.The results show that the regional climate segmentation points of lakes are relatively concentrated from 1995 to 2005,and the number of lakes with regional climate change after 2005 is less.Therefore,2005 can be used as the dividing point of climate change in the lake area.（3）On the basis of time series clustering,taking C3 model lakes as the research object,XGBoost model is used as the regression model of Lake growth rate to extract the influence factors.The results show that precipitation,evaporation/condensation and surface temperature have the highest influence,and have the highest correlation with the area growth rate of C3 lake.The experimental results show that precipitation has the greatest impact on the growth rate of the lake area,followed by transpiration/condensation.With the average monthly precipitation in the lake area increased by1 mm,the growth rate of C3 Lake increases 0.004667 percentage points.For every1 mm increase in condensate,the growth rate of C3 mode lake will increase 0.002802 percentage points.The results are of great significance for understanding global climate change and regional response,as well as for lake evolution and ecological protection on the Qinghai-Tibet Plateau.