| Under the background of global warming.Fully understand the characteristics and mechanism of Lake dynamic change in Pan-Third Pole.It is convenient for more reasonable development,management and utilization of water resources.At the same time providing a decision-making basis for the construction of for the Belt and Road Initiative.The formation of lakes is inseparable from the topography of the lake basin,and the dynamic change of lakes can not be separated from the support of topographic information.Digital elevation model(DEM)is to simulate the surface morphology in the form of digitization with limited sampling points of terrain elevation.In recent years,the development of computer,geographic information and remote sensing technology provides abundant DEM data for the study of Lake dynamic change.However,due to the influence of observation means,observation time,data processing methods,topography and geomorphology,the quality of DEM data is often restricted in the aspects of spatial resolution,data accuracy and coverage.Especially in the lake dynamic research,DEM data collection can not get through the water surface to obtain the lake bottom terrain information.When DEM data collection,the lake water area coverage is direct Then it affects the extent of the lake bottom topography information provided by DEM data.To fully understand the data characteristics of various DEM and their advantages and limitations in Lake Science Research and application,mine the complementary characteristics of data accuracy and data coverage between multi-source data,and construct fusion strategy combined with application requirements,so as to improve the data quality as much as possible,and improve the accuracy of subsequent application and analysis.The research is mainly carried out from the following three aspects:(1)DEM data evaluation.Firstly,the application characteristics of remote sensing DEM data in Lake dynamic research are analyzed.Secondly,SRTM DEM is further analyzed and studied.Because the degree of terrain information provided by DEM data is directly related to the water area of the lake at the time of data collection.In this paper,the global surface water data set and SRTM water body data are used to comprehensively analyze the situation that SRTM DEM data can provide more than10km~2 lake bottom terrain information in the global range of 56°s?60°n from 2000to 2018 from the aspects of inter annual variation trend of lake water area,seasonal variation law of lake water area,availability degree,availability index and available potential.(2)Study on the change of lake water area>1km~2 in Pan third pole typical lake area.Based on the max extend data of global surface water,4698 lakes with an area of>1km~2 in Central Asia and Tibet Plateau were extracted.Upload the data to the Google Earth Engine cloud platform,and use the Yearly data to get the annual water area of each lake from 1986 to 2018,and then make further analysis on the change of total Lake area,the change of Lake number,the change trend and distribution characteristics of lake.(3)Study on water storage change of typical lake in Pan-Third Pole.In this paper,Selinco in Tibet Plateau and Aral Sea in Central Asia are selected as research areas.Using multi-source DEM data to study the long-term variation of lake water quantity.Based on the evaluation results of DEM data,SRTM DEM was selected to estimate the water storage change of Selinco.For the Aral Sea,SRTM DEM can provide very limited topographic information.Therefore,this paper uses multi-source data fusion method to obtain the lake bottom terrain data.In order to carry out data fusion,it is necessary to analyze the data quality and error distribution characteristics of DEM data in the Aral Lake area.According to the analysis results,the fusion strategy is formulated.Finally,the lake water change in the long time series of the Aral Sea was estimated based on the optimal lake bottom DEM data obtained by fusion. |
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