Time Series Variation Of Typical Lake Area In Northeastern Tibetan Plateau Based On Landsat Image

Lakes are sensitive to global changes and are indicators of changes in the ecological environment.They have the role of regulating climate change in their basins and maintaining regional ecosystem balance.Plateau lakes are less affected by human activities,and their changes are mainly affected by natural factors.The development of technology makes it easy to dynamically monitor lake changes.Therefore,the use of remote sensing technology to monitor the dynamic changes of the Tibetan Plateau lakes can reveal the changes of regional ecological environment and provide reference for global climate change research.This paper selects the Qinghai Lake,the largest lake in the Qinghai-Tibet Plateau,and the Hala Lake in the northwest of Qinghai Lake Basin as the research object.It uses remote sensing technology to monitor the change of lake area,and combines the precipitation and temperature data in the study area to explore the response of lake area change to climate.relationship.The main research work of this paper is as follows:(1)By comparing the inter-spectral relationship and the MNDWI(Modified Normalized Difference Water Index)water body enhancement,combined with the Canny operator edge detection algorithm,the water body extraction was carried out in the Qinghai Lake research area,and the inter-spectral relationship was combined with the Canny operator method.It is superior to the MNDWI method in water body boundary continuity and fine water body extraction.The edge single-pixel breakpoint connection is performed on the extraction result,which reduces the subsequent work(2)Analysis of the climate data of Qinghai Lake and Hala Lake Research Area(mainly precipitation and temperature),and found that the precipitation in Qinghai Lake and Hala Lake Research Area changed from dry season to high water period,while the temperature showed an upward trend.,from cold to warm.Therefore,the climate of the study area has changed from “cold-dry” to “warm-wet”.It can be seen from wavelet analysis that the fluctuation of precipitation in Hala Lake is greater than that in Qinghai Lake,and the temperature fluctuations are consistent.(3)The area extraction of Qinghai Lake and Hala Lake Research Area was found,and the area of Qinghai Lake was first decreased(1987-2003)and then increased(2004-2018).The change trend of the area of Hala Lake was the same as that of Qinghai Lake.The area reaches the minimum.Wavelet analysis of the time series data shows that both study areas have periodicity on the 28-year and 22-year time scales.Correlation analysis was carried out on the same area of precipitation and temperature data in the study area.It was found that the influence of precipitation on area change lags behind,the area change of Qinghai Lake was correlated with precipitation,but it was not related to temperature change.The area of Hala Lake was correlated with precipitation and temperature.Although the temperature rises,the evaporation of lake water increases,but at the same time it increases the supply of glacial meltwater,which leads to an increase in the area of Hala Lake.