Trend Analysis And Prediction Of The Chahannaoer Lake Area Under Climate Change

As an important carrier of surface water resources,lakes play an irreplaceable role in ecological environment protection,biodiversity maintenance,water resources security,flood control and drought relief,economic and social development.In recent years,global climate change has intensified,causing a series of ecological and environmental problems,resulting in the shrinkage or expansion of the water area of lakes.Chahannaoer Lake is located at the junction of Inner Mongolia Autonomous Region and Hebei Province.It is the largest inland saltwater lake in North China and belongs to the continental monsoon climate zone.Affected by natural water cycle elements,the water area of Chahannaoer Lake has shown a significant trend of shrinkage and is almost dry.In this paper,the Chahannaoer Basin is taken as the research area to identify the impact of meteorological and hydrological factors on the evolution of the water area of Chahannaoer Lake,quantify the historical trend of the water area of lakes evolution,and predict the change trend of lake water area in the future.The research content of this paper mainly includes:(1)The typical meteorological stations in and around the Chahannaoer Basin are selected to analyze the spatiotemporal evolution of meteorological and hydrological factors based on historical measured data.The results show that the spatial distribution of precipitation,temperature and evaporation in the basin is uneven,the temperature is on the rise,and the precipitation and evaporation are on the decline.(2)Based on the Google Earth Engine platform,the JRC surface water historical dataset has been selected to obtain the historical distribution of the water area of the Chahannaoer Lake,and the spatiotemporal variation characteristics of lake area and its response to meteorological and hydrological factors have been analyzed.The results show that the annual and interannual fluctuations of the lake area in Chahannaoer are complex,and the overall trend is declining under the combined effects of precipitation,temperature,evaporation and other factors.(3)Based on the GES DISC platform,the GLDAS grid precipitation,temperature and evaporation data involved in the Chahannaoer Basin have been obtained,and the groundwater exploitation has been introduced to build a CNN-LSTM data-driven model to simulate the evolution of the water area of the Chahannaoer Lake.The results show that the model can effectively simulate and predict the water area change of Chahannaoer Lake.(4)Based on the measured data series of meteorological stations and NCEP historical reanalysis data,the SDSM downscaling model has been used to predict the precipitation,temperature and evaporation under three future climate scenarios of RCP2.6,RCP4.5 and RCP8.5 by using the Can ESM2 model under the CMIP5 comparison plan.The predicted results have been input into the verified CNN-LSTM model to predict the water area of Chahannaoer Lake under three different climate scenarios in the future.The results show that the area of lake water will increase in the future,and the trend of lake shrinking and drying up will be alleviated.