Dynamic Change Of Area And Water Level Of Daihai Lake And Its Driving Force Analysis

As one of the three inland lakes in Inner Mongolia,the Daihai Lake and its watershed are located in the southern of the Hanshan Mountains in Inner Mongolia Plateau.It is important water resource in arid and semi-arid regions and component in regulating regional climate and participating in the hydrological cycle.Studies have shown that in recent years,due to global climate change and frequent human activities,lakes in Mongolian plateau have significantly shrunk.This paper selects the 6th phase of the US Landsat series satellite remote sensing image data from 1989-2018,and uses object-oriented multi-scale to segment the lake surface area and different land use types of the Daihai Basin for extraction analysis.Combining natural factors and social factors to the lake area and water level change of the Daihai Lake,the driving factors of this dynamic change are discussed.The results of the thesis have great significance and reference value for the adjustment of land use and the suppression of lake and lake surface shrinkage in the Daihai River Basin.The main findings of the paper are as follows:(1)During the period of 1989-2018,the Daihai Lake area showed a decreasing trend.During the29 years,the Daihai Lake area shrank at an average speed of 2.15km~2/a,and the Daihai Lake water level showed a downward trend,with an average decrease speed of 0.25m/a.From the dynamic degree of 1989-2018,the area with the largest reduction are the forest and the Daihai Lake area,the dynamic degree is-4.61%,-4.06%,respectively;and the area with the largest increase are artificial grassland and forest,dynamic degree are 3.32%and 2.71%respectively.(2)The change of wetland land use type in the Daihai Basin is:the swamp grassland and shrub swamp area showed an increasing trend;the area of inland tidal flats,seasonal rivers and waters the area showed a decreasing trend.The main five wetland areas in the basin showed a decreasing trend,and the overall reduction rate is 0.52 km~2/a.The increase of swamp grassland and shrub swamp area is mainly due to the fact that the bare land of the Daihai Lake has gradually turned into swamp grassland and shrub swamp.(3)Grey correlation,correlation analysis and principal component analysis are used to quantify the relationship between the area change of the Daihai Lake,the change of water level,the land use/cover change and the natural driving factors and social drivers in the Daihai Lake.According to the principal component analysis,the first principal component causing the shrinkage of the Daihai Lake are mainly social factors,and the second principal component are mainly natural factors.Correlation analysis shows that are change of constructive,unused and artificial forest land caused by human has the greatest impact on the shrinkage of the Daihai Lake area.According to Deng's correlation analysis,increase of crop area and population in the social factors contributed the most to the shrinking of the Daihai Lake area and the water level,and the industrial output value contributed the least.In the natural factors,the sunshine duration contributed the most to the shrinkage of the Daihai Lake area and the decrease of the water level,and the wind speed contributed the least.