RS-based Bosten Lake Water Level Inversion And Characteristics Of Lake Shoreline

Bosten Lake(hereinafter referred to as Bohu)is the largest inland freshwater lake in China,and is also the mother lake and important water source in Bayingolin Mongol Autonomous Prefecture.If the water level of Bohu is too high or too low,it will seriously affect the surrounding ecological environment and the water cycle of Bohu.Therefore,the dynamic monitoring of the water level is of great significance to the rational utilization of local water resources and the protection of the ecological environment.The use of RS technology to dynamically monitor Bosten Lake waters and water levels can effectively solve problems such as slow data updating and poor real-time in the field observation process,significantly increase monitoring efficiency,study the relationship between Bohu water area and water level,and explore remote sensing images and lake water level.The inversion method is of great significance for better monitoring the water level of Bohu,studying the dynamic changes of its historical water level,and giving better play to the ecological functions of the Bohu region.Based on the landsat satellite images of Bohu waters from 1972 to 2016 and the data of Bohu water level during the period,the paper establishes the relationship curve between water area and water level in the Great Lakes region of Bohu,and discusses the relationship between water level and lake area and the dynamics of lake level.The role of monitoring.Through the extraction of the boundary of the Bohu coastline,the characteristics of the Bohu shoreline at different water level stages and its impact on the surrounding land use were analyzed.The main findings are as follows:(1)The "Bohu water area-water level" function and "shoreline shape factor-water level" function curve were established.Comparing the sensitivity of the water area and shape factor with the change of water level indicates that the water area area is more sensitive to the change of water level,and the water area is used-The inversion of historical water level and water area data by the inversion of the water level curve effectively compensates for the difficulty of data updating and timely monitoring of omissions.(2)The water level data(elevation)is divided into six sections depending on the rate of increase in area with the water level.Section I: 1045.13 to 1045.76m;Section II: 1045.76 to 1046.48m;Section III: 1046.48 to 1046.94m;Section IV: 1046.94 to 1047.75m;Section V: 1047.75 to 1048.48m;Section VI: 1048.48 ~ 1049.28 m.In the second water level(1045.76~1046.48m),the lake area is increasing at a rapid rate of 70.22km2/m(the lake area increases by 1m for every 1m rise in water level),indicating that the water level of the lake is higher and the water storage efficiency is the highest.The development and utilization of resources in the surrounding areas have a positive impact;in the third water level section,the Bohu area has been growing at a slow rate of 8.83km2/m,indicating that the lake has the least capacity for water storage and cannot guarantee the surrounding living and agricultural water use;the water levels in sections V and VI High,beyond the normal water level,threatening surrounding buildings and attractions.(3)Analysis of changes in water level along the lake's shoreline: The water level data is divided into seven segments based on the shape factor and the rate of increase of the water level.In the lower water level(1045.76~1045.97m),the shape of the shoreline of the lake changed the fastest,being 0.7281/m(increase of the shape factor for every 1m of water level).The performance of the shoreline was more and more tortuous,but the overall expansion was not obvious.This stage is a normal water level and is suitable for planning and construction of scenic buildings and tourist attractions;the medium-low water level(1045.97 to 1046.43m),the slowest change in the shape of the shoreline,is 0.0474/m.This stage is normal water storage.In addition,the scenic spots around the lake are not affected by the change of the shoreline,and the scenic spots are close to the waters of the lake and are suitable for the development of the scenic spots;the high water level section(1047.28 ~ 1049.28m)has the most twists and turns on the shoreline,and the coastline expands to the largest extent.The maximum migration distance of the shoreline is 4.4km,and the isolated sand islands within the lake are all submerged by water bodies.The shoreline boundary extends directly beyond the floodplain sandbank.At this stage,protective bank embankments should be reinforced to protect the permanent attractions.In all water levels,the shoreline in the southern part of the lake has the smallest change,with a maximum migration distance of 0.9km.Bailuzhou and other scenic spots and viewing buildings in the southern part are not affected by shoreline changes.(4)The stability of the lake shoreline reflects the evolution of the lake basin,comparing the shape evolution of the Bohu basin in the last 30 years under the same water level,indicating that the northwestern coastline has migrated 2km northwards,6.5km eastwards,and the southeastern area shoreline After migrating south for 2.6km,there is no obvious change in the coastline of the rest of the area.Attention should be paid to avoid changes in the southeastern and northwestern lake basins when planning sites and buildings.