Analysis Of Temporal And Spatial Evolution Of Lakes In Inner Mongolia Based On Remote Sensing Image Data

Lakes are important national land resources and have important ecological adjustment functions for arid and semi-arid regions.As an important agricultural production base in my country,the Inner Mongolia Autonomous Region has a very fragile ecological environment due to year-round unstable climatic conditions and human over-exploitation.The area of large lakes has continued to shrink over the years,and some small lakes have even dried up.Using remote sensing technology to monitor the changes of lakes and analysis its influence factors are of great significance to regional ecological environment planning and sustainable development.With the help of GEE cloud computing platform,this paper uses random forest method to extract the main lake water bodies in Inner Mongolia from Landsat images in 2000,2005,2010and 2018,and obtains the distribution and change data of lakes in Inner Mongolia over the years.In the area of Inner Mongolia,a regional study was conducted.A key lake was selected in the eastern,central,and western regions to calculate its annual area from 2000 to 2018,combined with natural climate,population,and socio-economic data,and partial correlation analysis was used to analyze its changes.The relevant reasons for the analysis are carried out to draw conclusions about the factors related to the changes of lakes in different regions of Inner Mongolia.The main work and conclusions of this paper are as follows:(1)Aiming at the technical issues of lake extraction,this paper compares the performance differences between commonly used water index analysis methods and random forest classification methods in lake extraction.The experimental results show that compared to the more commonly used water index method,the random forest method can be used to extract water faster and more accurately.The accuracy of the extraction results of the four phases in this study were94.48%,92.09%,92.38%,and 97.6%,and the average was as high as 94.14%.The use of the GEE cloud computing platform for water body extraction eliminates the need for data downloading when using offline software,which is more efficient and convenient for a large research area such as Inner Mongolia.(2)The characteristics and changing trends of the spatial distribution of lakes in Inner Mongolia are analyzed.The results of the study show that the lakes in Inner Mongolia have a large number but most of the small-scale distribution characteristics.Between 2000 and 2018,there was a trend of shrinking first and then expanding.In 18 years,the number of lakes in the study area increased by 384,but the total area decreased by 677.17 km~2.From 2000 to 2005,the total area decreased from 4,706.45 km~2 in 2000 to 3545.69 km~2(a decrease of 24.66%);from 2005 to 2010,both the area and the number of lakes have decreased.The total area has decreased from 3,545.69km~2 in 2005 to 3,09.88 km~2(a decrease of 12.71%),and the number has decreased by 88(a decrease of 8.01%);From 2010 to 2018,the overall area and number of lakes increased,with 876new lakes(an increase of 86.73%),and the total area expanded from 3,09.88 km~2 in 2010 to4,029.28 km~2(an increase of 30.19%).(3)Analyzed the factors related to the lake changes in Inner Mongolia.According to climatic conditions and differences in human activity regions,Hulun Lake,Dalinuoer Lake and Dongjuyanhai are the key lakes in the eastern,central and western parts of Inner Mongolia,discuss the correlation of lake area changes in the three regions by studying these lakes.Based on SPSS software,partial correlation analysis found that lake area changes in eastern Inner Mongolia are positively correlated with precipitation changes,negatively correlated with changes in evaporation,positively correlated with the total output value of agriculture,forestry,animal husbandry and fishery,and negatively correlated with the total annual industrial output value.Therefore,the lake changes in eastern Inner Mongolia are the result of the dual effects of climatic factors and social factors.Lake changes in central Inner Mongolia are positively correlated with changes in annual precipitation,negatively correlated with changes in annual evaporation,and have no obvious correlation with human social activities.Due to the harsh natural environment and sparse population in western Inner Mongolia,the lake changes mainly come from artificial ecological water replenishment,which has no obvious correlation with other factors.