Gee-based Study On Temporal And Spatial Variation Of Permanent Water Body In Inner Mongolia

Inland water is of great significance to water cycle,energy cycle and ecosystem,and the expansion and shrinkage of water body is also an important indicator of environmental change.Inner Mongolia Autonomous Region is located in the typical arid and semi-arid climate zone,where there is little precipitation and uneven distribution of precipitation.Therefore,the water body in Inner Mongolia is relatively more sensitive and fragile,and the climate change in the past period of time and the increasing productive activities of human beings have posed a great threat to the water environment.This article uses the open water body of the Inner Mongolia Autonomous Region as the research object.Based on Google Earth Engine and combined with the frequency method of the water body,it extracts the spatial distribution data of the permanent water body of the Inner Mongolia area from 1990-2020;at the same time,based on the extracted water body boundary,the average annual transparency of water body with area greater than 1km~2 is retrieved by remote sensing;the temporal and spatial distribution and change characteristics of water body area and transparency in Inner Mongolia were discd according to different administrative regions and eco-geographical divisions.Finally,combining the natural factors such as temperature and precipitation with the economic factors such as cultivated land area and total energy production,the driving factors of water area and transparency are analyzed.The main conclusions of this paper are as follows:(1)From 1990 to 2020,the development trend of the area and quantity of Inner Mongolia water body changed greatly,the turning point of time appeared in 2009:from1990 to 2009,the area and quantity of water body in the whole region continued to decrease,only in 1998 to 1999,there was a significant recovery in area and quantity and reached the maximum value in the study period in 1999;in 2009-2013,the water body area and quantity showed a continuous increasing trend and the expansion rate was increasing;after 2013,the quantity of water body decreased greatly,while the area of water body decreased slowly.After 2017,both of them recovered slightly and entered a period of stable development.(2)Among the various types of water bodies in the study area,the number of small water bodies(1-10km~2)is the absolute majority,and it is also the main contributor to the change of water bodies over the years;the number of large water bodies(>50km~2)is the least,it is the main contributor to the change of water body area in the study area.The number of micro-water body is the largest,but the total area of micro-water body is at the same level as that of small water body.(3)The Inner Mongolia water body mainly distributes in the Hulunbeier City and the Xilingol League area,the two places water body quantity is close,but the Hulunbeier city's total water body area is more than four times Xilingol League.The proportion of water bodies in the two cities to the total water bodies is 34.3%-53.5%.However,the sum of water area always accounts for more than 70%of the total water area of the whole region,and the two places play a leading role in the process of the change of water area of the whole region.(4)In the water body larger than 1km~2 in Inner Mongolia Autonomous Region,the total transparency of water body showed an increasing trend,while that of natural water body was not obvious,and that of artificial water body showed an increasing trend.In 12 prefecture-level cities,the data of water transparency in Hinggan League showed no obvious fluctuation,the water transparency in Hulunbeier showed a downward trend,and the water transparency in the other 10 cities showed an upward trend.(5)Multiple regression analysis results show that annual cumulative precipitation,total energy production,cultivated land area and total population have significant impacts on water factors in the study area:annual cumulative precipitation has a significant positive effect on water quantity and water area;total energy production has a significant positive effect on artificial water area and transparency,but a significant negative effect on total water area,total quantity and natural water area;the cultivated land area has a significant positive effect on the micro water area,total water transparency and natural water transparency;population size has a significant negative effect on the transparency of natural water bodies.