Monitoring Of Poyang Lake Water Reserves Based On Multi-source Remote Sensing Data

The change of lake water storage is an important part of the ecological environment system,and is also an important influence factor of surface water cycle and global climate change.Poyang Lake is the largest freshwater lake in China,and monitoring the change of water storage in Poyang Lake is of great significance for regional economic development,biodiversity maintenance and ecological balance.The traditional monitoring of lake water storage depends on hydrological stations or field observation,which requires a lot of manpower and material resources,and due to the confidentiality of the data,it is difficult to obtain the measured data.On the other hand,due to the limited number of hydrological observation stations,different lake surfaces may be isolated into disconnected water body areas during the dry season,resulting in some water body areas without corresponding observation stations,and then the water storage changes cannot be estimated by hydrological stations alone.Compared with the shortcomings of traditional observation methods,satellite remote sensing technology has become a common means for dynamic monitoring and research of lake water storage due to its advantages of wide coverage,real-time efficiency and low cost.Poyang Lake belongs to throughput-type lake,with significant spatial and temporal variations in water storage,"one piece of abundant water,one line of dry water".Although a study has been conducted to establish a dataset of inter-annual changes of water storage in Poyang Lake,it is relatively difficult to estimate the dynamic changes of water storage during the dry water period,which leads to fewer or insufficiently shared data for monitoring the high temporal and spatial frequency changes of water storage in Poyang Lake.The main objective of this paper is to establish a dataset of high temporal frequency change of water storage in Poyang Lake by using multi-source satellite remote sensing data,and to analyze the hydrological spatial-temporal change trend of Poyang Lake from the perspective of area,water level and water storage from2019-2021 based on this dataset,so as to provide effective data support for the ecological management of the lake,and for the rational protection and scientific development of the lake.In this paper,based on Sentinel-1 radar remote sensing images and ICESat-2 and Sentinel-3 satellite altimetry data,we extracted the area and water level data of Poyang Lake every 12 days from 2019-2021,analyzed the temporal and spatial characteristics of the lake’s water body area and water level,and established a high temporal frequency change dataset of Poyang Lake’s water storage based on the area and level data,and investigated the temporal change characteristics of the water storage of Poyang Lake.water storage time change characteristics.The main research results are as follows:(1)The water body area of Poyang Lake in 2019-2021 shows an overall trend of decreasing year by year,with a large difference in the area during the abundant and dry periods,and the change range of the water body area is 885～3302Km~2,and the lake’s abundant state is mainly from June to September every year,and the dry period is mainly from November every year to February the following year.The result of inundation frequency shows that the inundation frequency of the waterway into the river in the north of Poyang Lake,the middle channel,the deepwater area in the east,and the disk-shaped lake in the wetland is high,accounting for 36.33% of the total area of the lake.The inundation frequency of the lake center island,hills,villages and other areas is low,accounting for 7.52% of the total area.The inundation frequency of the central part of Poyang Lake is obvious in the area spreading to both sides with the navigation channel as the center,the delta area of five rivers entering the lake and the wetland protection area.(2)The water level changes observed by satellite have strong correlation with the measured water level changes,and the accuracy of the error-corrected lake water level series is improved,which can ensure the high-precision dynamic monitoring of water level of Poyang Lake by ICESat-2 and Sentinel-3 altimetry data.The overall trend of the water level after error correction and the measured water level at the hydrological station is more consistent with each other,which shows the trend of rising first and then falling.The water level of Poyang Lake has obvious seasonal change rule,the difference of water level is more than 10 m during the year,and the water level changes drastically.The high water level period of the lake is from July to September every year,and the water level of the lake is lower from December to February,and the average water level within the season is summer(15.70m)> fall(11.46m)> spring(10.49m)>winter(7.37m).(3)The 2019-2021 Poyang Lake water level-area cubic polynomial fit was the best and significantly correlated.Taking the initial date water level and area as the benchmark,the change of water storage in Poyang Lake showed an overall increasing trend on the basis of the initial date water volume;taking the adjacent time as the benchmark,the change of lake water storage fluctuated greatly,and the change of the adjacent date could be up to 2.756 billion m~3.Seasonal change of water storage in Poyang Lake is obvious,and the difference between abundant and depleted water periods is large.2019-2021 water storage increase shows a decreasing trend year by year.The overall trend of lake area,water level and water storage change is consistent.