Analysis Of The Relationship Between Water Level And Lake Surface Area Of Poyarng Lake Based On EFDC Model

Poyang Lake is the largest freshwater lake in China.The relationship between the water level and the area of Poyang Lake is of great significance in studying the changes of the ecological environment in Poyang Lake.At present,the research on the relationship between Poyang Lake water level and area is different,and there are some uncertainties.The reason is that ignoring the influence of rising and falling of water to the water level and area of Poyang Lake,Therefore,it is impossible to fundamentally reasonably explain the phenomenon that there are multiple lake areas under the same water level in Poyang Lake.In this paper,the corresponding lake area data are obtained by numerical simulation of the EFDC hydrodynamic model and combined with the measured water level data of the water level station,based on the analysis of the influence of the rising and falling water on the water level-area relationship in Poyang Lake through remote sensing images,the mathematical relationship between the measured water level and the area of the lake in the typical years of rising and retreating water in Poyang Lake was statistically analyzed,in order to establish a more reasonable relationship between the Poyang Lake water level and the lake area.The results of the study are as follows:(1)when analyzing the statistical relationship between the water level and the surface area of 4 different spatial location hydrology stations in Poyang Lake,such as Xingzi,Duchang,Tang Yin and Kangshan,the relationship between the water level of Xingzi station and the lake surface area is the best among the 4 sites.(2)In the analysis of the relationship between the water level of the Xingzi Station and the water surface area of the lake,the relationship between the water level and the water surface area shows obvious nonlinear characteristics,especially when the water level is higher than 15 m,it shows a typical “lake-type”Characteristics,and when less than the water level,it presents a typical "river phase type" feature.(3)The relationship between water surface area and water level of Poyang Lake is uncertain,which is mainly due to the different water surface gradients of Poyang Lake during the rising and falling of Poyang Lake.As a result,the spatialdistribution of water level in Poyang Lake is different,which makes it appear more surface area at the same water level.(4)Under the same water level condition,the water surface area of Poyang Lake during the process of rising water is often larger than the water area of the water falling process.At the same time,the increase and decrease of water surface area is consistent with the changing trend of rising and falling water,and the rate of increase or decrease of water is higher,and vice versa.(5)The effect of rising and falling water on the water level and area of Poyang Lake is mainly reflected in the low and medium water levels.As the water level increases to a high water level,the impact will be smaller and smaller.(6)In the analysis of the relation between the water level and the area of the typical year in the process of rising and falling water,the correlation and fitting precision of the relationship between the water level and the water surface area of the rising and falling areas are all different in different years.This is an improvement over the original.