Analysis Of Impacts Of The Lake Poyang Hydraulic Project On The Relationship Between Water Level And Surface Area

Poyang Lake is the largest fresh water lake in China, where water level and surface area are crucial parameters to the lake ecosystem. Due to the high seasonal dynamic changes of water level, in wet season, when water level raises and surface area becomes wider, a unique ecological landscape and pattern can be formed; in dry season, water level lowers,surface area becomes narrow, then it is prone to happen drought.The lake Poyang hydraulic project is an important infrastructure for the construction of Poyang Lake Ecological Economic Zone and maintain water clear in Jiangxi province. The project not only has the ecological functions which can regulate the runoff water and protect ecosystem, but has social functions which can boost the local economic development. The construction of the project will inevitably lead to the disruption of continuity between Poyang Lake and Changjiang river, and the existing relationship between river and lake should be affected, resulting in the formation of different ecological environment effect. Therefore, which effect that the project will have on water level and surface area, this is a problem worthy of study.This paper takes Poyang lake as the research object, data of water level and surface area are obtained by EFDC hydrodynamic model, the statistical relationships between water level and surface area are established in the Kangshan, Tangyin,Duchang and Xingzi station, and choose the most suitable site as example, the relationship was tested and verified by using Landsat 7 remote sensing data. Based on the best site, this paper aims to analyze the influence of lake Poyang hydraulic project has on the relationship between lake level and surface area in the dry, normal, and wet year. The main conclusions drawn are as follows:(1) In the absence of the lake Poyang hydraulic project, the correlation of actual water level and simulated area of Duchang stations is better than other stations in dry,normal and wet year. Therefore, the Duchang stations can be chose as the basic station in the analysis of the influence of lake Poyang hydraulic project has on the relationship between lake level and surface area.(2) Compared the water level in the condition of whether the project exists or not in the dry, normal and wet year, it can be found: the influence of project has on the water level mainly shows as, uplift the water level in dry seasons and decrease the change range of water level, the mean uplift of water level in the lake will be 1 ~ 2 m,the mean decrease of water level amplitude is about 2 m.(3) Compared the water level in the condition of whether the project exists or not in the dry, normal and wet year, it can be found : the influence of project has on the surface area mainly shows as, maintain the minimum area in the dry seasons and decrease amplitude of surface area, the mean uplift of surface area will be about 200km2, the mean decrease of area amplitude is about 200 ~ 300 km2.(4) The lake Poyang hydraulic project has more influence on relationship between water level and surface area in the period of low-water level, but when water level is high, the influence is little. Therefore, in the dry year, the project has more effect, in the wet year has little.