Abstract: Poyang Lake is an important flood mediation lake of the middle and lower reaches of the Yangtze River. It is also recognized as an important international wetland that provides key wintering habitats for migratory birds. Therefore the proposal for construction of the Poyang Lake hydraulic project has aroused a broad attention from ecologists, environmental protection organizations and the public. Referencing historical hydrological data, distribution data of wintering migratory birds and basic geographical data, and from the perspectives of historical regimes of lake shape and ecological protection of wintering migratory birds, this article presents a study on the scheme of water level regulation of the Poyang Lake Hydraulic Project. The study achieved the following conclusions and suggestions: (1) under the scenario of keeping the lake shape unchanged and protecting the habitats of wintering migratory birds from being affected by the water level regulation of the hydraulic project, the engineering controlled water level should not be higher than 12 meters. Because lower water level does not benefit from the hydraulic project and higher water level does not favor the protection of wintering migratory birds, to balance the interests of engineering benefits and habitat protection, we suggest that certain farmland areas should be returned to lake use in order to promote the execution of the proposed hydraulic project. (2) Based on the information about topography, distribution of migratory birds, residential areas and land use patterns within existing levees, we suggest the area of about 640 km² should be returned from enclosed lowland to lake use. (3) With the scenario of returning farmland to lake use and following the principle 'regulating lake level in dry season but not in flood season', we put forward the scheme of water level regulation of the Poyang Lake hydraulic project as a reference for the promotion and execution of the proposed hydraulic engineering.

Key words: Poyang Lake Dam, returning farmland to lake, migrant farmer, wintering birds