Abstract: Poyang Lake, which connects to the Yangtze River, has historically suffered from frequent flooding, with the flood process being influenced by various factors. The construction of the Poyang Lake Project (PLP) will bring about alterations to the complex hydrodynamic processes in flood periods. This study aims to examine the impacts of PLP using a two-dimensional hydrodynamic model. The severe flood in 1954 and the backward flow in 1991 were selected as scenarios to simulate the potential impacts with and without the PLP. The findings indicate that the PLP will moderate the discharge process at Hukou and reduce the peak flood value, while leaving the water level in the Yangtze River unchanged. In the scenario of the severe flood in 1954, PLP raises the water level in Poyang Lake, resulting in a maximum water level increase of 0.021 m at representative hydrological stations. Conversely, in the scenatio of backward flow in 1991, PLP reduces the water level in the lake region. The fluctuation pattern of water level aligns with the discharge process at Hukou, while the phase of water level slightly lags behind the flow process. The research outcomes offer technical support for ensuring the safety of both the Yangtze River and Poyang Lake.

Key words: hydro-dynamic process, Poyang Lake, Water Conservancy Hub Project, flood period, MIKE21 FM model, numerical simulation