A modeling study of the influences of Yangtze River and local catchment on the development of floods in Poyang Lake, China

Poyang Lake, one of the most frequently flooded regions in China, connects with the Yangtze River and the five sub-tributaries in the local catchment. The lake9s hydrological regime is complicated by a complex hydraulic connection and strong river–lake interaction, especially for the extreme hydrological regime. This study analyzes the relationships between the lake level changes and the flow regimes of Yangtze River and local catchment during the flood season and employs a physically based hydrodynamic model to quantify their relative contributions to the development of floods. The study found that the large catchment runoff and Yangtze River discharge were both significant contributors to flood development but that their contributions were unevenly distributed in time and space. The local catchment imposed more influence during the period of April–May and at the middle parts of the lake, and its influence decreased toward the north and south; in contrast, the most remarkable lake level changes were observed in July–August and at the northern lake for the Yangtze River cases, and these changes reduced from north to south. Moreover, Yangtze River imposed far stronger influences on the lake level changes than the catchment runoff and dominated the duration of floods to a great extent.