Potential Impact of Hydrology and Sedimentation Changes to Biodiversity, Dongting Lake, China

Science Center Objects

Dongting Lake, one of the wetlands that make up the floodplains of China's Yangtze River, is important habitat for migratory waterfowl and other wildlife. However, the re-engineering of the water way and the intensification of agricultural practices has contributed to changes in hydrology and sedimentation. USGS and partners from China are assessing the potential impact of these changes to the area's biodiversity. 

 

Sediment Elevation Table assembly and field shelter, Dongting Lake, China
Sediment elevation table (SET) assembly and field shelter, Dongting Lake, China

Science Issue and Relevance: Floodplains of the Yangtze River contain many large wetlands including Dongting Lake, which have been managed for fish, vegetable and Phragmites production since ancient times. At the same time, this large wetland comprises excellent habitat for migratory waterfowl and other wildlife. Re-engineering of the waterway and intensification of agricultural practices has contributed to hydrology and sedimentation changes, which have then altered the natural vegetation of the floodplain. Researchers of USGS and Beijing Forestry University are collaborating via a Technical Assistance Agreement to study the problem. The study will be useful for developing climate change mitigation plans for this wetland complex.

Methods for Addressing the Issue: The purpose of these studies is to conduct an ecosystem assessment of vegetation, sediment, and hydrologic dynamics of Dongting Lake and associated floodplains of the Yangtze River, particularly with regards to sedimentation and impoundment. A seed bank assessment will be completed because some plant species can live for a long time in the seed bank, and these may be the most likely to survive changing water regimes in the watershed. Sediment elevation tables (SETs) will be positioned in Dongting Lake to monitor the rate of elevation increase. SETs will also be used to construct hydrographs in conjunction with local water level recorders to determine hydrologic regimes for vegetation in research sites. To address potential long-term species loss to changing environments in the Dongting Lake wetlands, Beijing Forestry will survey biodiversity and environmental changes.

Future Steps: A better understanding of current conditions related to the function of alternating periods of drought and flooding is important for protecting biodiversity during climate change. Managers can use the information from this study to predict effects of water level and flow changes on sedimentation/downcutting rates, and to manage for desired vegetation.

Related projects: Modeling the connections between surface and groundwater hydrology, water quality, and ecosystem health to support coastal preservation efforts, northern Gulf Coast (US).