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WATER RESOURCES RESEARCH, VOL. 42, W04407, doi:10.1029/2005WR003970, 2006

Dam impacts on the Changjiang (Yangtze) River sediment discharge to the sea: The past 55 years and after the Three Gorges Dam

Z. Yang

College of Marine Geosciences, Ocean University of China, Qingdao, China
Key Laboratory of Seafloor Science and Exploration Technology, Ocean University of China, Qingdao, China


H. Wang

College of Marine Geosciences, Ocean University of China, Qingdao, China
Key Laboratory of Seafloor Science and Exploration Technology, Ocean University of China, Qingdao, China


Y. Saito

Institute of Advanced Industrial Science and Technology, Geological Survey of Japan, Tsukuba, Japan


J. D. Milliman

Virginia Institute of Marine Science, Gloucester Point, Virginia, USA


K. Xu

Virginia Institute of Marine Science, Gloucester Point, Virginia, USA


S. Qiao

College of Marine Geosciences, Ocean University of China, Qingdao, China
Key Laboratory of Seafloor Science and Exploration Technology, Ocean University of China, Qingdao, China


G. Shi

Changjiang Water Resource Commission, Wuhan, China


Abstract

In 5 recent years (2000–2004), the Changjiang (Yangtze) River has discharged past Datong (600 km from the river mouth) an average of ∼250 million tons (mt) of sediment per year, a decrease of more than 40% since the 1950s and 1960s, whereas water discharge at Datong has increased slightly. Water and sediment discharge data from the upper, middle, and lower reaches of the river suggest that the reduction of the Changjiang sediment load has occurred in two phases between 1950 and 2002: following the closure of the Danjiangkou Reservoir on the Hanjiang tributary in 1968 and following the installation of numerous dams and water-soil conservation works in the Jialingjijang catchment after 1985. As the Three Gorges Dam (TGD) started operating in 2003, the Changjiang entered a third phase of sediment reduction with annual sediment loads at Datong less than 200 mt/yr. Upon completion of the Three Gorges Dam (TGD) in 2009, the sediment load at Datong will decrease to ∼210 mt/yr for the first 20 years, then will recover to ∼230 mt/yr during 2030–2060, and will reach ∼310 mt/yr during 2060–2110. From the sediment budget and sediment erosion data for the Changjiang subaqueous delta, it can be assumed that the delta will be eroded extensively during the first five decades after TGD operation and then will approach a balance during the next five decades as sediment discharging from TGD again increases.

Received 18 January 2005; accepted 9 November 2005; published 15 April 2006.

Keywords: Changjiang (Yangtze) River; dam impacts; deltaic erosion; phasic change; sediment discharge; TGD.

Index Terms: 1808 Hydrology: Dams; 1834 Hydrology: Human impacts; 1862 Hydrology: Sediment transport (4558); 3022 Marine Geology and Geophysics: Marine sediments: processes and transport.

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Citation: Yang, Z., H. Wang, Y. Saito, J. D. Milliman, K. Xu, S. Qiao, and G. Shi (2006), Dam impacts on the Changjiang (Yangtze) River sediment discharge to the sea: The past 55 years and after the Three Gorges Dam, Water Resour. Res., 42, W04407, doi:10.1029/2005WR003970.