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

Z. Yang,1,2 H. Wang,1,2 Y. Saito,3 J. D. Milliman,4 K. Xu,4 S. Qiao,1,2 and G. Shi5

[1] In 5 recent years (2000?004), 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?060, and will reach
310 mt/yr during
2060?110. 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.

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.

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