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

In 5 recent years (2000-2004), the Changjiang (Yangtze) River has discharged past Datong (600 km from the river mouth) an average of approximately 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 slight...

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Bibliographic Details
Published in:Water resources research 2006-04, Vol.42 (4), p.n/a
Main Authors: Yang, Z, Wang, H, Saito, Y, Milliman, J.D, Xu, K, Qiao, S, Shi, G
Format: Article
Language:English
Subjects:
Changjiang (Yangtze) River
dam impacts
dams (hydrology)
deltaic erosion
Freshwater
phasic change
rivers
sediment discharge
sediment transport
temporal variation
TGD
time series analysis
water erosion
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Summary:In 5 recent years (2000-2004), the Changjiang (Yangtze) River has discharged past Datong (600 km from the river mouth) an average of approximately 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 approximately 210 mt/yr for the first 20 years, then will recover to approximately 230 mt/yr during 2030-2060, and will reach approximately 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.
ISSN:0043-1397
1944-7973
DOI:10.1029/2005WR003970