The reservoir is retaining about 151 million tonnes/year of sediment, according to researchers from the State Key Laboratory of Estuarine and Coastal Research at the East China Normal University, in Shanghai.
'In response to this, significant erosion has occurred in the downstream riverbed,' they said in an abstract of their joint paper, published in the latest issue of Geophysical Research Letters*.
They based their research on gauge measurements, sediment budgets and regression analyses to quantify the influence of Three Gorges dam on the Yangtze. They added that the erosion in the downstream riverbed did not offset that sediment retained upstream in the reservoir, which has resulted in sediment flux in the estuary decreasing by about 85 million tonnes/year, they estimate.
* Influence of the Three Gorges Dam on downstream delivery of sediment and its environmental implications, Yangtze River; by Yang, S. L., J. Zhang, and X. J. Xu; May 2007; Geophysical Research Letters, published by the American Geophysical Union.
