Dramatic sediment load changes and sedimentation characteristics upstream of the Three Gorges Dam due to the large reservoirs construction  

作　　者：Jie LIU Wenwu ZHANG Ying SHEN Xin WANG 

机构地区：[1]National Inland Waterway Regulation Engineering Research Center,Chongqing Jiaotong University,Chongqing 400074,China [2]State Key Laboratory of Hydraulic Engineering Simulation and Safety,Tianjin University,Tianjin 300072,China [3]School of River&Ocean Engineering,Chongqing Jiaotong University,Chongqing 400074,China [4]Tianjin Research Institute for Water Transport Engineering,Tianjin 300456,China

出　　处：《Frontiers of Earth Science》2024年第3期565-578,共14页地球科学前沿（英文版）

基　　金：funded by the National Natural Science Foundation of China(Grant No.5210090851);the Opening Fund of State Key Laboratory of Water Simulation and Safety,Tianjin University(No.HESS-1720);the Special funded project for basic scientific research business expenses of central public welfare scientific research institutes(No.TKS 190104).

摘　　要：After the construction of cascade reservoirs in the upper reaches of the Three Gorges Reservoir(TGR),the sediment load outflow of the upper Yangtze River Basin(YRB)has been significantly altered,decreasing from 491.8 Mt/yr(1956–2002)to 36.1 Mt/yr(2003–2017)at Yichang station.This has widely affected river hydrology,suspended sediment grain size distribution,and channel morphology.This study analyzed hydrological variations in water discharge and sediment load of the upper YRB over the past 62 years(1956–2017)by employing a double mass curve.The variations in the source areas of sediment yielding for the upper YRB were quantified,and field measurement data of the cross-channel profile were collected to investigate the sedimentation process in the TGR from 2003 to 2017.More than 90%of the sediment load reduction in the upper YRB may be explained by human activities.The Jinshajiang River was no longer the largest sediment source area for the Zhutuo station(accounting for 5.23%)in the 2013–2017 time span,and the sediment rating rates for the inflow and outflow of the TGR shifted to negatively correlated.A longitudinal fining trend was revealed in the suspended sediment size.Still,the mean median grain size of suspended sediment in the TGR had an increasing trend in the 2013–2017 period.This result may be closely related to sediment regulation in reservoirs and incoming sediment load reduction.Sedimentation in the TGR decreased sharply from 299.8 Mt/yr in 2003–2012 to 47.2 Mt/yr in 2013–2017,but the sedimentation rate of the TGR remained at>80%annually.Moreover,some cross sections in the fluctuating backwater zone experienced scouring.

关 键 词：cascade reservoirs sediment load sedimentation characteristics suspended sediment grain size Three Gorges Reservoir 

分 类 号：TV14[水利工程—水力学及河流动力学]