Analysis of equilibrium sediment transport in the middle and lower reaches of the Yangtze River after the impoundment of the Three Gorges Reservoir

??????????????????????????????????????????????????????????????????????????????????????????????.????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????.??????1?2003—2018????????????10.76?t?????d<0.125 mm?????????90.9%.????????????“????”?????????“????”??2????????2003—2018??????????????????????71%?????????????????????????????????????????????????????????????????????86%??3??????????????????????????20%???????????????13.2%?26.7%?????20%???????????????????????????????????????????????????????????????????????????.;The operation of the Three Gorges Project has significantly altered flow and sediment conditions, causing long space-time scale erosion deposition adjustment downstream dam. Analysis equilibrium transport in middle lower reaches Yangtze River is an important basis for rationally evaluating impact dam construction, also a key support management protection rivers lakes. Based on long-term series observation data, balance method used to analyze recovery characteristics River. Comparing with section topographical method, reasons two different calculated results scouring-silting amount are revealed from several factors including error bottom suspension test, cross-section representativeness or interval distances, sand mining. The show: (1) From 2003 2018, Yichang-Datong scoured 10.76 billion tons sediment, which volume particles d<0.125 mm accounted 90.9%. Taking Luoshan as boundary, river Yichang presents “coarse fine scouring”, between Datong “fine scouring coarse silting”; (2) relative deviation silting 2003-2018 71%. Longitudinal distribution absolute differences by methods indicates that Shashi closer smaller, while relatively larger, accounting nearly 86% entire reach Datong; (3) mining accounts about 20% measured erosion, correction ratio suspended 13.2% 26.7% (average 20%). After correction, calculation fit. However, main include fixed layout,