摘要
Reservoir sedimentation is an unsolved problem.In this paper,based on measured data,theoretical analysis and numerical computations,we prove that a proportion of the sediment coarser than 0.1 mm(CS) is sorted and deposited in specific reaches in the upper backwaters or in run-of-river reservoirs.The ratio of CS is usually small but it impacts the slope of deposition delta greatly and raises the backwater in later stages for a river shaped reservoir(RSR).Based on these facts,we propose to remove such CS from a fixed basin(FB) in the upper backwater by dredging and we prove that the removal of CS is effective in reducing sediment deposition and in preserving the long-term capacity of reservoirs.A numerical model computation of the Three Gorges Project(TGP) reservoir indicates that dredging 30×106-50×106 t/a of CS could reduce 20% total deposition by the end of 100th year,so that the slope of deposition can be slowed down by 25%-30%.This would be remarkable for a long extended RSR.This method of removing CS can also be applied to the Xiaolangdi reservoir(XLD) on the Yellow River(YR) to not only limit reservoir deposition but also filter out the CS from entering the Lower Yellow River(LYR) to slow down the rise of the perched LYR.It provides a new alternative to postpone the continuous siltation of the LYR.
Reservoir sedimentation is an unsolved problem.In this paper,based on measured data,theoretical analysis and numerical computations,we prove that a proportion of the sediment coarser than 0.1 mm（CS） is sorted and deposited in specific reaches in the upper backwaters or in run-of-river reservoirs.The ratio of CS is usually small but it impacts the slope of deposition delta greatly and raises the backwater in later stages for a river shaped reservoir（RSR）.Based on these facts,we propose to remove such CS from a fixed basin（FB） in the upper backwater by dredging and we prove that the removal of CS is effective in reducing sediment deposition and in preserving the long-term capacity of reservoirs.A numerical model computation of the Three Gorges Project（TGP） reservoir indicates that dredging 30×106-50×106 t/a of CS could reduce 20% total deposition by the end of 100th year,so that the slope of deposition can be slowed down by 25%-30%.This would be remarkable for a long extended RSR.This method of removing CS can also be applied to the Xiaolangdi reservoir（XLD） on the Yellow River（YR） to not only limit reservoir deposition but also filter out the CS from entering the Lower Yellow River（LYR） to slow down the rise of the perched LYR.It provides a new alternative to postpone the continuous siltation of the LYR.
基金
supported by the State Key Laboratory of Hydroscience and Engineering, Tsinghua University (Grant No. 2011-KY-2)
the Independent Research Plans of Tsinghua University (Grant No. 20101081780)
