Countermeasures to control the rising of Tongguan riverbed and the sediment aggradations in lower reaches of Weihe River

The rising of Tongguan riverbed is the inherent cause of sediment aggradations and channel shrinkage of lower Weihe River,so to make Tongguan riverbed lowering is the precondition to control channel shrinkage of lower Weihe River.It is demonstrated that it is feasible to make Tongguan riverbed lowering by Sanmenxia reservoir operational practice and observed data,such as changes in water level at Tongguan station with discharge of 1 000 m~3/s,observed data of riverbed flushing at Tongguan station in flood-period operation in Sanmenxia reservoir control operation,and observed data in flood period and non-flood period operation in 2003.There are many methods and measures to make Tongguan riverbed lowering,such as trapping coarse sediment on the upstream tributary river of Tongguan,diverting muddy flow and making sediment settle down on the outside of embankment,adjusting operation mode of Sanmenxia reservoir,dredging up and enhancing effectiveness of the conservation of soil and water.It is an effective and emergent measure and first scheme to adjust and perfect operation mode of Sanmenxia reservoir to make Tongguan riverbed down,that is to say,to lower water level of Sanmenxia reservoir in flood period and non-flood period operation.However,it is radical measure to resolve the problem of the rising of Tongguan riverbed and channel shrinkage of lower Weihe River to enhance the measure of the conservation of soil and water.