Ponder over Integrated Management of the Yellow River

Large numbers of existing reservoirs,hydraulic power plants and diversion works built on the tributaries and the main Yellow River and soil and water conservation measures in large area have greatly changed the process of silt and discharge of the channel,causing the channel sedimentation and atrophy.The main river training of Ning-Meng reach is to narrow the channel and stabilize flow path for increasing sediment carrying capacity of moderate and low-flow channels.River harnessing measures can take water conservation function into consideration.The comprehensive measures of dumping sediment on floodplain and guiding river regime of Long-Tong reach should combine closely with the planning and design of Guxian Reservoir.The basic requirements for river training of the lower Yellow River are to keep the longitudinal balance of sediment transport of the channel and river regime stable in plane,revise plans according to the reduction of water and sediment and the corrected river width should be smaller along with the reduction of gradient.Only the operation of regulated discharge regime of reservoirs on tributaries and the main river cooperating with river training,can maximize the functions of deepening the channel,stabilizing flow path and discharging sediment into the sea.Considering the variation of underlying surface and regulation function of reservoirs of the Yellow River,it suggests to recalculate runoff by using the past precipitation data for revising silt-discharge series and flood frequency.