Author(s): Yuqian Long; Guoting Liang; Yuanfeng Zhang
Keywords: Reservoir operation; Reservoir deposition; Sedimentation; Management of water and sediment
Abstract: Variation of water and sediment runoff in the Yellow River is noticeable and the inflow to the Lower Yellow River is greatly modified by the operation of Sanmenxia and Xiaolangdi Reservoirs. Operational policies are adopted so as to preserve usable capacities in these reservoirs and to make the released water and sediment more compatible to each other to facilitate the transport in lower reaches. Analysis of the measured data indicates that, by proper regulation of water and sediment released from the Sanmenxia Reservoir, certain usable capacity may be preserved in the reservoir and deposition in the Lower Yellow River may be reduced. The operation mode is to store relatively clear water in non-flood season and dispose sediment during flood season. This is a kind of management of water and sediment in the reservoir on a sediment-laden river. However, certain amount of water and adequate magnitude of discharge are needed in flood season to maintain the equilibrium of sedimentation in the reservoir. In Xiaolangdi Reservoir, another type of regulation is adopted. Under appropriate situation, artificial flood could be created with properly regulated sediment concentration to erode the main channel of the LYR. In practice, proper management of water and sediment in reservoir is proved to be an effective way of reducing the aggradation in the LYR. However its capability is limited. During sustained low flows, the main channel would be seriously silted up and the flood conveyance and sediment transport capacity in both the up and downstream of reservoir would be greatly reduced. Certain amount of water is needed to maintain an adequate capacity of the main channel. For this purpose, proper management of water and sediment in the whole river basin would be required, that relates closely to the reasonable utilization of water resources. It is a challenging topic of study in the coming years.