Operational Mode for Water–Sediment Regulation in Plain-Type Sand-Laden Reservoirs: A Case Study of the Haibowan Reservoir

Abstract

Excessive sedimentation in sand-laden rivers significantly hinders the normal operation and overall effectiveness of reservoirs. This is observed particularly in plain-type sand-laden reservoirs where weak hydraulic conditions in the reservoir area contribute to sediment deposition. Water–sediment regulation is essential in reducing sedimentation and prolonging the lifespan of such reservoirs. Taking the plain-type reservoir of the primary stream of the Yellow River—Haibowan Reservoir as an example, based on a two-dimensional shallow water equation, a two-dimensional mathematical model of water and sediment in the reservoir area is established, the corresponding boundary conditions are improved, and the reliability of the model is verified. Under the premise of ensuring the flood control safety of the reservoir dam, considering the impact on the power generation of the reservoir and the downstream river, and maintaining the long-term large effective storage capacity of the reservoir as the basic principle, the water–sediment regulation scheme is proposed. A two-dimensional kinetic model of sediment transport and representative water–sediment series are employed to simulate the erosion and sedimentation processes in the reservoir under different schemes. The optimisation and comparison of multiple schemes reveal that the sediment-flushing scheme, which lowers the water level to 1072 m above sea level when the inflow discharge is 1500–2760 m3/s and inflow sediment concentration is 5–10 kg/m3, can yield an effective reservoir capacity of 97 million m3 and an average annual hydropower generation of 389.5 million kWh after 15 years of operation. This scheme outperforms the existing sediment-flushing scheme and is recommended as an optimised approach for water–sediment regulation in reservoirs. The results of this study provide technical support for the application of water–sediment regulation in the Haibowan Reservoir and may be useful in the exploration and management of water–sediment regulation for plain-type reservoirs on sand-laden rivers.