Study and application of a coupled modelling of flow-sediment transport and hydropower generation in the Sanmenxia Reservoir

To obtain a compromise between the short-term benefits of water resources utilization and the long-term benefits of sedimentation reduction in reservoirs constructed in a heavy sediment-laden river, it is of great significance to study the comprehensive benefits of sedimentation reduction and power generation by means of mathematical modelling.Fully incorporating the interaction between flow and sediment transport and bed deformation processes, a numerical model coupling flow-sediment transport and power generation is developed by integrating a 1-D morphodynamic module, a reservoir operation module and a power generation module.The proposed model was respectively calibrated and verified with the measured hydrological and electric data in the Sanmenxia Reservoir in 2019 and 2020, and moreover the influences of different hydrological regimes and operation schemes on sedimentation volume and power generation were analyzed.The results show that the calculated values of water level, discharge and sediment concentration were in good agreement with the measured values, and the relative error of power output was within 15%, so the model can be used to simulate the processes of both bed deformation and power generation in reservoirs reasonably well.The variations in the amounts of sedimentation volume and power generation can reach 129%—360% and 18%—52% respectively, compared with those under the condition of large water volumes and small sediment discharges.Lowering the initial pool level of the non-flood season can control the sedimentation in a non-flood season, and increasing the critical inflow discharge for sluicing in a flood season can improve the comprehensive benefits of sedimentation reduction and power generation.