In the circular forebay of sediment-laden rivers, adverse flow patterns such as vortices emerge, leading to substantial sediment accumulation along the sidewalls of the diversion channel and in the forebay. This sediment accumulation significantly impacts the operational efficiency of water pumps. To address these challenges, a combination of numerical simulations and engineering experiments was employed to reveal the factors contributing to the development of these patterns. Based on these findings, seven distinct flow rates and operating conditions were introduced to obtain the optimal inlet flow rate and increase the sustainability of engineering use. The findings revealed that the different inlet flow rates exert varying influences on the flow patterns in the circular forebay, leading to changes in sediment levels in both the forebay and diversion channels. Following comprehensive comparison, Scheme 6 was identified as the optimal flow rate scheme. In this scheme, the flow uniformity, deviation angle, ratio of the vortex reduction area parameter, and rate of vortex area reduction in sections z1−3 were markedly enhanced. The effectiveness of this scheme was validated through rigorous numerical simulations and engineering experiments, thereby offering indispensable theoretical insights into the operation of pumping stations in circular forebays.

Chute cutoff represents a significant geomorphic event in the evolution of meandering rivers. Following the chute cutoff, channel adjustments occur rapidly. Therefore, investigating the interaction between the flow dynamics and channel morphology is relatively challenging. However, numerical simulations provide enhanced insights into the hydrodynamic characteristics of artificial chute cutoff. In the initial year of an artificial chute cutoff evolution in the Ningxia section of the Yellow River, we collected data on the channel topography and three-dimensional flow velocity. These measurements were utilized to calibrate the established two dimensional mathematical model and explore the impacts of different hydrological conditions on the hydrodynamics of the chute channel after the artificial cutoff. The simulation results revealed the complexity of the two-dimensional flow field within the artificial chute cutoff characterized by several regions of flow separation and recirculation zones, which was related to chute channel topography and boundary conditions. These recirculation zones varied with the inlet flow. Across the three discharges, most of the flow remained concentrated in the main channel. At higher discharges increasing the water levels, the floodplain became inundated, and a shear layer between the main channel and floodplain emerged. This study presented a detailed depiction of the flow structure within artificial chute cutoff under diverse river geomorphological and hydrological conditions. This research can bridge knowledge gaps regarding chute cutoffs in the upper reaches of the Yellow River, contributing to the improvement of conceptual models concerning chute cutoff phenomena.