Numerical and experimental investigation of hydrodynamics in an artificial chute cutoff under different hydrologic conditions

Abstract Artificial chute cutoffs contribute to the mitigation of flood disasters in meandering rivers, but they also significantly alter the original equilibrium conditions of the channels. After the cutoff, the channels undergo rapid morphological changes, complicating the investigation of the relationship between riverbed topography and hydraulic characteristics based solely on field measurements. However, numerical simulations can provide insights into the co-evolution of channel morphology and hydraulic properties. This study aimed to explore the influence of hydrological variations on hydrodynamics within a newly formed artificial chute cutoff. In the initial year of artificial chute cutoff evolution in the Ningxia section of the Yellow River, we collected data on channel topography and three-dimensional flow velocity. These data were used to calibrate the established two-dimensional mathematical model. The simulation results revealed that the dimensions of the recirculation zone at the diversion outlet progressively increased with inlet discharge. As the discharge increased, the floodplain of the new diversion channel became submerged, causing the pre-existing recirculation zone to gradually disappear, which in turn intensified the near-bank velocity. Particularly during flood periods, the threat posed by high water levels was replaced by the threat of high velocities. The increased velocities exerted a more significant erosive impact on the floodplain. These findings provide essential hydrodynamic data on artificial chute cutoffs in the upper reaches of the Yellow River, contributing to the refinement of conceptual models related to chute cutoff phenomena.