Numerical Simulation Analysis of the Cumulative Impact of Non‐Submerged Spur Dike Groups on River System

ABSTRACT The construction of spur dike groups exerts a profound impact on rivers. To thoroughly explore the cumulative effects of spur dike groups on river systems, this study builds on the previous research results regarding the classification criteria for the impact scales of non‐submerged double spur dikes and employs the numerical simulation method for investigation. Three types of spur dike spacings corresponding to small, medium, and large scales are selected. Numerical experiments are conducted to examine the cumulative variation laws of the flow structure, time‐averaged velocity, and turbulence intensity of non‐submerged spur dike groups under eight arrangement scenarios with the number of spur dikes ranging from 1 to 8. The results indicate that for small‐scale spur dike groups, the cumulative effects on the length of the recirculation zone, the resultant velocity, and the turbulence intensity are significant. For medium‐scale spur dike groups, the cumulative effect on the length of the recirculation zone weakens, while the cumulative effects on the flow velocity and the turbulence intensity remain prominent. When the number of spur dikes accumulates to approximately 5, various flow factors tend to stabilize. For large‐scale spur dike groups, the cumulative effects on the length of the recirculation zone and the resultant velocity are insignificant, and the values are close to those of a single spur dike. Only the turbulence intensity shows a certain cumulative effect. Overall, as the action scale of the spur dike groups increases, the cumulative changes of the three hydrodynamic factors gradually weaken. The large‐scale flow structure recovers first, followed by the time‐averaged flow velocity, and finally the turbulence intensity. This study provides new insights for evaluating the impact of river‐related structure groups (e.g., spur dikes) on river health.