Assessment of the disturbance of cofferdam demolition timing in tidal-influenced areas on downstream fish migration
潮汐影响区围堰拆除时序对下游鱼类洄游的干扰评估

摘要

本研究以潮汐影响区典型河段为对象，通过水动力模拟与声学监测相结合的方法，分析不同拆除时序下水流速度、流向及浑浊度的变化特征，并评估其对鱼类洄游行为的干扰程度。结果表明，分阶段、顺水流方向逐步拆除围堰，能够有效降低高浑浊度区的持续时间，减轻鱼类感知障碍和通道阻断的发生概率；而一次性整体拆除会在短时间内造成显著水文扰动，加大洄游延迟风险。本研究为潮汐影响区水工工程拆除施工的生态优化提供了数据支持与管理建议，有助于在保障工程进度的兼顾水生生物的生态需求。

Abstract

This study focuses on typical river sections in tidal-influenced areas. By combining hydrodynamic simulation with acoustic monitoring, it analyzes the variation characteristics of flow velocity, flow direction, and turbidity under different demolition timings, and assesses the degree of disturbance to fish migration behavior. The results show that phased, step-by-step demolition of the cofferdam in the direction of the water flow can effectively reduce the duration of high-turbidity zones and lower the probability of fish perception barriers and channel blockages. In contrast, one-time overall demolition causes significant hydrological disturbances in a short period, increasing the risk of migration delays. This study provides data support and management recommendations for the ecological optimization of hydraulic engineering demolition in tidal-influenced areas, helping to balance the ecological needs of aquatic organisms while ensuring project progress.