Wave impact under tidal influence is a critical factor affecting coastal erosion. However, studies focusing on the independent effects of tidal characteristics on wave impact are relatively scarce. [Objective] This study aims to elucidate the influence of tidal characteristics and topographic factors on wave impact dynamics, providing a scientific basis for coastal protection. [Methods] Using Distributed Acoustic Sensing (DAS) technology, a 21-day field monitoring campaign was conducted along the northern coast of Zhairuoshan Island, Zhoushan, Zhejiang Province. A 160-meter vibration sensing optical cable was deployed, and the dynamic patterns of wave impact under tidal influence were analyzed by integrating Power Spectral Density (PSD) energy and tidal data. [Results] The findings demonstrate that tidal height, tidal intensity, and topographic features jointly influence the strength and spatial distribution of wave impacts. Wave impacts were most pronounced during spring tides, particularly when tidal height at high tide exceeded a specific threshold, resulting in a substantial amplification of impact forces. During moderate tides, wave impacts process exhibited multi-phase and multi-peak characteristics. . In contrast, wave impacts during neap tides were relatively weak and predominantly concentrated during the ebb tide phase. Topographic features further modulated the distribution of wave impacts, with the eastern coast experiencing prolonged impact due to extended tidal duration, while concave areas exhibited weaker impacts due to wave cancellation caused by tidal currents. [Conclusion] This study validates the efficacy of DAS technology in monitoring wave impacts under tidal influence and uncovers the intricate interactions between tidal characteristics and topographic factors. The results contribute to advancing the understanding of wave impact dynamics and offer valuable insights for optimizing coastal protection strategies.
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