潮汐汊道及其沙滩的安全风险和动力机制

Risk and the Dynamic Mechanism of the Beach Close to the Tidal Inlets

为提高海水浴场的安全性,避免发生溺水事故,文章以潮汐汊道及其沙滩的动力地貌结构和发育演变为基础,研究青岛市灵山湾城市阳台海水浴场沙滩的安全风险和动力机制,并提出风险防范建议。研究结果表明:河口潮汐汊道落潮流三角洲的潮汐水道延伸至沙滩滩面,高潮时淹没,落急时水流集中,形成流向外海的高速水流,极易引发海水浴场安全事故;区域落潮流与汊道落潮流相叠加、落潮流三角洲阻挡沿岸输沙造成下游局部岸段侵蚀以及沿岸输沙变化导致水道迁移摆动等因素进一步加大潮汐汊道附近沙滩的安全风险;安全风险最大的地点位于沿岸输沙下游与区域落潮流流向一致的潮汐水道末端附近沙滩,且该位置不稳定,随波浪场发生年际和季节变化;在潮汐汊道沙滩岸段设置海水浴场前应研究其动力地貌和发育演变,划分危险区和安全区,浴场设置后定期监测并确定危险区的位置,并在沙滩安全维护和质量评价等方面将潮汐汊道作为重要判定指标。

In order to improve the safety of bathing beach and avoid drowning accidents,risk and the dynamic mechanism of Chengshiyangtai bathing beach in Lingshan bay of Qingdao was studied based on the dynamic geomorphologic structure and the evolution of the two tidal inlets close to the beach as well as the beach itself.The results showed that the ebb tidal channels in the ebb tidal delta of the tidal inlets extend to the beach,and they are submerged during the high tides while the water concentrates in them and rapid flows to the sea are formed during the ebb,which is extremely easy to cause safety accidents on the beach.Besides,the overlap of the regional ebb tidal currents with that from the tidal inlets,and the down-drift erosion caused by the sand sink in the ebb tidal deltas as well as the seasonal and inter-annual channel shifts caused by the variation of wave field and the longshore sediment transport increased the risk on the beach adjacent to the tidal inlets.It was suggested that the dynamic geomorphology and evolution of the beach and the adjacent tidal inlets should be studied before a bathing beach setting up,and the dangerous area and safe area should be divided.The water depth and the landform should be surveyed regularly to ensure the safety area.And tidal inlets should be considered as an important indicator when management methods and quality evaluation was made of bathing beaches.