Profile response to storm events of sandy beach: observation and modelling

Beach erosion under the influence of frequent and severe storm events is generally increasing. Understanding the process of beach profile change under the influence of storm events is essential for the protection of sandy coast erosion. To clarify the response characteristics of the embayed beach profile to the storm, this study combined field observation during the typhoon and the XBeach model to reveal the profile morphological changes of the Dongsha beach in Zhujiajian Island, Zhejiang Province, under the influence of typhoon Tapah, and the influence of different factors on the beach storm response was discussed. The main results are as follows. Under the influence of typhoon Tapah, the profile of the Dongsha beach showed a significant pattern of erosion in the upper part of the profile and accretion in the lower part, and there was almost no change in the topography on the seaward side of the 400 m offshore (sand-mud transition). The calculation of different storm scenarios shows that the significant wave height controls the erosion and deposition amplitude of the profile, while the tidal level controls the position of erosion and deposition on the profile. When the storm wave height is large, the difference in profile changes caused by different settings of fine to medium sand grain size range is small. The offshore distance of the stop point of profile change is farther when there is beach nourishment. The results of this study can provide a scientific reference for the protection of storm erosion in the sandy coast.