Dynamic geomorphology and storm response characteristics of the promontory-straight beach—a case of Gulei Beach, Fujian

As one of the main areas of tropical storm action in the northwestern Pacific Ocean, South China experiences several typhoons each year, and coastal erosion is a problem, making the area a natural testing ground for studying the dynamic geomorphological processes and storm response of promontory-straight coasts. This study is based on three years of topographic data and remote sensing imagery of Gulei Beach and uses topographic profile morphology, single width erosion-accretion and mean change, combined with the Coastsat model to quantify the seasonal and interannual variability and storm response of the beach and to explain the evolution of shoreline change and beach dynamics geomorphology in the last decade. Gulei Beach has been in a state of overall erosion and local accretion for a long time, with relatively obvious cyclical changes; seasonal changes are also obvious, which are mainly characterized by summer accretion and winter erosion, with accretion at the top of the bay and accretion and erosion on the north and south sides of the bay corner, respectively; the seasonal erosion-accretion volume of the beach profile ranges from −80 m 3 /m to 95.52 m 3 /m, and the interannual erosion-accretion volume ranges from −69.09 m 3 /m to 87.31 m 3 /m. The response of beaches to typhoons with different paths varies greatly depending on the length, slope, orientation and scale of beach development. The large and gently developing Futou beach is less responsive to storms, while the less developed headlands in the southern Gulei Peninsula are more susceptible to disturbance by external factors and respond more strongly to typhoons. Storm distance is more influential than storm intensity. Under the influence of human activities, obvious erosion hotspots develop during normal weather, but storm processes produce redistribution of beach material patterns, and erosion hotspots disappear after storms. The results of this study enrich the theory of beach dynamics geomorphology and provide technical support for disaster prevention and mitigation, as well as ecological restoration of coastal zones.