The response of three main beach types to tropical storms in South China

Based on the observational data of 6 storms and 8 different beaches on the coasts of southern China, the paper is concerned with the characteristics of storm-effects on beaches with different morphodynamic types in South China. A dissipative beach is very stable and has a weak response to tropical storms. The storm-induced morphological changes for this type of beach are characterized by erosion at the dune toe and minor changes on the beach face. A low-tide terrace beach has a strong response to storms, with marked changes in the upper profile. A barred beach usually experiences berm erosion, swash bar smoothening, and seaward bar migration during storms. Overwash may occur for the beach without backshore dune or protection. In this paper, backshore changes and the alteration of beach gradient in response to tropical storms are discussed. With taking into account tidal influences, a new morphodynamic parameter (εT) is proposed in order to highlight the beach response intensity to storm action. Results show that the inherent morphodynamic properties have significant effects on the beach response to storm. The more dissipative beach has a smaller response intensity and shows a moderate change in beach profile during a storm, while a more reflective beach has a greater response intensity and changes markedly under storm conditions.