Morphological response to storms in an embayed beach having limited sediment thickness

Abstract

The morphological response of a wave-dominated embayed beach to large storms was investigated via field data collection and numerical simulation. Hydrodynamic and morphological field data collected in Haeundae Beach facing SSE in the south-eastern corner of Korea were analysed. During the southerly storm waves (i.e. almost shore-normal direction), the upper part sediments of the beach were eroded, and redistributed to the surf zone. Meanwhile, easterly storm waves transported sediment from east to west, resulting in coastline advancement in the west, and retreat in the east. In order to investigate the morphological response of the beach with limited sediment availability under storm conditions, the numerical model XBeach was used. With the assumption of unlimited sediment availability, the southerly storms led to overestimation of sediment transports, and unrealistic erosion and deposition patterns in the middle part of the beach. In contrast, the model results with the option of sediment layer thickness showed good agreement with the erosion and deposition patterns analysed from field data. This suggests that sediment availability can be one of the key factors in determining the morphological response in a wave-dominated embayed beach, where sediment supply from neighbouring beaches or rivers is limited.