The Influence of Reef Topography on Storm-Driven Sand Flux

Abstract

Natural formations of rock and coral can support geologically controlled beaches, where the beach dynamics are significantly influenced by these structures. However, little is known about how alongshore variations in geological controls influence beach morphodynamics. Therefore, in this study we focus on the storm response of a beach (Yanchep in south Western Australia) that has strong alongshore variation in the level of geological control because of the heterogeneous calcarenite limestone reef. We used a modified version of XBeach to simulate the beach morphodynamics during a significant winter storm event. We find that the longshore variation in topography of the reef resulted in: (1) strong spatial difference in current distribution, including areas with strong currents jets; and (2) significant alongshore differences in sand flux, with larger fluxes in areas strongly geologically controlled by reefs. In particular, this resulted in enhanced beach erosion at the boundary of the reef where strong currents jet-exited the nearshore.

Morphodynamic Evolution and Sustainable Development of Coastal Systems

“…Beach morphodynamics in a geologically controlled area from calcarenite limestone reefs were investigated by Bosserelle et al [8]. Numerical experiments during a winter storm event were carried out using a modified version of the XBeach model at Yanchep beach in Southwest Australia.…”

“…Numerical experiments during a winter storm event were carried out using a modified version of the XBeach model at Yanchep beach in Southwest Australia. The modification of the model formulation included considering different values for the bottom dissipation parameter (see f w in Equation (1) [8]) and the bed friction parameter (see c f in Equation ( 2) [8]) for sandy and reef outcrops. Simulated currents showed that the model was twice as sensitive to roughness than wave braking parameters, and three-times more sensitive to the roughness than to the roller dissipation viscosity factor (see Table 4 [8]).…”

“…Analyses of field data for morphodynamic evolution [1][2][3]; • Sustainable development for coastal protection [4,5]; • Numerical modelling of hydro-morphodynamic processes [6][7][8][9][10];…”

Holocene Erosional Processes in a Highly Exposed Intertidal Sandstone Reef Inferred from Remote Sensing Data

“…In many coasts, natural reefs are interposed offshore, safeguarding the sedimentary stability of the sandy beaches [13,14]. Rocky and erosional coastal environments support sedimentary deposits and beaches of very diverse characteristics, controlled by complex geological structures and their erosion-deposition dynamics [15].…”