Impact of sea-level rise on cross-shore sediment transport on fetch-limited barrier reef island beaches under modal and cyclonic conditions

• Published in: Marine pollution bulletin 2015-08, Vol.97 (1-2), p.188-198
• Main Authors: Baldock, T.E., Golshani, A., Atkinson, A., Shimamoto, T., Wu, S., Callaghan, D.P., Mumby, P.J.
• Format: Article
• Language: English
• Subjects: Beach stability; Cyclonic Storms; Geologic Sediments; Hydrodynamics; Island beaches; Islands; Marine; Models, Theoretical; Oceans and Seas; Reef bathymetry; Reef top wave dynamics; Sea level rise; Sediment transport
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2015.06.017

•The influence of sea-level rise on sediment transport is investigated.•A 1D wave model and analytical sediment transport model are combined.•Effects of SLR are variable and controlled by the bathymetry of the reef and lagoon.•Shallow and narrow reefs may be stable or even accrete under SLR.•Loss of reef complexity increases the chance of loss of sediment from beaches. A one-dimensional wave model is combined with an analytical sediment transport model to investigate the likely influence of sea-level rise on net cross-shore sediment transport on fetch-limited barrier reef and lagoon island beaches. The modelling considers if changes in the nearshore wave height and wave period in the lagoon induced by different water levels over the reef flat are likely to lead to net offshore or onshore movement of sediment. The results indicate that the effects of SLR on net sediment movement are highly variable and controlled by the bathymetry of the reef and lagoon. A significant range of reef-lagoon bathymetry, and notably shallow and narrow reefs, appears to lead hydrodynamic conditions and beaches that are likely to be stable or even accrete under SLR. Loss of reef structural complexity, particularly on the reef flat, increases the chance of sediment transport away from beaches and offshore.