Sediment Transport Processes in the Swash Zone of Sandy Beaches

BUTT, T., RUSSELL, P., MILES, J. AND TURNER, I., 2007. Sediment Transport Processes in the Swash Zone of Sandy Beaches. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 636 – 640. Gold Coast, Australia, ISSN 0749.0208 In recent years, there has been a general resurgence of interest in the swash zone. However, it still remains one of the least well understood parts of the coastal zone. The sediment transport and resulting morphological changes in the swash zone are notoriously difficult to predict. Energetics-type formulations are less useful for predicting sediment transport in the swash zone than further seaward, particularly as conditions become more reflective. One reason for this is the existence of processes in the swash zone such as bore turbulence, inexfiltration and sediment advection. This paper presents an overview of the findings from a recent 3-year UK swash-zone field study with particular focus on these processes and the way their influence varies according to the prevalent hydrodynamic and morphological conditions. There is now evidence that (a) the influence of bore turbulence decreases with increasing dissipativeness, (b) in-exfiltration biases the transport onshore or offshore above and below a particular grain size respectively and (c) sediment advection may bias the transport onshore in reflective conditions and offshore in high-energy dissipative conditions. ADDITIONAL INDEX WORDS: Advection, Backwash, Bore turbulence, Energetics, In-exfiltration, Uprush.