Can standard energetics models be used to predict net cross-shore sediment flux at the beach face?

Abstract

This paper makes use of comprehensive new measurements of net cross-shore sediment flux and flow velocity from hundreds of individual swash events to assess the use of velocity moments to predict cross-shore sediment transport in the swash zone. It is shown that the commonly used Bagnold energetics model and Shields parameter model make inadequate predictions of net sediment transport in the swash zone over individual swash cycles. In their basic form it is demonstrated that both these approaches are too simplistic to correctly capture aspects of the complex physical phenomena that drive sediment transport in the swash, such as sediment advection from the surfzone, localised suspension of sediment and swash-swash interactions. Due to the significant remaining uncertainties involved in incorporating these modifications into a fully deterministic modelling scheme, it is proposed that parallel development of longer-term, behavioural swash zone models also be pursued.