A Transport Model of Graded Sands in the Oscillatory Sheet-flow Regime

The 1DV two-layer model of oscillatory sheet flow of Malarkey et al. (2003) which was developed for a single grain size has been modified to include grain fractions. The model includes a suspension layer above a sheet-flow layer consisting of prescribed profiles of concentration and velocity. Since this model keeps track of the total sediment in the water column through the wave cycle it is ideally suited for representing graded sediments. The modified model has been compared with the graded sediment data of Hassan et al. (1999). The results show that the model can reproduce the statistical characteristics of the sediment in suspension and produces fractional transport rates that are consistent with the experiments. However, it also demonstrates that a sediment weighting function limited by the amount of sediment in suspension is not sufficient to give rise to the apparent effects of hiding and exposure seen in the data.