There exists a large uncertainty about the importance of crossshoreface sediment fluxes both in relation to the dynamic evolution of the shoreface profile and the potential role as a sink or souree to the 'active' zone. The increasing availability of more reliable long-term observational data (direct and indirect) and of more detailed shoreface field observations seems to support earlier suggestions that the shoreface may be a potential souree of coarser sediments to the nearshore. Here, this process is investigated by hindcasting and extrapolating long- and short-term observations available for the shoreface along the Ebro Delta. Analysis of the field data indicates that a structural onshore sediment flux is likely. Although a direct proofthat this is also true on longer-term seales is not easy to substantiate, the careful conclusion is drawn that there exists circumstantial evidence that there is a net long-term feeding of coarser sediment towards the nearshore to an amount which is just about enough to compensate for 'Iosses' due to the present sea-level rise rate in the region.@en

This paper presents the experimental results obtained at prototype scale in the Large Oscillating Water Tunnel (LOWT) facility of WL I Delft Hydraulics with graded sediment subjected to non-linear waves and linear waves plus current flows. The objective of this experiment is to increase our present understanding and physical insight of the basic mechanisms of bed-load and suspended load transport in oscillatory flow conditions when graded sediments are present in the bed. The sediment bed consists of a mixture of two well sorted sands (two fractions) that have been used before in the tunnel in order to make comparisons possible. Net sediment transport rates, time averaged suspended sediment profiles, time dependent concentrations in the suspension and sheet flow layers as well as time dependent velocity profiles are measured. Moreover, the sediment bed composition before and after each test is recorded in order to calculate the transport rate of each sediment fraction. Selected results are presented here. Full details are included in the data report (Hamm et al, 1998). The data will be used for the development of mathematical model formulations for graded sediment transport.@en