Wave and current fields around sand barrier at a river mouth

Experimental investigation and numerical computation for wave run-up on the opposing current for one-dimensional case have been carried out to study wave shoaling, breaking process including a determination of the breaker point, and the decay mechanism. Measured data of wave set-up under wave-current interaction has also been presented, and it was used to examine the accuracy of the model to compute wave set-up on the opposing current. Generally the model could simulate wave transformation out and inside surfzone well in agreement with experimental data. The model also could simulate wave set-up fairly.
The measured data of flow field around the sand barrier of a river mouth was presented and was used to examine the model to compute current field. Parabolic model, including wave-current interaction as proposed by Kirby (1986), was used for wave field computation. The bore model for wave energy dissipation was also included in the parabolic model, and the model reproduced well the wave height decay in the surfzone. Sakai's breaking criterion (1988) was used for the initiation of the breaking, since this criterion includes current effect on the breaking. For the current field computation, the depth-averaged continuity and momentum equations proposed by Dally (1998) has been adopted. These equations include roller effect due to breaking phenomena, since the diffusion function is of paramount importance for the flow fields around sand barrier at a river mouth. Here, diffusion function that includes current-current interaction as developed by Svendsen and Putrevu (1994) was adopted. For the long-shore current, at the weather side, at the river axis as well as at the lee side, the model was found to agree well with the laboratory data. However, for the cross-shore current the degree of agreement was low.
The method for computing wave and current fields around the river mouth were applied for The Abukuma River mouth in Japan and the Krueng Aceh River mouth in Indonesia. These sites were selected since they had sand barrier and good data were available such as topography map, river discharge, and wave conditions.