Narrow Results

This paper presents a 3D beach evolution model using quasi-3D nearshore current model that can predict the shoreline changes. Sediment transport rates in the run-up region are taken into account in order to compute the shoreline change. The shoreline change model is based on the SBEACH model. First, in order to examine the performance of the presented model, several model tests for the beach evolution around detached breakwaters and pocket beach were carried out. Furthermore, the applicability of the model was investigated by comparing with an experiment in the 3D wave basin and field measurement around offshore-type fishing port in Japan.

When we construct coastal structures such as the breakwaters, jetties and harbours, the prediction of medium or long term beach evolution around the coastal structures is required. Some mophodynamic models for predicting the mediumterm beach evolution(coasta1 area models) have been proposed such as, Watanabe et al(l986),de Vriend et al(1993). A coastal area model coupled with the shoreline model have been proposed by Shimizu et aL(1996). In the coastal area model, the nearshore current field has been determined using a depth-averaged (2DH) model. Recently, some coastal area models using a quasi-3D nearshore current model have been also proposed (e.g. Kuroiwa et al. 2000). Although these coastal area models have been applied to some practical problems, these models are still uncompleted because shoreline changes have not been sufficiently incorporated. Therefore, in order to predict 3D beach evolution with better accuracy, a 3D morphodaynamic model, that considers the effect of nearshore current profile and estimates the shoreline changes, is needed…

A 3D morphodynamic model that can simulate shoreline change and sorting of mixed-size sand was proposed. The computed results were compared with the experiments of bar formation and shoreline change due to alongshore sediment transport. Furthermore, the performance of the model to 3D beach evolution with the sorting of the mixed-size sand around coastal structures was investigated. Finally, the applicability of the model was discussed, according to the computed results.

This paper deals with a prediction model of bottom topographical change. The morphodynamic model, which can take into account the vertical distribution of nearshore current and suspended load concentration in the surf zone, was proposed. In the prediction model, nearshore current profiles were determined by using quasi three-dimensional model. The sediment transport rate was considered the effect of the suspended load that was estimated by using advection and diffusion equation. The presented model was calibrated and verified by comparing with data measured in the large-scale wave flume. Furthermore, the presented model was applied to the field sites with barred beach and coastal structures. Finally, the applicability of the presented model was discussed.

The applicability of a three dimensional coastal area model based on a Hybrid model for medium-term beach evolution was investigated. The three dimensional model was first tested against groins for three cases in order to investigate the influence of the time history of the incident waves, and the time stepping techniques to feedback on the predicted final bathymetry. Then, the model was applied to Kunnui fishing port for 1, 3, and 4 years, to calibrate and verify the model. For the model tests, the performane of the model was investagated; and for Kunnui fishing port, the model results show good agreement with the field observations.