A NUMERICAL MODEL OF WAVE-RUN-UP AND RESULTING LONGSHORE SEDIMENT TRANSPORT DUE TO OBLIQUELY INCIDENT WAVE

冲刷带动力学是计算海岸输沙速率的重要因素。本文建立了考虑岸线移动边界条件的岸线输沙率陆上分布的数值模型。控制方程采用了包含非线性和色散的boussinesq型方程，并引入了破缺模型。在假定岸岸方向水深均匀的情况下，将岸岸坐标和时间合并为一个自变量。近海边界条件包括能吸收出波的辐射边界条件；建立了滨岸边界条件，再现了冲积带的移动岸线。将该模型应用于斜入射波的数值计算中，模拟了包括冲刷运动在内的波浪动力学，结果表明，该模型能较好地再现岸线的运动以及波浪的变形和破碎。除波浪场外，还考虑了底部摩擦对近岸流场的影响。该模型结合Dibajnia和Watanabe（1994）提出的输沙公式，得到了一个峰在断裂点附近，另一个峰在海岸线附近的双峰分布，这在实验室实验中得到了认可。由此，建立了近海直、平行等高线底部地形上斜入射波的通用数值模型，该模型可以再现波浪的非线性变形、冲刷运动、岸流和岸输沙率的陆上分布

Swash zone dynamics is an important factor in computing longshore sediment transport rate. In the present study, a numerical model is developed to predict the onshore distribution of the longshore sediment transport rate by taking into account the moving shoreline boundary condition.Boussinesq-type equations were adopted as the governing equations that include non-linearity and dispersivity, and a breaking model was incorporated. The longshore coordinate and the time were combined into one independent variable under the assumption of a uniform water depth in the longshore direction. The offshore boundary condition included the radiation boundary condition which can absorb the outgoing waves ; the onshore boundary condition was developed to reproduce the moving shoreline in the swash zone.We applied this model to the numerical computations with obliquely incident waves to simulate wave kinetics including swash motion, and found that the model can reproduce the moving shoreline as well as wave deformation and breaking correctly.In addition to the wave field, the nearshore current field was modeled by considering the bottom friction. By incorporating the sediment transport formula proposed by Dibajnia and Watanabe (1994), the model resulted in a bi-modal distribution, with one peak around the breaking point and the other around the shoreline, which has been recognized in the laboratory experiment.As a result, a general numerical model for obliquely incident waves on the bottom topography of straight and parallel offshore contours is developed, which can reproduce non-linear wave deformation, swash motion, longshore current, and onshore distribution of the longshore sediment transport rate