Abstract
In numerical models considering wave-current coexistence field, bottom shear stress is generally calculated from representative values of the wave and current fields. However, the actual bottom flow velocity fluctuates instantaneously from moment to moment, and the velocity within a given time period is represented by a probability distribution. In this study, we improved the evaluation method of bottom shear stress by using an erosion calculation formula based on an evaluation method that takes into account the probability distribution of bottom flow velocity fluctuations. Furthermore, the improved model was used in a reproduction of a previous typhoon. Compared to the average model, in which bottom shear stress is uniquely determined from representative values of wave and current, the stochastic model reproduces the observed values for SS more accurately by taking into account the ever-changing bottom current velocity. In addition, it was confirmed that the stochastic model is more accurately able to account for the effects of wave during high-wave conditions, while the average model is bottom shear stress is dominated by the average flow velocity.
