Modelling Wave-Driven Setup

在这项研究中，伍兹霍尔海洋研究所的科学家将开发和验证流体和沉积物过程的模型，这些过程会在几天到几个月的时间里影响海岸线的演变。波动量通量的梯度(辐射应力)驱动近岸环流，而近岸环流又驱动泥沙输送。近岸环流的一个重要方面是波浪驱动的结构，也就是海岸线附近平均水位的升高。1997年在北卡罗来纳州的达克附近以及2000年和20003年在加利福尼亚州的拉荷亚附近进行了设置的观测。这些研究表明，根据海浪涌浪的岸上波能的线性理论，先前对跨岸辐射应力的估计比观测到的要小。这项研究将扩展一个数值模型，以包括四个以前被忽视的过程：波浪滚滚、底部应力、波浪非线性和亚重力波反射。然后，该模型的预测将与现有的现场和实验室观测结果进行比较。实验室对水流垂直剖面的观测将用于比较波能和辐射应力的线性和非线性表达式。如果非线性被证明是重要的，深度平均的非线性表达式将被检查并合并到设置模型中。此外，将使用准三维近岸社区和Delft3D模式的模拟来检验近岸测深不均匀对波浪驱动装置的重要性。在风暴期间，观测到波浪驱动装置使封闭层增加超过一米。正如卡特里娜飓风期间所清楚的那样，风暴潮和海浪的共同作用造成的洪水破坏可能会给社会带来巨大的损失。这项研究中正在开发的模型可能对负责预测沿海洪水的沿海管理人员有用。这项研究构成了博士论文的基础，其结果将为新英格兰的基于互联网的本科生课程提供材料。

ABSTRACTOCE-0622844In this study, scientists at Woods Hole Oceanographic Institution will develop and validate models for the fluid and sediment processes that affect the evolution of the shoreline over periods of days to months. Gradients in wave momentum fluxes (radiation stresses) drive the near-shore circulation which in turn drives sediment transport. One important facet of the near-shore circulation is wave-driven setup, which is an elevation of mean water levels near the shoreline. Observations of setup were made in 1997 near Duck, North Carolina and in 2000 and 20003 near La Jolla, CA. These studies have shown that prior estimates of the cross-shore radition stress, which were based on a linear theory of onshore wave energy from sea swell, are smaller than what is observed. This study will extend a numerical model to include four previously neglected processes: wave rollers, bottom stress, wave nonlinearities, and infragravity wave reflection. The predictions of that model will then be compared with existing field and laboratory observations.Laboratory observations of the vertical profile of flows will be used to compare linear and nonlinear expressions for wave energy and radiation stress. If nonlinearities are shown to be important, depth-averaged nonlinear expressions will be examined and incorporated in the setup models. Additionally, the importance of alongshore bathymetric inhomogenities to the wave-driven setup will be examined using simulations of the quasi three-dimensional NearShore Community and Delft3D models.During storms, wave-driven setup has been observed to increase the seal level more than a meter. As became clear during Hurricane Katrina, flood damage by a combination of storm surge and wave setup can result in a significant cost to society. The model that is being developed in this study could be useful to coastal managers who are tasked with the prediction of coastal flooding. This study forms the basis of a PhD dissertation and results will provide material for internet-based undergraduate classes in New England.