Collaborative Research: Swash zone dynamics driven by obliquely incident waves

海滩是海岸线特征，提供经济效益、生态系统服务和抵御洪水的天然屏障。因此，海滩的可持续管理需要对海岸过程和海滩沉积物预算有深刻的了解。这种知识在冲浪区尤其不发达，在那里，海浪每波都会使沙子湿润和干燥，并移动大量的沉积物。这个项目将研究这些过程，因为它们发生在到达一个角度的海浪，这是海滩上常见的场景。以前的研究已经开发了新的工具、测量技术和知识来了解冲浪区过程，但由于这些研究更容易在小规模波浪水槽和二维模拟中进行，因此只专注于跨岸动力学。在这个项目中，将使用密集的实验室实验、理论分析和数值模拟来将冲浪区的知识扩展到所有三个空间维度和时间。近岸动力和泥沙输运在波浪以一定角度靠近的领域中尤为重要，但也是最不了解的。实验室实验将包括一系列波浪强迫条件和波浪入射角，并辅之以使用开放源码模型的数值模拟以及基于理论考虑开发新的预测公式。该项目的目的是在研究水流动力学的基本方面的基础上开发一个新的知识框架，以改变我们对海滩上水流和泥沙输送模式的理解。这将对研究人员和利益相关者产生深远的影响，因为美国(和全球)近一半的海滩面临着与沉积物输送趋势相关的管理挑战，这些趋势因海浪作用而发生不可预测的变化。该项目将分别在威斯康星大学麦迪逊分校和特拉华大学培养两名博士生，以及四所大学的众多本科生。该项目还将为博士后研究员提供部分支持，他们将获得宝贵的经验，并为未来的教授职业生涯提供指导。此外，来自不同地区的四名高中教师将获得有意义的研究实验室体验，并帮助他们为课堂开发新的学习模块。该项目还将启动威斯康星大学麦迪逊分校、加勒比海沿岸海洋观测系统、特拉华大学应用海岸研究中心和女王大学海岸工程实验室之间的新合作。最后，项目成果将通过期刊出版物和会议广泛传播，包括将在项目期间首次在中西部(威斯康星州麦迪逊)举行的美洲沿海青年科学家和工程师会议。所有实验数据将托管在NSF资助的数据库中，并将使用开放源码的数值模型来促进进一步的发展。利用最先进的实验测量技术和数值模拟工具，该项目将发现在入射波段波的强迫下沿海岸方向的水流和泥沙运移的物理基础。尽管近岸水流和输运在整个海滩沉积物预算中很重要，但在冲浪区描述得很差。详细的测量，结合数值模拟和理论分析，将揭示在不同的波浪条件下，在一定的波浪入射角范围内，钻孔坍塌和水流湍流是如何驱动沿岸流的。同样，详细的泥沙浓度分布和通量将从根本上揭示冲刷带三维泥沙输送模式的新见解，包括近岸的片状水流输送如何增强跨岸侵蚀/淤积。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Beaches are coastline features that offer economic benefits, ecosystems services, and a natural barrier against flooding. Thus, sustainable management of beaches requires a firm understanding of coastal processes and beach sediment budgets. Such knowledge is particularly underdeveloped in the swash zone, where waves wet and dry the sand with each wave and shift enormous amounts of sediment. This project will investigate these processes as they occur by waves that arrive at an angle, a common scenario on beach beaches. Previous research efforts that have developed new tools, measurement techniques, and knowledge to understand swash zone processes have focused solely on cross-shore dynamics since these studies are easier to perform in small-scale wave flumes and two-dimensional simulations. In this project, an intensive campaign of laboratory experiments, theoretical analysis, and numerical simulations will be used to expand swash zone knowledge to all three spatial dimensions and time. The alongshore dynamics and sediment transport are particularly important in the field where waves approach at an angle, but they are also the least understood. The laboratory experiments will include a range of wave forcing conditions and wave incidence angles and be complemented by numerical modeling using open-source models as well as development of new predictive formulations based on theoretical considerations. The project will aim to develop a new knowledge framework based on studying fundamental aspects of swash dynamics to transform our understanding of the flow and sediment transport patterns on beaches. These will have far reaching implications for researchers and stakeholders since almost half of all beaches in the US (and globally) face management challenges related to sediment transport trends that change unpredictably due to wave action. The project will train two PhD students at UW-Madison and U Delaware, respectively, and numerous undergraduate students across four institutions. The project will also provide partial support to a postdoctoral researcher, who will gain valuable experience and mentoring for a future career as a professor. Additionally, four high-school teachers from different regions will receive a meaningful research laboratory experience and help in developing a new learning module for their classrooms. The project will also start a new collaboration between University of Wisconsin-Madison, the Caribbean Coastal Ocean Observing System, the Center for Applied Coastal Research at University of Delaware, and the Coastal Engineering Laboratory at Queen’s University. Finally, project results will be widely disseminated via journal publications and conferences, including the Young Coastal Scientists and Engineers Conference - Americas, which will be held in the Midwest (Madison, WI) for the first time during the project. All experimental data will be hosted on NSF-funded data repositories and open-source numerical models will be used to promote further development. Using state-of-the-art experimental measurement techniques and numerical modeling tools, the project will discover the physical basis for flow and sediment transport in the alongshore direction under forcing from incident-band waves. The alongshore flow and transport is poorly described in the swash zone, despite its importance in overall beach sediment budgets. Detailed measurements coupled with numerical modeling and theoretical analysis will reveal how bore collapse and flow turbulence drive alongshore currents under different wave conditions and across a range of wave incidence angles. Similarly, detailed sediment concentration profiles and fluxes will reveal fundamentally new insights into three-dimensional sediment transport patterns in the swash zone, including how sheet flow transport in the alongshore may enhance cross-shore erosion/accretion.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.