Collaborative Research: Swash zone dynamics driven by obliquely incident waves

海滩是海岸线的特色，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一个坚定的理解。这方面的知识在冲刷带尤其不发达，在那里，海浪每次都会把沙子弄湿或弄干，并带走大量的沉积物。这个项目将研究这些过程，因为它们是由波浪到达一定角度时发生的，这是海滩上常见的场景。以前的研究工作已经开发了新的工具、测量技术和知识来理解冲浪区过程，这些研究只集中在跨海岸动力学上，因为这些研究更容易在小尺度波浪水槽和二维模拟中进行。在这个项目中，一个密集的实验室实验，理论分析和数值模拟活动将被用来扩展到所有三个空间维度和时间的冲刷区知识。在波浪以一定角度接近的领域，沿岸动力学和沉积物运输尤为重要，但它们也是最不为人所知的。实验室实验将包括一系列波浪强迫条件和波浪入射角，并辅以使用开源模型的数值模拟以及基于理论考虑的新预测公式的开发。该项目的目标是在研究冲刷动力学基本方面的基础上建立一个新的知识框架，以改变我们对海滩上水流和沉积物运输模式的理解。这些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）几乎一半的海滩面临着与泥沙运输趋势相关的管理挑战，这些趋势由于波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，以及四所院校的众多本科生。该项目还将为博士后研究员提供部分支持，这些博士后研究员将为未来的教授生涯获得宝贵的经验和指导。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经验，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，项目结果将通过期刊出版物和会议广泛传播，包括美洲青年沿海科学家和工程师会议，该会议将在项目期间首次在中西部（威斯康星州麦迪逊）举行。所有实验数据将存储在nsf资助的数据存储库中，开源数值模型将用于促进进一步的发展。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带波的强迫下沿海岸方向流动和沉积物运输的物理基础。尽管冲刷带在整个海滩沉积物预算中很重要，但它对沿岸流动和运输的描述却很差。详细的测量加上数值模拟和理论分析将揭示在不同波浪条件下和波浪入射角范围内，钻孔塌陷和湍流是如何驱动沿岸流的。同样，详细的沉积物浓度剖面和通量将从根本上揭示冲刷带三维沉积物运输模式的新见解，包括沿岸的片流运输如何加强跨岸侵蚀/增积。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.