Collaborative Research: Long (Tsunami) Waves in Riverine Estuaries

人们对海啸在河流环境中传播的物理认识还不够深入，无法合理地确定危险程度。河流中意外的海啸行为可能会对河岸港口、码头、桥梁和其他关键基础设施造成危害。海啸在河流中的渗透在很大程度上取决于海啸、河流和潮汐的水流成分之间的相互作用以及河流的形态。该项目利用分析、实验室实验和数值模拟工作，旨在揭示决定海啸入侵和在河流中传播的条件。这些发现将使人们能够准确预测河流海啸的转化，这直接有利于公共安全，并有助于减少河流沿线地区的基础设施破坏。该研究计划强调对进入物理海洋学、应用数学和工程学领域的本科生和研究生的教育。由于这一主题的吸引力，该项目将有效地促进学生进一步推进他们的教育和研究，从而潜在地引导他们走向学术生涯。实验室实验将产生复杂的长波模式的时间演变，这些模式将被打包成视觉材料，可以在从高中到大学研究生水平的课堂上使用；这些材料将强调数学和海洋学之间的紧密联系。此外，实验室实验的结果将产生可靠的基准案例，用于验证适合在研究界内进行基准测试的河流海啸模拟数值代码。这项研究旨在通过整合理论方法、数值模拟和实验室实验来推进海啸力学的基本原理，所有这些方法都是以现场数据分析为指导的。它将使我们深入了解海啸转变为河流的相关机制，从而引导我们确定应该进行哪些调整，以改善这些关键海啸过程的数字表示。需要解决的具体问题包括：1)突发海啸如何通过河口环境传递能量；2)解释海啸入侵河流导致水长期积聚的原因；3)探讨海啸与河流流量之间的相互作用。在分析方面，将利用潮汐研究界的大量工作来确定哪些现有的关于河流中潮汐传播的理论考虑适用于海啸。将在2011年日本观测的指导下，对实地规模的条件进行数值模拟，以确定适当设计实验室实验所需的物理参数。此外，将同时进行数值实验和受控实验室实验，以进一步探讨与海啸从海洋向河流过渡有关的水动力学问题。这项实验室研究利用了两个不同但免费赠送的实验设施：1)南加州大学设计的2D水槽，用于研究自由表面波、内波和垂直切变流之间的相互作用；2)俄勒冈州立大学设计的3D波池，用于高精度研究水平平面上的非线性自由表面波变换。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。

Physics of tsunami propagation through riverine environments is not understood well enough to quantify the hazard with reasonable confidence. Unanticipated tsunami behavior in rivers can be harmful to riverine ports, marinas, bridges, and other critical infrastructure. Tsunami penetration in rivers is largely determined by the interaction among the flow components of the tsunami, river, and tide as well as by river morphology. This project utilizes analytical, laboratory experimental and numerical modeling work, designed to reveal the conditions that determine tsunami intrusion and propagation in rivers. The findings would enable accurate predictions of riverine tsunami transformation that is directly beneficial for public safety and for reducing infrastructure damage in areas along rivers. The research program emphasizes education for undergraduate and graduate students entering the fields of physical oceanography, applied mathematics and engineering. Because of the topic's appeal, the project will be effective in promoting students to further advance their education and research, thereby potentially leading them to academic careers. The laboratory experiments will yield the time evolution of complex long-wave patterns which will be packaged into visual material that could be used in classrooms from high school to college graduate levels; the material will emphasize the tight linkage between mathematics and oceanography. In addition, outcomes from laboratory experiments will yield solid benchmark cases for the validation of numerical codes for simulating tsunamis in rivers suitable for benchmark testing within the research community. The research is designed to advance fundamentals in tsunami mechanics through the integration of theoretical approaches, numerical simulation, and laboratory experiments, all guided by field data analyses. It will bring insight into the mechanics associated with tsunami transition into a river, thereby leading us to identify which adjustments should be made to improve numerical representation of these critical tsunami processes. The specific questions to be addressed are: 1) how incident tsunamis transmit their energy through the river-mouth environment, 2) explaining why tsunami intrusion into a river results in a prolonged water accumulation, and 3) exploring interactions of tsunamis with river discharge. For analytical considerations, the large body of work from the tidal research community, will be utilized to determine which existing theoretical consideration for propagation of tides in rivers are applicable to tsunamis. Numerical simulations will be implemented for field-scale conditions, guided by 2011 Japan observations, to determine the physical parameters necessary to properly design the laboratory experiments. In addition, numerical experiments will be carried out in tandem with the controlled laboratory experiments to further explore the hydrodynamics associated with the tsunami transition from ocean to river. The laboratory research makes use of two different but complimentary experimental facilities: 1) a 2D flume designed to study the interaction between free surface waves, internal waves, and vertically sheared currents at the University of Southern California, and 2) a 3D wave basin designed for the high-precision study of nonlinear free surface wave transformation in the horizontal plane at Oregon State University.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.