Prediction and Mitigation of Beach Overwash and Resultant Urban Flooding in Coastal California

该项目将涉及实地研究和建模，以提高对城市地区地块规模的波浪驱动洪水的预测。最近的研究表明，利用现代数据(如激光雷达)和模型资源进行地块尺度的洪水预报是可能的，但由于复杂的基础设施和波浪驱动的洪水带来的困难，城市海岸线仍然是一个重大挑战。一类很有前途的泥石流模型将被应用于模拟冲浪区的动力学，并量化海堤和海滩沙丘的溢流率，这是城市洪水模型的关键强迫数据。我们还将部署波浪仪和地面激光雷达系统，以监测在冬季风暴之前建造的防沙护堤的侵蚀情况。我们寻求更好地了解可用于改进应急准备的护堤性能，以及短期沿海洪水预报的可靠性。海平面上升、风暴活动增加和城市化的趋势都表明沿海洪水破坏的风险越来越大，这些趋势的结合增加了在加利福尼亚州发达的沿海低地发生重大灾难的可能性。美国地质勘探局的一项研究表明，持续几周的大气河流事件可能会给全州造成7250亿美元的洪水损失，是同样概率的南加州大地震预期损失的几倍。为了规划一个可持续的未来，沿海社区需要审查许多不同的适应措施，以寻求一种平衡该区域经济、环境和社会优先事项的组合。此外，沿海社区需要可靠的洪水预报系统，以将极端事件期间的损失降至最低。这项工作将促进对过程、数据和模型的基本理解，这些过程、数据和模型是满足南加州这些需求所需的。这些进展将使工程师和沿海管理人员能够为目前建立更具弹性的社区，并为未来规划更可持续的沿海社区。此外，纽波特海滩的一项详细调查提供了沿海适应范例的潜力，使全国和其他地区的社区受益。

This project will involve field studies and modeling to improve the prediction of wave-driven flooding at the scale of land parcels in urban areas. Recent research has shown that parcel-scale flood prediction is possible with modern data (e.g., lidar) and modeling resources, but urban coastlines remain a major challenge due to complex infrastructure and the difficulties posed by wave-driven flooding. A promising class of debris flow models will be applied to simulate swash zone dynamics and quantify sea wall and beach dune overtopping rates, critical forcing data for urban flooding models. We will also deploy wave gages and a terrestrial lidar system to monitor the erosion of protective sand berms that are constructed before winter storms. We seek an improved understanding of berm performance that can be used to improve emergency preparedness as well as the reliability of short-term coastal flooding forecasts. Trends of higher sea level, increased storm activity, and urbanization all point to a growing risk of coastal flood damage and the combination of these trends raises the possibility of a major disaster in developed coastal lowlands of California. A study by the USGS suggests that an atmospheric river event lasting several weeks is capable of $725 billion in flood losses across the State, several times the expected losses from a major southern California earthquake of the same probability. To plan a sustainable future, coastal communities need to examine many different adaptation measures in search of a mix that balances the economic, environmental and social priorities of the region. In addition, coastal communities need reliable flood forecasting systems to minimize losses during extreme events. This work will advance a fundamental understanding of processes, data and models that is needed to address these needs in southern California. These advances will position engineers and coastal managers to build more resilient communities for the present, and plan more sustainable coastal communities for the future. Moreover, a detailed investigation at Newport Beach offers the potential for a coastal adaptation paradigm that benefits communities across the Nation and beyond.