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

点击翻译按钮获取中文摘要

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.