Patterns and projects of high tide flooding along the US coastline using a common impact threshold

This report aims to provide an objective and nationally consistent set of impact thresholds for minor/moderate/major coastal flooding in the US. Such definitions are currently lacking, which limits the ability to deliver new products as well as the effectiveness of existing coastal flood products. Coastal communities along all U.S. coastlines need consistent guidance about flooding, which is 1) forecasted in the near future (e.g., severity/depth of 4-day predictions of storm surge heights ‘above ground level’), 2) likely in the coming season or year (e.g., probabilistic outlooks) or 3) possible over the longer term (e.g., decadal to end-of-century scenarios).

The primary emphasis is to use the derived threshold for minor flooding, which this report refers to as ‘high tide’ flooding (also known as ‘nuisance’, ‘sunny day’ and ‘recurrent tidal’ flooding), to assess nationally how exposure—and potential vulnerability—to high tide flooding has and will continue to change with changing sea levels.