Presenter: Margaret Palmsten (U.S. Geological Survey)

Description:
Over the last two decades, the U.S. Geological Survey has invested in basic research that led to the development of the Total Water Level and Coastal Change Forecast model, a collaborative effort with the National Oceanic and Atmospheric Administration (NOAA). The model is deployed on approximately 4,700 km of open, sandy coastline on the Atlantic and Gulf Coasts, with ongoing expansion to the Pacific Coast and non-sandy environments. It is the only national-scale, real-time model for coastal change in the United States. Although tropical systems with high surge often receive the most attention, we hypothesize that over the course of a year, the wave contribution to total water level exceeding the elevation of the dune base represents an important mechanism for coastal change, and when waves exceed the elevation of the dune crest there can be a potential for nuisance flooding or more catastrophic inundation or breaching. We analyzed hourly forecasts of total water level from January 1, 2020 to December 31, 2020 in comparison to the elevation of the dune base. Over the twelve-month period, dune erosion was forecast to occur at least once at all locations, and wave interaction with the dunes was forecast to occur more than 24 hours at nearly 50% of the 3,053 forecast locations. We also determined that during erosion events, wave runup accounted for an average of 72% of the total water level, demonstrating the importance of ongoing wave contributions in driving coastal change.