Integrated Modeling of Storm Surge, Waves and Tides to Support Coastal Flood Risk Management in Puget Sound

The Pacific Northwest coastal communities are subject to the threat of storm surge and extreme waves induced by extreme windstorms. Coastal flood risks caused by storm surge and extreme waves can be exacerbated by high tides and sea-level rise as a result of global warming. To better prepare for anticipated future coastal flood risks, it is important to accurately predict storm surge, waves and tides. This paper presents an integrated modeling study of simulating coastal inundation induced by storm surge, waves and tides in the Salish Sea using the unstructured-grid finite volume coastal ocean model FVCOM. Tidal simulation was driven by tidal open boundary conditions obtained from the Oregon State University global inverse tidal model. The wave model was forced with the NOAA regional WaveWatchIII model outputs at the open boundary off the outer-continental shelf. Storm surge simulation was forced by sea surface wind and air pressure obtained from the Global Forecast System (GFS) reanalysis products produced by NOAA’s National Centers for Environmental Prediction (NCEP). The wave model was validated with observed wave buoy data along the US west coast. Tide and storm surge simulations were validated with NOAA tide gage data along the west coast as well as in Puget Sound. Comparisons of model results with observed data indicated that the Salish Sea model successfully simulated tides, waves and storm surge under normal sea state as well as extreme windstorm conditions. Model results also indicated that the effect of wave-current interaction on significant wave height was significant in the shallow-water estuaries and coastal bays. Finally, coastal flooding induced by the combined effects of storm surge, waves, tides, as well as future sea-level rise in Puget Sound are quantified and discussed