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St. Petersburg Coastal and Marine Science Center > National Assessment of Storm-Induced Coastal Change Hazards > Hurricane Irma

National Assessment of Storm-Induced Coastal Change Hazards

Hurricane Irma Storm Response

Pre- and Post-Storm Photo Comparisons - East Florida

The coastal change forecast model predicts the probability of where and how primary sand dunes along the coast will be impacted by water levels during a storm. This includes the combined effect of surge and wave runup. The color band closest to the shoreline is the probability of dune erosion, the middle color band is the probability that sand dunes will be overtopped by waves during the storm and the outer color band is the probability that the sand dunes will be completely inundated/flooded. The model forecast is available on the coastal change hazards portal: https://marine.usgs.gov/coastalchangehazardsportal/  and more information about the model can be found here: https://coastal.er.usgs.gov/hurricanes/assessments/background.php
Below is an initial comparison of imagery collected by the National Oceanic and Atmospheric Administration (NOAA) in 2017 with similar imagery taken a few days after Hurricane Irma’s landfall (https://storms.ngs.noaa.gov/). These photos provide information about how the coastal was impacted by the storm and can be used as validation for the model.

    Predicted probabilities of dune erosion (inner strip), overwash (middle strip), and inundation (outer strip) for Hurricane Irma. Pictures are representative of coastal change observed during past storm events.
Predicted probabilities of dune erosion (inner strip), overwash (middle strip), and inundation (outer strip) for Hurricane Irma. Pictures are representative of coastal change observed during past storm events. [larger version]

Location Map
Locations of observed coastal change due to Hurricane Irma.



pre- and post-storm photos
Location 1: High waves during Hurricane Irma eroded the wide stretch of sand at Daytona Beach, but did not overtop the seawall. The predicted probability of overwash for this location was 30%. [larger version]



pre- and post-storm photos
Location 2: Elevated water levels during Hurricane Irma overtopped low dunes and transported sand across the roadway in Palm Coast. The predicted probability of overwash for this location was 76%. [larger version]



pre- and post-storm photos
Location 3: In the Matanzas area, elevated water levels during Hurricane Irma overtopped low dunes and transported sand landward, covering vegetation and filling in a small pond. The predicted probability of overwash for this location was 87%. [larger version]



pre- and post-storm photos
Location 4: Three homes were destroyed in South Ponte Vedra when waves and surge from Hurricane Irma eroded the dune face and scoured areas behind the seawall, undermining their foundations. Erosion is often more severe on sections of beach behind and adjacent to the end of a section of seawall. The predicted probability of dune erosion for this location was 99%. [larger version]



pre- and post-storm photos
Location 5: Waves from Hurricane Irma reached the toe of the dunes in Ponte Vedra, causing the dune face to erode and leaving a steep scarp. The predicted probability of dune erosion for this location was 58%. [larger version]



pre- and post-storm photos
Location 6: The beach near Mayport illustrates the processes of overwash and dune erosion due to Hurricane Irma. Lower elevation dunes, roads, and walkways overwashed due to high surge and waves while the higher elevation dunes show scarping indicative of dune erosion. Predicted probabilities of dune erosion and overwash were 97% and 57% for this location. The predicted probability of coastal change is calculated for every 1 kilometer of coast and does not resolve small areas of overwash such as walkovers and roadways. [larger version]



pre- and post-storm photos
Location 7: Elevated water levels during Hurricane Irma overtopped the dunes in this section of Huguenot Park, transporting sand landward over the vegetation and into the lagoon. The predicted probability of overwash for this location was only 41%. [larger version]



pre- and post-storm photos
Location 8: The northern end of Little Talbot Island illustrates the processes of overwash and dune erosion due to Hurricane Irma. The low-lying sand spit near the top of the image overwashed due to high surge and waves while the dunes to the south show scarping indicative of dune erosion. Predicted probabilities of dune erosion and overwash were 98% and 73% for this location. [larger version]

St. Petersburg Coastal and Marine Science Center > National Assessment of Storm-Induced Coastal Change Hazards > Hurricane Irma

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Page Last Modified: October 24, 2017 03:19 PM (JSG)

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