Hurricane Dorian - Forecast and Documentation of Coastal Change
Science Center Objects
Hurricane Dorian coastal change forecast and pre- and post-storm photos documenting coastal change.
Hurricane Dorian impacted a large portion of the U.S. Southeast coast, from Florida to North Carolina, from September 3-6, 2019. Storm surge reached 0.5 to 1.5 meters above predicted tides. Offshore wave heights in excess of 7 meters were observed near Cape Canaveral, FL and wave heights in excess of 8 meters were observed near Cape Hatteras, NC. These large waves contributed an additional 1-3 meters of wave runup at the shoreline. The combined effects of surge and storm-induced wave runup created elevated total water levels at the shoreline, causing extensive erosion of the beach and dunes.
Current response activities include:
Planned activities:
- Qualitative validation of coastal change forecast (coming soon)
- Post-storm lidar survey of open coast shoreline from Florida to Virginia
- Quantitative observations of coastal change (coming soon)
Forecast of Potential Coastal Change
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 and more information about the model can be found at: https://www.usgs.gov/centers/spcmsc/science/scenario-based-assessments-used-coastal-change-hazard-forecasts.
Predicted probabilities of dune erosion (inner band), overwash (middle band), and inundation (outer band) for Hurricane Dorian. Pictures are representative of coastal change observed during past storm events. (Public domain.)
Pre-and Post-Storm Photo Comparisons
Below is an initial comparison of imagery collected by the National Oceanic and Atmospheric Administration (NOAA) in 2019 with similar imagery taken a few days after Hurricane Dorian passed near the coast. (https://storms.ngs.noaa.gov/). These photos provide information about how the coast was impacted by the storm and can be used as validation for the model.
Locations of observed coastal change due to Hurricane Dorian. (Public domain.)
Location 1: A breach which first opened during Hurricane Matthew re-opened during Hurricane Dorian due to elevated water levels and large storm waves that overwashed and flooded a low-lying section of the coast. The predicted probability of inundation was 60% for this location. (Public domain.)
Location 2: The low lying coastline of Georgia was overwashed in many locations and sand was deposited over the marsh, such as on St. Catherine’s Island. The predicted probability of overwash was 100% for this location. (Public domain.)
Location 3: On the southern end of Pawley’s Island, elevated water levels overtopped the low-elevation dunes, transporting sand landward and over the road. The predicted probability of overwash was 100% for this location. (Public domain.)
Location 4: Core Banks within Cape Lookout National Seashore was heavily impacted by waves and surge from Hurricane Dorian. The cuts seen in the island were driven by surge exiting Core Sound as Hurricane Dorian’s winds rapidly changed direction. The predicted probability of inundation for this location was 50%. These predictions are made for surge and waves coming from the ocean, and do not account for processing coming from the sound side of the island. (Public domain.)
Location 5: An area of previous overwash in Core Banks was completely eroded during Hurricane Dorian. The beach likely experienced erosion and overwash during the approach of Dorian, and then a large storm surge from the sound side after Dorian’s eye passed over. The pattern of wave breaking on the ocean side of the new inlet indicates sand was transported seaward by the surge. The probability of inundation for this location was 60%. (Public domain.)
Location 6: The Longpoint Cabin Camp in Cape Lookout National Seashore was heavily impacted by Hurricane Dorian’s waves and surge. All of the cabins were damaged and a few supporting structures were destroyed. The area is now inaccessible due to the cut from the harbor to the cabins. These cuts were likely formed when surge flowed over the island from the sound side. The dunes in front of the 2 southern cabins are still intact, indicating that waves and surge from the ocean did not reach the top of the dunes. (Public domain.)
Location 7: Another cut, likely from sound-side flooding on Portsmouth Island. The dunes are intact and a scarp can be seen on the back side of the dunes, indicating that the process of erosion and inundation came from the sound rather than the ocean. (Public domain.)
Location 8: Elevated water levels during Hurricane Dorian eroded the dunes in Hatteras Village and transported sand inland across the road. The probability of dune erosion for this location was 95%, while the probability of overwash was only 30%. (Public domain.)
Location 9: Large waves and storm surge during Hurricane Dorian overtopped the low dunes along NC Highway 12 in Pea Island National Wildlife Refuge, transporting sand inland across the road. Bulldozers can be seen in the post-storm photograph clearing the road of sand. The probability of dune erosion for this location was only 55%, while the probability of overwash was only 2%. (Public domain.)
Forecasts showing the timing and magnitude of elevated water levels at the shoreline are available in real-time for the U.S. coastline from Florida through Maine in the Total Water Level and Coastal Change Forecast Viewer.
If additional response activities are initiated by the Coastal Change Hazards team (lidar, photography, or ground surveys) updates will be posted here.
Find additional information and data for Hurricane Dorian, including inland and coastal flood data on the USGS Dorian website
Scenario-Based Assessments for Coastal Change Hazard Forecasts
A decade of USGS research on storm-driven coastal change hazards has provided the data and modeling capabilities needed to identify areas of our coastline that are likely to experience extreme and potentially hazardous erosion during an extreme storm.
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Date published: September 4, 2019Status: ActiveReal-Time Storm Response
Coastal change forecasts and pre- and post-storm photos documenting coastal change for landfalling storms. Currently responding to Hurricane Dorian.
Contacts: Kara Doran -
Date published: January 18, 2018Status: ActiveNational Assessment of Storm-Induced Coastal Change Hazards
This project focuses on understanding the magnitude and variability of extreme storm impacts on sandy beaches. The overall objective is to improve real-time and scenario-based predictions of coastal change to support management of coastal infrastructure, resources, and safety.
Contacts: Kara Doran
Coastal Change Hazards Portal
Interactive access to coastal change science and data for our Nation’s coasts. Information and products are organized within three coastal change hazard themes: 1) extreme storms, 2) shoreline change, and 3) sea-level rise. Displays probabilities of coastal erosion.
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Date published: January 19, 2018Total Water Level and Coastal Change Forecast Viewer
Total water level (TWL) at the shoreline is the combination of tides, surge, and wave runup. A forecast of TWL is an estimate of the elevation where the ocean will meet the coast and can provide guidance on potential coastal erosion and flooding hazards.