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St. Petersburg Coastal and Marine Science Center

St. Petersburg Coastal and Marine Science Center > Coastal Change Hazards: Hurricanes and Extreme Storms

Coastal Change Hazards: Hurricanes and Extreme Storms

Storm-Impact Scale

Collision Regime

Collision Regime
cartoon illustration of collsion regime
Net dune erosion
If wave runup exceeds the elevation of the base of the dune, the runup will collide with the dune causing erosion and dune retreat. Unlike the temporary changes of the swash regime, this change is considered a net, or (semi-) permanent, change to the dune.

Dune Erosion During the Collision Regime

remains of a shipwreck Extensive dune erosion along the Outer Banks of North Carolina after Hurricane Isabel's 2003 landfall reveals the remains of a shipwreck on the beach near the town of Buxton. [larger version]

Below are a pair of before and after Hurricane Fran photographs show that the system was in Collision Regime, with significant dune retreat.

before-storm oblique aerial photograph of Topsail Island, North Carolina
Before: July 1996, Hurricane Fran, Topsail Island, NC.
after-storm oblique aerial photograph of Topsail Island, North Carolina
After: September 1996, Hurricane Fran, Topsail Island, NC.

Below are cross-sections of lidar data showing dune retreat of 20 meters during Hurricane Dennis (1999).

Plot of pre- and post-storm Lidar data showing dune erosion in the wake of Hurricane Dennis.

return to Storm Impact Scale Overview | continue to Overwash Regime


St. Petersburg Coastal and Marine Science Center > Coastal Change Hazards: Hurricanes and Extreme Storms

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