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Storm-Impact Scale
Collision Regime
Collision 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
Below are a pair of before and after Hurricane Fran photographs show that the system was in Collision Regime,
with significant dune retreat.
Before: July 1996, Hurricane Fran, Topsail Island, NC. |
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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).
return to Storm Impact Scale Overview | continue to Overwash Regime
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