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Before and After Photo Pairs
On Friday September 17, 2004, scientists from the U.S. Geological Survey (USGS) conducted an aerial photographic survey of the barrier islands in Alabama and Florida that were impacted by Hurricane Ivan. The photographs have been compared to pre-storm photographs to illustrate extreme coastal change.
The barrier islands exposed to Ivan's strongest winds, for example, the communities of Gulf Shores and Orange Beach, AL, are, in places, low lying, their dunes rising up only several meters, which is insufficient to have contained Ivan's storm surge. The Gulf spilled across the islands in a strong current capable of transporting massive amounts of sand landward, undermining buildings and roads, and opening new island breaches. On top of the surge, breaking waves nearly as tall as the water was deep, eroded dunes and battered structures.
See examples of extreme coastal change in the photo pairs below. For each pair, the upper photo was taken by the USGS on July 17, 2001 and the lower photo was taken by the USGS on September 17 after Ivan’s landfall.
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Collapsed five-story building, Romar Beach, AL:
The lower two floors of the five-story building in the center of these photos have collapsed and the third floor has fallen to ground level. Erosion in front of the buildings undermined pools and walkways, and perhaps the buildings themselves (although the failure mode must await analysis by structural engineers.) Note the sandy overwash deposits that were driven landward between the buildings by storm waves and currents. [larger version] |
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Collapsed front of multistory building, Orange Beach, AL:
This five-story building was perched on top of a dune that was eroded during Hurricane Ivan. The Gulf-front portion of the building collapsed. Compare the pilings in the pre and post-photos of the house adjacent to the multi-story structure to determine the scale of vertical erosion of the dune. In the post-storm photo, the lower, unpainted portions of the pilings were below sand level prior to Hurricane Ivan. [larger version] |
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Destroyed houses on top of a dune, Orange Beach, AL:
These houses were on built top of a dune that was severely eroded during Ivan. Note the walkways in the pre-storm photo that once served as pathways down to the beach. [larger version] |
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Breach through barrier island, Pine Beach, AL:
The island was severed by a breach that may have developed as the back bay drained excess water following the peak of the storm surge, although the breach could have been initiated by waves and surge from the Gulf side. More analyses are required to determine the forcing processes. [larger version] |
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Overwash across barrier island, Gulf Shores, AL:
In places, the barrier islands are narrow. Currents and waves transported sand from Gulf–front beaches across the island and into the back bay. [larger version] |
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U. S. Department of the Interior | U.S. Geological Survey
