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					Pre-Ivan
 November, 1998




Post-Ivan
 September 19, 2004




Post-Ivan
 September 17, 2004




                                                                                                                                                                                                                                                                   USGS Photograph
Figure 3. Pine Beach, Alabama. Top and Center: Topography/bathymetry measured with lidar before and after the impact of Hurricane Ivan showing a new breach that severed the island. (Note the new houses that were built between the surveys. Houses appear in the topography as rec-
tangular mounds. Their warmer colors indicate higher elevations.) Bottom image: A USGS aerial photograph shows the new breach following landfall. (Arrows in all images point to the same features.)
 Pre-Ivan, July 17, 2001                                                Pre-Ivan, May 24, 2004



                                                                                                                                                   Coastal Change During Hurricane Ivan 2004
                                                                                                                                                     Category 3 Hurricane Ivan came
                                                                                                                                                   ashore near Gulf Shores, Alabama,
                                                                                                                                                   on September 16, 2004. The bar-
                                                                                                                                                   rier islands of the northern Gulf
                                                                                                                                                   of Mexico near the Florida/Ala-
                                                                                                                                                   bama border were exposed to the
                                                                                                                                                   strongest winds. The communities
                                                                                                                                                   of Gulf Shores, Pine Beach, and
                                                   USGS Photograph                  Gulf of Mexico                           elevation in meters   Orange Beach, Alabama, are, in
                                                                                                                                                   places, very low lying with their
 Post-Ivan, September 19, 2004                                          Post-Ivan, May 24, 2004                                                    dunes rising up only several me-
                                                                                                                                                   ters. These dunes were unable to
                                                                                                                                                   contain the 3- to 4-m storm surge.
                                                                                                                                                     The U.S. Geological Survey
                                                                                                                                                   (USGS), National Aeronautics and
                                                                                                                                                   Space Administration (NASA),
                                                                                                                                                   and U.S. Army Corps of Engi-
                                                                                                                                                   neers (USACE) are collaborating
                                                                                                                                                   in a research project investigating
                                                                                                                                                   coastal change during Hurricane
                                                                                                                                                   Ivan. On Friday, September 17,
                                                                                                                                                   2004, the USGS acquired oblique                                                                                              Pre-Ivan, July 17, 2001
                                                                                                                                                   aerial photography to better un-                                                                                                         USGS Photograph

                                                   USGS Photograph
                                                                                    Gulf of Mexico
                                                                                                                             elevation in meters
                                                                                                                                                   derstand the impact of Ivan on the
                                                                                                                                                   coastal environment. On Sunday,
                                                                                                                                                   September 19, 2004, airborne
         Patterns of Erosion and Accretion                                                                                                         lidar was collected using NASA
                                                                                                                                                   Experimental Advanced Airborne
                                                                                                                                                   Research Lidar (EAARL).
                                                                                                                                                     Gulf waters driven by hurricane-
                                                                                                                                                   force winds spilled across the
                                                                                                                                                   barrier islands as storm surge and
                                                                                                                                                   created currents strong enough to
                                                                                                                                                   transport massive amounts of sand
                                                                                                                                                   landward. These waters under-
                                                                                                                                                   mined buildings and roads and
                                                                                                                                                   opened new island breaches. On
                                                                                                                                                   top of the surge, breaking waves
                                                                                                                                                   nearly as tall as the depth of the
                                                                                                                                                   surge, eroded dunes and battered
                                                                                                                                                   structures.
                                                                                                                                                         Alabama
                                                               Gulf of Mexico                                                                                          Florida

                                                                                                      Accretion    Erosion                          MS



                                                                                                              Change
                                                                                                                                                    Mobile
                                                                                                                                                                   Area Shown
                                                                                                                                                                                       Orange                                                                          Post-Ivan, September 19, 2004
                                                                                                                                                                              Gulf     Beach
Figure 4. Gulf Shores, Alabama. Upper left: USGS before and after aerial photographs showing the loss of houses during Ivan. Upper
                                                                                                                                                     Bay
                                                                                                                                                                     Pine    Shores            Figure 2                                                                                     USGS Photograph
                                                                                                                                                                    Beach
right: Before and after laser mapping (lidar) topography of the same area shown in the photos (warmer colors represent higher eleva-                                  Figure 4
tions, (for example, houses). Bottom center: Vertical elevation change (erosion and accretion) that occurred as a result of the storm.                         Figure 3                                             Figure 2. Orange Beach, Alabama. USGS aerial photographs taken before and after
The red rectangles indicate houses that were completely destroyed and swept from the island into the back bay. (Arrows in all images                                                  Gulf of Mexico
                                                                                                                                                                                                                    the landfall of Hurricane Ivan show the failure of a five-story condominium tower. The
point to the same features.)                                                                                                                                                                           Kilometers   only parts of the structure that remain standing after Hurricane Ivan are the elevator
                                                                                                                                                             Path of Ivan                              3   0    3
                                                                                                                                                                                                                    and stairwell shafts. Airborne laser mapping data showed that the sand dune on which
            Project Contact: Asbury (Abby) Sallenger, USGS asallenger@usgs.gov 727-803-8747 x 3015                                                 Figure 1. Map showing track of Hurri-                            this building was constructed was subjected to about 3 m of vertical erosion during the
                                       http://coastal.er.usgs.gov/hurricanes/                                                                      cane Ivan.                                                       storm. (Arrows in all images point to the same feature.)
                                                                                                                                                   U.S. Department of the Interior                                                Printed on recycled paper
                                                                                                                                                                                                                                                                                              Fact Sheet 2009-3026
                                                                                                                                                   U.S. Geological Survey                                                                                                                             March 2009

				
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