IMPACTS OF HURRICANE KATRINA ON GULF COAST BARRIER ISLANDS

The U.S. Geological Survey, NASA, the U.S. Army Corps of Engineers, and the University of New Orleans are cooperating in a research project investigating coastal change that occurred as a result Hurricane Katrina, which made landfall as a category 4 storm in Plaquemines Parish, Louisiana on August 29, 2005. Aerial video, still photography, and laser altimetry surveys of post-storm beach conditions were collected August 31 and September 1, 2005. The data were immediately made available to local, state, and federal agencies for purposes of disaster recovery and erosion mitigation. Comparisons of post-storm data with earlier surveys were used to show the nature, magnitude, and spatial variability of coastal changes such as beach erosion, overwash deposition, and island breaching.

Changes observed along two barrier island systems illustrate the dramatic coastal impacts of Hurricane Katrina. Louisiana's Chandeleur Islands are an undeveloped, north-south oriented chain of barriers located approximately 110 km east of the city of New Orleans and 70 km east of Katrina's path. These low-lying barrier islands were totally stripped of sand and heavily fragmented by large waves and storm surge. Dauphin Island, Alabama, located more than 150 km east of landfall, suffered extensive overwash, and a major breach was formed near the center of the island. Many structures were destroyed, particularly in the area immediately east of the breach where pre-storm island elevations were low.

The observed differences in island response, both within and between these two locations, will be discussed with respect to island topography and predicted storm surge magnitudes.