Type of Document Master's Thesis Author Bianchette, Thomas Author's Email Address email@example.com URN etd-06052007-112453 Title Using Hurricane Ivan as a Modern Analog in Paleotempestology: Lake Sediment Studies and Environmental Analysis in Gulf Shores, Alabama Degree Master of Science (M.S.) Department Geography & Anthropology Advisory Committee
Advisor Name Title Kam-biu Liu Committee Chair Nina Lam Committee Member Robert Rohli Committee Member Keywords
- storm surge
- overwash deposit
- proxy record
Date of Defense 2007-05-11 Availability unrestricted AbstractPaleotempestology is a young field in the science community, aimed at discovering evidence of past catastrophic hurricanes by analyzing geological proxy records, mostly overwash sand layers derived from barrier beach inundation. Gulf State Park in Gulf Shores, Alabama, is an ideal location to study this emerging science due to its unique geography of having three coastal lakes just north of a long beach system.
Hurricane Ivan, a Category 3 storm, made landfall at Gulf Shores, Alabama, on 16 September 2004, with 130 mph winds. It was expected that the overwash fan created by the storm surge was sufficient to reach the lakes and create a storm signature which could be useful as a modern analog.
A vegetation survey was done to examine Ivan's ecological damage to the forest around the Shelby Lakes. The results suggest quantitatively that elevation was a major factor in tree mortality. This study establishes that most damage to the forest was from storm surge and not high winds, as the latter would have led to a more continuous spatial pattern of destruction. Remote sensing work with Landsat 5 images was performed to reveal the spatial pattern of ecological damage to the forest at the landscape scale.
Cores taken near the center of Lake Shelby do not contain a sand layer at the top attributable to Ivan, primarily due to the lake's large size. Cores from Middle Lake do show visible sand layers at the top (ML-10, ML-06, ML-01, and ML-TV2). Little Lake, the easternmost lake, had two cores with a visible Ivan layer (LL-06 and LL-08).
Loss-on ignition data and radiocarbon dating results from core ML-TV2 indicate a minimum return period of 213 years. This estimate is comparable to results in Liu et al. (2003), who reported a return period of 180 years for Little Lake. The fact that Ivan left a sedimentary signature in both Middle Lake and Little Lake supports the interpretation that sand layers in cores taken from the southern ends of both lakes represent direct hits by major hurricanes of Category 3 or higher intensity according to the Saffir-Simpson intensity scale.
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