Gordon H. Anderson¹, Thomas J. Smith III¹, Ginger Tiling², Greg A. Ward³ and Arthur D. Cohen^4
1U.S. Geological Survey, Florida Integrated Science Center, St. Petersburg, FL, USA
²ETI Professionals, St. Petersburg, FL, USA
³Computer Sciences Corporation, St. Petersburg, FL, USA
⁴Dept. Geological Sciences, University of South Carolina, Columbia, SC, USA

Hurricanes have crossed from west to east over the southwest coastal Everglades only twice in the last hundred years (1948 and 1910). On October 24, 2005, Hurricane Wilma moved across the Gulf of Mexico (GOM) from the Yucatan Peninsula, making landfall south of Everglades City, Florida with sustained west winds of 105 knots (Category 3 on the Saffir-Simpson Hurricane Scale). Wilma affected the remote southwest mangrove coastal zone of Everglades National Park with both wind and water. A storm surge of more than three meters was estimated at the entrance of the Shark, Harney, Broad, and Lostmans river estuaries. Marine coastal deposits were observed at all four rivers. We documented the presence/absence of storm surge marine sediments transported and deposited along the Shark River and measured the sediment depths.

The mangrove-forest sediment is composed of autochthonous, brown-colored, peat with little mineral-soil content (<2%). The storm surge deposited large amounts of gray marine sediment on top of the peat surface, with a mud layer that spread from 60-300 m inland from the river channel. Within weeks after the storm, we took cores at 14 sites along the Shark River from the GOM to Tarpon Bay (~ 14 km). We found marine lime mud on the peat surface, in thicknesses from 13 to 64 mm (average observed depth - 36 mm) in ten of the fourteen sample cores. Sediment deposits terminated abruptly at 12 km upriver from the GOM, suggesting insufficient storm energy for farther transport upstream. The largest sediment deposit (64 mm) was observed about three km from the GOM. Based on our preliminary measurements, marine sediment-deposition volume along the Shark River was estimated to be more than 27,000 m³-approximately 40,000 metric tons of sediment.

Contact Information: Gordon H. Anderson, USGS FISC-Everglades Field Station, 40001 S.R. 9336, Homestead, FL 33034, USA, Phone: 305-242-7891, Fax 305-242-7836, Email: gordon_anderson@usgs.gov

(This abstract is from the 2006 Greater Everglades Ecosystem Restoration Conference.)

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