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Presenters Notified: November 2012

Program Schedule Posted:November 2012

Abstracts Available: January 2013

Meeting:
17-22 February 2013

Smith, C. G., US Geological Survey, USA, cgsmith@usgs.gov
Marot, M. E., US Geological Survey, USA, mmarot@usgs.gov

PRELIMINARY ANALYSIS OF BACK-BARRIER SEDIMENTATION ON THE CHANDELEUR ISLANDS, LOUISIANA, FOLLOWING THE CONSTRUCTION OF THE OIL-MITIGATION SAND BERM.

Possible effects from the constructing the oil-mitigation-sand berm on the sediment budget of the Chandeleur Islands (CI) in Louisiana are complicated. By design, the 2-m sand berm limited ocean-sound exchange through natural breaches, limiting sediment transport to the back-barrier during normal wave activity. Alternatively, the berm added sand to an otherwise sediment-starved system. Sediment cores collected from back-barrier environments of CI are being used to assess the effects of the berm (i.e., barrier or source) and storm activity on cross-barrier sedimentation. Recent sedimentation rates (sub-annual) are being assessed using thorium-234 and beryillum-7 from repeat, seasonal coring of back-barrier environments. Cores were analyzed for organic matter, bulk density, porosity, grain size, and radionuclides. All short-cores collected along the back-barrier flats have a fining upward pattern and three of the seven sites had measureable sub-annual deposition. These observations suggest an environment transitioning into more quiescent conditions; ongoing analyses of cores collected after Hurricane Isaac may alter this perception, as the islands experienced considerable overwash and reworked most of the berm sediment.

Oral presentation

Session #:SS25
Date: 2/22/2013
Time: 11:45