Storm deposition in a coastal backbarrier lake in Louisiana caused by Hurricanes Gustav and Ike

Document Type

Conference Proceeding

Publication Date

12-1-2011

Abstract

We investigated the patterns and processes of storm deposition in coastal lakes by conducting sediment-coring, coupled with hydrodynamic measurements, before and after Hurricanes Gustav and Ike in Bay Champagne, Lafourche Parish, in Louisiana. Bay Champagne is a brackish-water backbarrier lake separated from the Gulf of Mexico by a low sand barrier < 1 m above mean sea level, thus this lake is vulnerable to overwash processes caused by hurricanes. Two bottom-mounted CTDs (Conductivity, Temperature and Depth sensors) deployed on August 29, 2008, three days before Hurricane Gustav's landfall, recorded a maximum storm surge of ∼ 2.7 m. A sharp drop of salinity was recorded at the peak of the surge, suggesting an impact of heavy rain and possibly freshwater coming from the surrounding wetlands. A core taken along a transect in Bay Champagne after Hurricanes Gustav and Ike indicates that a sand layer up to 17 cm in thickness was deposited in the lake. A segment of loose sediment occurring in the middle of this storm deposit was probably formed by the reworking of the upper part of the Gustav storm deposit by Hurricane Ike, when the latter storm struck 12 days later. This interpretation is also supported by pollen data, which show that the presumed Gustav and Ike storm deposits have different palynological contents. This pilot study in process-oriented paleotempestology allows us to examine the relationship between the sedimentary process and the sedimentary pattern in a coastal lake resulting from a hurricane strike.

Publication Source (Journal or Book title)

Journal of Coastal Research

First Page

1866

Last Page

1870

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