Update on Barataria Barrier-Shoreline Feasibility Study

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Update on Barataria Barrier-Shoreline Feasibility Study

By Jim Flocks
July 2000

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R/V Gilbert
R/V G.K. Gilbert at anchor(s). Bow and stern anchors hold the vessel steady while the vibracorer is deployed.

The previous issue of Sound Waves showcased the launching of a new cooperative study between the USGS CMGP, University of New Orleans (UNO), and the U.S. Army Corps of Engineers (USACE) under the direction of project chief Jack Kindinger (SPFC). The primary goal of the study is to identify sand resources in the lower Barataria Basin for barrier-island restoration (see the story from Sound Waves Issue 18, June 2000). The following is an update of activities.
In late May, more than 100 potential sand-resource sites were identified throughout the eastern half of the 560-km² study area using High Resolution Seismic Profiling (HRSP) and CHIRP sonar. The sites were located during data acquisition on board the R/V G.K. Gilbert, piloted by Rich Young and Dave Bennett (SPFC). Dana Wiese (SPFC) yet again managed to keep three separate data-acquisition systems (HRSP, CHIRP and bathymetry with DGPS) operating during the survey while Jim Flocks (SPFC) and UNO scientists Drs. Shea Penland and Mark Kulp selected sites.

Crane lowers coring rig
Deploying the coring rig: A 20-ft aluminum barrel is attached to a cart that slides down a mast mounted on a base. A crane lowers the rig to the bottom to take the core. After the mast and frame are lowered to the bottom, compressed air from the vessel operates an air hammer that drives the core barrel into the sediment.

The R/V Gilbert subsequently revisited the selected sites for sediment sampling with a vibracore. An additional 77 vibracores were collected from these sites, bringing the number of recovered cores to 141. Assisting in this effort were Jim, Dave, Keith Ludwig, B.J. Reynolds, Mike Stallings (SPFC) and numerous UNO students. The sediment cores were then transferred to the core facility at UNO and are currently being analyzed and described by Mark and UNO students Phil McCarty, Nicolas Ferina, Carlos Alonso, Mike Brown, Rebecca Murphy, and Allyson Peters. Nick, Carlos, and Allyson will use the data for their Master's Theses.

Back at the SPFC, Shawn Dadisman further processed the HRSP and CHIRP data. Jim and Eckerd College scientist Dr. Gregg Brooks used the processed data to develop an initial interpretation of the regional geologic setting.

In addition to the vibracore study, a boxcore survey of selected sites was conducted offshore from Barataria Bay by Greg Berman (SPFC) and Eckerd College summer intern Chandra Dreher. Marci Marot and Chuck Holmes (SPFC) will analyze subsamples from the boxcores for Be⁷ and Pb²¹⁰ isotopes. Results of these analyses will help determine recent accumulation rates of sediments in the nearshore environment.

By mid-month the HRSP and CHIRP equipment was again deployed from the R/V Gilbert during a second leg of surveys to focus on the western half of the study area. This time the survey was led by Jack to pick additional potential sand-resource sites. Accompanying Jack were Keith, Dana, Mark and Chandra. Gregg Brooks and various UNO students will subsequently sample these sites by vibracore in late June and early July.

Plugging the core barrel: After the vibracorer is lifted back on deck, the core barrel is immediately plugged, then removed from the air hammer and capped.

The next phase of the project will be correlation of all core descriptions, HRSP and CHIRP profiles with U.S. Army Corps of Engineers criteria to identify the 5-10 areas with highest potential for borrow material. These 1- to 2-km² 'focus areas' will be revisited with additional HRSP, CHIRP, vibracore, and sidescan sonar to obtain a high-resolution survey that will verify their source potential.

By mid-July the scientists will have examined over 500 line-km each of HRSP and CHIRP data and over 200 sediment core descriptions. The project goal by the end of July is to present to USACE an interim report of the recent geologic framework of the study area and to provide the best potential sites of available sand for beach renourishment.

Barataria Barrier-Shoreline Feasibility Study
June, 2000

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July 2000

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in this issue: Snake Pond

Delmarva Inland Bays

Barataria Barrier-Shoreline

OBS Recovery

Lake Mead

Joint USGS/BRD/WRD Studies

SeaMap Program

Coastal Erosion

Woods Hole Field Center

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Marine Ecology Workshop

Southern California Academy of Sciences

Penrose Conference

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