Subsidence and Sea-Level Rise in Southeastern Louisiana: Implications for Coastal Management and Restoration

Work Plan

Principal Investigators: Jack Kindinger, Jeff Williams, and Jim Flocks

Task 1. Database and GIS Development

Develop and populate relevant databases, data layers , and web sites. This is a critical task to the overall success of the project and will include data catalogue, updated annotated bibliography, digital document library, slide archive, and data rescue.

Task 2. Subsidence and Sea-level Rise Investigations

Long-Term Trend Analysis Ð Geologic Framework

Collect long cores (30 to 50 m) for age dating, lithology, and stratigraphy of Mississippi deltaic depositional events and incorporate these new data with existing data to get long-term relative subsidence rates.

Task 3. Impacts of Subsidence and Sea-Level Rise

Coastal Marshes and Land Loss - Geologic Framework

Use high-resolution seismics and vibracores to document and analysis the impact of subsidence on coastal marshes. This task will be closely coordinated with the ongoing USGS projects in the Gulf of Mexico dealing with Subsidence caused by hydrocarbon production.

Task 4. Technology Transfer

Following on the work from Task 1 the USGS and UNO will maintain and promote information transfer to managers and scientists, including the production of reports and publications.

University of New Orleans

Principal Investigators: Mark Kulp, Shea Penland, and Denise Reed

Task 1 and 2. Data Base Development and Subsidence and Sea-level Rise Investigations

Long-Term Trend Analysis Ð Delta Plain Geologic Framework

Compile all of the available vibracore, deep borehole, seismic, and seismic data to construct an isopach of Holocene sediments as well as structure contour maps of key stratigraphic horizons within the shallow Mississippi delta stratigraphic framework. These maps and data will provide information key to assessing the variability of relative sea-level rise and determining the underlying mechanisms of subsidence. Existing and recently acquired radiocarbon data will be integrated to better understand the relationship between Holocene sea-level rise and actual subsidence processes. These data will also be used to delineate the depth and extent of key intra Holocene stratigraphic markers such as the high-stand and transgressive systems tracts.

Task 2. Subsidence and Sea-level Rise Investigations

Short-Term Trend Analysis Ð Tide Gage Analysis

Continue and/or update our analysis of NOAA and USACE tide gage data in LA and the surrounding Gulf Coast states. Long-term and short-term records will be constructed and analyzed. These data will be correlated to available geologic framework data for coastal LA and provide critical insight to the underlying relationships between rates of relative sea-level rise and geologic framework across the north-central Gulf coast.

Task 3. Impacts of Subsidence and Sea-Level Rise

Coastal Marshes and Land Loss - Marsh Response to Subsidence

St. Bernard Delta Complex (thin abandoned deltaic sequence/low subsidence rates) - Continue the SET and shallow subsurface work in the Bayou LaLoutre distributary investigating marsh accretion, marsh elevation, and stratigraphy away from the channel. The relative contributions of mineral and organic components to marsh soil development on an annual basis will be evaluated. A transect of deep borings will be acquired, analyzed, and integrated with existing vibracore and radiocarbon data available within the study area.

Extend the St. Bernard research methodology into areas affected by riverine influence adjacent to the Caernarvon freshwater diversion. Establish the same research program underway at Bayou LaLoutre in the vicinty of Bayou Terre aux Boeufs. Sites will be selected for similarity in vegetation to the Bayou LaLoutre sites.

Reoccupy the SET locations established during the USGS Critical Processes of Wetland Loss in the 1990's. These sites include Old Oyster Bayou, Bayou Chitique, Bayou Carencro, and Bayou Blue.