Mon, 09/23/2024 - 3:30pm Skidaway Dr. Sam Bentley Geology and Geophysics LSU Dr. Bentley's Personnel Page Seminars Professor Sam Bentley, Sam Bentley, Professor and Harrison Chair, LSU Department of Geology and Geophysics, and LSU Coastal Studies Institute Title: 21st Century Look at Mass Transport on the Subaqueous Delta of the Mississippi River: OASIS Partnership Preliminary Observations Abstract: Since the 1950’s researchers have understood that mass-wasting processes shape the subaqueous delta of the Mississippi River, offshore of the iconic Mississippi Birdsfoot Delta. Federal agencies began investigating these geohazards when hydrocarbon exploration expanded onto the continental shelf in the 1960s. However, major knowledge gaps remain in understanding associated hazards, gaps exacerbated by changing river conditions. To address these gaps, the US Bureau of Ocean Energy Management (BOEM) funded the OASIS Partnership (Offshore Analysis of Sediment InStability). Led by Louisiana State University, the partnership includes an interdisciplinary team of scientists and engineers from the USGS, BOEM, National Oceanic and Atmospheric Administration, National Energy Technology Laboratory, Naval Research Laboratory, SEARCH Inc, and the Water Institute of the Gulf to conduct the first comprehensive analysis since the 1970s and next-generation geohazard assessment. Specific objectives include (1) remapping the seabed for the first time since 1980 using modern seafloor mapping techniques to identify instability zones; (2) assessing seafloor instability preconditioning and triggering factors via sediment and observational studies; (3) conducting marine archeological surveys of study-area shipwrecks and using those wrecks as tracers of seabed sediment movement; (4) developing numerical and machine learning models and tools to predict future conditions and geohazards in the region; (5) providing interactive GIS-based online public access to all non-sensitive data products. Initial observations that build on a 2017 pilot study suggest the following. (A) Rapid sedimentation still occurs offshore of three major delta passes despite reduced sediment loads. (B) Parts of the subaqueous delta are in retreat. (C) Seabed mass transport appears to move mudflow lobes offshore faster than replenishment by new sediments. (D) Mass transport appears to occur along a continuum, from near-continuous creep to hurricane-triggered major catastrophic mudflows. Future work will expand on these observations, testing hypotheses via combined numerical, machine learning, and field study, and integrating findings into a multifaceted geohazard analysis for use by industry and government stakeholders.
