NSF Org:	OCE Division Of Ocean Sciences
Recipient:	LOUISIANA STATE UNIVERSITY
Initial Amendment Date:	November 12, 2021
Latest Amendment Date:	November 12, 2021
Award Number:	2203111
Award Instrument:	Standard Grant
Program Manager:	Joseph Carlin OCE  Division Of Ocean Sciences GEO  Directorate for Geosciences
Start Date:	November 15, 2021
End Date:	October 31, 2023 (Estimated)
Total Intended Award Amount:	$82,404.00
Total Awarded Amount to Date:	$82,404.00
Funds Obligated to Date:	FY 2022 = $82,404.00
History of Investigator:	Kehui Xu (Principal Investigator) kxu@lsu.edu Carol Wilson (Co-Principal Investigator) Navid Jafari (Co-Principal Investigator)
Recipient Sponsored Research Office:	Louisiana State University 202 HIMES HALL BATON ROUGE LA  US  70803-0001 (225)578-2760
Sponsor Congressional District:	06
Primary Place of Performance:	Louisiana State University Baton Rouge LA  US  70803-2901
Primary Place of Performance Congressional District:	06
Unique Entity Identifier (UEI):	ECQEYCHRNKJ4
Parent UEI:
NSF Program(s):	Marine Geology and Geophysics
Primary Program Source:	01002223DB NSF RESEARCH & RELATED ACTIVIT
Program Reference Code(s):	7914, 9150
Program Element Code(s):	162000
Award Agency Code:	4900
Fund Agency Code:	4900
Assistance Listing Number(s):	47.050

ABSTRACT

Hurricane Ida was a very destructive Category 4 storm that made landfall at Elmer?s Island and Caminada Headlands, Louisiana on 29 August 2021, bringing storm surge and waves of 13 feet, not seen since Hurricane Katrina. The importance of the role of these large storms on shelf sediment transport and the effect of these events on coastal change has become apparent in recent years. With improvements in instrumentation and technology, more field studies have been conducted to measure sediment transport processes on offshore continental shelves during storm events. However, due to the unpredictability of storm paths and the difficulties and expense in obtaining measurements, there is still a lack of field data. During this project, samples will be obtained in two dredge pits, which are used to replenish beaches after these storms, to test the overarching hypothesis that hurricanes play a major role in redistributing sediment on the continental shelf and likely produce massive sediment deposition in dredge pits and extensive mass wasting of the dredge pit walls. Dredge pits may be a sustainable resource for this sand in Louisiana, but their efficacy as sediment traps requires an understanding of their long-term evolution and marine processes along the continental shelf. Data collection is time-sensitive because of the goal of capturing the post-hurricane sediment on the continental shelf and within the two dredge pits. The project supports the training of undergraduate and graduate students at sea.

While it is readily known that continental shelves can be energetic environments, there is a lack of marine observational data for sediment transport and deposition that occurs during and immediately after major hurricanes. In particular, the sediment fluxes of bed and suspended loads can increase one to two orders of magnitude during hurricanes. However, these deposits may be obliterated by subsequent events. Dredge pits serve as excellent recorders of post-hurricane sediment deposition and can provide natural capture basins on continental shelves that record these major events. This project will result in a post-hurricane quantification of sediment transport and stratigraphy of the South Pelto and Sandy Point dredge pits as well as multiple stations east and west of Hurricane Ida along the 10-m isobath on the inner Louisiana shelf. A comparison will be made between the pre- and post-hurricane conditions by leveraging historical data over the past seven years (2014 to 2021). Hurricane conditions often cause mass wasting and submarine landslides in coastal environments, which pose a hazard to existing critical infrastructure on the continental shelf, such as renewable wind energy and telecommunication infrastructure. It is also likely that Hurricane Ida triggered dredge pit wall collapse and outward migration, possibly posing a major hazard to hurricane-impacted platforms and pipelines in the vicinity.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

PROJECT OUTCOMES REPORT

Disclaimer

This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.

While it is readily known that continental shelves can be energetic environments, there is a paucity of marine observational data for sediment transport and deposition that occurs during and immediately after major hurricanes. In particular, the sediment fluxes of bed and suspended loads can increase one to two orders of magnitude during hurricanes. Dredge pits serve as excellent “amplified recorders” of post-hurricane sediment deposition and can provide natural capture basins on continental shelves that can record these major events and pit wall collapses. The intellectual merit of this project is the timely post-hurricane quantification of sediment transport and stratigraphy of the South Pelto and Sandy Point dredge pits as well as more than 10 stations east and west Hurricane Ida along 10-m isobath on inner Louisiana shelf.  Our results show that hurricanes Zeta, Laura, Delta, and Ida together generated strong currents which played a major role in sediment resuspension and pit wall collapse. The collapses in Sandy Point dredge pit were downstream of dominant currents and near the west pit wall, but not much collapse occurred on the steeper east pit wall. Although all three factors played some roles, it was found that currents played a larger role than hurricane waves and oversteepening in triggering submarine landslides. This research helps our scientific community improve future modeling and benefits the decision makers of oil and gas industry and resource management. Our data are critical to the calibration and validation of not only suspended load but also bed load used in sediment transport models.

 

Last Modified: 01/04/2024
Modified by: Kehui Xu

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