Master of Science (MS)
Civil and Environmental Engineering
Fourchon Beach, a 9-mile coastal headland located in Louisiana Gulf Coast, has been heavily impacted by the Deepwater Horizon (DWH) oil spill, which began on April 20th 2010. Once on the beach, the oil spill residues were moved, suspended and transported by subsequent washover events. These washover events occur during storm surges, hurricanes or other situations with high water levels; pushing oil residues from the subtidal and intertidal zone of the beach and then depositing them in the supratidal marshes and mudflat areas. In order to determine the impacts of washover events on oil residues, two complementary studies regarding degradation and transport of oil residues have been conducted. The first one is a laboratory study that has been conducted to understand the stability of oil:sand aggregates in new environments. Oil residue samples of surface residue balls (SRBs) collected from Fourchon Beach on March 7th, May 5th, and May 18th in 2016, were used in the degradation experiment. The degradation experiment was further divided into two parts: one with shaking treatment and the other without. In the static test, the stability of aggregate oil residues is negatively correlated with salinity: specifically, water with lower salinity dissolves SRBs more readily. In the shaking test, porosity was the main influencing factor of SRBs stability. SRBs with higher porosity were completely broken apart due to water energy, even if they were in water with high salinity. In the second study, data were collected for hurricanes and tropical storms that occurred after the DWH oil spill event that directly impacted the Louisiana Gulf Coast. These data were used to estimate the factors responsible for transport of SRBs. The data analysis revealed that the SRBs on Fourchon Beach were mobilized by every extreme washover event. Further, return time of washover events is also discussed at different locations with various elevations. Beach crests or coastal dunes with heights lower than 0.529 m above Mean Sea Level (MSL) would be washed over every year.
Document Availability at the Time of Submission
Release the entire work immediately for access worldwide.
Wen, Sirui, "Transport and Degradation of Oil Residues on Coastal Beaches" (2017). LSU Master's Theses. 4420.