Numerical study of sediment dynamics during hurricane Gustav. (June 2018)

• Record Type: Journal Article
• Authors: Zang, Zhengchen; Xue, Z. George; Bao, Shaowu; Chen, Qin; Walker, Nan D.; Haag, Alaric S.; Ge, Qian; Yao, Zhigang
• Is Part Of: Ocean modelling. Volume 126(2018)
• Page Start: 29
• Page End: 42
• Publication Date: 2018-06
• Subjects: COAWST -- Cohesive sediment -- Gulf of Mexico -- Sediment flux; Oceanography -- Periodicals; Océanographie -- Périodiques; Oceanography; Periodicals; 551.46
• DOI: 10.1016/j.ocemod.2018.04.002
• Languages: English
• ISSNs: 1463-5003

Abstract

Highlights: Coupled ocean-wave-atmosphere and sediment transport model for hurricane Gustav. Ocean stratification broke down on inner shelf and recovered after one week. Cohesive sediment algorithm ideal representation of fine deltaic sediment dynamics. Post-hurricane deposition up to 40 times that during normal ocean conditions. Abstract: In this study, the coupled ocean-atmosphere-wave-and-sediment transport (COAWST) modeling system was employed to explore sediment dynamics in the northern Gulf of Mexico during hurricane Gustav in 2008. The performance of the model was evaluated quantitatively and qualitatively against in-situ and remote sensing measurements, respectively. After Gustav's landfall in coastal Louisiana, the maximum significant wave heights reached more than 8 m offshore and they decreased quickly as it moved toward the inner shelf, where the vertical stratification was largely destroyed. Alongshore currents were dominant westward on the eastern sector of the hurricane track, and offshoreward currents prevailed on the western sector. High suspended sediment concentrations (>1000 mg/l) were confined to the inner shelf at surface layers and the simulated high concentrations at the bottom layer extended to the 200 m isobaths. The stratification was restored one week after landfall, although not fully. The asymmetric hurricane winds induced stronger hydrodynamics in the eastern sector, which led to severe erosion. The calculated suspended sediment flux (SSF) was convergent to the hurricane center and the maximum SSF was simulated near the south and southeast of the Mississippi river delta. The averaged post-hurricane deposition over the Louisiana shelf was 4.0 cm, which was 3.2–26 times higher than the annual accumulation rate under normal weather conditions.