Observations of inner shelf cross-shore surface material transport adjacent to a coastal inlet in the northern Gulf of Mexico

Mathias K. Roth, Jamie MacMahan, Ad Reniers, Tamay M. Özgökmen, Kate Woodall, Brian Haus

Research output: Contribution to journalArticleScientificpeer-review

9 Citations (Scopus)

Abstract

Motivated by the Deepwater Horizon oil spill, the Surfzone and Coastal Oil Pathways Experiment obtained Acoustic Doppler Current Profiler (ADCP) Eulerian and GPS-drifter based Lagrangian “surface” (<1 m) flow observations in the northern Gulf of Mexico to describe the influence of small-scale river plumes on surface material transport pathways in the nearshore. Lagrangian paths are qualitatively similar to surface pathlines derived from non-traditional, near-surface ADCP velocities, but both differ significantly from depth-averaged subsurface pathlines. Near-surface currents are linearly correlated with wind velocities (r =0.76 in the alongshore and r =0.85 in the cross-shore) at the 95% confidence level, and are 4–7 times larger than theoretical estimates of wind and wave-driven surface flow in an un-stratified water column. Differences in near-surface flow are attributed to the presence of a buoyant river plume forced by winds from passing extratropical storms. Plume boundary fronts induce a horizontal velocity gradient where drifters deployed outside of the plume in oceanic water routinely converge, slow, and are re-directed. When the plume flows west parallel to the beach, the seaward plume boundary front acts as a coastal barrier that prevents 100% of oceanic drifters from beaching within 27 km of the inlet. As a result, small-scale, wind-driven river plumes in the northern Gulf of Mexico act as coastal barriers that prevent offshore surface pollution from washing ashore west of river inlets.

Original languageEnglish
Pages (from-to)142-153
Number of pages12
JournalContinental Shelf Research
Volume137
DOIs
Publication statusPublished - 1 Apr 2017

Keywords

  • Coastal barriers
  • Dispersion
  • Nearshore
  • River Plume
  • Surface drifters
  • Surface material transport

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