Transformation of infragravity waves during hurricane overwash

Katherine Anarde, Jens Figlus, Damien Sous, Marion Tissier

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

Infragravity (IG) waves are expected to contribute significantly to coastal flooding and sediment transport during hurricane overwash, yet the dynamics of these low-frequency waves during hurricane impact remain poorly documented and understood. This paper utilizes hydrodynamic measurements collected during Hurricane Harvey (2017) across a low-lying barrier-island cut (Texas, U.S.A.) during sea-to-bay directed flow (i.e., overwash). IG waves were observed to propagate across the island for a period of five hours, superimposed on and depth modulated by very-low frequency storm-driven variability in water level (5.6 min to 2.8 h periods). These sea-level anomalies are hypothesized to be meteotsunami initiated by tropical cyclone rainbands. Estimates of IG energy flux show that IG energy was largely reduced across the island (79-86%) and the magnitude of energy loss was greatest for the lowest-frequency IG waves (<0.01 Hz). Using multitaper bispectral analysis, it is shown that, during overwash, nonlinear triad interactions on the sea-side of the barrier island result in energy transfer from the low-frequency IG peak to bound harmonics at high IG frequencies (>0.01 Hz). Assuming this pattern of nonlinear energy exchange persists across the wide and downward sloping barrier-island cut, it likely contributes to the observed frequency-dependence of cross-barrier IG energy losses during this relatively low surge event (<1 m)

Original languageEnglish
Article number545
Number of pages24
JournalJournal of Marine Science and Engineering
Volume8
Issue number8
DOIs
Publication statusPublished - 2020

Keywords

  • Barrier island
  • Bispectral analysis
  • Groundwater
  • Hurricane harvey
  • Infragravity (IG) waves
  • Meteotsunami
  • Multitapers
  • Overwash
  • Tropical cyclones

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