Print Email Facebook Twitter Identification and classification of very low frequency waves on a coral reef flat Title Identification and classification of very low frequency waves on a coral reef flat Author Gawehn, M. (Deltares) van Dongeren, AR (Deltares; University of Western Australia) van Rooijen, A.A. (Deltares) Storlazzi, C.D. (Pacific Coastal and Marine Science Center) Cheriton, O.M. (Pacific Coastal and Marine Science Center) Reniers, A.J.H.M. (TU Delft Environmental Fluid Mechanics) Date 2016 Abstract Very low frequency (VLF, 0.001–0.005 Hz) waves are important drivers of flooding of low-lying coral reef-islands. In particular, VLF wave resonance is known to drive large wave runup and subsequent overwash. Using a 5 month data set of water levels and waves collected along a cross-reef transect on Roi-Namur Island in the Republic of the Marshall Islands, the observed VLF motions were categorized into four different classes: (1) resonant, (2) (nonresonant) standing, (3) progressive-growing, and (4) progressive-dissipative waves. Each VLF class is set by the reef flat water depth and, in the case of resonance, the incident-band offshore wave period. Using an improved method to identify VLF wave resonance, we find that VLF wave resonance caused prolonged (∼0.5–6.0 h), large-amplitude water surface oscillations at the inner reef flat ranging in wave height from 0.14 to 0.83 m. It was induced by relatively long-period, grouped, incident-band waves, and occurred under both storm and nonstorm conditions. Moreover, observed resonant VLF waves had nonlinear, bore-like wave shapes, which likely have a larger impact on the shoreline than regular, sinusoidal waveforms. As an alternative technique to the commonly used Fast Fourier Transformation, we propose the Hilbert-Huang Transformation that is more computationally expensive but can capture the wave shape more accurately. This research demonstrates that understanding VLF waves on reef flats is important for evaluating coastal flooding hazards To reference this document use: http://resolver.tudelft.nl/uuid:600f4416-d924-4706-904b-cf50f3882543 DOI https://doi.org/10.1002/2016JC011834 Embargo date 2017-03-31 ISSN 2169-9275 Source Journal Of Geophysical Research-Oceans, 121 (10), 7560-7574 Part of collection Institutional Repository Document type journal article Rights © 2016 M. Gawehn, AR van Dongeren, A.A. van Rooijen, C.D. Storlazzi, O.M. Cheriton, A.J.H.M. Reniers Files PDF Gawehn_et_al_2016_Journal ... Oceans.pdf 2.23 MB Close viewer /islandora/object/uuid:600f4416-d924-4706-904b-cf50f3882543/datastream/OBJ/view