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Wave transformation and shoreline water level on F unafuti A toll, T uvalu
Author(s) -
Beetham Edward,
Kench Paul S.,
O'Callaghan Joanne,
Popinet Stéphane
Publication year - 2016
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2015jc011246
Subject(s) - swell , geology , shore , surf zone , significant wave height , wave height , reef , wave model , breaking wave , wave setup , wind wave , oceanography , geomorphology , meteorology , wave propagation , physics , longitudinal wave , mechanical wave , quantum mechanics
The influence of sea swell (SS) waves, infragravity (IG) waves, and wave setup on maximum runup ( R max ) is investigated across different tidal stages on Fatato Island, Funafuti Atoll, Tuvalu. Field results illustrate that SS waves are tidally modulated at the shoreline, with comparatively greater wave attenuation and setup occurring at low tide versus high tide. A shoreward increase in IG wave height is observed across the 100 m wide reef flat at all tidal elevations, with no tidal modulation of IG wave height at the reef flat or island shoreline. A 1‐D shock‐capturing Green‐Naghdi solver is used to replicate the field deployment and analyze R max . Model outputs for SS wave height, IG wave height and setup at the shoreline match field results with model skill >0.96. Model outputs for R max are used to identify the temporal window when geomorphic activity can occur on the beach face. During periods of moderate swell energy, waves can impact the beach face at spring low tide, due to a combination of wave setup and strong IG wave activity. Under mean wave conditions, the combined influence of setup, IG waves and SS waves results in interaction with island sediment at midtide. At high tide, SS and IG waves directly impact the beach face. Overall, wave activity is present on the beach face for 71% of the study period, a significantly longer duration than is calculated using mean water level and topographic data.