Print Email Facebook Twitter The dynamics of infragravity wave transformation over a fringing reef Title The dynamics of infragravity wave transformation over a fringing reef Author Pomeroy, A. Lowe, R. Symonds, G. Van Dongeren, A. Moore, C. Faculty Civil Engineering and Geosciences Department Hydraulic Engineering Date 2012-11-20 Abstract A 3 week field study was conducted to investigate the dynamics of low-frequency (infragravity) wave motions over a fringing reef at Ningaloo Reef, Western Australia. Short-period wave motions (0.04–0.2 Hz) were observed to dissipate on the reef crest beyond which infragravity wave motions (0.004–0.04 Hz) gradually dominated toward the lagoon. However, both the short waves and the infragravity waves were relatively small (both <0.3 m) on the reef flat owing to the shallow water depth (<2 m). The results revealed that the surf zone generation of free infragravity wave motions on the steep (?1:20) fore-reef slope was dominated by breakpoint forcing (as opposed to shoaling bound waves), which was also supported by detailed numerical simulations of the generation process. This is consistent with theory suggesting the efficiency of the breakpoint forcing mechanism should be high in this steep-slope regime. Shoreward propagating infragravity waves traveled across the reef but were damped by bottom friction dissipation; however, this was at a rate much smaller than experienced by the residual short waves. With these rates of frictional dissipation also strongly dependent on the water depth over the reef, the infragravity wave heights increased at higher water levels and hence were strongly modulated by the tide. Due to the strong dissipation of infragravity waves over this wide and shallow reef that is hydraulically rough, any seaward propagating infragravity waves that reflected at the shoreline were small, leading to the dominance of progressive (shoreward propagating) infragravity wave motions throughout the reef and lagoon. Subject Ningaloo Reefbottom frictioncoral reefsinfragravity waveswave dissipationwave transformation To reference this document use: http://resolver.tudelft.nl/uuid:d2bebbe2-b5bc-4ec6-873e-a976ca342f53 DOI https://doi.org/10.1029/2012JC008310 Publisher American Geophysical Union Embargo date 2013-05-30 ISSN 0148-0227 Source Journal of geophysical Research, 117, C11, 2012 Part of collection Institutional Repository Document type journal article Rights © 2012 American Geophysical Union Files PDF Pomeroy_2012.pdf 1.95 MB Close viewer /islandora/object/uuid:d2bebbe2-b5bc-4ec6-873e-a976ca342f53/datastream/OBJ/view