Wave-induced Benthic Velocity Variations in Shallow Waters

• Published in: Estuarine, coastal and shelf science Vol. 42; no. 6; pp. 787 - 802
• Main Authors: Jing, Lou, Ridd, P.V., Mayocchi, C.L., Heron, M.L.
• Format: Journal Article
• Language: English
• Published: London Elsevier Ltd 1996; Elsevier
• Subjects: benthic velocity; Brackish; Coastal oceanography, estuaries. Regional oceanography; diffraction; dissipation; Earth, ocean, space; Exact sciences and technology; External geophysics; Marine; Physics of the oceans; refraction; sediment concentration; wave; Australia; Oceania; benthic velocity; sediment concentration; refraction; diffraction; dissipation; wave; Wave propagation; Bay; Shallow water; Coastal zone; Benthic zone
• ISSN: 0272-7714; 1096-0015
• DOI: 10.1006/ecss.1996.0050

Waves propagating from deep water into shallow coastal areas produce oscillatory currents near the sea bottom. The magnitude of these currents depend upon the period and amplitude of the incoming waves, and the dissipation mechanism such as wave breaking and bottom friction. Field experiments in a gently shoaling bay, i.e. Cleveland Bay, Northern Australia, showed that there is a broad band of water at around 6
m depth, where the benthic surge velocities are maximum. Both further inshore and offshore, the bottom velocities were less than at 6
m depth, contrary to the normal expectation that the velocities should increase as the water becomes shallower. A new and computationally efficient wave model was developed and was able to reproduce experimental results for waves above 50
cm wave height, but not for small waves (wave height about 30
cm). One implication of this higher band of benthic surge velocities may be to produce high water turbidities in this region. Turbidity data from Cleveland Bay is consistent with this hypothesis.