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Measuring Breaking Waves Heights Using Video

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Title:Measuring Breaking Waves Heights Using Video
Authors:Hilmer, Tyson
Contributors:Merrifield, Mark (advisor)
Oceanography (department)
Global Environmental Science (department)
Keywords:waves
surfing
physical oceanography
Date Issued:2005
Publisher:University of Hawaiʻi at Mānoa
Place of Publication:Honolulu
Abstract:The dominant process for the transfer of mass and energy into the surf zone is
wave breaking. Typhoons and heavy storms create extreme conditions wherein storm
surge, coastal setup, and large swell combine to cause flooding and direct damage to
coastal infrastructure via wave energy. The majority of research in the nearshore has
been conducted under moderate conditions, presumably due to the logistical difficulties
of maintaining instrumentation under storm conditions, as well as the infrequency of such
events. This paper describes in detail a method for remotely measuring breaking wave
heights over a range of environmental conditions using video, and its on-going
application in a high-energy nearshore environment.
A 640x480 pixel analog surveillance camera, with a view of approximately 0.04
km2
and a mean horizontal resolution of 0.5 m, was affixed to a rigid structure
overlooking a uniform shallow reef near Ipan, Guam. Image data were collected at 2 Hz
along a shore-normal transect continuously for three months. Broken wave heights,
offshore and secondary swell wavelengths and velocities, and wave refractions are
successfully resolved using this technique. A novel feature-detection algorithm was
developed for accurately and autonomously generating a time series of broken wave
heights. Initial comparisons between video measurements of breaking wave height show
a strong correspondence with in-situ pressure sensor data.
Pages/Duration:26 pages
URI:http://hdl.handle.net/10125/67753
Rights:All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Rights Holder:Hilmer, Tyson
Appears in Collections: Global Environmental Science Theses


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