HR: 0800h
AN: OS11A-0500    [Abstracts]
TI: Validation of an Optical Swash Velocity Measurement Algorithm
AU: * Palmsten, M L
EM: mpalmsten@coas.oregonstate.edu
AF: Oregon State University, 104 Ocean Admin Building, Corvallis, OR 97331 United States
AU: Holman, R
EM: holman@coas.oregonstate.edu
AF: Oregon State University, 104 Ocean Admin Building, Corvallis, OR 97331 United States
AU: Clark, D
EM: dclark@coas.oregonstate.edu
AF: Oregon State University, 104 Ocean Admin Building, Corvallis, OR 97331 United States
AU: Killian, J
EM: jkillian@coas.oregonstate.edu
AF: Oregon State University, 104 Ocean Admin Building, Corvallis, OR 97331 United States
AU: Baker, D
EM: dbaker@coas.oregonstate.edu
AF: Oregon State University, 104 Ocean Admin Building, Corvallis, OR 97331 United States
AB: Along coastlines, damage to infrastructure and homes is caused by foreshore erosion which is, in turn, dependent on the swash flow velocity. However, velocity data is difficult to obtain in natural swash zones with an in situ instrument due to the temporal variation in bed and water levels, the potential flow disruption by such a sensor, and the overall hostile conditions. Last year an optical swash velocity algorithm was introduced based on the trajectories of foam tracers in the the swash. Argus time-space imagery (time stacks) are high-pass filtered to retain only the foam signatures, then transformed in the space domain using a Hilbert transform to yield phase and wave number as a function of time and space. Cross-shore velocity is found from the time rate of change of these signals. This year, development has continued and the algorithm has been tested with Acoustic Doppler velocity data from the swash zone in the wave flume of the Hinsdale Wave Research Laboratory, Oregon State University. Comparisions of swash velocities from the optical and in situ sensors will be made and accuracy and sensitivities of the technique determined. Image registration errors due to finite amplitude water surface displacement error will be corrected using wave gauges. Detergent was used to increase the duration of surface foam.
DE: 4546 Nearshore processes
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting