The measurement of nearshore processes in the laboratory and the field using video imagery

The application of video techniques to the measurement of water levels and velocity flow fields in a laboratory wave flame, and the remote bathymetric survey of beaches is described. In the laboratory, water levels were measured by tracking the image of the air-water interface, and fluid velocities were measured using the techniques of PIV and CIV. Results of water levels, velocity flow fields and turbulence levels for a plunging wave is presented. The remote video monitoring of beach profiles and bathymetric survey is accomplished by the computation and extraction of features from the time-averaged and standard deviation images of the scene. The experimental arrangement and analysis procedures are discussed. Results obtained at Melkbosstrand, on the west coast of South Africa, is presented and compared with conventional survey results.