REMOTE MEASUREMENT AND PREDICTION OF BREAKING WAVE PARAMETERS

Abstract

The analysis of wave breaking in shallow water has been on-going for almost 150 years. Numerous research papers have been published that investigate methods to predict breaking conditions and the geometric characteristics of breaking waves. This study presents a novel, safe, and low cost method to extract breaking wave properties from irregular waves in the surf zone, using optical and in-situ measurement systems. Sensitivities studies on methods of measuring the breaking water depth are compared and the water depth at the wave trough depth, corrected for optical offsets using a still water correction of 1/3 wave height, is found to be exhibit the least variability. A new effective seafloor slope definition, based on individual breaking wavelength to depth ratios, was found to increase predictive ability over previously variable seafloor slope extraction methods. Collected field data is compared against established breaking wave height formulas with general exponential form consistently finding best correlation. An optimized breaking wave height predictor featured a root mean square relative error of only 1.672% against the measured dataset. Finally, the study of the geometric shape of the plunging wave vortex as a possible indicator for the breaking intensity of ocean waves has been ongoing for almost 50 years with limited success. The validity of using the vortex ratio and vortex angle as a method of predicting breaking intensity is examined. Through the first complete analysis of field collected irregular wave breaking vortex parameters it is illustrated that the vortex ratio and vortex angle cannot be accurately predicted using standard breaking wave characteristics and hence are not suggested as a possible indicator for breaking intensity