Surf-zone Kinematics

A new method is described for making field measurements of broken surf fronts (turbulent bores) on coastal beaches. The position of a Garmin watch attached to a bodyboarder riding the surf front is recorded every second. The results of a large number of experiments on various beaches indicate that the surf fronts are uniformly retarded. From this, the retardations and initial breaking wave speeds are then obtained. The constant value of the retardation may vary from one wave to the next. The results are applied to derive a heuristic method for determining the approximate width of the surf zone by noting the total time of travel of any broken surf front. References J. A. Battjes. Surf-zone dynamics. Annu. Rev. Fluid Mech., 20:257–293, 1988. doi:10.1146/annurev.fl.20.010188.001353 N. de Mestre and G. McCoy. Safety indices for surf life saving competitions. In A. Bedford, editor, Proc. of the Eleventh Australasian Conf. on Maths and Computers in Sport, Melbourne, Australia, pages 54–64, 2012. http://www.anziam.org.au/Eleventh+MCS L. Hamm, P. A. Madsen, and D. H. Peregrine. Wave transformation in the nearshore zone: a review. Coastal Engineering, 21:5–39, 1993. doi:10.1016/0378-3839(93)90044-9 G. McCoy and N. de Mestre. Surf hazard rating: A decision-making system for application to competition through the surf zone. In P. L. Stephen and J. L. Lee, editors, Proc. 3rd International Rip Current Symposium, Busan, South Korea. Journal of Coastal Research, Special Issue, 72:10–14, 2014. doi:10.2112/si72-023.