Rip Current Prediction System for Swimmer Safety

Abstract

Rip currents are among the most dangerous coastal hazards for the bathing public, and contribute to the highest portion of beach rescues all over the world. In order to help life guards in planning and preparing rescue resources so as to minimize casualties, information about where and when rip currents may occur is needed. This can be provided by a predictive tool which combines meteorological forecasts, hydrodynamic models and remote-sensed observations. In this thesis, a methodology with which rip current forecasts for swimmer safety can be provided is developed and tested for Egmond aan Zee beach in the Netherlands. The approach is to make use of the numerical model system CoSMoS combined with daily estimates of nearshore-scale bathymetry obtained from a system called cBathy, which infers depths by estimating wave celerities from video imaging. Moreover, in order to gain more knowledge on occurrences of rips at Egmond, a numerical study on the kinematics of rip currents and the safety implications for swimmers is also presented. Coupling the video bathymetry estimates with CoSMoS in forecast mode shows that dangerous rips were correctly predicted. This thesis demonstrates the potential application of the proposed system in providing forecasts for rip currents at Egmond aan Zee.