Dynamic Modelling of Rip Currents for Swimmer Safety on a Wind-Sea-Dominated Mesotidal Beach

ABSTRACT Sembiring, L.; van Dongeren, A.; Winter, G., and Roelvink, D., 2016. Dynamic modelling of rip currents for swimmer safety on a wind-sea–dominated mesotidal beach. This study applied the process-based model XBeach to predict bathymetrically controlled rip current flow occurrence, velocities and duration in the wind-sea–dominated environment of Egmond aan Zee, The Netherlands. The model is validated against data obtained during a 5-day field experiment with GPS-equipped floating drifters. Numerical model results show good agreement with data and simulate flow patterns that resemble the offshore flow through the rip channel and subsequent alongshore drift of the drifters. The average relative error of the drifter position is 0.15 and 0.19 for the cross-shore and the alongshore position, respectively. Results from the numerical experiments suggest that the rip current intensity is tidally modulated. For the period of analysis, the rips are initiated approximately 5 hours before low tide, reaching a m...