Rip current variability and hazard along a macro-tidal coast

摘要: The role of beach safety management is becoming increasingly important along much the macro-tidal, high-energy Atlantic coast England, which experiences mean spring-tidal ranges 4.1-7.4 m and average significant wave heights 1.2 2.7 in summer winter, respectively. Growing pressures on resources due to increasing visitor numbers means an understanding nature hazards surrounding recreational user paramount. Rip currents are responsible for 80% all recorded incidents (2005-2007) this coast. Most investigations into rip current dynamics have been reported from micro- meso-tidal environments macro-tidal systems rarely considered. This research assesses spatio-temporal variability their associated west coasts Devon Cornwall between May October 2007. Analysis seasonal morphological hydrodynamic datasets coupled with detailed lifeguard incident data daily observations identified some key drivers 'mass rescue' events low-tide bar/rip terrace beaches; 1) Small long-period swell-waves, that favour development accretioary systems, shoal inner transverse bars generating strong alongshore variations breaking enhancing activity; 2) Well developed, phase-offset low- mid-tide morphologies lead generation active during mid-tidal stages; 3) Large (spring) tidal expose activating cut-off potential rate-of-change location through mid-tide. Low-tide times spring tides coincide patrol hours hence high usage.