https://ogma.newcastle.edu.au/vital/access/ /manager/Index en-au 5 Lagrangian observations of circulation on an embayed beach with headland rip currents https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:19139 s=1m) oblique wave forcing. In-situ wave and current data, and bathymetric data were also collected. Beach morphology was dominated by a large mid-beach rip channel with lesser headland rip channels. Mean flow rates were 0.6ms⁻¹ in the mid-beach channel and 0.4ms⁻¹ in the headland channels, with the majority of cross-shore water volume flux (~60%) through the central channel. A weak alongshore current O (0.1ms⁻¹) was forced by the oblique offshore wave angle. Rip current velocities, flow variability, and rate of surfzone exits by Lagrangian drifters increased as water level decreased. Transient currents on a planar bar along the northern half of the beach, with mean speeds velocity standard deviation up to 0.2ms⁻¹, were not tidally modulated. Lagrangian time series were used to differentiate four current regimes (rip cell, rip head, planar bar and offshore low energy zone) based on mean velocity, velocity variability and degree of tidal modulation. An increase in surfzone exit rates by drifters was observed from south (upwave) to north (downwave), with exit rates per drifter deployment of 22% at the south headland rip, 65% at the mid-beach open rip, and 80% at the north headland rip. The high rate of drifter exits contrasts previous observations on open coast beaches. Observed flow behaviours are attributed to wave shadowing at the upwave (protected) end of the beach, and longshore currents forced by oblique waves deflected offshore at the downwave headland. These field observations are in good agreement with recent numerical modelling. A relationship between bathymetric variability and current intensity was determined, with cross-shore average mean velocity correlating with a parameterisation of bathymetric alongshore non-uniformity. This study demonstrates that flow behaviour and exchange rates can vary along the length of an embayed beach due to geological control. This research has implications for transport of organisms, nutrients and pollutants, is relevant to beach safety practitioners, and can be used in calibration of numerical models.]]> Sat 24 Mar 2018 07:55:55 AEDT ]]> Examining rip current escape strategies in non-traditional beach morphologies https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:24072 RIP1= 0.66, t¯RIP2 = 2.68 min) in both systems, but durations and distances to safety in the RBB system often exceeded swimming abilities of weaker bathers. Although Swim Onshore was more successful (t¯RIP1= 0.22, t¯RIP2= 1.65 min) than Swim Parallel, promotion of such a strategy is strongly discouraged in conventional safety advice. Results suggest that contemporary rip current escape strategies may be inappropriate in non-TBR rip current systems and that alternative strategies should be considered, including Swim Onshore and a greater focus on preventative strategies, particularly in relation to bathers with limited swimming ability.]]> Sat 24 Mar 2018 07:09:39 AEDT ]]>