Articles | Volume 24, issue 11
https://doi.org/10.5194/nhess-24-4049-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/nhess-24-4049-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
26 Nov 2024
Research article |
| 26 Nov 2024
| 26 Nov 2024
New insights into combined surfzone, embayment, and estuarine bathing hazards
Christopher Stokes
CORRESPONDING AUTHOR
School of Biological and Marine Sciences, University of Plymouth, Plymouth, Devon, PL4 8AA, England, UK
Timothy Poate
School of Biological and Marine Sciences, University of Plymouth, Plymouth, Devon, PL4 8AA, England, UK
Gerd Masselink
School of Biological and Marine Sciences, University of Plymouth, Plymouth, Devon, PL4 8AA, England, UK
Tim Scott
School of Biological and Marine Sciences, University of Plymouth, Plymouth, Devon, PL4 8AA, England, UK
Steve Instance
Royal National Lifeboat Institution, West Quay Road, Poole, Dorset, BH15 1HZ, England, UK
Related authors
Christopher Stokes, Juliana Albertoni de Miranda, Tim Scott, Gerd Masselink, and Adam Wooler
EGUsphere, https://doi.org/10.5194/egusphere-2026-3638, https://doi.org/10.5194/egusphere-2026-3638, 2026
This preprint is open for discussion and under review for Natural Hazards and Earth System Sciences (NHESS).
Short summary
Short summary
Rip currents are dangerous wave-driven flows at the coast which cause hundreds of drownings globally each year. This study uses more than 20 years of lifeguard data (the largest of its kind to date) to identify wave, tide, and beach types associated with high rip hazard in New Zealand. The forecast correctly predicts 98 % of rip incidents in New Zealand and mimics a lifeguard’s perception of rip hazard. It could help forewarn the public especially when lifeguards are not present.
Christopher Stokes, Juliana Albertoni de Miranda, Tim Scott, Gerd Masselink, and Adam Wooler
EGUsphere, https://doi.org/10.5194/egusphere-2026-3638, https://doi.org/10.5194/egusphere-2026-3638, 2026
This preprint is open for discussion and under review for Natural Hazards and Earth System Sciences (NHESS).
Short summary
Short summary
Rip currents are dangerous wave-driven flows at the coast which cause hundreds of drownings globally each year. This study uses more than 20 years of lifeguard data (the largest of its kind to date) to identify wave, tide, and beach types associated with high rip hazard in New Zealand. The forecast correctly predicts 98 % of rip incidents in New Zealand and mimics a lifeguard’s perception of rip hazard. It could help forewarn the public especially when lifeguards are not present.
Cited articles
Aagaard, T., Greenwood, B., and Nielsen, J.: Mean currents and sediment transport in a rip channel, Mar. Geol., 140, 25–45, https://doi.org/10.1016/s0025-3227(97)00025-x, 1997.
Allen, G. P.: Relationship between grain size parameter distribution and current patterns in the Gironde estuary (France), J. Sediment. Res., 41, 74–88, https://doi.org/10.1306/74d721ee-2b21-11d7-8648000102c1865d, 1971.
Austin, M., Scott, T., Brown, J., MacMahan, J., Masselink, G., and Russell, P.: Temporal observations of rip current circulation on a macrotidal beach, Cont. Res., 30, 1149–1165, https://doi.org/10.1016/j.csr.2010.03.005, 2010.
Austin, M. J., Scott, T. M., Russell, P. E., and Masselink, G.: Rip current prediction: Development, validation, and evaluation of an operational tool, J. Coastal. Res., 29, 283–300, https://doi.org/10.2112/jcoastres-d-12-00093.1, 2013.
Austin, M. J., Masselink, G., Scott, T. M., and Russell, P. E.: Water-level controls on macro-tidal rip currents, Cont. Shelf Res., 75, 28–40, 2014.
Barnard, P. L. and Warrick, J. A.: Dramatic beach and nearshore morphological changes due to extreme flooding at a wave-dominated river mouth, Mar. Geol., 271, 131–148, https://doi.org/10.1016/j.margeo.2010.01.018, 2010.
Brander, R. W.: Field observations on the morphodynamic evolution of a low-energy rip current system, Mar. Geol., 157, 199–217, https://doi.org/10.1016/s0025-3227(98)00152-2, 1999.
Brander, R. W. and Short, A. D.: Flow kinematics of low-energy rip current systems, J. Coastal. Res., 17, 468–481, 2001.
Brighton, B., Sherker, S., Brander, R., Thompson, M., and Bradstreet, A.: Rip current related drowning deaths and rescues in Australia 2004–2011, Nat. Hazards Earth Syst. Sci., 13, 1069–1075, https://doi.org/10.5194/nhess-13-1069-2013, 2013.
Castelle, B. and Coco, G.: The morphodynamics of rip channels on embayed beaches, Cont. Shelf Res., 43, 10–23, https://doi.org/10.1016/j.csr.2012.04.010, 2012.
Castelle, B. and Coco, G.: Surf zone flushing on embayed beaches, Geophys. Lett., 40, 2206–2210, https://doi.org/10.1002/grl.50485, 2013.
Castelle, B., Michallet, H., Marieu, V., Leckler, F., Dubardier, B., Lambert, A., Berni, C., Bonneton, P., Barthélemy, E., and Bouchette, F.: Laboratory experiment on rip current circulations over a moveable bed: Drifter measurements, J. Geophys. Res.-Oceans, 115, C12008, https://doi.org/10.1029/2010jc006343, 2010.
Castelle, B., Almar, R., Dorel, M., Lefebvre, J.-P., Senechal, N., Anthony, E. J., Laibi, R., Chuchla, R., and Penhoat, Y. d.: Rip currents and circulation on a high-energy low-tide-terraced beach (Grand Popo, Benin, West Africa), J. Coastal. Res., 70, 633–638, 2014.
Castelle, B., Scott, T., Brander, R. W., and McCarroll, R. J.: Rip current types, circulation and hazard, Earth. Rev., 163, 1–21, https://doi.org/10.1016/j.earscirev.2016.09.008, 2016.
Castelle, B., Scott, T., Brander, R., McCarroll, J., Robinet, A., Tellier, E., de Korte, E., Simonnet, B., and Salmi, L.-R.: Environmental controls on surf zone injuries on high-energy beaches, Nat. Hazards Earth Syst. Sci., 19, 2183–2205, https://doi.org/10.5194/nhess-19-2183-2019, 2019.
Chandramohan, P., Kumar, V. S., and Jena, B.: Rip current zones along beaches in Goa, west coast of India, J. Water. Port Coast. and Ocea. Eng., 123, 322–328, https://doi.org/10.1061/(asce)0733-950x(1997)123:6(322), 1997.
Cooper, J. A. G.: Geomorphological variability among microtidal estuaries from the wave-dominated South African coast, Geomorphology, 40, 99–122, https://doi.org/10.1016/S0169-555X(01)00039-3, 2001.
Daly, C., Roelvink, D., van Dongeren, A., de Vries, J. v. T., and McCall, R.: Validation of an advective-deterministic approach to short wave breaking in a surf-beat model, Coast. Eng., 60, 69–83, https://doi.org/10.1016/j.coastaleng.2011.08.001, 2012.
Deltares, Delft University of Technology, Rijkswaterstaat, UNESCO-IHE, University of Miami, and US Army Corps of Engineers: XBeach model software, https://download.deltares.nl/xbeach, last access: 12 March 2021.
Dudkowska, A., Boruń, A., Malicki, J., Schönhofer, J., and Gic-Grusza, G.: Rip currents in the non-tidal surf zone with sandbars: numerical analysis versus field measurements, Oceanologia, 62, 291–308, https://doi.org/10.1016/j.oceano.2020.02.001, 2020.
Dusek, G. and Seim, H.: Rip current intensity estimates from lifeguard observations, J. Coastal. Res., 29, 505–518, https://doi.org/10.1306/74D721EE-2B21-11D7-8648000102C1865D, 2013a.
Dusek, G. and Seim, H.: A probabilistic rip current forecast model, J. Coastal. Res., 29, 909–925, https://doi.org/10.2112/jcoastres-d-12-00118.1, 2013b.
Engle, J., MacMahan, J., Thieke, R. J., Hanes, D. M., and Dean, R. G.: Formulation of a Rip Current Predictive Index Using Rescue Data. Proc. nat. conf. beach pres. tech. Florida Shore & Beach Preservation Association, Citeseer, Vol. 285, https://api.semanticscholar.org/CorpusID:110833857 (last access: 12 November 2024), 2002.
Gibbs, A., Dusek, G., Van der Westhuysen, A., Santos, P., Huddleston, S., Estupiñan, J., Rivera, E., Stripling, S., and Padilla, R.: Numerical Validation of a Coupled Probabilistic Rip Current Model and Nearshore Wave Prediction System For South Florida, Phoenix, Arizona, 4–8 January 2015, Proc. 13th Symp. Coast. Env., 1–9, https://ams.confex.com/ams/95Annual/webprogram/Manuscript/Paper265327/AMS_ripcurrent_2015_ext-abs_Final.pdf (last access: 12 November 2024), 2015.
Groeneweg, J. and Klopman, G.: Changes of the mean velocity profiles in the combined wave–current motion described in a GLM formulation, J. Mech., 370, 271–296, https://doi.org/10.1017/s0022112098002018, 1998.
Hartanto, I. M., Beevers, L., Popescu, I., and Wright, N. G.: Application of a coastal modelling code in fluvial environments, Environ. Modell. Softw., 26, 1685–1695, https://doi.org/10.1016/j.envsoft.2011.05.014, 2011.
Hird, S., Stokes, C., and Masselink, G.: Emergent coastal behaviour results in extreme dune erosion decoupled from hydrodynamic forcing, Mar. Geol., 442, 106667, https://doi.org/10.1016/j.margeo.2021.106667, 2021.
Hume, T. M. and Herdendorf, C. E.: A geomorphic classification of estuaries and its application to coastal resource management – a New Zealand example, Ocean and Shoreline Management, 11, 249–274, https://doi.org/10.1016/0951-8312(88)90022-7, 1988.
Hume, T. M., Snelder, T., Weatherhead, M., and Liefting, R.: A controlling factor approach to estuary classification, Ocean Coast Manage., 50, 905–929, https://doi.org/10.1016/j.ocecoaman.2007.05.009, 2007.
Jiang, A. W., Ranasinghe, R., and Cowell, P.: Contemporary hydrodynamics and morphological change of a microtidal estuary: a numerical modelling study, Ocean Dynam., 63, 21–41, https://doi.org/10.1007/s10236-012-0583-z, 2013.
Kastner, S., Horner-Devine, A., and Thomson, J.: A conceptual model of a river plume in the surf zone, J. Geophys. Res.-Oceans, 124, 8060–8078, 2019.
Kench, P. S.: Geomorphology of Australian estuaries: review and prospect, Aust. J. Ecol., 24, 367–380, https://doi.org/10.1046/j.1442-9993.1999.00985.x, 1999.
Kennedy, D. M., Sherker, S., Brighton, B., Weir, A., and Woodroffe, C. D.: Rocky coast hazards and public safety: Moving beyond the beach in coastal risk management, Ocean Coast Manage., 82, 85–94, https://doi.org/10.1016/j.ocecoaman.2013.06.001, 2013.
Kim, I., Lee, J., and Lee, J.: Verification of rip current simulation using a two-dimensional predictive model, HAECUM, J. Coast. Res., 65, 726–730, https://doi.org/10.2112/si65-123.1, 2013.
Koon, W., Brander, R. W., Dusek, G., Castelle, B., and Lawes, J. C.: Relationships between the tide and fatal drowning at surf beaches in New South Wales, Australia: Implications for coastal safety management and practice, Ocean Coast Manage., 238, 106584, https://doi.org/10.1016/j.ocecoaman.2023.106584, 2023.
Lascody, R. L.: East central Florida rip current program, National Weather Digest, 22, 25–30, https://www.weather.gov/media/mlb/marine/ripinit.pdf (last access: 10 November 2024), 1998.
Lessa, G. and Masselink, G.: Morphodynamic evolution of a macrotidal barrier estuary, Mar. Geol., 129, 25–46, https://doi.org/10.1016/0025-3227(95)00103-4, 1995.
Lippmann, T. C. and Holman, R. A.: The spatial and temporal variability of sand bar morphology, J. Geophys. Res., 95, 11575–11590, https://doi.org/10.1029/jc095ic07p11575, 1990.
Longuet-Higgins, M. S. and Stewart, R. W.: Radiation stress and mass transport in gravity waves, with application to “surf beats”, J. Mech., 13, 481–504, https://doi.org/10.1017/s0022112062000877, 1962.
Longuet-Higgins, M. S. and Stewart, R. W.: Radiation stresses in water waves; a physical discussion, with applications, Deep Sea Research and Oceanographic Abstracts, 11, 529–562, https://doi.org/10.1016/0011-7471(65)90982-4, 1964.
Lushine, J. B.: A study of rip current drownings and related weather factors, National Weather Digest, 16, 13–19, 1991.
MacMahan, J., Brown, J., Brown, J., Thornton, E., Reniers, A., Stanton, T., Henriquez, M., Gallagher, E., Morrison, J., and Austin, M. J.: Mean Lagrangian flow behavior on an open coast rip-channeled beach: A new perspective, Mar. Geol., 268, 1–15, 2010.
MacMahan, J., Reniers, A., Brown, J., Brander, R., Thornton, E., Stanton, T., Brown, J., and Carey, W.: An introduction to rip currents based on field observations, J. Coastal. Res., 27, 3–6, https://doi.org/10.2112/jcoastres-d-11-00024.1, 2011.
MacMahan, J. H., Thornton, E. B., Stanton, T. P., and Reniers, A. J.: RIPEX: Observations of a rip current system, Mar. Geol., 218, 113–134, https://doi.org/10.1016/j.margeo.2005.03.019, 2005.
MacMahan, J. H., Thornton, E. B., and Reniers, A. J. H. M.: Rip current review, Coast. Eng., 53, 191–208, https://doi.org/10.1016/j.coastaleng.2005.10.009, 2006.
Masselink, G. and Short, A. D.: The effect of tide range on beach morphodynamics and morphology: a conceptual beach model, J. Coastal. Res., 9, 785–800, 1993.
Masselink, G., Scott, T., Poate, T., Russell, P., Davidson, M., and Conley, D.: The extreme 2013/2014 winter storms: hydrodynamic forcing and coastal response along the southwest coast of England, Earth Surf. Proc. Land., 41, 378–391, https://doi.org/10.1002/esp.3836, 2016.
Masselink, G., Brooks, S., Poate, T., Stokes, C., and Scott, T.: Coastal dune dynamics in embayed settings with sea-level rise–Examples from the exposed and macrotidal north coast of SW England, Mar. Geol., 450, 106853, https://doi.org/10.1016/j.margeo.2022.106853, 2022.
McCarroll, R. J., Brander, R. W., Turner, I. L., Power, H. E., and Mortlock, T. R.: Lagrangian observations of circulation on an embayed beach with headland rip currents, Mar. Geol., 355, 173–188, https://doi.org/10.1016/j.margeo.2014.05.020, 2014a.
McCarroll, R. J., Brander, R. W., MacMahan, J. H., Turner, I. L., Reniers, A. J. H. M., Brown, J. A., Bradstreet, A., and Sherker, S.: Evaluation of swimmer-based rip current escape strategies, Nat. Hazards, 71, 1821–1846, https://doi.org/10.1007/s11069-013-0979-1, 2014b.
McCarroll, R. J., Castelle, B., Brander, R. W., and Scott, T.: Modelling rip current flow and bather escape strategies across a transverse bar and rip channel morphology, Geomorphology, 246, 502–518, https://doi.org/10.1016/j.geomorph.2015.06.041, 2015.
McCarroll, R. J., Brander, R. W., Scott, T., and Castelle, B.: Bathymetric controls on rotational surfzone currents, J. Geophys. Res.-Earth, 123, 1295–1316, https://doi.org/10.1029/2017jf004491, 2018.
McCarroll, R. J., Brander, R., and Scott, T.: Wave height and bathymetric controls on surfzone current velocity and dispersion across an embayed beach, Proc. Coast. Dyn. Conf., Helsingør, Denmark, 12–16 June 2017, 431–442, https://coastaldynamics2017.dk/onewebmedia/145_mccarroll.pdf (last access: 12 November 2024), 2017.
Moulton, M., Dusek, G., Elgar, S., and Raubenheimer, B.: Comparison of rip current hazard likelihood forecasts with observed rip current speeds, Weather Forecast., 32, 1659–1666, 2017a.
Moulton, M., Elgar, S., Raubenheimer, B., Warner, J. C., and Kumar, N.: Rip currents and alongshore flows in single channels dredged in the surf zone, J. Geophys. Res.-Oceans, 122, 3799–3816, 2017b.
Mouragues, A., Bonneton, P., Castelle, B., Marieu, V., Jak McCarroll, R., Rodriguez-Padilla, I., Scott, T., and Sous, D.: High-energy surf zone currents and headland rips at a geologically constrained mesotidal beach, J. Geophys. Res.-Oceans, 125, e2020JC016259, https://doi.org/10.1029/2020jc016259, 2020.
Mouragues, A., Bonneton, P., Castelle, B., and Martins, K.: Headland Rip Modelling at a Natural Beach under High-Energy Wave Conditions, Journal of Marine Science and Engineering, 9, 1161, https://doi.org/10.3390/jmse9111161, 2021.
Nairn, R. B., Roelvink, J. A., and Southgate, H. N.: Transition zone width and implications for modelling surfzone hydrodynamics, Coast. Eng., C5, 68–81, https://doi.org/10.1061/9780872627765.007, 1990.
Nordstrom, K. F.: Estuarine beaches: an introduction to the physical and human factors affecting use and management of beaches in estuaries, lagoons, bays and fjords, Springer Science & Business Media, ISBN 1851667288, 1992.
Olabarrieta, M., Geyer, W. R., and Kumar, N.: The role of morphology and wave-current interaction at tidal inlets: An idealized modeling analysis, J. Geophys. Res.-Oceans, 119, 8818–8837, 2014.
Panofsky, H. and Brier, G.: Some applications of statistics to meteorology, Pennsylvania State University, PA, https://digital.libraries.psu.edu/digital/collection/digitalbks2/id/48274/ (last access: 9 September 2024), 1953.
Phillips, O. M.: The dynamics of the upper ocean, Cambridge University Press, New York, ISBN 9780521298018, 1977.
Pye, K. and Blott, S. J.: The geomorphology of UK estuaries: The role of geological controls, antecedent conditions and human activities, Estuar. Coast. Shelf S., 150, 196–214, https://doi.org/10.1016/j.ecss.2014.05.014, 2014.
Reniers, A. J., MacMahan, J., Thornton, E., Stanton, T. P., Henriquez, M., Brown, J., Brown, J., and Gallagher, E.: Surf zone surface retention on a rip-channeled beach, J. Geophys. Res.-Oceans, 114, C10010, https://doi.org/10.1029/2008jc005153, 2009.
Rodriguez, A. R., Giddings, S. N., and Kumar, N.: Impacts of nearshore wave-current interaction on transport and mixing of small-scale buoyant plumes, Geophys. Lett., 45, 8379–8389, 2018.
Roelvink, D. and Reniers, A.: A guide to modeling coastal morphology, in: Advances in Coastal and Ocean Engineering, Vol. 12, World Scientific, Singapore, ISBN 9789814465120, 2011.
Roelvink, D., Reniers, A., Van Dongeren, A., Van Thiel de Vries, J., Lescinski, J., and McCall, R.: XBeach model description and manual, Unesco-IHE Institute for Water Education, Deltares and Delft University of Technology, the Netherlands, https://svn.oss.deltares.nl/repos/openearthtools/sandbox/DSD_2014/XBeachExecutable/xbeach_manual.pdf (last access: 10 November 2024), 2010.
Roelvink, D., McCall, R., Mehvar, S., Nederhoff, K., and Dastgheib, A.: Improving predictions of swash dynamics in XBeach: The role of groupiness and incident-band runup, Coast. Eng., 134, 103–123, https://doi.org/10.1016/j.coastaleng.2017.07.004, 2018.
Roelvink, J. A.: Dissipation in random wave groups incident on a beach, Coast. Eng., 19, 127–150, https://doi.org/10.1016/0378-3839(93)90021-y, 1993.
Roy, P.: New South Wales estuaries: their origin and evolution. In: Coastal geomorphology in Australia, Academic Press, ISBN 0126878803, 1984.
Saulnier, D., Dixit, A., Nunes, A. R., and Murray, V.: Disaster Risk Factors–Hazards, exposure, and vulnerability, in: WHO Guidance on Research Methods for Health Emergency and Disaster Risk Management, World Health Organization, 151–163, https://extranet.who.int/kobe_centre/sites/default/files/pdf/WHO Guidance_Research Methods_Health-EDRM_3.2.pdf (last access: 10 November 2024), 2020.
Scott, T., Masselink, G., and Russell, P.: Morphodynamic characteristics and classification of beaches in England and Wales, Mar. Geol., 286, 1–20, https://doi.org/10.1016/j.margeo.2011.04.004, 2011.
Scott, T., Masselink, G., Austin, M. J., and Russell, P.: Controls on macrotidal rip current circulation and hazard, Geomorphology, 214, 198–215, https://doi.org/10.1016/j.geomorph.2014.02.005, 2014.
Scott, T., Austin, M., Masselink, G., and Russell, P.: Dynamics of rip currents associated with groynes–field measurements, modelling and implications for beach safety, Coast. Eng., 107, 53–69, https://doi.org/10.1016/j.coastaleng.2015.09.013, 2016.
Scott, T., Masselink, G., Stokes, C., Poate, T., Wooler, A., and Instance, S.: A 15-year partnership between UK coastal scientists and the international beach lifeguard community, Cont. Shelf Res., 241, 104732, https://doi.org/10.1016/j.csr.2022.104732, 2022.
Scott, T. M., Russell, P. E., Masselink, G., Wooler, A., and Short, A.: High volume sediment transport and its implications for recreational beach risk, Proceedings 31st International Conference on Coastal Engineering, ASCE, Hamburg, Germany, 31 August to 5 September 2008, 4250–4262, https://doi.org/10.1142/9789814277426_0353, 2008.
Stokes, C., Masselink, G., Revie, M., Scott, T., Purves, D., and Walters, T.: Application of multiple linear regression and Bayesian belief network approaches to model life risk to beach users in the UK, Ocean Coastal Manage., 139, 12–23, https://doi.org/10.1016/j.ocecoaman.2017.01.025, 2017.
Svendsen, I. A.: Wave heights and set-up in a surf zone, Coast. Eng., 8, 303–329, https://doi.org/10.1016/0378-3839(84)90028-0, 1984.
Wright, L. D. and Short, A. D.: Morphodynamic variability of surf zones and beaches: A synthesis, Mar. Geol., 56, 93–118, https://doi.org/10.1016/0025-3227(84)90008-2, 1984.
Short summary
Currents at beaches with an estuary mouth have rarely been studied before. Using field measurements and computer modelling, we show that surfzone currents can be driven by both estuary flow and rip currents. We show that an estuary mouth beach can have flows reaching 1.5 m s−1 and have a high likelihood of taking bathers out of the surfzone. The river channels on the beach direct the flows, and even though they change position over time, it was possible to predict when peak hazards would occur.
Currents at beaches with an estuary mouth have rarely been studied before. Using field...
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