Numerical modelling of coastal morphology is a complex and sometimes unrewarding exercise and often not yielding tangible results. Typically, the underlying drivers of morphology are not properly accounted for in numerical models. Such inaccuracies combined with a paucity of validation data create a difficulty for coastal planners/engineers who are required to interpret such morphological models to develop coastal management strategies. This study develops an approach to long term morphological modelling of a barrier beach system that includes the findings of over 10 years of coastal monitoring on a dynamic coastal system. The novel approach to predicting the long term evolution of the area combines a mix of short term hydrodynamic monitoring and long term morphological modelling to predict future changes in a breached barrier system. A coupled wave, wind, hydrodynamic and sediment transport numerical model was used to predict the coastal evolution in the dynamic barrier beach system of Inner Dingle Bay, Co. Kerry, Ireland. The modelling approach utilizes the schematisation of inputs to reflect observed trends. The approach is subject to two stages of validation both quantitative and qualitative. The study highlights the importance of considering all the parameters responsible for driving coastal evolution and the necessity to have long term monitoring results for trend based validation.
KeywordsMorphodynamic ModellingSediment TransportTidal InletEbb Tidal BarLong Term Process
Larson, M. and Kraus, N.C. (1989) SBEACH: Numerical Model for Simulating Storm-Induced Beach Change. Technical Reports, CERC-89-9, U.S. Army Corps of Engineers, Vicksburg, MS. https://doi.org/10.5962/bhl.title.47893
Unesco-IHE, Deltares (2009) XBeach Model Description and Manual, TU Delft.
DHI (2007) MIKE 21:2007. Sediment Transport and Morphological Modelling-User Guide. DHI Water and Environment, Horsholm, Denmark, 388.
Soulsby, R.L. (1997) Dynamics of Marine Sands—A Manual for Practical Applications. Thomas Telford Publications, London, 249 p.
Austin, M. and Brown, J. (2009) Macrotidal Rip Current Experiment: Circulation and Dynamics. Journal of Coastal Research, 56, 24-28.
Gracia, V., García, M., Grifoll, M. and Sánchez-Arcilla, A. (2013) Breaching of a Barrier Beach under Extreme Events. The Role of Morphodynamic Simulations. Journal of Coastal Research, 65, 951-956. https://doi.org/10.2112/SI65-161.1
Deltares (2010) Delft3D-FLOW. Simulation of Multi-Dimensional Hydrodynamic Flow and Transport Phenomena, Including Sediments: User Manual. Version 3.04, Deltares, Delft, The Netherlands.
Deltares (2010) Delft3D-WAVE. Simulation of Short-Crested Waves with SWAN-User Manual. Version 3.04. Deltares, Delft, The Netherlands.
Hervouet, J.-M. (2007) Hydrodynamics of Free Surface Flows, Modelling with the Finite-element Method. John Wiley & Sons Ltd., West Sussex, England, 340 p.
Panigrahij, J.K., Ananth, P. and Umesh, P. (2009) Coastal Morphological Modelling to Assess the Dynamics of Arklow Bank, Ireland. International Journal of Sediment Research, 24, 299-314. https://doi.org/10.1016/S1001-6279(10)60005-4
Herrling, G. and Winter, C. (2014) Morphological and Sedimentological Response of Amixed-Energy Barrier Island Tidal Inlet to Storm and Fair-Weather Conditions. Earth Surface Dynamics, 2, 363-382. https://doi.org/10.5194/esurf-2-363-2014
Sala, P. (2010) Morphodynamic Evolution of a Tidal Inlet Mid-Bay Barrier System. Master’s Thesis, University College Cork, Cork, Ireland.
O’Shea, M. and Murphy, J. (2016) The Validation of a New GSTA Case in a Dynamic Coastal Environment Using Morphodynamic Modelling and Bathymetric Monitoring. Journal of Marine Science and Engineering, 4, 27. https://doi.org/10.3390/jmse4010027
Kristensen, S.E., Dronen, N., Deigaard, R. and Fredsoe, J. (2013) Hybrid Morphological Modelling of Shoreline Response to a Detached Breakwater. Coastal Engineering, 71, 13-27. https://doi.org/10.1016/j.coastaleng.2012.06.005
Williams, J.J., Esteves, L.S. and Rochford, L.A. (2015) Modelling Storm Responses on a High-Energy Coastline with XBeach. Modelling Earth Systems and Environment, 1, Article No. 3. https://doi.org/10.1007/s40808-015-0003-8
De Vriend, H.J., Capobianco, M., Chesher, T., De Swart, H.E., Latteux, B. and Stive, M.J.F. (1993) Approaches to Long Term Modeling of Coastal Morphology: A Review. Coastal Engineering, 21, 225-269. https://doi.org/10.1016/0378-3839(93)90051-9
Williams, J.J., Conduché, T. and Esteves, L.S. (2015) Modelling Long-Term Morphodynamics in Practice: Uncertainties and Compromises. Coastal Sediments, 11 p. https://doi.org/10.1142/9789814689977_0216
Latteux, B. (1995) Techniques for Long-Term Morphological Simulation under Tidal Action. Marine Geology, 126, 129-141. https://doi.org/10.1016/0025-3227(95)00069-B
Cayocca, F. (2001) Long-Term Morphological Modeling of a Tidal Inlet: The Arcachon Basin, France. Coastal Engineering, 42, 115-142. https://doi.org/10.1016/S0378-3839(00)00053-3
Xie, D., Wang, Z., Gao, S. and de Vriend, H.J. (2009) Modelling the Tidal Channel Morphodynamics in a Macro-Tidal Embayment, Hangzhou Bay, China. Continental Shelf Research, 29, 1757-1767. https://doi.org/10.1016/j.csr.2009.03.009
Villaret, C., Hervouet, J.M., Kopmann, R., Merkel, U. and Davies, A.G. (2013) Morphodynamic Modeling Using the Telemac Finite-Element System. Computers & Geosciences, 53, 105-113. https://doi.org/10.1016/j.cageo.2011.10.004
Wintle, A.G., Clarke, M.L., Musson, F.M., Orford, J.D. and Devoy, R.J.N. (1998) Luminescence Dating of Recent Dunes on Inch Spit, Dingle Bay, Southwest Ireland. The Holocene, 8, 331-339. https://doi.org/10.1191/095968398671791976
Delaney, C., Jennings, S. and Devoy, R.J.N. (2006) Controls on Medium to Long Term Organogenic Salt Marsh Sedimentation under Rising Relative Sea-Level along the Western European (East Atlantic) Margin: Evidence from Dingle Bay, Western Ireland. European Commissions Impacts Project Contract.
O’Shea, M. and Murphy, J. (2013) Predicting and Monitoring the Evolution of a Coastal Barrier Dune System Post Breaching. Journal of Coastal Research, 29, 38-50. https://doi.org/10.2112/JCOASTRES-D-12-00176.1
Kandrot, S., Farrell, E. and Devoy, R. (2016) The Morphological Response of Foredunes at a Breached Barrier System to Winter 2013/2014 Storms on the Southwest Coast of Ireland. Earth Surface Processes and Landforms, 41, 2123-2136. https://doi.org/10.1002/esp.4003
Vial, T. (2008) Monitoring the Morphological Response of an Embayed High Energy Beach to Storms and Atlantic Waves. Master’s Thesis, University College Cork, Cork, Ireland.
Duffy, M. and Devoy, R. (1998) Contemporary Process Controls on the Evolution of Sedimentary Coasts under Low to High Energy Regimes: Western Ireland. Geologie en Mijnbouw, 77, 333-349. https://doi.org/10.1023/A:1003619813284
O’Shea, M. (2015) Monitoring and Modelling the Morphodynamic Evolution of a Breached Barrier Beach System. Ph.D. Dissertation, University College Cork, Cork, Ireland.
Orford, J.D., Cooper, J.A.G. and McKenna, J. (1999) Mesoscale Temporal Changes to Foredunes at Inch Spit, South-West Ireland. Zeitschrift für Geomorphologie, 43, 439-461
Cooper, J. and Jackson, D. (2004) Geomorphology of a High-Energy Barrier Island on the Rocky West Coast of Ireland. Journal of Coastal Research, 64, 6-9.
Heron, M., O’Shea, M., Murphy, J., Petersen, L., Mollaghan, D. and Prytz, A. (2013) Interpretation of VHF Radar Echoes from a Complex Flow Field. OCEANS, San Diego, CA, 1-4.
Delaunay, B. (1934) Sur la sphère vide. A la mémoire de Georges Voronoi. Bulletin de l’Académie des Sciences de l’URSS. Classe des sciences mathématiques et na, No. 6, 793-800.