MODELLING WAVE OVERTOPPING FOR GRASS COVERS AND TRANSITIONS IN DIKE REVETMENTS
AbstractTransitions in the dike revetment or in the grass cover can significantly affect the wave overtopping discharge and the dike cover erosion. At the University of Twente, two PhD students recently started on the challenge of quantifying the effect of (1) waterside transition on the wave overtopping discharge and (2) transitions in grass covered dikes on dike erosion. In this paper we present their preliminary results and outline their future plans. Firstly, new laboratory experiments show that the existing wave overtopping formulas are not able to accurately predict the overtopping discharge in case of transitions on the waterside slope. Secondly, the analytical dike cover erosion model shows that transitions in grass covers significantly affect the location of maximum flow velocity and potential dike cover erosion. In future work, detailed numerical models will be developed for both the waterside slope and the landward slope to further increase our understanding of the effects of transitions on the wave overtopping discharge and the dike cover erosion.
Aguilar-López, J.P., Warmink, J.J., Bomers, A., Schielen, R.M.J. and Hulscher, S.J.M.H. (2018). Failure of Grass Covered Flood Defences with Roads on Top Due to Wave Overtopping: A Probabilistic Assessment Method. Journal of marine science and engineering, 6(3), 74.
Bomers, A., Aguilar-Lopez, J.P., Warmink, J.J. and Hulscher, S.J.M.H. (2018). Modelling effects of an asphalt road at a dike crest on dike cover erosion onset during wave overtopping. Natural hazards, 93(1), 1-30.
Capel, A. 2015. Wave run-up and overtopping reduction by block revetments with enhanced roughness. Coastal Engineering. 104, 76-92
Chen, W. (2018). Study on wave overtopping of flood defences. Literature Report, University of Twente, The Netherlands.
Etemad-Shahidi, A., Jafari, E. 2015. A model for prediction of overtopping at berm breakwaters, Proceedings of the 21st International Congress on Modelling and Simulation. pp. 2486-2492.
EurOtop. 2016. Manual on wave overtopping of sea defences and related structures, An overtopping manual largely based on European research, but for worldwide application. Van der Meer, J.W., Allsop, N.W.H, Bruce, T., De Rouck, J., Kortenhaus, A., Pullen, T., Schuttrumpf, H., Troch, P., Zanuttigh, B. www.overtopping-manual.com.
Hebsgaard, M., Sloth, P., Juhl, J. 1999. Wave overtopping of rubble mound breakwaters, Coastal Engineering 1998. pp. 2235-2248.
Hoffmans, G.J. (2012). The influence of turbulence on soil erosion. Eburon Uitgeverij BV. The Netherlands.
Hoffmans, G.J. (2014). Erosiebestendigheid overgangen. Deltares rapport 1209437-003-HYE-0001, Rijkwaterstaat WVL, The Netherlands.
Hoffmans, G.J. and Jacobsen, N.G. (2014). Erosiebestendigheid Afsluitdijk : Middenberm en grasberm IJsselmeerzijde. Deltares Report, 1207410-000. Deltares, Delft, The Netherlands.
Steendam, G.J., Van Hoven, A., Van der Meer, J. and Hoffmans, G. (2014). “Wave overtopping simulator tests on transitions and obstacles at grass covered slopes of dikes.â€ Coastal Engineering Proceedings, 1(34), 79.
Steendam, G.J., Van der Meer, J.W., Van Hoven, A. and Labrujere, A. (2016). “Wave Run-Up Simulation on Real Dikes.â€ Coastal Engineering Proceedings, 1(35), 2016.
TAW, 2002. Technical report wave run-up and wave overtopping at dikes, Technical Advisory Committee on Flood Defence, Delft, The Netherlands.
Van Bergeijk, V.M., Warmink, J.J., Van Gent, M.R.A., Hulscher. S.J.M.H. (submitted). An analytical model for wave overtopping flow velocities on dike crests and landward slopes.
Van Bergeijk, V.M. (2018). The effects of transitions on wave overtopping flow and dike cover erosion for flood defence reliability. Literature Review, CE&M research report 2018R-002/WEM-002, University of Twente, The Netherlands.
Van der Meer, J.W., Hardeman, B., Steendam, G.J., Schuttrumpf, H. and Verheij, H. (2011). Flow depths and velocities at crest and landward slope of a dike, in theory and with the wave overtopping simulator. Coastal Engineering Proceedings, 1(32), 10.
Van Steeg, P. (2014). Bureaustudie overgangen met gras in primaire waterkeringen Voorstudie ten behoeve van fysiek model onderzoek. Deltares report 1209380-006-VEB-0005, December 2014.
Verheij, H.J., Meijer, D.G., Kruse, G.A.M., Smith, G.M., & Vesseur, M. (1995). Investigation of the strength of a grass cover upon river dikes. Report Q1878, Deltares, Delft.
WBI (2017). Wettelijk BeoordelingsInstrumentarium 2017-2023 (Legal assessment protocol 2017-2023). Ministry of Infrastructure and the Environment/Rijkswaterstaat, The Hague, The Netherlands (in Dutch).