SEDIMENT SORTING AND BEACH MORPHOLOGY UNDER PLUNGING WAVE BREAKING

Adrián Pedrozo-Acuña, Diana Resendiz, Edgar Mendoza, Rodolfo Silva

Abstract


This paper presents an experimental investigation into the response of coarse-grained beaches under the action of plunging wave breaking. Beach profile results allowed the identification of three main morphological responses. These are: a beach profile which presented the generation of a clear step below the SWL; a beach shape that did not form any beach step; and a beach face which evolved a bar-like step. Additionally, high-resolution velocity measurements illustrate the prevailing hydrodynamic conditions in the surf-swash transition zone. These results were validated with ADV measurements collected at two cross-shore locations. Through Euler’s equation the pressure field was associated to the total acceleration in the fluid, allowing a careful assessment of the contribution of each the acceleration terms to the resulting momentum balance. In the region close to the impact point, the magnitude of the local acceleration under the plunging waves is insignificant, while at the same location the role of advective terms cannot be overlooked. Results indicate the relevance of including advection processes for the accurate calculation of sediment transport under the action of plunging breakers across the nearshore zone.

Keywords


plunging breaking; advection; sediment sorting; beach morphology

References


Alsina, J. M., Falchetti, S., Baldock T.E., 2009. Measurements and modelling of the advection of suspended sediment in the swash zone by solitary waves Coastal Engineering, 56 (5–6), pp. 621–631http://dx.doi.org/10.1016/j.coastaleng.2009.01.007

Austin, M.J., and Buscombe, D. 2008. Morphological Change and Sediment Dynamics of the Beach Step on a Macrotidal Gravel Beach. Marine Geology 249, 167-183.http://dx.doi.org/10.1016/j.margeo.2007.11.008 doi:10.1016/j.margeo.2007.11.008http://dx.doi.org/10.1016/j.margeo.2007.11.008

Baldock, T.E., Hughes, M.G., 2006. Field observations of instantaneous water slopes and horizontal pressure gradient in the swash-zone. Continental Shelf Research, 26(5), 574-588.http://dx.doi.org/10.1016/j.csr.2006.02.003

Baldock, T.E., Manoonvoravong, P., Pham, K.S., 2010. Sediment transport and beach morphodynamics induced by free long waves, bound long waves and wave groups. Coastal Engineering, 57(10), 898-916.http://dx.doi.org/10.1016/j.coastaleng.2010.05.006

Basco, D.R., 1985. A qualitative description of wave breaking. J. Waterw. Port Coastal Ocean Eng. ASCE, 111: 171-188.

Battjes, J.A., 1988. Surf-zone dynamics. Annu. Rev. Fluid Mech., 20: 257-293.http://dx.doi.org/10.1146/annurev.fl.20.010188.001353

Butt, T., Russell, P. 1999. Suspended sediment transport mechanisms in high-energy swash, Marine Geology, 161 (2-4), pp. 361-375.http://dx.doi.org/10.1016/S0025-3227(99)00043-2

Butt, T., Russell, P. and Turner, I., 2001. The influence of swash infiltration/exfiltration on beach face sediment transport: onshore or offshore? Coastal Engineering, 42: 35-52.http://dx.doi.org/10.1016/S0378-3839(00)00046-6

Brocchini, M., Baldock, T.E., 2008. Recent advances in modelling swash zone dynamics: Influence of Surf-Swash interaction on nearshore hydrodynamics and morphodynamics. Reviews of Chanson, H., Lee, J.F., 1997. Plunging jet characteristics of plunging breakers. Coast. Eng. 31, 125–141.

Geophysics, 46, RG3003. doi:10.1029/2006RG000215http://dx.doi.org/10.1029/2006RG000215

Chanson, H., Aoki, S., Maruyama, M., 2002. Unsteady air bubble entrainment and detrainment at a plunging breaker: dominant time scales and similarity of water level variations. Coast. Eng. 46, 139–157.http://dx.doi.org/10.1016/S0378-3839(02)00069-8

Cox, D.T., Hobensack, W. and Sukumaran, A., 2000. Bottom stress in the inner surf and swash zone.

In: B. Edge (Editor), 27th International Conference on Coastal Engineering. ASCE, Sidney, Australia, pp. 108-119.

Jackson, N.L., Masselink, G., Nordstorm, K.F., 2004. The role of bore collapse and local shear stresses on the spatial distribution of sediment load in the uprush of an intermediate state beach. Marine Geology, 203, 109–118.http://dx.doi.org/10.1016/S0025-3227(03)00328-1

Masselink, G., Puleo, J.A., 2006, Swash zone morphodynamics, Continental Shelf Research, 26, 661-680.http://dx.doi.org/10.1016/j.csr.2006.01.015

Pedrozo-Acu-a, A., Simmonds, D.J. and Reeve, D.E., 2008. Wave-impact characteristics of plunging breakers acting on gravel beaches. Marine Geology, 253(1-2): 26-35.http://dx.doi.org/10.1016/j.margeo.2008.04.013

Pedrozo-Acu-a, A., Torres-Freyermuth, A., Zou, Q., Hsu, T.-J., Reeve, D.E., 2010. Diagnostic modelling of impulsive pressures induced by plunging breakers impinging on gravel beaches, Coastal Engineering, Vol.57, No.3, 252-266.http://dx.doi.org/10.1016/j.coastaleng.2009.09.010

Pedrozo-Acu-a, A., Ruiz de Alegría-Arzaburu, A., Torres-Freyermuth, A., Mendoza, E., Silva R., 2011. Laboratory investigation of pressure gradients induced by plunging breakers. Coastal

Engineering, Vol.58, Elsevier, pp. 722-238, doi:10.1016/j.coastaleng.2011.03.013.http://dx.doi.org/10.1016/j.coastaleng.2011.03.013

Peregrine, D.H., 1983. Breaking waves on beaches. Annu. Rev. Fluid Mech., 15: 149-178.http://dx.doi.org/10.1146/annurev.fl.15.010183.001053

Puleo, J.A., Beach, R.A., Holman, R.A. and Allen, J.S., 2000. Swash zone sediment suspension and transport and the importance of bore-generated turbulence. Journal of Geophysical Research, 105(C7): 17021-17044.http://dx.doi.org/10.1029/2000JC900024

Raubenheimer, B., Elgar, S. and Guza, R.T., 2004. Observations of swash zone velocities: A note on friction coefficients. Journal of Geophysical Research, 109(C01027).

Rivillas-Ospina, G.D., Pedrozo-Acu-a, A., Silva R., Torres-Freyermuth, A., Gutiérrez, C., 2012. Estimation of the velocity field induced by plunging breakers in the surf and swash zones. Experiments in Fluids, doi: 10.1007/s00348-011-1208-x.http://dx.doi.org/10.1007/s00348-011-1208-x

Ryu, Y., Chang, K.A., Lim, H.J., 2005. Use of bubble image velocimetry for measurement of plunging wave impinging on structure and associated greenwater. Measurement Science and Technology 16, 1945–1953.http://dx.doi.org/10.1088/0957-0233/16/10/009

Ryu Y, Chang K-A, Mercier R, 2007. Runup and green water velocities due to breaking wave impinging and overtopping. Exp Fluids 43:555–567http://dx.doi.org/10.1007/s00348-007-0332-0

Stansby, P. and Feng, T. 2005. Kinematics and depth-integrated terms in the surf zone waves from laboratory measurement. J. Fluid Mech., 529, 279–310.http://dx.doi.org/10.1017/S0022112005003599

Suzuki, T., Shin, S., Cox, D.T., Mori, N., 2010, Spatio-temporal characteristics of near-bed pressure gradients on a barred beach. Journal of Waterway, Port, Coastal, and Ocean Engineering, Ting, F.C.K. and Kirby, J.T., 1994. Observation of undertow and turbulence in a laboratory surf zone. Coastal Eng., 24(1-2): 51-80. doi:10.1061/(ASCE)WW.1943-5460.0000055.http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000055

Ting, F.C.K. and Kirby, J.T., 1995. Dynamics of surf-zone turbulence in a strong plunging breaker. Coastal Eng., 24: 177-204.http://dx.doi.org/10.1016/0378-3839(94)00036-W

Turner, I.L., 1995. Simulating the influence of groundwater seepage sediment on sediment transported by the sweep of the swash zone across macro-tidal beaches. Marine Geology, 125(1-2): 153-174.http://dx.doi.org/10.1016/0025-3227(95)00026-U

Turner, I.L. and Masselink, G., 1998. Swash infiltration-exfiltration and sediment transport. Journal of Geophysical Research, 103(C13): 30813-30824.http://dx.doi.org/10.1029/98JC02606

Turner, I.L. and Nielsen, P., 1997. Rapid watertable fluctuations within the beachface: implications for swash zone sediment mobility? Coastal Engineering(32): 45-59.http://dx.doi.org/10.1016/S0378-3839(97)00015-X


Full Text: PDF

Creative Commons License
This work is licensed under a Creative Commons Attribution 3.0 License.