Suspended sediment transport and beach dynamics induced by monochromatic conditions, long waves and wave groups

Abstract This study presents the analysis of the water surface elevation, velocity and suspended sediment concentration measurements obtained at a large wave flume under mobile bed conditions. The wave reproduced erosive and accretive conditions, and included monochromatic, short waves perturbed with a free long wave, bichromatic and random conditions. Each tested condition started from a handmade 1/15 slope and lasted for an approximate time period of 2.4 h (6 runs of the selected wave condition), to compare the different beach profile developments and, in particular, the events that control sediment transport in the swash and surf zones. All erosive tested conditions produced a shoreline retreat and a bar at the breaking area whose development in time is directly correlated to the length of the breaking area. On the other hand, not all accretive conditions present a shoreward transport, and random conditions do not seem to alter the initial profile. The processed data show the suspended sediment event control produced by the existence or absence of wave–backwash interactions in the swash zone. The existence of these interactions, and their number within the wave group, will be a key parameter in controlling the sediment stirring, water velocity magnitudes and, therefore, the suspended sediment fluxes in the inner surf and outer swash.

[1]  S. Falchetti,et al.  Measurements and modelling of the advection of suspended sediment in the swash zone by solitary waves , 2009 .

[2]  A. Pedrozo‐Acuña,et al.  Laboratory investigation of pressure gradients induced by plunging breakers , 2011 .

[3]  Iván Cáceres,et al.  Sediment suspension events in the inner surf and swash zone. Measurements in large-scale and high-en , 2011 .

[4]  T. Baldock,et al.  Beach face and berm morphodynamics fronting a coastal lagoon , 2006 .

[5]  T. Baldock,et al.  Berm formation and dynamics on a gently sloping beach; the effect of water level and swash overtopping , 2009 .

[6]  John P. Downing,et al.  Laboratory apparatus for calibrating optical suspended solids sensors , 1989 .

[7]  C. Nucci,et al.  On return stroke currents and remote electromagnetic fields associated with lightning strikes to tall structures: 2. Experiment and model validation , 2007 .

[8]  P. Osborne,et al.  Sand re-suspension events in a high energy infragravity swash zone , 1999 .

[9]  Ian L Turner,et al.  Rapid water table fluctuations within the beach face: Implications for swash zone sediment mobility? , 1997 .

[10]  A. Hine.  Mechanisms of berm development and resulting beach growth along a barrier spit complex , 1979 .

[11]  P. Russell,et al.  Observations of Hydraulic Jumps in High-Energy Swash , 2005 .

[12]  R A Bagnold,et al.  BEACH FORMATION BY WAVES: SOME MODEL EXPERIMENTS IN A WAVE TANK. (INCLUDES PHOTOGRAPHS). , 1940 .

[13]  P. Komar,et al.  Undular hydraulic jumps and the formation of backlash ripples on beaches , 1979 .

[14]  Robert G. Dean,et al.  Heuristic Models of Sand Transport in the Surf Zone , 1973 .

[15]  A. Sánchez-Arcilla,et al.  Large-scale experiments on beach profile evolution and surf and swash zone sediment transport induced by long waves, wave groups and random waves , 2011 .

[16]  K. Nordstrom,et al.  The role of bore collapse and local shear stresses on the spatial distribution of sediment load in the uprush of an intermediate-state beach , 2004 .

[17]  Tom E. Baldock,et al.  Low frequency swash motion induced by wave grouping , 1997 .

[18]  M. Hughes,et al.  Sediment suspension and turbulence in the swash zone of dissipative beaches , 2006 .

[19]  P. Russell,et al.  Suspended sediment transport mechanisms in high-energy swash , 1999 .

[20]  Vladimir Nikora,et al.  Despiking Acoustic Doppler Velocimeter Data , 2002 .

[21]  T. Baldock,et al.  Eulerian flow velocities in the swash zone: Field data and model predictions , 2004 .

[22]  Tom E. Baldock,et al.  Discussion of “Effect of Seepage-Induced Nonhydrostatic Pressure Distribution on Bed-Load Transport and Bed Morphodynamics” by Simona Francalanci, Gary Parker, and Luca Solari , 2010 .

[23]  R. Bagnold.  An approach to the sediment transport problem from general physics , 1966 .

[24]  Michael G. Hughes,et al.  Hydrokinematic regions within the swash zone , 2007 .

[25]  T. O’Hare,et al.  Cross‐shore sediment transport on natural beaches and its relation to sandbar migration patterns: 1. Field observations and derivation of a transport parameterization , 2007 .

[26]  Ian L Turner,et al.  Swash zone sediment fluxes: Field observations , 2011 .

[27]  T. Baldock,et al.  Hydrodynamics and sediment transport in the swash zone: a review and perspectives , 2002 .

[28]  J. A. Roelvink,et al.  Bar-generating cross-shore flow mechanisms on a beach Barre provoquant des mecanismes d' ecoulement perpendiculaires a la plage , 1989 .

[29]  Paul Russell,et al.  Hydrodynamics and Cross-Shore Sediment Transport in the Swash-Zone of Natural Beaches: A Review , 2000 .

[30]  R. Brander,et al.  FLOW VELOCITY AND SEDIMENT TRANSPORT IN THE SWASH ZONE OF A STEEP BEACH , 1997 .

[31]  K. Holland,et al.  Variable swash motions associated with foreshore profile change , 2001 .

[32]  R. Holman,et al.  Swash zone sediment suspension and transport and the importance of bore‐generated turbulence , 2000 .

[33]  T. O’Hare,et al.  Breakpoint generated surf beat induced by bichromatic wave groups , 2000 .

[34]  M. Brocchini,et al.  An experimental study on sediment transport and bed evolution under different swash zone morphological conditions , 2012 .

[35]  I. Cáceres,et al.  A detailed, event-by-event analysis of suspended sediment concentration in the swash zone , 2012 .

[36]  C. Houser,et al.  Divergent behavior of the swash zone in response to different foreshore slopes and nearshore states , 2010 .

[37]  M. Larson,et al.  Prediction of swash motion and run-up including the effects of swash interaction , 2005 .

[38]  R. Hallermeier,et al.  A PROFILE ZONATION FOR SEASONAL SAND BEACHES FROM WAVE CLIMATE , 1980 .

[39]  D. Horn,et al.  Swash zone sediment transport modes , 1994 .

[40]  Gerhard Masselink,et al.  Swash-zone morphodynamics , 2006 .

[41]  Maurizio Brocchini,et al.  Recent advances in modeling swash zone dynamics: Influence of surf‐swash interaction on nearshore hydrodynamics and morphodynamics , 2008 .

[42]  M. Hughes,et al.  Hydrodynamics and Sediment Fluxes across an Onshore Migrating Intertidal Bar , 2006 .

[43]  R. Dalrymple.  Physical Modelling of Littoral Processes , 1989 .

[44]  Fangfang Zhu,et al.  Net beach change in the swash zone: A numerical investigation , 2013 .

[45]  Ian L Turner,et al.  Net sediment transport and morphological change in the swash zone of a high-energy sandy beach from swash event to tidal cycle time scales , 2009 .

[46]  D. A. Barry,et al.  Modeling sediment transport in the swash zone: A review , 2009 .