Modeling Beach Morphology Changes Coupled to Incident Wave Climate and Low Frequency Currents

2001 ◽  
Author(s):  
James T. Kirby
Keyword(s):  
Incident Wave ◽  
Low Frequency ◽  
Wave Climate ◽  
Beach Morphology ◽  
Morphology Changes

scholarly journals Assessing Cross-Shore and Alongshore Variation in Beach Morphology Due to Wave Climate: Storms to Decades

Oceanography ◽  
2017 ◽  
Vol 30 (3) ◽  
Author(s):  
Shari Gallop ◽  
◽  
Mitchell Harley ◽  
Robert Brander ◽  
Joshua Simmons ◽  
...  
Keyword(s):  
Wave Climate ◽  
Beach Morphology

scholarly journals EXCITATION OF LOW FREQUENCY TRAPPED WAVES

1978 ◽  
Vol 1 (16) ◽  
pp. 25
Author(s):  
Robert King ◽  
Ronald Smith
Keyword(s):  
Incident Wave ◽  
Standing Waves ◽  
Low Frequency ◽  
Nonlinear Interactions ◽  
Edge Waves ◽  
Constant Depth ◽  
Side Band ◽  
Rectangular Basin ◽  
Trapped Wave ◽  
Narrow Wave

Weak nonlinear interactions in water of non-constant depth between an incident wave, a side-band incident wave and a relatively low frequency trapped wave are shown to lead to the generation of the trapped wave. Three situations are considered in detail: edge waves in a wide rectangular basin, progressive edge waves on a straight beach, and standing waves in a narrow wave tank.

scholarly journals A Comparison of Methods for Estimating Reynolds Stress from ADCP Measurements in Wavy Environments

2011 ◽  
Vol 28 (11) ◽  
pp. 1539-1553 ◽  
Author(s):  
Anthony R. Kirincich ◽  
Johanna H. Rosman
Keyword(s):  
Low Frequency ◽  
Acoustic Doppler Current Profiler ◽  
Spatial Filtering ◽  
Wave Climate ◽  
Coastal Ocean ◽  
Wave Band ◽  
Reynolds Stresses ◽  
Spectral Fitting ◽  
Quadratic Drag ◽  
Adcp Measurements

Abstract Turbulent Reynolds stresses are now routinely estimated from acoustic Doppler current profiler (ADCP) measurements in estuaries and tidal channels using the variance method, yet biases due to surface gravity waves limit its use in the coastal ocean. Recent modifications to this method, including spatially filtering velocities to isolate the turbulence from wave velocities and fitting a cospectral model to the below-wave band cospectra, have been used to remove this bias. Individually, each modification performed well for the published test datasets, but a comparative analysis over the range of conditions in the coastal ocean has not yet been performed. This work uses ADCP velocity measurements from five previously published coastal ocean and estuarine datasets, which span a range of wave and current conditions as well as instrument configurations, to directly compare methods for estimating stresses in the presence of waves. The computed stresses from each were compared to bottom stress estimates from a quadratic drag law and, where available, estimates of wind stress. These comparisons, along with an analysis of the cospectra, indicated that spectral fitting performs well when the wave climate is wide-banded and/or multidirectional as well as when instrument noise is high. In contrast, spatial filtering performs better when waves are narrow-banded, low frequency, and when wave orbital velocities are strong relative to currents. However, as spatial filtering uses vertically separated velocity bins to remove the wave bias, spectral fitting is able to resolve stresses over a larger fraction of the water column.

scholarly journals An early warning system for wave-driven coastal flooding at Imperial Beach, CA

2021 ◽  
Author(s):  
Mark A. Merrifield ◽  
Mele Johnson ◽  
R. T. Guza ◽  
Julia W. Fiedler ◽  
Adam P. Young ◽  
...  
Keyword(s):  
Water Level ◽  
Sea Level ◽  
Incident Wave ◽  
High Tide ◽  
Warning System ◽  
Model Errors ◽  
Wave Runup ◽  
Peak Period ◽  
Beach Morphology ◽  
Wave Forecast

AbstractWaves overtop berms and seawalls along the shoreline of Imperial Beach (IB), CA when energetic winter swell and high tide coincide. These intermittent, few-hour long events flood low-lying areas and pose a growing inundation risk as sea levels rise. To support city flood response and management, an IB flood warning system was developed. Total water level (TWL) forecasts combine predictions of tides and sea-level anomalies with wave runup estimates based on incident wave forecasts and the nonlinear wave model SWASH. In contrast to widely used empirical runup formulas that rely on significant wave height and peak period, and use only a foreshore slope for bathymetry, the SWASH model incorporates spectral incident wave forcing and uses the cross-shore depth profile. TWL forecasts using a SWASH emulator demonstrate skill several days in advance. Observations set TWL thresholds for minor and moderate flooding. The specific wave and water level conditions that lead to flooding, and key contributors to TWL uncertainty, are identified. TWL forecast skill is reduced by errors in the incident wave forecast and the one-dimensional runup model, and lack of information of variable beach morphology (e.g., protective sand berms can erode during storms). Model errors are largest for the most extreme events. Without mitigation, projected sea-level rise will substantially increase the duration and severity of street flooding. Application of the warning system approach to other locations requires incident wave hindcasts and forecasts, numerical simulation of the runup associated with local storms and beach morphology, and model calibration with flood observations.

scholarly journals Unforced Oscillation of Rip-Current Vortex Cells

2013 ◽  
Vol 43 (3) ◽  
pp. 477-497 ◽  
Author(s):  
Joseph D. Geiman ◽  
James T. Kirby
Keyword(s):  
Incident Wave ◽  
Surf Zone ◽  
Low Frequency ◽  
Surface Gravity Wave ◽  
Wave Forcing ◽  
Forcing Function ◽  
Single Dipole ◽  
Wide Range ◽  
Simple Scaling ◽  
Good Agreement

Abstract A numerical simulation of a monochromatic surface gravity wave–driven flow over an alongshore quasi-periodic rip-channeled beach using the wave-resolving model Funwave is used to investigate coherent, very low-frequency (VLF) motions with characteristic frequencies f < 4.0 mHz inside of the surf zone generated by wave breaking. These oscillations of the nearshore cellular vorticity pattern occur for shore-normal waves over a wide range of amplitudes of the incident wave field and occur despite the wave forcing being essentially constant. The oscillations occur at the lower end of the VLF spectrum or around fp = 0.55 mHz. For small incident wave amplitudes, an equilibrium state consisting of a staggered counterrotating vortex array generates a net weak alongshore current that is also seen in drifter trajectories observed in the field. Using a simpler pseudospectral vorticity model of a single dipole generated by a smooth, stationary in time forcing function sb, this study shows show that the Strouhal number of the vortex shedding process responsible for the oscillation is dependent on the circulation strength of the vortices in the dipole, as well as the bottom friction parameter. This process includes the pinching off, advection, and eventual regeneration of the vortex in the dipole. A simple scaling argument shows good agreement with the frequencies observed in the simulations.

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