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Elwany, MHS, Flick RE, Hamilton MM.  2003.  Effect of a small southern California lagoon entrance on adjacent beaches. Estuaries. 26:700-708.   10.1007/bf02711981   AbstractWebsite

This paper considers the effects of natural and artificial openings of a typical, small, southern California coastal estuarine lagoon on the adjacent barrier beach. A detailed history of beach profiles and lagoon entrance transects before and after flood-induced and artificial openings of San Dieguito Lagoon in Del Mar, California, has been analyzed. The results suggest that there is no statistically significant erosional effect on the adjacent beach when the lagoon inlet is artificially opened to tidal flow.

Elwany, MHS, Oreilly WC, Guza RT, Flick RE.  1995.  Effects of Southern California Kelp Beds on Waves. Journal of Waterway Port Coastal and Ocean Engineering-Asce. 121:143-150.   10.1061/(asce)0733-950x(1995)121:2(143)   AbstractWebsite

The effect of a Macrocystis kelp forest on shoreward propagating surface gravity waves was measured. Observations were made over a 67-day period at four locations around a 350-m-wide kelp bed off Carlsbad, California. Instruments were located directly offshore and onshore of the kelp bed at depths of 13 m and 8 m, respectively, and at control stations at the same depths, but displaced 750 m alongshore, away from the kelp bed. The bathymetry between the offshore and onshore sites was gently sloping and featureless. The measured spectra, significant wave height, mean wave direction at peak frequency, and total radiation stress differed only slightly between the offshore kelp and control stations and were similar at the onshore sites. The similarity of the wave field at the onshore kelp and control sites shows that this typical southern California kelp bed, with an average density of about 10 plants per 100 m(2), does not have a significant effect on waves. These measurements can be used to place upper bounds on drag coefficients in numerical models of the effect of kelp on waves.

Flick, RE, Guza RT, Inman DL.  1981.  Elevation and Velocity-Measurements of Laboratory Shoaling Waves. Journal of Geophysical Research-Oceans and Atmospheres. 86:4149-4160.   10.1029/JC086iC05p04149   AbstractWebsite

Measurements of wave elevation and orbital velocity in the shoaling, breaking, and bore regime of single-frequency laboratory waves show that third-order Stokes theory, when energy flux is conserved, predicts the wave height change and harmonic growth in the regime where the Ursell number Ur = (H/ h)/(kh)2 is 0(1) or less. Shoreward of the Stokes region and up to the breakpoint, harmonic amplitudes are well described by the cnoidal theory. It is shown theoretically that a smooth transition regime exists between Stokes and cnoidal regions for waves which eventually break by plunging. The wave profile asymmetry about the vertical plane observed in near-breaking waves and bores is due to slow changes of phase of the harmonics relative to the primary wave as the wave train shoals. By contrast, only asymmetry about the horizontal plane is possible in the Stokes and cnoidal wave theories, since these classical solutions allow no relative phase shifts between harmonics. Velocity measurements made with hot-film anemometers show that ‘unorganized’ fluctuations at the bottom under breaking waves are of the order of half the rms amplitude of the wave-induced ‘organized’ flow. The correlation between surface elevation and bottom velocity under breakers and bores suggests that turbulence contributes more strongly to the unorganized flow at the bottom under plunging than under spilling waves.

Young, AP, Flick RE, O'Reilly WC, Chadwick DB, Crampton WC, Helly JJ.  2014.  Estimating cliff retreat in southern California considering sea level rise using a sand balance approach. Marine Geology. 348:15-26.   10.1016/j.margeo.2013.11.007   AbstractWebsite

A sand balance coastal profile model for estimating cliff and shoreline retreats considering sea level rise is discussed. The model, specifically designed for cliffed coasts fronted by sandy beaches, conditionally permits beach and cliff retreat to occur independently, and includes subaerial cliff erosion and external beach sand sources. The model accommodates complex nearshore and inland topography, high volume beaches, and variable cliff composition, and is suitable where local sand balance is thought to be a primary controller of coastal evolution over decade–century time scales. Designating an upper active beach boundary and beach–cliff intersection divides the coastal profile into active beach and cliff sections separated by a back beach buffer. The buffer acts as a sand reservoir and delays marine driven cliff erosion, resulting in lower estimated cliff retreat compared to previous models neglecting protective beaches. The model was applied on 21 km of cliffs in Marine Corps Base Camp Pendleton, California considering sea level rise ranging from 0.5 to 2 m over 100 yrs using 207 profiles, sand budget deficits estimated from historical data, and sand inputs from terrestrial erosion estimated from a time series of lidar data. Modeled mean and maximum scenario cliff retreats ranged from 4–87 m and 21–179 m, respectively, and provide order of magnitude estimates, but are reliant on model assumptions and do not include potential coastal changes unrelated to local sand balance. The results underscore the influence of protective beaches on cliff retreat.