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Cayan, DR, Bromirski PD, Hayhoe K, Tyree M, Dettinger MD, Flick RE.  2008.  Climate change projections of sea level extremes along the California coast. Climatic Change. 87:S57-S73.   10.1007/s10584-007-9376-7   AbstractWebsite

California's coastal observations and global model projections indicate that California's open coast and estuaries will experience rising sea levels over the next century. During the last several decades, the upward historical trends, quantified from a small set of California tide gages, have been approximately 20 cm/century, quite similar to that estimated for global mean sea level. In the next several decades, warming produced by climate model simulations indicates that sea level rise (SLR) could substantially exceed the rate experienced during modem human development along the California coast and estuaries. A range of future SLR is estimated from a set of climate simulations governed by lower (B1), middle-upper (A2), and higher (A1fi) GHG emission scenarios. Projecting SLR from the ocean warming in GCMs, observational evidence of SLR, and separate calculations using a simple climate model yields a range of potential sea level increases, from 11 to 72 cm, by the 2070-2099 period. The combination of predicted astronomical tides with projected weather forcing, El Nino related variability, and secular SLR, gives a series of hourly sea level projections for 2005-2100. Gradual sea level rise progressively worsens the impacts of high tides, surge and waves resulting from storms, and also freshwater floods from Sierra and coastal mountain catchments. The occurrence of extreme sea levels is pronounced when these factors coincide. The frequency and magnitude of extreme events, relative to current levels, follows a sharply escalating pattern as the magnitude of future sea level rise increases.

Young, AP, Raymond JH, Sorenson J, Johnstone EA, Driscoll NW, Flick RE, Guza RT.  2010.  Coarse Sediment Yields from Seacliff Erosion in the Oceanside Littoral Cell. Journal of Coastal Research. 26:580-585.   10.2112/08-1179.1   AbstractWebsite

The coarse sediment fraction of geologic formations exposed in 42 km of southern California seacliffs in the Oceanside Littoral Cell was estimated using more than 400 samples An impulse laser, oblique photographs, and coastal maps were used to define thickness and alongshore extent of the geologic units exposed in the seacliffs The coarse sediment (defined as diameter > 0 06 mm) fraction in each geologic unit was estimated by sieving About 80% of the exposed cliff face is coarse and can contribute to beach building Finer cliff sediments are transported offshore by waves and currents Although there are some differences, the observed 80% coarse fraction is generally consistent with previous estimates based on an order of magnitude fewer samples Coastal development has largely eliminated about 40% of seacliffs in the Oceanside Littoral Cell as potential beach sand sources For the remaining seacliffs, 1 cm of average cliff retreat yields 10,000 m(3) of potential beach-building material

Young, AP, Adams PN, O'Reilly WC, Flick RE, Guza RT.  2011.  Coastal cliff ground motions from local ocean swell and infragravity waves in southern California. Journal of Geophysical Research-Oceans. 116   10.1029/2011jc007175   AbstractWebsite

Ground motions atop a southern California, USA coastal cliff are compared with water level fluctuations observed at the cliff base, and with ground motions observed 10 km inland. At high tide, cliff top ground motions in three frequency bands were generated locally by ocean waves at the cliff base: (1) high-frequency (>0.3 Hz) "shaking" caused by waves impacting the cliff, and (2) gravitational loading-induced "swaying" at the frequency of the incident sea swell waves (0.05-0.1 Hz), and (3) slow "swaying" at infragravity frequencies (0.006-0.05 Hz). At high tide, at infragravity and incident sea swell wave frequencies, cliff top vertical ground displacement and cliff base water level fluctuations are coherent and oscillate in phase (with occasional deviation at sea swell frequencies), and spectral levels at the cliff top are much higher than at the inland seismometer. In contrast, at "double frequencies" (0.1-0.3 Hz) spectral levels of vertical motions are nearly identical inland and at the cliff top, consistent with a common (distant or spatially distributed) source. At low tide, when ocean waves did not reach the cliff base, power levels of vertical ground motions at the cliff top decreased to inland levels at incident wave frequencies and higher, and only infragravity-band motions were noticeably forced by local ocean waves.

Young, AP, Olsen MJ, Driscoll N, Flick RE, Gutierrez R, Guza RT, Johnstone E, Kuester F.  2010.  Comparison of Airborne and Terrestrial Lidar Estimates of Seacliff Erosion in Southern California. Photogrammetric Engineering and Remote Sensing. 76:421-427. AbstractWebsite

Seacliff changes evaluated using both terrestrial and airborne lidar are compared along a 400 m length of coast in Del Mar, California. The many large slides occurring during the rainy, six-month study period (September 2004 to April 2005) were captured by both systems, and the alongshore variation of cliff face volume changes estimated with the airborne and terrestrial systems are strongly correlated (r(2) = 0.95). However, relatively small changes in the cliff face are reliably detected only with the more accurate terrestrial lidar, and the total eroded volume estimated with the terrestrial system was 30 percent larger than the corresponding airborne estimate. Although relatively small cliff changes are not detected, the airborne system can rapidly survey long cliff lengths and provides coverage on the cliff top and beach at the cliff base.

Young, AP, Flick RE, Gutierrez R, Guza RT.  2009.  Comparison of short-term seacliff retreat measurement methods in Del Mar, California. Geomorphology. 112:318-323.   10.1016/j.geomorph.2009.06.018   AbstractWebsite

Seacliff retreat has been variously characterized as the recession rate of the cliff top, of the cliff base, and as the bulk recession rate based on volumetric changes of the entire cliff face. Here, these measures of retreat are compared using nine semi-annual airborne LiDAR (Light Detection And Ranging) surveys of southern California seacliffs. Changes in the cliff base location (where the steeply sloping cliff face intersects the beach) include cliff retreat owing to basal erosion, but also reflect changes in beach sand level and basal talus deposits. Averaged over the 2.5 km alongshore study span, the cliff base actually prograded seaward about 12 cm during the 4-year study. Cliff top change was dominated by few, relatively large (several meters) localized retreats. Cliff face changes, that include failures and deposits anywhere on the cliff profile, had a relatively small mean magnitude compared to cliff top changes and were more widely distributed alongshore. However, the similar alongshore averaged. cumulative cliff top and net bulk cliff face end-point retreat (14 and 19 cm, respectively) suggest that mean cumulative cliff top retreat can potentially be a viable surrogate for mean net cumulative cliff-wide erosion (and vice versa) over relatively short time periods. Cliff face erosion occurred repeatedly at some locations, confirming the presence of seacliff erosion hot-spots during the study period. (C) 2009 Elsevier B.V. All rights reserved.

Young, AP, Guza RT, Adams PN, O'Reilly WC, Flick RE.  2012.  Cross-shore decay of cliff top ground motions driven by local ocean swell and infragravity waves. Journal of Geophysical Research-Oceans. 117   10.1029/2012jc007908   AbstractWebsite

Ground motions at the frequencies (between 0.01 and 0.1 Hz) of ocean infragravity and swell waves were observed on a cross-shore transect extending landward from the edge of a southern California coastal cliff. Cliff top ground motions are coherent and in phase with water level fluctuations at the cliff base. Vertical ground motions at infragravity and single frequencies decay rapidly with inland distance from the cliff edge (e-folding scale is about 12 m), and at the edge decrease by several orders of magnitude between high tide when waves reach the cliff base, and low tide when the waterline is about 50 m from the cliff base. The observed cross-shore decay scales are qualitatively consistent with gravitational loading and attraction of water waves at tidally modulated distances from the cliff base. At approximately constant distance from the waterline, ground motions vary roughly linearly with nearshore swell wave energy. In contrast to these locally forced ground motions, double frequency band (0.1-0.2 Hz) cliff top vertical ground motions are remotely generated with spatially uniform magnitudes approximately equal to those observed 14 km inland. Near the cliff edge, ground tilt dominates the observed large (relative to vertical) cross-shore acceleration at infragravity frequencies, contributes significantly to cross-shore acceleration at swell frequencies, and is a small fraction of cross-shore acceleration at higher frequencies.

Inman, DL, Nordstrom CE, Flick RE.  1976.  Currents in Submarine Canyons - Air-Sea-Land Interaction. Annual Review of Fluid Mechanics. 8:275-310.   10.1146/annurev.fl.08.010176.001423   AbstractWebsite
Bromirski, PD, Miller AJ, Flick RE, Auad G.  2011.  Dynamical suppression of sea level rise along the Pacific coast of North America: Indications for imminent acceleration. Journal of Geophysical Research-Oceans. 116   10.1029/2010jc006759   AbstractWebsite

Long-term changes in global mean sea level (MSL) rise have important practical implications for shoreline and beach erosion, coastal wetlands inundation, storm surge flooding, and coastal development. Altimetry since 1993 indicates that global MSL rise has increased about 50% above the 20th century rise rate, from 2 to 3 mm yr(-1). At the same time, both tide gauge measurements and altimetry indicate virtually no increase along the Pacific coast of North America during the satellite epoch. Here we show that the dynamical steric response of North Pacific eastern boundary ocean circulation to a dramatic change in wind stress curl, tau(xy), which occurred after the mid-1970s regime shift, can account for the suppression of regional sea level rise along this coast since 1980. Alarmingly, mean tau(xy) over the North Pacific recently reached levels not observed since before the mid-1970s regime shift. This change in wind stress patterns may be foreshadowing a Pacific Decadal Oscillation regime shift, causing an associated persistent change in basin-scale tau(xy) that may result in a concomitant resumption of sea level rise along the U.S. West Coast to global or even higher rates.

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.

Kochnower, D, Reddy SMW, Flick RE.  2015.  Factors influencing local decisions to use habitats to protect coastal communities from hazards. Ocean & Coastal Management. 116:277-290.   10.1016/j.ocecoaman.2015.07.021   AbstractWebsite

Coastal hazard mitigation policy in the US has historically focused on construction of hardened, or gray, infrastructure. Recently, there is increased public interest and policy supporting the use of habitats, or natural infrastructure (NI), following decades of increasingly supportive ecological, engineering, and economic evidence. This trend suggests that behavioral and institutional factors may also be important for mainstreaming NI. To understand what factors affected decisions to use NI, we conducted semi-structured interviews with a total of 16 individuals associated with three NI cases: Ferry Point Park Living Shoreline, Maryland (MD); Surfer's Point Managed Retreat, California (CA); and Durant's Point Living Shoreline, North Carolina (NC). Our grounded theory analysis of the interview transcripts revealed four common themes across the decisions: 1) perception of benefits (N = 45) and costs (N = 31), 2) diffusion of innovation led by innovators (N = 34), 3) local champions (N = 46), and 4) social networks and norms (N = 30). This grounded theory suggests that the decisions to use NI were driven by innovators (citizens, local non-governmental organization (NGO) staff, and/or state government resource managers) who were influenced by seeing NI successes implemented by trusted experts and perceived NI benefits beyond protecting coastlines (e.g., maintaining coastal heritage and sense of place). Innovators also acted as local champions, getting others "comfortable" with NI and connecting to local interests. In addition, our analysis shows the role of regulatory permitting requirements in perpetuating or controlling biases against innovations like NI. In 2008, MD passed a policy that helped address biases against NI by changing NI from a preferred option to the required option except in places where scientific analysis suggested that gray infrastructure would be needed, while in CA and NC gray infrastructure remains only a preferred option. These results suggest an opportunity to harness heuristics, such as visual demonstrations and messaging from trusted persons, in addition to policy tools to mainstream NI in places where there is evidence that it would be effective. These results also suggest that heuristics could result in biases that not only lead to underuse but also to inappropriate use of NI; and, policies, similar to the policy in Maryland, are needed to control these biases. (C) 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (

Gallien, TW, O'Reilly WC, Flick RE, Guza RT.  2015.  Geometric properties of anthropogenic flood control berms on southern California beaches. Ocean & Coastal Management. 105:35-47.   10.1016/j.ocecoaman.2014.12.014   AbstractWebsite

Coastal flood riskfrom coincident high tides' and energetic waves is concentrated around low-lying urban areas. Municipalities construct temporary sand berms (also known as sacrificial dunes) to manage potential flooding, however the relationships between berm geometry (e.g., height, width and length) and performance are not understood. Concomitant pressures of sea level rise and urbanization will increase active beach berming. Effective future coastal flood risk management will depend upon optimizing berm efficacy relative to geometry, placement, and water levels. Here, 34 individual berms at seven southern California locations are characterized using 18 LiDAR datasets spanning nearly a decade. Three berm classifications emerged based on deployment duration: event, seasonal and persistent. Event berms, deployed to manage specific storms or high water events, are triangular in cross-section, relatively low volume (similar to 4 m(3)/m) and low crest elevation (similar to 5 m NAVD88). Seasonal berms are larger, volumes vary from 6 to 28 m(3)/m, and average crest elevations are between 5.3 and 6.4 m. A persistent berm, captured in all LiDAR data for that area, is the largest (48 m(3)/m), longest (1.2 km), and highest mean crest elevation (7 m NAVD88) of all study berms. Total water levels, estimated using observed tides and a regional wave model coupled with an empirical runup formula, suggest that overtopping is rare. Currently, event berms are vulnerable to wave attack only a few hours per year. However, even with modest sea level rise (similar to 25 cm) or El Nino conditions, exposure increases significantly, and substantial nourishments may be required to maintain current flood protection levels. (C) 2014 Elsevier Ltd. All rights reserved.

Young, AP, Guza RT, Dickson ME, O'Reilly WC, Flick RE.  2013.  Ground motions on rocky, cliffed, and sandy shorelines generated by ocean waves. Journal of Geophysical Research-Oceans. 118:6590-6602.   10.1002/2013jc008883   AbstractWebsite

We compare ground motions observed within about 100 m of the waterline on eight sites located on shorelines with different morphologies (rock slope, cliff, and sand beaches). At all sites, local ocean waves generated ground motions in the frequency band 0.01-40 Hz. Between about 0.01 and 0.1 Hz, foreshore loading and gravitational attraction from ocean swell and infragravity waves drive coherent, in-phase ground flexing motions mostly oriented cross-shore that decay inland. At higher frequencies between 0.5 and 40 Hz, breaking ocean waves and wave-rock impacts cause ground shaking. Overall, seismic spectral shapes were generally consistent across shoreline sites and usually within a few orders of magnitude despite the diverse range of settings. However, specific site response varied and was influenced by a combination of tide level, incident wave energy, site morphology, ground composition, and signal decay. Flexing and shaking increased with incident wave energy and was often tidally modulated, consistent with a local generation source. Flexing magnitudes were usually larger than shaking, and flexing displacements of several mm were observed during relatively large incident wave conditions (Hs 4-5 m). Comparison with traffic noise and earthquakes illustrate the relative significance of local ocean-generated signals in coastal seismic data. Seismic observations are not a simple proxy for wave-cliff interaction.

Flick, RE, Bromirski PD.  2019.  Ham Radio from McMurdo Station and Yesterday Camp, Ross Ice Shelf, Antarctica. QST Journal of the American Radio Relay League. 103(2):65-67.
Flick, RE, Knuuti K, Gill SK.  2013.  Matching Mean Sea Level Rise Projections to Local Elevation Datums. Journal of Waterway Port Coastal and Ocean Engineering-Asce. 139:142-146.   10.1061/(asce)ww.1943-5460.0000145   AbstractWebsite

A method is presented to consistently tie future mean sea level rise (MSLR) scenario projections to local geodetic and tidal datums. This extends the U. S. Army Corps of Engineer (USACE) guidance for incorporating the effects of future MSLR into coastal projects. While USACE relies on the National Oceanic and Atmospheric Administration (NOAA) 19-year National Tidal Datum Epoch (NTDE) for its datum relationships, the approach proposed herein generalizes this guidance by choosing the appropriate 19-year epoch centered on the start year of the MSLR scenario under consideration. The procedure takes into account the local annual sea level variability, which confounds the matching to any given single year while generalizing and preserving the 19-year averaging long used by NOAA to calculate the NTDE. Examples of the MSLR scenario matching procedure are given using actual data and projections for La Jolla, California, and Sewells Point (Hampton Roads), Virginia. DOI: 10.1061/(ASCE)WW.1943-5460.0000145. (C) 2013 American Society of Civil Engineers.

Graham, NE, Cayan DR, Bromirski PD, Flick RE.  2013.  Multi-model projections of twenty-first century North Pacific winter wave climate under the IPCC A2 scenario. Climate Dynamics. 40:1335-1360.   10.1007/s00382-012-1435-8   AbstractWebsite

A dynamical wave model implemented over the North Pacific Ocean was forced with winds from three coupled global climate models (CGCMs) run under a medium-to-high scenario for greenhouse gas emissions through the twenty-first century. The results are analyzed with respect to changes in upper quantiles of significant wave height (90th and 99th percentile H-S) during boreal winter. The three CGCMs produce surprisingly similar patterns of change in winter wave climate during the century, with waves becoming 10-15 % smaller over the lower mid-latitudes of the North Pacific, particularly in the central and western ocean. These decreases are closely associated with decreasing windspeeds along the southern flank of the main core of the westerlies. At higher latitudes, 99th percentile wave heights generally increase, though the patterns of change are less uniform than at lower latitudes. The increased wave heights at high latitudes appear to be due a variety of wind-related factors including both increased windspeeds and changes in the structure of the wind field, these varying from model to model. For one of the CGCMs, a commonly used statistical approach for estimating seasonal quantiles of H-S on the basis of seasonal mean sea level pressure (SLP) is used to develop a regression model from 60 years of twentieth century data as a training set, and then applied using twenty-first century SLP data. The statistical model reproduces the general pattern of decreasing twenty-first century wave heights south of similar to 40 N, but underestimates the magnitude of the changes by similar to 50-70 %, reflecting relatively weak coupling between sea level pressure and wave heights in the CGCM data and loss of variability in the statistically projected wave heights.

Young, AP, Guza RT, O'Reilly WC, Burvingt O, Flick RE.  2016.  Observations of coastal cliff base waves, sand levels, and cliff top shaking. Earth Surface Processes and Landforms. 41:1564-1573.   10.1002/esp.3928   AbstractWebsite

Concurrent observations of waves at the base of a southern California coastal cliff and seismic cliff motion were used to explore wave-cliff interaction and test proxies for wave forcing on coastal cliffs. Time series of waves and sand levels at the cliff base were extracted from pressure sensor observations programmatically and used to compute various wave impact metrics (e.g. significant cliff base wave height). Wave-cliff interaction was controlled by tide, incident waves, and beach sand levels, and varied from low tides with no wave-cliff impacts, to high tides with continuous wave-cliff interaction. Observed cliff base wave heights differed from standard Normal and Rayleigh distributions. Cliff base wave spectra levels were elevated at sea swell and infragravity frequencies. Coastal cliff top response to wave impacts was characterized using microseismic shaking in a frequency band (20-45Hz) sensitive to wave breaking and cliff impacts. Response in the 20-45Hz band was well correlated with wave-cliff impact metrics including cliff base significant wave height and hourly maximum water depth at the cliff base (r(2) = 0.75). With site-specific calibration relating wave impacts and shaking, and acceptable anthropogenic (traffic) noise levels, cliff top seismic observations are a viable proxy for cliff base wave conditions. The methods presented here are applicable to other coastal settings and can provide coastal managers with real time coastal conditions. Copyright (C) 2016 John Wiley & Sons, Ltd.

George, R, Flick RE, Guza RT.  1994.  Observations of Turbulence in the Surf Zone. Journal of Geophysical Research-Oceans. 99:801-810.   10.1029/93jc02717   AbstractWebsite

Turbulence generated by waves breaking on a natural beach is examined using hotfilm anemometer data. Turbulence intensity is estimated from dissipation rates determined from wavenumber spectra of short (1/8 s) hotfilm time series. The resulting Froude-scaled turbulence intensities are relatively uniform between the seabed and the wave trough level and are similar in vertical structure but lower in magnitude than in existing laboratory studies. The magnitudes of the turbulence intensities observed in both the field and laboratory are consistent with an existing macroscopic model of bore dissipation in the surf zone. Scaling by this bore model relates turbulence intensities generated by monochromatic waves in small-scale laboratory experiments to those generated by random waves in the natural surf zone.

Bromirski, PD, Flick RE, Graham N.  1999.  Ocean wave height determined from inland seismometer data: Implications for investigating wave climate changes in the NE Pacific. Journal of Geophysical Research-Oceans. 104:20753-20766.   10.1029/1999jc900156   AbstractWebsite

Knowing the wave climate along the California coast is vital from the perspectives of climatological change and planning shore protection measures. Buoy data indicate that the wave climate is very similar along much of the California coast. We show that elements of the wave climate can be accurately reconstructed using near-coastal inland broadband seismometer data. Such reconstructions are possible because swell approaching the coast generates pressure fluctuations that are locally transformed into seismic waves at the seafloor that propagate inland and are detectable by land-based seismometers. Buoy and seismometer data show that most of the microseism energy recorded inland near the coast is generated from wave events at nearby coastal locations. A site-specific, empirically derived seismic-to-wave transfer function is demonstrated to be applicable to seismic data from the same location for any year. These results suggest that ocean wave heights estimated from near-coastal broadband seismometer data are sufficiently reliable for monitoring the coastal wave height when buoy data are unavailable, provided that adequate simultaneous nearby buoy measurements are available to calibrate the seismometer data. The methodology presented here provides an important tool that allows the investigation of potential wave climate changes from reconstructions using archived seismic data collected since the 1930s.

Elwany, MHS, Flick RE, Aijaz S.  1998.  Opening and closure of a marginal southern California lagoon inlet. Estuaries. 21:246-254.   10.2307/1352472   AbstractWebsite

Over the past 50 yr, direct observations of the inlet status (open or closed) of San Dieguito Lagoon, a typical southern California lagoon located in Del Mar, California, have shown that river flooding is the major natural determinant of inlet conditions on time scales longer than a few years. River flooding is strongly dependent on rainfall in the San Dieguito River watershed and on the influences of two water storage reservoirs in the area. Rainfall fluctuates on yearly and longer time scales and undergoes cycles of wet and dry periods. Over short time periods, ranging from a few months to several years, inlet status is primarily determined by the available tidal prism and littoral sand transport. Recognition of these factors is crucial in order to correctly evaluate the probability that a small lagoon will remain open naturally. A probability approach is essential because the variables controlling inlet conditions are random in nature. The results of our study show that the inlet will remain open naturally 34% of the time. The tendency to remain open is vastly smaller during years of dry weather (12%) versus times of above-average rainfall (66%).

Flick, RE, Guza RT.  1980.  Paddle Generated Waves in Laboratory Channels. Journal of the Waterway Port Coastal and Ocean Division-Asce. 106:79-97. AbstractWebsite
Zetler, BD, Flick RE.  1985.  Predicted Extreme High Tides for California - 1983-2000. Journal of Waterway Port Coastal and Ocean Engineering-Asce. 111:758-765. AbstractWebsite