Pacific Coastal and Marine Science Center
Wednesday, Nov. 29th, 2:00 pm
Port and Airport Research Institute, Japan
Long-term daily beach observation and shoreline projection for climate change
Summary: Port and Airport Research Institute (PARI) have measured daily beach profiles since 1986 at the Hasaki coast of Japan. This long-term and high-time-resolution beach profile data is used to understand the nearshore processes and predict the future geomorphological change. Masayuki will talk about the data set and the future projected shoreline change at the coast due to SLR and wave climate change.
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Monday, Nov. 20th, 12:00 pm
Corrugations and roughness along the Costa Rica megathrust from 3D seismic reflection data: Implications for earthquakes
Wednesday, November 8th at 2:00 pm
USGS PCMSC, Santa Cruz, CA
Digging into Landscape Evolution: Subtropical Icebergs, Paleodrainage Patterns, Seafloor Seeps, Submarine Slides, and Subduction Zones
Weds., Oct. 18, 2017
Mark Buckley, Shawn Harrison, Pat Limber, and Ferdinand Oberle
USGS PCMSC Postdoctoral Researchers
USGS PCMSC Research Group Seminar Series
Weds., August 23rd, 2:00 pm
Deltares, South Holland, Netherlands
Modeling incident-band and infragravity wave dynamics on rocky shore platforms
Approximately three-quarters of the world’s coastline consists of rocky and cliffed coasts. Rocky shore platforms, low-gradient rock surfaces that occur within or close to the intertidal zone, play an important role on such coasts by dissipating waves and reducing the amount of wave energy reaching the base of the cliff. However, despite recent investigations of wave dynamics on rocky shore platforms few data exist with which to develop and validate numerical models that can be used to accurately predict wave transformation across shore platforms and wave impact at the cliff. The WASP (Waves Across Shore Platforms) project was set up to address the current lack of data and models for these types of coasts. To this end, field deployments were carried out during the winter of 2014–2015 at four rocky shore platforms in the UK and one platform in Ireland. Water levels were recorded at 4 Hz over 8–13 tides by a cross-shore array of 12–15 pressure transducers spaced approximately 10–15 m apart across the width of the intertidal shore platform. Shore platform morphology was surveyed using RTK-GPS to determine a representative cross-shore profile through the cross-shore instrument array, as well as using a Leica P20 terrestrial laser scanner to map platform roughness at high resolution (3.1 mm at 10 m distance). The field data were used to set up, calibrate and validate one-dimensional, cross-shore profile XBeach models. At each field site the incident-band wave height was calibrated by varying the incident-band bed friction factor used in the wave action balance in XBeach (fw), the incident-band wave breaker parameter (γ), and the infragravity wave related friction factor used in the non-linear shallow water equations in XBeach (cf). Model validation was carried out using wave height data from the 7–12 tides not used in the model calibration. The results of the model simulations show that after calibration of the three free model parameters, XBeach is able to simulate incident-band and infragravity-band wave height transformation well. Interestingly, the calibration method shows that the optimal value for the infragravity wave related friction factor (cf) for particularly the rougher sites depends on the level of bathymetric / topographic detail given as input to the model. It is thought that this is because the explicit inclusion of bed roughness elements in the model bathymetry in itself leads to infragravity wave energy loss in the non-linear shallow water equations.
Weds., August 9th, 2017, 2:00 pm
USGS Pacific Coastal and Marine Science Center, Santa Cruz, CA
Using detrital geochronology to track the erosion, transport, and deposition of sand: case studies from California
Fri., July 21st, 2017, 2:00pm
USGS St. Petersburg Coastal and Marine Sci. Center
Observation and Assessment of Coastal Sediment Availability and Flux
Coral reefs are unique environments due to the strong link between ecological processes, the sediment reservoir, and the morphology of the adjacent coastline. However, despite the prevalence of reef-fringed coastlines globally, there is still a lack of understanding of sediment dynamics governing shoreline variability in fringing reef environments. Therefore, predicting future changes to these coastlines in response to climate change requires a more in-depth, process-based understanding of these environments. Here we utilize both field-based and numerical techniques to examine the timescales and mechanisms of sediment transport along a section of Australia’s largest fringing reef, Ningaloo Reef, under both typical and extreme (cyclonic) conditions.
Data collected after direct impact of category 3 Tropical Cyclone Olwyn (2015) showed remarkably minimal morphological change to beaches in the lee of the reef, compared to what would be expected along an exposed sandy coast. The modest morphologic changes were explained by the spatial variability in nearshore hydrodynamics caused by the interaction of incident wind and wave energy with the reef and channel geometry. Furthermore, within one year, the coastline was restored to its pre-cyclone positon.
Over longer timescales and under more typical conditions, wave-driven bedload transport (in the form of shoreward migrating ripples) was identified as a primary mechanism of sediment transport across the lagoon towards the shoreline. Extrapolation of our observed ripple migration rates, and comparison with radiometric ages of sediment, suggests this mechanism could have built the modern shoreline morphology (i.e. large shoreline salient) within the age of the oldest measured sediment (~5,000 ka). More generally, our results suggest that the active sediment reservoir and calcifying community are temporally disconnected (i.e. sediments are derived from an older reef system), and therefore, the sediment budget in this system maybe be somewhat resilient to climate change induced declines in modern reef ecology.
The Southern California Coastal Water Research Project (SCCWRP) is a leading U.S. environmental research institute that works to develop a scientific foundation for informed water-quality management in southern California and beyond. Since its founding as a public agency in 1969, SCCWRP has been a champion of sound interdisciplinary approaches to solving complex challenges in water management. In this presentation, Executive Director, Stephen Weisberg, will provide an overview of research and monitoring activities at SCCWRP and highlight opportunities for future collaborative science.
In the time of big data, it is still difficult to make informed decisions to rebuild our crumbling infrastructure and invest in “the infrastructure of tomorrow” that is resilient to climate change and sea-level rise. A data dilemma is preventing data from supporting decision making. On the one hand, data are being overwhelmingly produced by sensor networks, high-resolution remote sensing, and large-scale parallel computing, but we still lack tools to translate data into information and insights that can inform decision making. On the other hand, data resolution and coverage may not meet decision makers’ needs.
I am fusing mechanistic modeling and data-driven analysis to address these issues. We performed a series of numerical simulations for San Francisco Bay to examine various shoreline scenarios and a series of short and long-term sea-level variability. A new Model Order Reduction technique -- Dynamic Mode Decomposition was applied to interpret the complicated tidal dynamics in space and time. An inverse method was developed to quantify the interaction of coastal infrastructure and storm events. A sensitivity analysis was performed to reveal the interaction of the counties around San Francisco Bay. At last, I will introduce my recent big-data work, which is aiming to address the resolution and coverage issue of the urban flooding datasets.
This research focused on the knowledge gap about how sediment moves around headlands. Historically, studies on the hydrodynamics of headlands have emphasized tide-dominated systems through observations and numerical modeling. This yielded an opportunity to explore circulation and sediment transport around headlands located on wave-dominated coasts. Three studies were undertaken to investigate the geomorphic, oceanographic, and sedimentologic influences on sediment flux: (i) a GIS-based classification of headlands, (ii) field observations at Pt. Dume, Malibu, a large headland in southern California, and (iii) a numerical modeling effort on four idealized headlands using Delft-3D-SWAN, the last two with extensive involvement of the USGS. Through the studies, headland size and shape coupled with incident wave angle emerged as the dominant factors influencing sediment pathways and sediment grain size determined the volume of sediment flux. The findings in each study were interpreted in the context of littoral cell boundaries, in particular to assess the “openness” of a headland-defined boundary. Assigning gradations of boundaries instead of the more commonly used “boundary” or “no boundary” monikers became apparent from the results that revealed sediment pathways varied by sediment grain size. The overarching conclusion from this dissertation was that a new set of parameters should be utilized to define littoral cell boundaries at headlands that take into account size, shape, and sediment. The headlands most likely to be candidates for absolute boundaries are large, pointed ones for most common beach-sized sand while large, broad-faced ones are barriers for coarser sand but not finer sand; smaller headlands are less likely to be absolute boundaries in general but can be barriers for coarser sand under certain conditions. Our knowledge of headland dynamics has been expanded as it relates to particle transport and delineation of dynamic littoral cell boundaries, which could lead to improved coastal management decisions in an era of profound coastal change.
Tip's presentation will highlight results from HR3D seismic data acquisition using Pcable technology in the Gulf of Mexico with the aim of developing collaborative research opportunities for further data acquisition for diverse application in a variety of geologic and geographic settings.
Sediment dynamics along the California coast are largely influenced by spatial and temporal variability in nearshore wave energy. The vastness of the Pacific Ocean and the complexity of California’s nearshore bathymetry, which is rife with canyons and, in the case of Southern California, exhibits a wide shelf protected by islands, yields multimodal wave spectra that are difficult to model and therefore predict. Towards this goal, a statistical method was developed to downscale local multimodal wave conditions from large-scale atmospheric patterns. This work improves existing methods by partitioning wave spectra into wave systems, defined by discrete generation regions, and by considering the average wave speed of waves generated in different parts of those regions. For an example case offshore of Southern California, which experiences bimodal wave spectra, this new methodology yields improvements to the prediction of daily wave conditions over a reanalysis period. Statistical downscaling and a dynamical wave model were combined for a hybrid approach to assess the relative contribution of different wave systems to nearshore energy in Southern California. The relative contribution of wave energy by local seas, swell generated in the North Pacific, and swell generated in the South Pacific varies with large-scale atmospheric drivers, coastline orientation, and island shadowing. Surprisingly, swell generated in the Southern Hemisphere contributes nearly 40% of energy along some coasts during annual maximum events, with implications for alongshore sediment transport.