Pacific Coastal and Marine Science Center
Weds., July 25th, 2:00pm
University of Western Australia
The impact of bathymetry and roughness on the transport of reef generated sediment
Abstract: The three-dimensional structure of coral reef bathymetry and bottom roughness affects the hydrodynamic processes that mobilize and transport sediment. These processes vary both spatially and temporally due to the physical characteristics of the reef. Attempts to describe sediment suspended from the bed have typically focused on correct representation of these hydrodynamic processes (which can be readily measured) with bottom friction parameters often adjusted until predicted wave heights and flow match field measurements. While this approach yields ‘correct’ representation of the hydrodynamic processes, large roughness substantially alters the boundary layer structure. Sediment transport equations do not account for these boundary layer changes and this has important consequences for the prediction of sediment dynamics in these environments. This seminar will focus on what is known about the type of sediment being transported, the contribution of different physical processes as well as how a range of new techniques are being combined to improve insight into how sediment transport processes in reef environments.
Thurs., June 21st at 11:00 am
NOAA National Centers for Coastal Ocean Science (NCCOS)
Introduction to NOAA National Centers for Coastal Ocean Science (NCCOS)
Abstract: The United States has been endowed with a tremendous asset: our ocean and coastal resources. The facts are incontrovertible. Coastal counties contribute over $6.6 trillion to our nation’s gross domestic product, which is nearly 50 percent of national output. Approximately 40 percent of U.S. citizens live in these counties, attracted by both the natural beauty of the coasts and plentiful employment opportunities. It is here that Americans live, work, recreate, and seek to reconnect with nature.
With such a concentration of human activity, there exists the potential for conflict between various uses of these resources. In addition, the coastal environment is a dynamic place; sea levels change, natural resources shift, patterns of human use vary, and industries wax and wane. Officials at the local, state, tribal, and federal level, along with those in the corporate and nonprofit sectors, must use the best available information to make decisions that affect livelihoods, property values, human health, preparedness for disasters, management of our natural resources, and protection of special places for future generations.
Our role is to conduct the research and provide the information necessary to address these complex coastal challenges. The mission of the National Centers for Coastal Ocean Science (NCCOS) is to deliver ecosystem science solutions for stewardship of the nation’s ocean and coastal resources to sustain thriving coastal communities and economies.
June 13th, 2018, 2:00pm
Greater Farallones National Marine Sanctuary (GFNMS) and Central and Northern California Ocean Observing System (CeNCOOS)
The Sediment Swirl: Knowledge Gaps in Sediment Transport Along the North-Central California Coast
June 6th, 2018, 2:00pm
USGS Geology, Minerals, Energy, and Geophysics Science Center
Where is the Sediment Coming From? Mapping, Monitoring, and Modeling Sources of Sediment Pollution in West Maui
Abstract: Episodic storm runoff in West Maui (Hawai’i) brings plumes of terrestrially-sourced fine sediment to the nearshore ocean environment, degrading coral reef ecosystems. The sediment pollution sources were largely unknown, though suspected to be due to modern human disturbance of the landscape, and initially assumed to be from visibly obvious exposed soil on agricultural fields and unimproved roads. To determine the sediment sources and estimate a sediment budget for the West Maui watersheds, we mapped the geomorphic processes in the field and from DEMs and orthoimagery, monitored erosion rates in the field, and modeled the sediment flux using the mapped processes and corresponding rates. We found the primary source of fine sands, silts and clays to be previously unidentified fill terraces along the stream bed. These terraces, formed during legacy agricultural activity, are the banks along 40-70% of the streams where the channels intersect human-modified landscapes. Monitoring over the last year shows that a few storms erode the fill terraces 10-20 mm annually, contributing up to 100s of tonnes of sediment per catchment. Compared to the average long-term, geologic erosion rate of 0.03 mm/yr, these fill terraces alone increase the suspended sediment flux to the coral reefs by 50-90%. Additionally, we are testing our ability to use geochemical fingerprints to track the contribution from each geomorphic source. The goal is for stakeholders to use our resulting geomorphic process map and sediment budget to inform the location and type of mitigation needed to limit terrestrial sediment pollution. We are also applying this mapping, monitoring, and modeling (M3) workflow to West Hawaii to quantify the terrestrial sediment reaching Pelekane Bay from the cattle-grazed uplands.
May 30th, 2018, 2:00pm
UC-Santa Cruz and NOAA National Marine Fisheries Service
The chaos and mayhem of juvenile salmon migration through the San Francisco estuary
Abstract: Beneath the familiar ebbs and swells of tidal estuaries, migratory aquatic animals run the gauntlet of violent buffeting by erratic eddies and sudden death by predatory strikes. We are attempting to shed light on the essential processes at this vivid but tumultuous interface of the physical and biological worlds using seemingly simplistic, but nonetheless informative models.
I will be describing the hydrodynamic component of the Central Valley Chinook Life Cycle Model (CVCLCM), a nested modeling framework to describe the movement and fate of juvenile salmonids as they migrate to the ocean from California's rivers through the Sacramento-San Joaquin Delta (hereafter, the Delta). The endangered species act protects these fish by requiring that flows and water operations are regulated to ensure their safe passage through the Delta, and the National Marine Fisheries Service has been mandated to provide a robust scientific model based expert opinions on these water operations. The CVCLCM describes the dynamic evolution of a salmonid population governed by various ecological parameters. The survival through the Delta is a crucial parameter in this model. This survival is estimated by tracking the physical and biological trajectories of simulated fish using a 3D stochastic Enhanced Particle Tracking Model (ePTM) based on a 1D shallow-water equation solver, DSM2. Sub-models nested within the ePTM are the "enhancements" which render the behavior of simulated fish, as well as parametrize higher dimensional physical processes into the 1D hydrodynamic solver.
The migration system involves several multi-scale non-linear feedbacks, and potential opportunities to address critical data-gaps: (i) what hydrodynamic and environmental drivers govern fish behaviors at the scales at which they possess memory?, (ii) how can these localized behaviors be integrated into a reach-scale migration model?, (iii) what role does the highly perturbation-sensitive (chaotic) movement of scalars due to the interaction of tides and residual currents through multiple channel junctions within the Delta play on the availability of environmental cues (if any) for fish?, (iv) are fish impacted by or able to overcome the effects of increased dispersal through the system due to the chaotic mixing dynamics within the distributed network of tidal channels in the Delta?, (v) what spatio-temporal scales of hydrodynamic motion must be modeled accurately in order to recover the macro-scale statistics of movement and fate of both scalars and the fish?, and (vi) what data-gaps exist that render modeling this system challenging, and what can we do to overcome them?
As we are currently developing the ePTM and parameterizing complex physics into the DSM2, I will keep much of the discussion at the conceptual level and show a few preliminary results. I will also showcase some ancillary tools that we are developing that can be applicable in other areas of research.
May 23rd, 2018, 2:00pm
Data-augmented wave modelling with distributed sensor networks
Abstract: The capital investments required for acquisition, deployment and maintenance of buoy networks has resulted in sparse data networks. As a consequence, wave nowcasts (and forecasts) in coastal regions, rely almost exclusively on global model output to provide boundary conditions for local and regional models. This means that the local model inherits all potential errors accumulated over long distance propagation in global models (e.g. swell propagation). However, with the availability of low-cost, high-fidelity wave sensors, a more data-centric approach to nowcasts (and forecasts) is possible. Specifically, a limited array of sensors strategically deployed in a coastal section (say 100km alongshore), can fully constrain the model boundaries and does not require any outside information (from e.g. global models). Conceptually, the sensor network acts as a single observation system from which the best fitting wave field is reconstructed (in a least squares sense), thus eliminating the need for a global model for nowcast boundary conditions.
In this work we present results from such a data-augmented system, combining a dense network of low-cost directional wave buoys (Spoondrift Spotters) with an efficient assimilation method. The assimilation back-traces wave spectra and directional moments from the array to reconstruct the offshore incident directional-frequency spectrum in real-time, and a conventional wave model (SWAN) then forward propagates the information back into the domain. We discuss the underlying theory and present results from a the real-time data-assimilation system in which we integrate a dense network of 18 Spotters that were deployed seaward of Point Sal (California) for two months as part of the ONR Innershelf DRI experiment. We compare assimilated results with conventional model predictions forced with predictions from the global NOAA WAVEWATCH III model to illustrate the modeling improvements.
May 17th, 2018, 2:00pm
University of Hawaiʻi at Mānoa, Department of Geology and Geophysics
Mālama honua: Bridging traditional knowledge and modern science through observation. Island Sea-level History and Habitation
Abstract: In June 2017, Hōkūleʻa, a traditional Hawaiian voyaging canoe, completed a three year voyage around the world sharing the message of mālama honua (to care for island Earth). The voyage bridged traditional knowledge and modern science to communicate the changing conditions of our islands and oceans. The ʻōlelo noʻeau (Hawaiian proverb) "ka wā ma mua, ka wā ma hope" (time in front, time in back) describes the value of looking to the past to solve current and future dilemmas. Inspired by this ʻōlelo noʻeau and Hōkūleʻa, our research investigates a former sea-level event known as the mid-Holocene highstand. Analysis of island sediment and fossil reef cores improves understandings of the implications of sea-level change upon island stability. Our research calls upon the importance of understanding an islands sea-level history to interpret island habitability during initial colonization and into the future.
May 9th, 2018, 12:00pm
Improving parameterizations of fine sediment processes in large-scale models using direct-numerical simulations of sediment-laden wave-current boundary layers
May 2nd, 2018, 2:00pm
Humboldt State University
Improving subduction zone hazards assessments using diatom-based earthquake and tsunami reconstructions
April 25th, 2018, 2:00pm
USGS Earthquake Science Center
Vertical land motion of levees and flood overtopping potential in the Sacramento-San Joaquin Delta, and wave-glider-based seafloor geodesy
Abstract: The talk will discuss two topics related to geodesy and water. The first part will cover our recent study of subsidence associated with levees in California's Sacramento-San Joaquin Delta. We assess flood overtopping potential to the levees surrounding the islands in the interior of the Delta. We focus on those levees that are crossed by the network of the state's natural gas pipelines. We use laser scanning data collected during 2015/2016 to estimate subsidence rates since 2007 when an earlier, Delta-wide, airborne laser scanning topographic dataset was collected. For each levee studied, we combine: (1) the estimated subsidence rate; (2) a conservative range of sea-level rise projections and, (3) an estimate of the 100-year freshwater flood stage to project the time until exceedance of the Federal levee height standard (PL84-99). The second part will discuss our efforts in the Earthquake Science Center to develop wave-glider-based seafloor geodetic capability. I will introduce the concept and discuss our progress on deploying this Spring a wave-glider capable of performing GPS-A (GPS-acoustic) measurements in the Aleutian subduction zone.
April 11th, 2018, 12:00pm
USGS Earthquake Science Center
What's in the leftovers? Path and site effects in ground-motion prediction equations, and their residuals
Abstract: Large uncertainties in ground-motion estimation can be problematic for seismic hazard assessment, particularly critical facilities. Traditionally, ground-motion prediction equations are the main method of estimating ground motion for PSHA, and reducing uncertainty in them has been based on empirical observations of ground-motion alone. This is often problematic in regions which are not that seismically active, and therefore do not allow for such empirical methods. Another approach is including information about physical properties or processes in a region into ground-motion models, to use knowable, repeatable (and obtainable) parameters in models of ground-motion. I will present some work investigating ways to include crustal velocity or attenuation parameters or processes in ground-motion models for path-specific ground-motion estimation. To do this, I look at the relationships between GMPE residuals, and available crustal models, focusing on the Southern California region. Finally, I will show some observations of ground-motion residuals from the recent September 2017 earthquakes in Mexico, and discuss what information can be gleaned from them regarding regional properties, and GMPEs.
March 28th, 2018, 2:00pm
UC Santa Cruz
Measuring the extent and value of flood risk reduction by nature-based solutions: An overview
Abstract: There is increasing interest these days around nature-based solutions for reducing risk. Nature-based solutions in this context refer to risk reduction measures which incorporate natural coastal habitats such as coastal wetlands or reefs to varying degrees. Translating this interest into practical solutions requires as a first and crucial step, the assessment of the physical and economic extent to which these natural features contribute to risk reduction. As a growing corpus of work demonstrates, the risk reduction role played by nature-based solutions varies considerably depending on several hydrodynamic, physical, ecological and also socio-economic parameters. In this seminar I will present an overview of recent and on-going work in understanding when, where, how, and how much, nature-based solutions help reduce coastal flood risks, being done by our team of coastal engineers, ecologists and economists, and in close partnership with the private risk and insurance industry.
Biography: Siddharth Narayan is a coastal engineer, currently doing postdoctoral research at the University of California Santa Cruz. Sid is from Chennai in South India, where he did his bachelor’s degree in civil engineering. His research interests focus on developing tools and approaches to understand the interactions between natural and human coastal systems, to help develop sustainable measures for coastal adaptation. At present, he works with a team of coastal engineers, ecologists to assess the role and value of ecosystems for coastal protection and risk reduction. Sid did a CoMEM Master’s degree (NTNU – Delft – Soton) and then did his PhD here in Southampton, with Prof. Robert Nicholls and Dr. Derek Clarke. In his PhD he worked within the EU THESEUS project to develop a conceptual model to describe the coastal floodplain as a set of spatially distributed natural and human elements. The model allowed multiple users to build a shared understanding of how different coastal and floodplain elements are linked to, and influence one another, with regard to flood risk propagation.
March 27th, 2018, 2:00pm
San Diego State University
Deglacial stratigraphy of Beaufort Margin sediments, Arctic Ocean with a side of Oregon continental shelf paleodrainages
Abstract: The Arctic Ocean is rapidly changing in response to a warming climate. For insight into environmental response to climate change, we typically examine periods of rapid change in the past. However, the Arctic is a hard place to study due to the seasonal sea ice and minimal development along the coast, leading to a lack of data when compared to other ocean basins. We aim to fill in some of these knowledge gaps by examining the Wisconsin deglacial history of the Beaufort Margin in the western Arctic. In 2013, we conducted a cruise on the USCGC Healy to collect high-resolution CHIRP seismic reflection data, multibeam bathymetry data, and sediment cores to examine the deglacial sediment dispersal patterns for the region. The data indicate that the western margin, from Barrow Canyon to the Mackenzie Trough, is characterized by thick Holocene sediments mostly sourced from Barrow Canyon and continental discharge. The eastern Beaufort, from the Mackenzie Trough to the Amundsen Gulf, is dominated by event deposits. These include ice rafting events from the Amundsen Gulf ice stream and glacial lake discharge events that entered the Arctic via the Mackenzie. One of these discharge events coincides with the onset of the Younger Dryas cold period and could be discharge from glacial Lake Agassiz. In this talk, I will elaborate on the significance of this finding and the overall sediment dispersal patterns for the margin. I will also present a few slides on the work we have been doing on the continental shelf offshore of south-central Oregon. We have been developing a paleoenvironmental model for the area as a basis for potential archeological resources. As part of this, we have been mapping the paleodrainages on the shelf as well as the faulting and folding observed within chirp data.
March 21st, 2018, 2:00pm
Maialen Irazoqui Apecechea
Deltares - The Netherlands
The next generation Global Tide and Surge Model (GTSMv3.0)
Abstract: The GTSM is a hydrodynamic model based on Delft3D-FM which produces accurate tides and surges globally both for historical periods and for future climate change scenarios. In this lecture the model development, challenges, and a series of (business) opportunities and applications will be presented.
March 16th, 2018, 12:00pm
Airborne surveys by Rambol and SkyTem from Copenhagen, Denmark
We need more data to reduce the uncertainties — geophysics as a valuable component in groundwater investigations
March 14th, 2018, 2:00pm
University of California - Santa Cruz
Runoff processes from mountains to foothills: The role of the critical zone in influencing runoff across high to low relief landscapes
March 9th, 2018, 2:00pm
Sylvain Courrech du Pont
Université Paris Diderot
Morphology and dynamics of dunes
Abstract: The physics of dunes relies on the interaction between a wind flow and an erodible topography. Thus, if strong enough to transport grains, the wind shapes sandy areas into dune fields. These dunes are reminiscent of a wavy sea so that sandy deserts are called sand seas. However, the comparison stops there. Contrary to water waves, dunes propagate only under wind action and when the wind stops, they do not vanish but stand. Consequently, dunes are not only the result of the present winds, but can integrate the wind regimes over long periods. Thus, they exhibit a range of shapes and sizes with superimposed patterns. They are witnesses of past wind regimes and their shape and orientation are used to constraint climatic models on other planetary bodies where they are observed as well (e.g., Mars, Titan, and Venus). During the seminar, I will discuss the morphodynamics of dunes and endeavor to identify and to explain the physical mechanisms at play in the selection of their shape, size, and orientation, whilst focusing on Earth desert sand dunes.
March 8th, 2018, 12:00pm brown bag
eCoast Ltd in Raglan, New Zealand, and University of Southern California's Tsunami Research Center
Using the Rip Curl 'Search GPS' watch for the analysis, mapping, and monitoring of surfbreaks
March 7th, 2018, 2:00pm
USGS Pacific Coastal and Marine Science Center
The Impact of Sea-Level Rise and Climate Change on Atolls—Trying to Predict the Timing of the U.S.’s First Climate Change Refugees
February 28th, 2018, 2:00pm
University of California, Santa Cruz
Preservation of climatic signals in and across the Chinese Tian Shan piedmont
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February 21st, 2018, 2:00pm
University of Delaware
Filling in the Blank Spots on the Map
Abstract: SWASH is an open-source non-hydrostatic wave-flow model that is capable of simulating the wave and flow dynamics in realistic coastal regions. Over the past years, such wave-flow models have become an increasingly popular tool for both scientific and engineering purposes within the field of harbour and coastal engineering. Applications include, for example, modelling of complex nonlinear nearshore wave dynamics, agitation of waves in harbours, wave-induced flows (e.g., longshore and rip-currents), and runup oscillations at the beach. With this talk, I will present the basic modelling philosophy and an overview of the current capabilities of the SWASH model. Furthermore, several recent developments will be highlighted that have pushed the capabilities of the non-hydrostatic approach. This includes a subgrid approach that makes the modelling of 3D wave-induced flow features (e.g., undertow) feasible at field scales, and an extension of the model to simulate the interactions of waves with floating structures (e.g., ships and wave energy converters).
February 20th, 2018, 2:00pm
University of Delaware
Filling in the Blank Spots on the Map
Abstract: Coastal science and engineering has long battled with the dynamic and complex environments of the coastal zone and the difficulties of collecting data, teasing out multi-scale processes, and designing suitable projects for the conditions. Rapid improvements in technology, coupled with decreases in costs, enables researchers, managers, engineers, and policy makers improved data collection methods. These platforms have resulted in higher resolution information, both spatially and temporally, using low-cost, user-friendly, and mobile technologies such as aerial drones, autonomous surface vehicles, terrestrial lasers, and boat mounted sonars. This presentation shares the methodologies and results of several pilot studies performed using robotic systems in varied coastal areas such as natural dune systems, nourished beaches, tidal marshes, and shallow nearshore waters. Insights into benthic community ecosystem services, storm-related coastal morphology, beach and dune vegetation life cycles, and marsh vegetation mapping are providing quantitative data at a resolution and accuracy traditionally unobtainable in theses areas. Realistic operation times, equipment costs, easy-of-use, uncertainties, resolutions, and feasibilities will be discussed as well as methods for mapping and collecting data in these various environments. Site-specific hypothetical and what-if scenario questions are highly encouraged and welcomed!
February 9th, 2018, 2:00pm
USGS Woods Hole Coastal and Marine Science Center
Sediment transport in salt marshes both stable and massively eroding: Refining marsh vulnerability metrics
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January 24th, 2018, 2:00pm
Noisy sand in high velocity shear flow experiments
Abstract. Granular flows are ubiquitous in nature, yet defy easy characterization or simple rheological laws. A major unresolved question is the contribution of the fluctuations in the velocity field to the mean field response. Our experiments on angular sands show that acoustic energy created by a granular flow is an effective proxy for velocity fluctuations of grains within the flow, and we use this tool to explore granular flow rheology near the transition from creeping to inertially-driven fast flow.
January 10th, 2018, 2:00pm
Integral Consulting Inc.
Understanding wave energy on the west coast
The marine renewable energy industry requires robust tools to evaluate site characteristics and the potential environmental effects of marine hydrokinetic energy (MHK) devices. Working on multiple spatial and temporal scales, the application of predictive tools such as numerical models can help developers and regulators optimize device performance while also identifying potential ecosystem effects and determine appropriate mitigation measures. In coastal regions, the waves and nearshore currents govern the movement of sediments along the coastline. The transport patterns have a direct effect on coastal geomorphic features and the associated nearshore habitat. Modifications to the nearshore environment can modify sediment dynamics, altering sediment availability in adjacent regions. The presence of a Wave Energy Converter (WEC) array can cause modifications to these dynamics that can be both helpful and detrimental to coastal features and the associated ecology. The present work has three goals:
The case study is used to demonstrate how the changes in the physical environment, in particular waves, can be spatially mapped and quantified using a validated model. A discussion of how probabilistic spatial maps of physical alterations in the area are developed is included in the final section. The overall framework will allow for optimization of WEC deployments to minimize environmental impacts while power output is maximized.
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January 9th, 2018, 2:00pm
University of Wyoming
Coastal groundwater modeling for the eastern U.S.
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