Science Seminar Series Active
Welcome to the Pacific Coastal Marine Science Center (PCMSC) Seminar Series! Our seminars are on the first and third Tuesday of every month, usually from 10:00 – 11:00 am Pacific Time (1:00 - 2:00 pm Eastern) via Microsoft Teams. Please check each seminar announcement closely, as times may change.
In addition, we also co-host a special “Coastal Change Hazards” seminar on the second Tuesday every other month at 10am Pacific/1pm Eastern.
Link to join the Microsoft Teams live stream will be posted before each seminar.
WEDNESDAY, April 2, 2024 11:00 am-12:00 pm PST
Niky Taylor (Geographer, USGS Western Geographic Science Center)
Monitoring and mapping mercury species in south San Francisco Bay waters
Mercury is a neurotoxin that has polluted San Francisco Bay, California since the Gold-rush era. Historical mining and modern-day sources of mercury pollution pose risks to wildlife and human health. Previous studies have mapped mercury in water bodies by taking advantage of the biogeochemical relationships between mercury and water quality variables visible with remote sensing. These relationships include 1) Colored Dissolved Organic Matter (CDOM) and dissolved total mercury and methylmercury, and 2) Total Suspended Sediments (TSS) and particulate total mercury and methylmercury. Since both TSS and CDOM can be mapped using remote sensing data, our goal is to leverage those optically available constituents and develop in-water mercury relationships to model and map mercury species concentrations. We are collecting an in-water dataset to be paired with satellite imagery for creating these models.
Extreme precipitation events—such as atmospheric rivers—can lead to increased transport of mercury from the upper watersheds into the bay. In early 2023, northern California was hit by a sequence of severe atmospheric rivers, triggering several runoff events which impacted water quality within San Francisco Bay and presumably washed an unknown amount of mercury into the estuary system. We generated a Sentinel-2 satellite image time series of TSS over the course of the atmospheric river events from October 2022 through April 2023 (7 cloud-free images). The time series revealed large increases in TSS in January and March 2023 at creek outflows following periods of the most intense rainfall.
Patterns of mercury mobilization associated with restoration of the South Bay Salt Ponds is another unconstrained variable in mercury into SF Bay proper. The South Bay Salt Pond Restoration Project (SBSPRP) is in the process of reestablishing tidal flushing of former salt production ponds with the bay. An immediate science need of the SBSPRP is to evaluate the capacity to accurately map mercury species in surface water across space and time, to understand how salt pond breaches affect mercury species concentration patterns in bay surface water. The most recent SBSPRP breach occurred on December 13, 2023, reconnecting the Ravenswood Pond to the bay. A week prior, we deployed a continuously sampling C6P fluorometer in the waters just outside of the breach site. We observed a marked shift in water quality (i.e. increased turbidity and fDOM) just after the breach, prompting more investigation into potential mercury concentrations associated with this change.
WEDNESDAY, MARCH 20, 2024 1:00 pm-2:00 pm PST
Maria Winters, PhD
Modeling and Observations of Anthropogenic Dunes on Energetic Coastlines
Sea-level rise will increase the frequency and severity of coastal flooding events. Even minor water level increases will propagate wave energy landward, promote coastal erosion and, in turn, jeopardize backshore infrastructure. Critical infrastructure requires evolving coastal management and advanced engineering designs to facilitate long-term urban coastal realignment compatible with rising seas. Traditional coastal engineering uses hard infrastructure such as seawalls and revetments to protect urbanized backshores. Infrastructure failure during extreme water levels leads to catastrophic human and economic consequences. Evolving,
nature-inspired features such as living shorelines and artificial dunes present an attractive hardscape alternative. Although dune erosion modeling is prevalent in the literature, there is a paucity of information regarding the construction, design and efficacy of the hybrid dune counterparts, especially on energetic, wave-dominated coastlines (e.g., Pacific). The objective of this research is to advance nature-based coastal engineering through high-resolution spatiotemporal observations and numerical modeling.
TUESDAY, FEBRUARY 27, 2024 11:00 am-12:00 pm PST
Emily Bristol (USGS Mendenhall Fellow, Alaska Coastal Hazards and Processes)
Sources and Fate of Terrestrial Organic Matter in the Arctic Ocean
Rivers and coastal erosion supply tremendous quantities of terrestrial organic matter (OM) to the Arctic Ocean. In the marine environment, this organic matter may be decomposed, releasing greenhouse gases like carbon dioxide and methane, as well as inorganic nutrients that may fuel primary production. This terrestrial organic matter is also an energy subsidy for heterotrophs, accumulating in multiple trophic levels. Despite the importance of terrestrial inputs to nearshore biogeochemical cycling and food webs, very little is known about OM inputs from eroding soils or coastal groundwater along the Alaska Beaufort Sea. Here, various geochemical and experimental techniques are used to characterize the amount, composition, and biodegradability of organic matter in eroding coastal soils, groundwater, and surface waters. These data show that coastal erosion and supra-permafrost groundwater are likely important sources of biodegradable OM to the Beaufort Sea in the summer open water season when river inputs are low. Future work along the Alaska Beaufort Sea will use dual-carbon isotopic mixing models and lipid biomarkers to characterize OM in lagoon surface sediments, helping track terrestrial OM in the marine environment. These results will provide insight about how varying erosion rates, river inputs, and other factors impact benthic habitats and regional carbon cycling.
WeDNESday, OCTOBER 18, 2023 10:00 am-11:00 am PST
Manuel Zornoza-Aguado (University of Cantabria, Spain)
An efficient metamodel to downscale total water levels in open beaches
More frequent and intense storms, combined with growing coastal populations, make proper coastal management a key challenge for the coming years. As the potential impacts are highly damaging to societies, environments and economies, holistic approaches are being implemented to adequately reduce coastal risks. To achieve this goal, Disaster Risk Reduction strategies are being developed, within which hazard characterization is a cornerstone of the process. Herein, a hybrid methodology is described to obtain the wave setup and infragravity wave level components for estimating total water levels (TWLs) in coastal areas, taking into account the surf zone hydrodynamics involved. By combining statistical tools and numerical methods, high-resolution spatial distributions of wave height and water level components are calculated in an efficient and seamless manner. The proposed methodology is tested and numerically validated on La Salvé beach (Spain), showing a robust performance for diverse scenarios. The resulting TWLs allow for a more efficient evaluation of coastal hazards, having strong potential as guideline for coastal engineers, managers and emergency planners in the elaboration of adaptation and mitigation strategies. As an application of the metamodel to these coastal management tasks, significant past events are reconstructed, and their associated water level hazard is analyzed using a vertical hazard scale.
monday, april 24, 2023 10:00 am-11:00 am PST
Helen Dow, USGS (Pacific Coastal and Marine Science Center)
Post-wildfire sediment mobilization and its downstream implications across California, 1984 – 2021
Global climate change is already impacting California’s hydroclimate via compression of the rainy season and an increased frequency of hydrologic extremes. The western US has also seen a twofold increase in the number of fires and a fourfold increase in median annual area burned in recent decades. Post-wildfire studies reveal that fire greatly facilitates erosion via changes to vegetation and soil properties, with significant erosion observed when extreme rainfall follows wildfire. This suggests that the spatial and temporal patterns of post-wildfire erosion across the state may carry signatures of global climate change, with potential impacts to water resources, aquatic and riparian ecosystems, and near-shore environments. To quantify the potential impacts of post-wildfire erosion across California, we used the process-based model, Water Erosion Prediction Project (WEPP), to simulate post-fire erosion in watersheds impacted by wildfires greater than 100 km2 in the time period 1984-2021 for a total of 202 fires and ~21,500 watersheds. To account for post-fire debris flows, which are not included in WEPP, we compiled measured and modeled debris flow volumes from various sources. Our results provide the first regional-scale multi-decade assessment of the magnitude of post-fire sediment mobilization in a region that is experiencing a rapidly intensifying fire regime. We find that annual sediment mobilized is highly variable in space and time with big sediment years likely reflecting major impacts to coastal ecosystems and communities as well as water resources. With the likelihood for precipitation whiplash events occurring alongside an intensifying fire regime, our results suggest that post-fire erosion poses a significant hazard for water resource security.
Wednesday, January 25, 2023 9:30 am-10:30 am PST
Dr. Christopher H. Lashley (University of Delaware)
The Importance of Infragravity Waves at Coasts with Shallow Foreshores
Abstract: As storm waves propagate over shallow foreshores—such as marshes, mudflats, sandy beaches, and coral reefs—two notable processes occur. The first, which is more widely known, is the attenuation of the high-frequency waves that are collectively referred to as wind-sea and swell (SS), with periods less than 25 seconds. The limited water depth over the foreshore forces the SS waves to shoal and ultimately break. This shoaling and breaking, in turn, results in the second process: the growth of infragravity (IG) waves, with periods in the order of minutes. Current practice for the design and assessment of coastal flood defenses often relies on spectral wave modelling (e.g., SWAN) to estimate the nearshore wave height and period. While this approach accurately accounts for SS waves, it largely neglects the influence of IG waves. Here, the XBeach numerical model is used to: i) identify when and where IG waves play a significant role; and ii) develop an empirical model that can be combined with spectral wave models, allowing them to account for IG waves.
Check out our archive of past seminars.
Check out the archive of our past seminars.
Science Seminar Series Archives
- Overview
Welcome to the Pacific Coastal Marine Science Center (PCMSC) Seminar Series! Our seminars are on the first and third Tuesday of every month, usually from 10:00 – 11:00 am Pacific Time (1:00 - 2:00 pm Eastern) via Microsoft Teams. Please check each seminar announcement closely, as times may change.
In addition, we also co-host a special “Coastal Change Hazards” seminar on the second Tuesday every other month at 10am Pacific/1pm Eastern.
Link to join the Microsoft Teams live stream will be posted before each seminar.
WEDNESDAY, April 2, 2024 11:00 am-12:00 pm PST
Niky Taylor (Geographer, USGS Western Geographic Science Center)
Monitoring and mapping mercury species in south San Francisco Bay waters
Mercury is a neurotoxin that has polluted San Francisco Bay, California since the Gold-rush era. Historical mining and modern-day sources of mercury pollution pose risks to wildlife and human health. Previous studies have mapped mercury in water bodies by taking advantage of the biogeochemical relationships between mercury and water quality variables visible with remote sensing. These relationships include 1) Colored Dissolved Organic Matter (CDOM) and dissolved total mercury and methylmercury, and 2) Total Suspended Sediments (TSS) and particulate total mercury and methylmercury. Since both TSS and CDOM can be mapped using remote sensing data, our goal is to leverage those optically available constituents and develop in-water mercury relationships to model and map mercury species concentrations. We are collecting an in-water dataset to be paired with satellite imagery for creating these models.
Extreme precipitation events—such as atmospheric rivers—can lead to increased transport of mercury from the upper watersheds into the bay. In early 2023, northern California was hit by a sequence of severe atmospheric rivers, triggering several runoff events which impacted water quality within San Francisco Bay and presumably washed an unknown amount of mercury into the estuary system. We generated a Sentinel-2 satellite image time series of TSS over the course of the atmospheric river events from October 2022 through April 2023 (7 cloud-free images). The time series revealed large increases in TSS in January and March 2023 at creek outflows following periods of the most intense rainfall.
Patterns of mercury mobilization associated with restoration of the South Bay Salt Ponds is another unconstrained variable in mercury into SF Bay proper. The South Bay Salt Pond Restoration Project (SBSPRP) is in the process of reestablishing tidal flushing of former salt production ponds with the bay. An immediate science need of the SBSPRP is to evaluate the capacity to accurately map mercury species in surface water across space and time, to understand how salt pond breaches affect mercury species concentration patterns in bay surface water. The most recent SBSPRP breach occurred on December 13, 2023, reconnecting the Ravenswood Pond to the bay. A week prior, we deployed a continuously sampling C6P fluorometer in the waters just outside of the breach site. We observed a marked shift in water quality (i.e. increased turbidity and fDOM) just after the breach, prompting more investigation into potential mercury concentrations associated with this change.
WEDNESDAY, MARCH 20, 2024 1:00 pm-2:00 pm PST
Maria Winters, PhD
Modeling and Observations of Anthropogenic Dunes on Energetic Coastlines
Sea-level rise will increase the frequency and severity of coastal flooding events. Even minor water level increases will propagate wave energy landward, promote coastal erosion and, in turn, jeopardize backshore infrastructure. Critical infrastructure requires evolving coastal management and advanced engineering designs to facilitate long-term urban coastal realignment compatible with rising seas. Traditional coastal engineering uses hard infrastructure such as seawalls and revetments to protect urbanized backshores. Infrastructure failure during extreme water levels leads to catastrophic human and economic consequences. Evolving,
nature-inspired features such as living shorelines and artificial dunes present an attractive hardscape alternative. Although dune erosion modeling is prevalent in the literature, there is a paucity of information regarding the construction, design and efficacy of the hybrid dune counterparts, especially on energetic, wave-dominated coastlines (e.g., Pacific). The objective of this research is to advance nature-based coastal engineering through high-resolution spatiotemporal observations and numerical modeling.TUESDAY, FEBRUARY 27, 2024 11:00 am-12:00 pm PST
Emily Bristol (USGS Mendenhall Fellow, Alaska Coastal Hazards and Processes)
Sources and Fate of Terrestrial Organic Matter in the Arctic Ocean
Rivers and coastal erosion supply tremendous quantities of terrestrial organic matter (OM) to the Arctic Ocean. In the marine environment, this organic matter may be decomposed, releasing greenhouse gases like carbon dioxide and methane, as well as inorganic nutrients that may fuel primary production. This terrestrial organic matter is also an energy subsidy for heterotrophs, accumulating in multiple trophic levels. Despite the importance of terrestrial inputs to nearshore biogeochemical cycling and food webs, very little is known about OM inputs from eroding soils or coastal groundwater along the Alaska Beaufort Sea. Here, various geochemical and experimental techniques are used to characterize the amount, composition, and biodegradability of organic matter in eroding coastal soils, groundwater, and surface waters. These data show that coastal erosion and supra-permafrost groundwater are likely important sources of biodegradable OM to the Beaufort Sea in the summer open water season when river inputs are low. Future work along the Alaska Beaufort Sea will use dual-carbon isotopic mixing models and lipid biomarkers to characterize OM in lagoon surface sediments, helping track terrestrial OM in the marine environment. These results will provide insight about how varying erosion rates, river inputs, and other factors impact benthic habitats and regional carbon cycling.
Sources/Usage: Public Domain. View Media DetailsWeDNESday, OCTOBER 18, 2023 10:00 am-11:00 am PST
Manuel Zornoza-Aguado (University of Cantabria, Spain)
An efficient metamodel to downscale total water levels in open beaches
More frequent and intense storms, combined with growing coastal populations, make proper coastal management a key challenge for the coming years. As the potential impacts are highly damaging to societies, environments and economies, holistic approaches are being implemented to adequately reduce coastal risks. To achieve this goal, Disaster Risk Reduction strategies are being developed, within which hazard characterization is a cornerstone of the process. Herein, a hybrid methodology is described to obtain the wave setup and infragravity wave level components for estimating total water levels (TWLs) in coastal areas, taking into account the surf zone hydrodynamics involved. By combining statistical tools and numerical methods, high-resolution spatial distributions of wave height and water level components are calculated in an efficient and seamless manner. The proposed methodology is tested and numerically validated on La Salvé beach (Spain), showing a robust performance for diverse scenarios. The resulting TWLs allow for a more efficient evaluation of coastal hazards, having strong potential as guideline for coastal engineers, managers and emergency planners in the elaboration of adaptation and mitigation strategies. As an application of the metamodel to these coastal management tasks, significant past events are reconstructed, and their associated water level hazard is analyzed using a vertical hazard scale.
monday, april 24, 2023 10:00 am-11:00 am PST
Helen Dow, USGS (Pacific Coastal and Marine Science Center)
Post-wildfire sediment mobilization and its downstream implications across California, 1984 – 2021
Global climate change is already impacting California’s hydroclimate via compression of the rainy season and an increased frequency of hydrologic extremes. The western US has also seen a twofold increase in the number of fires and a fourfold increase in median annual area burned in recent decades. Post-wildfire studies reveal that fire greatly facilitates erosion via changes to vegetation and soil properties, with significant erosion observed when extreme rainfall follows wildfire. This suggests that the spatial and temporal patterns of post-wildfire erosion across the state may carry signatures of global climate change, with potential impacts to water resources, aquatic and riparian ecosystems, and near-shore environments. To quantify the potential impacts of post-wildfire erosion across California, we used the process-based model, Water Erosion Prediction Project (WEPP), to simulate post-fire erosion in watersheds impacted by wildfires greater than 100 km2 in the time period 1984-2021 for a total of 202 fires and ~21,500 watersheds. To account for post-fire debris flows, which are not included in WEPP, we compiled measured and modeled debris flow volumes from various sources. Our results provide the first regional-scale multi-decade assessment of the magnitude of post-fire sediment mobilization in a region that is experiencing a rapidly intensifying fire regime. We find that annual sediment mobilized is highly variable in space and time with big sediment years likely reflecting major impacts to coastal ecosystems and communities as well as water resources. With the likelihood for precipitation whiplash events occurring alongside an intensifying fire regime, our results suggest that post-fire erosion poses a significant hazard for water resource security.
Wednesday, January 25, 2023 9:30 am-10:30 am PST
Dr. Christopher H. Lashley (University of Delaware)
The Importance of Infragravity Waves at Coasts with Shallow Foreshores
Abstract: As storm waves propagate over shallow foreshores—such as marshes, mudflats, sandy beaches, and coral reefs—two notable processes occur. The first, which is more widely known, is the attenuation of the high-frequency waves that are collectively referred to as wind-sea and swell (SS), with periods less than 25 seconds. The limited water depth over the foreshore forces the SS waves to shoal and ultimately break. This shoaling and breaking, in turn, results in the second process: the growth of infragravity (IG) waves, with periods in the order of minutes. Current practice for the design and assessment of coastal flood defenses often relies on spectral wave modelling (e.g., SWAN) to estimate the nearshore wave height and period. While this approach accurately accounts for SS waves, it largely neglects the influence of IG waves. Here, the XBeach numerical model is used to: i) identify when and where IG waves play a significant role; and ii) develop an empirical model that can be combined with spectral wave models, allowing them to account for IG waves.
Check out our archive of past seminars.
- Science
Check out the archive of our past seminars.
Science Seminar Series Archives
A list of past science seminars hosted by the Pacific Coastal and Marine Science Center, Santa Cruz, California