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.
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.
Sources/Usage: Public Domain.Wildfire-burned hillside in California. 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.
Sources/Usage: Public Domain.Dr. Christopher H. Lashley. 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.
Sources/Usage: Some content may have restrictions. Visit Media to see details.Natural Bridges State Beach, shown here in the middle of the photo, is nestled amongst coastal neighborhoods in the southwestern part of Santa Cruz, California. View is looking south. The offices of the USGS Pacific Coastal and Marine Science Center are just a few hundred feet north, outside the bottom portion of the photograph. - 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