Rachel M. Allen, PhD (Former Employee)
Science and Products
Idealized COAWST model cases for testing sensitivity of sediment transport and marsh accretion to vegetation, wave, and sediment parameters Idealized COAWST model cases for testing sensitivity of sediment transport and marsh accretion to vegetation, wave, and sediment parameters
Marshes may drown if they are unable to accrete sediment at the rate of sea level rise, but predicting the rate of sediment accretion at different marshes is challenging because many processes (e.g. tidal range, wave frequency) and conditions (e.g. available sediment, vegetation density, shape of the marsh edge) impact it. The Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST...
Hydrodynamic, sediment transport, and sediment flocculation data from south San Francisco Bay, California, summer 2020 Hydrodynamic, sediment transport, and sediment flocculation data from south San Francisco Bay, California, summer 2020
The U.S. Geological Survey (USGS) Pacific Coastal and Marine Science Center collected hydrodynamic and suspended sediment flocculation data at channel and shallow water sites in south San Francisco Bay in July 2020. The data were used to determine water column stratification, turbulence profiles, and floc size evolution. The goal of this project was to bound the controls on floc size and...
Hydrodynamic and sediment transport model of San Pablo Bay, California, Nov-Dec 2014 Hydrodynamic and sediment transport model of San Pablo Bay, California, Nov-Dec 2014
A three-dimensional hydrodynamic and sediment transport model of San Pablo and Suisun Bays was constructed using the Delft3D4 (D3D) modeling suite (Deltares, 2021a) to simulate water levels, flow, waves, and suspended sediment for time period of Nov 1 to Dec 31, 2014. This data release describes the construction and validation of the model application and provides input files suitable to...
Hydrodynamic and sediment transport data from San Pablo Bay and Grizzly Bay, California, 2019 Hydrodynamic and sediment transport data from San Pablo Bay and Grizzly Bay, California, 2019
The U.S. Geological Survey Pacific Coastal and Marine Science Center collected hydrodynamic and sediment-transport data at shallow water sites in San Pablo Bay and Grizzly Bay, in northern San Francisco Bay between June and November 2019. The data were collected to determine hydrodynamic forcing, bed roughness, suspended-sediment concentration, and physical properties of the sediment bed...
Sediment transport and aquatic vegetation data from three locations in the Sacramento-San Joaquin Delta, California, 2017 to 2018 Sediment transport and aquatic vegetation data from three locations in the Sacramento-San Joaquin Delta, California, 2017 to 2018
We measured currents, suspended-sediment concentration (SSC), bed sediment characteristics, and vegetation biomass density in the Sacramento-San Joaquin Delta in 2017-2018, as part of a project investigating the influence of invasive aquatic vegetation (IAV) on flow and sediment flux. This data release includes data from three sites: Lindsey Slough (April 2017), Middle River (March 2018)...
Hydrodynamic and sediment transport data from San Pablo Bay and China Camp marsh (northern San Francisco Bay), 2013-2016 Hydrodynamic and sediment transport data from San Pablo Bay and China Camp marsh (northern San Francisco Bay), 2013-2016
The U.S. Geological Survey Pacific Coastal and Marine Science Center collected data to investigate sediment dynamics in the shallows of San Pablo Bay and sediment exchange between bay shallows and the tidal salt marsh in China Camp State Park in a series of deployments between December 2013 and June 2016. This data release includes two related groups of data sets. The first group...
Sensitivity analysis of a dynamic vegetation-sediment transport model using equadratures: Exploring inorganic accretion on a marsh platform Sensitivity analysis of a dynamic vegetation-sediment transport model using equadratures: Exploring inorganic accretion on a marsh platform
Salt marsh systems require a net import of inorganic sediment to maintain their structure in response to sea‐level rise. Marshes are affected by physical processes including tides, waves, sediment transport, and the influence of vegetation, and these processes interact in complex ways leading to sediment accretion or erosion. We implement a 3‐D hydrodynamic sediment transport model in an...
Authors
Rachel Allen, Neil K. Ganju, Tarandeep Kalra, Alfredo Aretxabaleta, Jessica R. Lacy
Observations of flocs in an estuary and implications for computation of settling velocity Observations of flocs in an estuary and implications for computation of settling velocity
The settling velocity (ws) in estuarine environments can impact whether a region is eroding or accreting sediment on the bed, yet determining this rate can be an indirect process requiring a number of assumptions. Accurate determination of ws is especially needed for numerical models to reproduce observed sediment concentrations at the appropriate timescale. We collected information on...
Authors
Rachel Allen, Daniel Livsey, Samantha C. McGill
Cohesive sediment modeling in a shallow estuary: Model and environmental implications of sediment parameter variation Cohesive sediment modeling in a shallow estuary: Model and environmental implications of sediment parameter variation
Numerical models of sediment transport in estuarine systems rely on parameter values that are often poorly constrained and can vary on timescales relevant to model processes. The selection of parameter values can affect the accuracy of model predictions, while environmental variation of these parameters can impact the temporal and spatial ranges of sediment fluxes, erosion, and...
Authors
Rachel Allen, Jessica R. Lacy, Andrew W. Stevens
Influence of invasive submerged aquatic vegetation (E. densa) on currents and sediment transport in a freshwater tidal system Influence of invasive submerged aquatic vegetation (E. densa) on currents and sediment transport in a freshwater tidal system
We present a field study combining measurements of vegetation density, vegetative drag, and reduction of suspended-sediment concentration (SSC) within patches of the invasive submerged aquatic plant Egeria densa. Our study was motivated by concern that sediment trapping by E. densa, which has proliferated in the Sacramento–San Joaquin Delta, is impacting marsh accretion and reducing...
Authors
Jessica R. Lacy, Madeline R. Foster-Martinez, Rachel M. Allen, Judith Z. Drexler
Seasonal, spring-neap, and tidal variation in cohesive sediment transport parameters in estuarine shallows Seasonal, spring-neap, and tidal variation in cohesive sediment transport parameters in estuarine shallows
Numerical models for predicting sediment concentrations and transport rely on parameters such as settling velocity and bed erodibility that describe sediment characteristics, yet these parameters are rarely probed directly. We investigated temporal and spatial variation in sediment parameters in the shallows of San Pablo Bay, CA. Flow, turbulence, and suspended sediment data were...
Authors
Rachel Allen, Jessica R. Lacy, Mark T. Stacey, Evan A Variano
Measuring settling velocity in a strongly tidal estuary Measuring settling velocity in a strongly tidal estuary
Predicting sediment transport in estuarine systems requires understanding sediment settling velocity, its range of fluctuations, and the shortcomings of the tools to measure it. Previous studies have used Laser In-Situ Scattering and Transmissometry (LISST) instruments to measure particle size and Acoustic Doppler Velocimeters (ADV) to return estimates of settling velocity. We deployed...
Authors
Rachel Allen, Jessica R. Lacy, Evan A Variano
Science and Products
Idealized COAWST model cases for testing sensitivity of sediment transport and marsh accretion to vegetation, wave, and sediment parameters Idealized COAWST model cases for testing sensitivity of sediment transport and marsh accretion to vegetation, wave, and sediment parameters
Marshes may drown if they are unable to accrete sediment at the rate of sea level rise, but predicting the rate of sediment accretion at different marshes is challenging because many processes (e.g. tidal range, wave frequency) and conditions (e.g. available sediment, vegetation density, shape of the marsh edge) impact it. The Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST...
Hydrodynamic, sediment transport, and sediment flocculation data from south San Francisco Bay, California, summer 2020 Hydrodynamic, sediment transport, and sediment flocculation data from south San Francisco Bay, California, summer 2020
The U.S. Geological Survey (USGS) Pacific Coastal and Marine Science Center collected hydrodynamic and suspended sediment flocculation data at channel and shallow water sites in south San Francisco Bay in July 2020. The data were used to determine water column stratification, turbulence profiles, and floc size evolution. The goal of this project was to bound the controls on floc size and...
Hydrodynamic and sediment transport model of San Pablo Bay, California, Nov-Dec 2014 Hydrodynamic and sediment transport model of San Pablo Bay, California, Nov-Dec 2014
A three-dimensional hydrodynamic and sediment transport model of San Pablo and Suisun Bays was constructed using the Delft3D4 (D3D) modeling suite (Deltares, 2021a) to simulate water levels, flow, waves, and suspended sediment for time period of Nov 1 to Dec 31, 2014. This data release describes the construction and validation of the model application and provides input files suitable to...
Hydrodynamic and sediment transport data from San Pablo Bay and Grizzly Bay, California, 2019 Hydrodynamic and sediment transport data from San Pablo Bay and Grizzly Bay, California, 2019
The U.S. Geological Survey Pacific Coastal and Marine Science Center collected hydrodynamic and sediment-transport data at shallow water sites in San Pablo Bay and Grizzly Bay, in northern San Francisco Bay between June and November 2019. The data were collected to determine hydrodynamic forcing, bed roughness, suspended-sediment concentration, and physical properties of the sediment bed...
Sediment transport and aquatic vegetation data from three locations in the Sacramento-San Joaquin Delta, California, 2017 to 2018 Sediment transport and aquatic vegetation data from three locations in the Sacramento-San Joaquin Delta, California, 2017 to 2018
We measured currents, suspended-sediment concentration (SSC), bed sediment characteristics, and vegetation biomass density in the Sacramento-San Joaquin Delta in 2017-2018, as part of a project investigating the influence of invasive aquatic vegetation (IAV) on flow and sediment flux. This data release includes data from three sites: Lindsey Slough (April 2017), Middle River (March 2018)...
Hydrodynamic and sediment transport data from San Pablo Bay and China Camp marsh (northern San Francisco Bay), 2013-2016 Hydrodynamic and sediment transport data from San Pablo Bay and China Camp marsh (northern San Francisco Bay), 2013-2016
The U.S. Geological Survey Pacific Coastal and Marine Science Center collected data to investigate sediment dynamics in the shallows of San Pablo Bay and sediment exchange between bay shallows and the tidal salt marsh in China Camp State Park in a series of deployments between December 2013 and June 2016. This data release includes two related groups of data sets. The first group...
Sensitivity analysis of a dynamic vegetation-sediment transport model using equadratures: Exploring inorganic accretion on a marsh platform Sensitivity analysis of a dynamic vegetation-sediment transport model using equadratures: Exploring inorganic accretion on a marsh platform
Salt marsh systems require a net import of inorganic sediment to maintain their structure in response to sea‐level rise. Marshes are affected by physical processes including tides, waves, sediment transport, and the influence of vegetation, and these processes interact in complex ways leading to sediment accretion or erosion. We implement a 3‐D hydrodynamic sediment transport model in an...
Authors
Rachel Allen, Neil K. Ganju, Tarandeep Kalra, Alfredo Aretxabaleta, Jessica R. Lacy
Observations of flocs in an estuary and implications for computation of settling velocity Observations of flocs in an estuary and implications for computation of settling velocity
The settling velocity (ws) in estuarine environments can impact whether a region is eroding or accreting sediment on the bed, yet determining this rate can be an indirect process requiring a number of assumptions. Accurate determination of ws is especially needed for numerical models to reproduce observed sediment concentrations at the appropriate timescale. We collected information on...
Authors
Rachel Allen, Daniel Livsey, Samantha C. McGill
Cohesive sediment modeling in a shallow estuary: Model and environmental implications of sediment parameter variation Cohesive sediment modeling in a shallow estuary: Model and environmental implications of sediment parameter variation
Numerical models of sediment transport in estuarine systems rely on parameter values that are often poorly constrained and can vary on timescales relevant to model processes. The selection of parameter values can affect the accuracy of model predictions, while environmental variation of these parameters can impact the temporal and spatial ranges of sediment fluxes, erosion, and...
Authors
Rachel Allen, Jessica R. Lacy, Andrew W. Stevens
Influence of invasive submerged aquatic vegetation (E. densa) on currents and sediment transport in a freshwater tidal system Influence of invasive submerged aquatic vegetation (E. densa) on currents and sediment transport in a freshwater tidal system
We present a field study combining measurements of vegetation density, vegetative drag, and reduction of suspended-sediment concentration (SSC) within patches of the invasive submerged aquatic plant Egeria densa. Our study was motivated by concern that sediment trapping by E. densa, which has proliferated in the Sacramento–San Joaquin Delta, is impacting marsh accretion and reducing...
Authors
Jessica R. Lacy, Madeline R. Foster-Martinez, Rachel M. Allen, Judith Z. Drexler
Seasonal, spring-neap, and tidal variation in cohesive sediment transport parameters in estuarine shallows Seasonal, spring-neap, and tidal variation in cohesive sediment transport parameters in estuarine shallows
Numerical models for predicting sediment concentrations and transport rely on parameters such as settling velocity and bed erodibility that describe sediment characteristics, yet these parameters are rarely probed directly. We investigated temporal and spatial variation in sediment parameters in the shallows of San Pablo Bay, CA. Flow, turbulence, and suspended sediment data were...
Authors
Rachel Allen, Jessica R. Lacy, Mark T. Stacey, Evan A Variano
Measuring settling velocity in a strongly tidal estuary Measuring settling velocity in a strongly tidal estuary
Predicting sediment transport in estuarine systems requires understanding sediment settling velocity, its range of fluctuations, and the shortcomings of the tools to measure it. Previous studies have used Laser In-Situ Scattering and Transmissometry (LISST) instruments to measure particle size and Acoustic Doppler Velocimeters (ADV) to return estimates of settling velocity. We deployed...
Authors
Rachel Allen, Jessica R. Lacy, Evan A Variano