Rachel M. Allen, PhD
My work focuses on sediment transport in estuarine systems. Using observations and numerical models of physical processes like flow, waves, vegetation, turbulence, and sediment flocculation, I'm searching for ways to better understand how sediment moves around.
Prior to grad school, I worked at the San Francisco Estuary Institute with their Regional Monitoring Program for water quality, learning about the interactions between scientists and managers. During my PhD and as a post-doc, I worked with Dr. Jessica Lacy at the USGS Pacific Coastal and Marine Science Center in Santa Cruz CA. I started a Mendenhall with Dr. Neil Ganju at the USGS Woods Hole Coastal and Marine Science Center in 2021.
Professional Experience
USGS Woods Hole Coastal and Marine Science Center, 2021-present
USGS Pacific Coastal and Marine Science Center, 2018-2021
San Francisco Estuary Institute, 2009-2012
Education and Certifications
University of California, Berkeley, Master of Science and PhD - Civil Engineering, 2012-2018
Williams College, Bachelor of Arts - Chemistry and Mathematics, 2004-2008
Science and Products
Idealized COAWST model cases for testing sensitivity of sediment transport and marsh accretion to vegetation, wave, and sediment parameters
Hydrodynamic, sediment transport, and sediment flocculation data from south San Francisco Bay, California, summer 2020
Hydrodynamic and sediment transport model of San Pablo Bay, California, Nov-Dec 2014
Hydrodynamic and sediment transport data from San Pablo Bay and Grizzly Bay, California, 2019
Sediment transport and aquatic vegetation data from three locations in the Sacramento-San Joaquin Delta, California, 2017 to 2018
Hydrodynamic and sediment transport data from San Pablo Bay and China Camp marsh (northern San Francisco Bay), 2013-2016
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 deposition in the r
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 turbidity. In
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 measured at sites
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 both instru
Science and Products
Idealized COAWST model cases for testing sensitivity of sediment transport and marsh accretion to vegetation, wave, and sediment parameters
Hydrodynamic, sediment transport, and sediment flocculation data from south San Francisco Bay, California, summer 2020
Hydrodynamic and sediment transport model of San Pablo Bay, California, Nov-Dec 2014
Hydrodynamic and sediment transport data from San Pablo Bay and Grizzly Bay, California, 2019
Sediment transport and aquatic vegetation data from three locations in the Sacramento-San Joaquin Delta, California, 2017 to 2018
Hydrodynamic and sediment transport data from San Pablo Bay and China Camp marsh (northern San Francisco Bay), 2013-2016
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 deposition in the r
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 turbidity. In
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 measured at sites
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 both instru