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Jessie Lacy

Research Oceanographer with the USGS Pacific Coastal and Marine Science Center

My research interests include: Hydrodynamics of the coastal ocean, estuaries, and lakes; Lateral dynamics in estuaries with complex topography, and their influence on mixing; The dynamics of stratification and baroclinic transport; Estimation of bottom roughness, bottom shear stress, and sediment resuspension in wave-dominated environments; Interaction between aquatic vegetation and hydrodynamics

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View from the sky looking at mouth of river with lots of sediment deposited at a beach.

Sediment Transport in Coastal Environments

Our research goals are to provide the scientific information, knowledge, and tools required to ensure that decisions about land and resource use, management practices, and future development in the coastal zone and adjacent watersheds can be evaluated with a complete understanding of the probable effects on coastal ecosystems and communities, and a full assessment of their vulnerability to natural...
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, Sediment Lab Suite and Carbon Analysis Laboratory, San Francisco Bay and Sacramento-San Joaquin Delta Estuary
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Sediment Transport in Coastal Environments

Our research goals are to provide the scientific information, knowledge, and tools required to ensure that decisions about land and resource use, management practices, and future development in the coastal zone and adjacent watersheds can be evaluated with a complete understanding of the probable effects on coastal ecosystems and communities, and a full assessment of their vulnerability to natural...
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View from the air across a tidal march, mudflat, and channels with bay water to the right and a city in the background.

Sediment transport between estuarine habitats in San Francisco Bay

We investigate mechanisms of sediment transport, resuspension dynamics in shoals, wave evolution in the shallows, wave attenuation in marshes, and transport of sediment between mudflats and marshes. We produce data sets for calibration of and comparison with sediment transport models, including wave parameters, suspended sediment concentration, and sediment flux.
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Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, San Francisco Bay and Sacramento-San Joaquin Delta Estuary
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Sediment transport between estuarine habitats in San Francisco Bay

We investigate mechanisms of sediment transport, resuspension dynamics in shoals, wave evolution in the shallows, wave attenuation in marshes, and transport of sediment between mudflats and marshes. We produce data sets for calibration of and comparison with sediment transport models, including wave parameters, suspended sediment concentration, and sediment flux.
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Two people hold onto a large metal tripod with instruments suspended from a cable as they guide it into the water.

Drag and sediment transport: conditions at the bottom boundary

Research on bed sediment grain size, bedform morphology, vegetation characteristics, and sediment resuspension and transport.
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Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, Sediment Lab Suite and Carbon Analysis Laboratory, San Francisco Bay and Sacramento-San Joaquin Delta Estuary
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Drag and sediment transport: conditions at the bottom boundary

Research on bed sediment grain size, bedform morphology, vegetation characteristics, and sediment resuspension and transport.
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Invasive Aquatic Vegetation

Ecosystem Engineers: Impacts of Invasive Aquatic Vegetation on the Delta’s Critical Ecosystems

The Sacramento-San Joaquin Delta (Delta) is home to a diverse community of plants and animals and is the hub of California’s freshwater delivery system. The Delta supplies water for over 25 million Californians and supports millions of acres of farming, commercial and sport fishing, shipping and ports, and recreational boating.
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California Water Science Center, Pacific Coastal and Marine Science Center, San Francisco Bay and Sacramento-San Joaquin Delta Estuary
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Ecosystem Engineers: Impacts of Invasive Aquatic Vegetation on the Delta’s Critical Ecosystems

The Sacramento-San Joaquin Delta (Delta) is home to a diverse community of plants and animals and is the hub of California’s freshwater delivery system. The Delta supplies water for over 25 million Californians and supports millions of acres of farming, commercial and sport fishing, shipping and ports, and recreational boating.
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Filter Total Items: 14

Grain size, bulk density, and carbon content of sediment collected from Whale's Tail South marsh and adjacent bay floor, South San Francisco Bay, California, 2021-2022

Sediment samples were collected on and adjacent to the Whale's Tail South marsh. Short push-cores of bed sediment were collected in South San Francisco Bay adjacent to Whales Tail South marsh on five days from June through August 2021 and 3 days from November 2021 to January 2022. Additional samples were taken from ceramic tiles placed on the marsh to measure sediment deposition and from rip-up cl
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Pacific Coastal and Marine Science Center

Structure-from-motion derived orthomosaic imagery and digital surface models (DSMs) from the intertidal region at Whale's Tail Marsh, South San Francisco Bay, CA

This data release presents digital surface models (DSMs) and orthomosaic images of the Whale's Tail Marsh region of South San Francisco Bay, CA. The data were created using structure-from-motion (SfM) processing of repeat aerial imagery collected from fixed-wing aircraft. The raw images were acquired from an approximate altitude of 427 meters (1,400 feet) above ground level (AGL), using a Hasselbl
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Pacific Coastal and Marine Science Center

Hydrodynamic and sediment transport data from Whale's Tail marsh and adjacent waters in South San Francisco Bay, California 2021-2022

The U.S. Geological Survey Pacific Coastal and Marine Science Center collected hydrodynamic and sediment-transport data at shallow water sites in South San Francisco Bay and in the Whale's Tail South marsh in Eden Landing Ecological Reserve in Alameda County, CA in 2021 and 2022. This data release includes hydrodynamic and sediment transport time-series data spanning from June 2021 to January 2022
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Pacific Coastal and Marine Science Center

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 floc sett
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Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, San Francisco Bay and Sacramento-San Joaquin Delta Estuary

Hydrodynamic and sediment transport data from San Pablo Bay and Grizzly Bay, California, 2020

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 January and September 2020. The data were collected to determine hydrodynamic forcing, bed roughness, suspended-sediment concentration, and physical properties of the sediment bed. This
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, San Francisco Bay and Sacramento-San Joaquin Delta Estuary

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. This dat
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Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Near-bed velocity measurements in Monterey Bay during arrival of the 2010 Chile Tsunami

On February 27, 2010, a tsunami originating near Chile arrived in Monterey Bay, California. This data release comprises two hours of pressure and near-bed velocity data spanning the largest tsunami waves. At the time, the U.S. Geological Survey Pacific Coastal and Marine Science Center had a remotely-controlled instrumented platform deployed adjacent to the Santa Cruz Municipal Wharf (mean depth 9
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Pacific Coastal and Marine Science Center

Aerial imagery and structure-from-motion derived data products from UAS survey of the Liberty Island Conservation Bank Wildlands restoration site, Sacramento-San Joaquin Delta, California, October 2018

Unmanned aerial systems (UAS) were used to acquire high-resolution imagery of the Liberty Island Conservation Bank Wildlands restoration site in the Sacramento-San Joaquin Delta in California, with the goal of using structure-from-motion (SfM) photogrammetric techniques to derive a digital surface model, orthomosaic imagery, and a topographic point cloud. The survey was conducted using two Depart
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Pacific Coastal and Marine Science Center

Bed sediment properties in Little Holland Tract and Liberty Island, Sacramento-San Joaquin Delta, California, 2014 to 2019 (ver. 3.0, April 2023)

Bed sediments were collected by the USGS Pacific Coastal and Marine Science Center (PCMSC) in two submerged agricultural tracts, Liberty Island and Little Holland Tract, in the northern Sacramento-San Joaquin Delta, California. Samples were analyzed for grain size distribution, bulk density, or both. Analyses were conducted using PCMSC sediment lab standard techniques (see Process Step in metadata
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Pacific Coastal and Marine Science Center

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) and the l
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Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Bathymetry, topography, and acoustic backscatter data, and a digital elevation model (DEM) of the Cache Slough Complex and Sacramento River Deep Water Ship Channel, Sacramento-San Joaquin Delta, California

This data release presents bathymetric and topographic data from surveys performed between 2017 and 2018 in the Cache Slough Complex and the Sacramento River Deep Water Ship Channel (DWSC), northern Sacramento-San Joaquin Delta, California. The shallow, highly vegetated aquatic habitats of this region necessitated a variety of survey platforms and techniques. In the deeper channels, swath bathymet
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Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, San Francisco Bay and Sacramento-San Joaquin Delta Estuary

Wind-wave and suspended-sediment data from Liberty Island and Little Holland Tract, Sacramento-San Joaquin Delta, California (ver. 2.0, September 2019)

Data were collected by the U.S. Geological Survey (USGS) Pacific Coastal and Marine Science Center to investigate the influence of wind waves on sediment dynamics in two flooded agricultural tracts in the northern Sacramento-San Joaquin Delta: Little Holland Tract and Liberty Island. This effort is part of a large interdisciplinary study led by the USGS California Water Science Center and funded b
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Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center
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Climate Science Champions Season 3: Jessica Lacy, Research Oceanographer
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Climate Science Champions Season 3: Jessica Lacy, Research Oceanographer (AD)
Image of early morning Sediment Transport Fieldwork in San Francisco Bay link
Sediment Transport in San Francisco Bay (AD)
Image of early morning Sediment Transport Fieldwork in San Francisco Bay link
Sediment Transport in San Francisco Bay
Two men in a small boat, one is at the wheel, the boat is in a calm waterway with trees in the background.
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PCMSC boat Fast Eddy
A small boat sits on calm waters with trees in the distance, and a cloudy sky.
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Mokelumne River survey
Photos show people preparing data and sample collection devices to go into the water.
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Collecting data and samples from San Pablo Bay
Two photos show a metal frame that holds instruments to collect data in murky water.
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San Pablo Bay instrument frames
video thumbnail: Turbid Bay: Sediment in Motion link
Turbid Bay: Sediment in Motion
Filter Total Items: 32

The influence of vegetated marshes on wave transformation in sheltered estuaries

Assessing the influence of marshes on mitigating flooding along estuarine shorelines under the pressures of sea level rise requires understanding wave transformation across the marsh. A numerical model was applied to investigate how vegetated marshes influence wave transformation. XBeach non-hydrostatic (XB-NH) was calibrated and validated with high frequency pressure data from the marsh at China
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Rae M. Taylor-Burns, Kees Nederhoff, Jessica R. Lacy, Patrick L. Barnard
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Pacific Coastal and Marine Science Center

What controls suspended-sediment concentration and export in flooded agricultural tracts in the Sacramento-San Joaquin Delta?

We investigated wind-wave and suspended-sediment dynamics in Little Holland Tract and Liberty Island, two subsided former agricultural tracts in the Cache Slough complex in the northern Sacramento-San Joaquin Delta which were restored to tidal shallows to improve habitat. Turbidity, and thus suspended-sediment concentration (SSC), is important to habitat quality because some species of native fish
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Jessica R. Lacy, Evan Dailey, Tara L. Morgan-King
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Pacific Coastal and Marine Science Center

Numerical simulation of the boundary layer flow generated in Monterey Bay, California by the 2010 Chilean tsunami: Case study

This work presents a case study involving the numerical simulation of the unsteady boundary layer generated by the 2010 Chilean tsunami, as measured by field equipment in Monterey Bay, California, USA. A one-dimensional vertical (1DV) boundary layer model is utilized, solving Reynolds-averaged Navier–Stokes equations, coupled with two-equation k–ω turbulence closure. Local effects of convective ac
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Athanasios Makris, Jessica R. Lacy, David R. Fuhrman
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Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, Deep Sea Exploration, Mapping and Characterization

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

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Rachel Allen, Jessica R. Lacy, Andrew W. Stevens
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Mendenhall Research Fellowship Program, Pacific Coastal and Marine Science Center

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

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Jessica R. Lacy, Madeline R. Foster-Martinez, Rachel M. Allen, Judith Z. Drexler
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Natural Hazards Mission Area, Water Resources Mission Area, Coastal and Marine Hazards and Resources Program, California Water Science Center, Mendenhall Research Fellowship Program, Pacific Coastal and Marine Science Center, San Francisco Bay and Sacramento-San Joaquin Delta Estuary

The role of surges during periods of very shallow water on sediment transport over tidal flats

Periods of very shallow water (water depth in the order of 10 cm) occur daily on tidal flats because of the propagation of tides over very gently sloping beds, leading to distinct morphodynamical phenomena. To improve the understanding of the characteristics of velocity and suspended sediment concentration (SSC) surges and their contribution to sediment transport and local bed changes during perio
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Qian Zhang, Zheng Gong, Changkuan Zhang, Jessica R. Lacy, Bruce E. Jaffe, Beibei Xu, Xindi Chen
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Carbon storage and sediment trapping by Egeria densa Planch., a globally invasive, freshwater macrophyte

Invasive plants have long been recognized for altering ecosystem properties, but their long-term impacts on ecosystem processes remain largely unknown. In this study, we determined the impact of Egeria densa Planch, a globally invasive freshwater macrophyte, on sedimentation processes in a large tidal freshwater region. We measured carbon accumulation (CARs) and inorganic sedimentation rates in su
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Judith Z. Drexler, Shruti Khanna, Jessica R. Lacy
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Water Resources Mission Area, Coastal and Marine Hazards and Resources Program, California Water Science Center, Pacific Coastal and Marine Science Center

Seasonal variation in sediment delivery across the bay-marsh interface of an estuarine salt marsh

Sediment transport across bay–marsh interfaces depends on wave energy, vegetation, and marsh-edge morphology, and varies over a range of timescales. We investigated these dynamics in a tidal salt marsh with a gently-sloped, vegetated edge adjacent to northern San Francisco Bay. Spartina foliosa (cordgrass) inhabits the lower marsh and Salicornia pacifica (pickleweed) predominates on the marsh plain
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Jessica R. Lacy, Madeline R. Foster-Martinez, Rachel (Contractor) Allen, Matthew C. Ferner, John C. Callaway
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Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, San Francisco Bay and Sacramento-San Joaquin Delta Estuary

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

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Rachel Allen, Jessica R. Lacy, Mark T. Stacey, Evan A Variano
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Coastal and Marine Hazards and Resources Program, Mendenhall Research Fellowship Program, Pacific Coastal and Marine Science Center

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

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Rachel Allen, Jessica R. Lacy, Evan A Variano
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Mendenhall Research Fellowship Program, Pacific Coastal and Marine Science Center

Bed shear stress estimation under wave conditions using near-bottom measurements: Comparison of methods

Understanding the influence of waves on bed shear stress is critical for predicting morphodynamical behaviours in coastal areas. Near-bed flow was measured on the middle and lower intertidal mudflats along the Jiangsu coast, China, using a three-dimensional acoustic velocimeter that collected a 3.5-cm vertical profile at 1mm resolution and sample rate of 25 Hz. On the lower and middle tidal flats,
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Qian Zhang, Zheng Gong, Changkuan Zhang, Jessica R. Lacy, Bruce E. Jaffe, Beibei Xu
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Pacific Coastal and Marine Science Center

The influence of neap-spring tidal variation and wave energy on sediment flux in salt marsh tidal creeks

Sediment flux in marsh tidal creeks is commonly used to gage sediment supply to marshes. We conducted a field investigation of temporal variability in sediment flux in tidal creeks in the accreting tidal marsh at China Camp State Park adjacent to northern San Francisco Bay. Suspended-sediment concentration (SSC), velocity, and depth were measured near the mouths of two tidal creeks during three
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Jessica R. Lacy, Matthew C. Ferner, John C. Callaway
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Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center
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Are Invasive Plants Trapping the Sediment that a Healthy Estuary Needs? Sweating the Small Stuff in California’s Sacramento-San Joaquin River Delta

In recent years, invasive aquatic plants have increased exponentially in the shallow waters of California’s Sacramento-San Joaquin River Delta...

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Making Waves and Ripples in a Giant Flume in Japan

Sand on the seafloor is rarely flat, particularly close to the shore. Currents and waves interact with bed sediment to produce bedforms: ripples...

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Eelgrass in Puget Sound—A New Study of Flow, Sediment Transport, and Zostera marina

Meadows of eelgrass (Zostera marina) provide essential habitat to a wide range of fish and wildlife in the nearshore parts of Puget Sound, Washington...

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