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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Wave exposure of Corte Madera Marsh, Marin County, California: A field investigation
Tidal wetlands provide valuable habitat, are an important source of primary productivity, and can help to protect the shoreline from erosion by attenuating approaching waves. These functions are threatened by the loss of tidal marshes, whether due to erosion, sea-level rise, or land-use practices. Erosion protection by wetlands is expected to vary geographically, because wave attenuation in marshe
Authors
Jessica R. Lacy, Daniel J. Hoover
The dynamics of fine-grain sediment dredged from Santa Cruz Harbor
In the fall and early winter of 2009, a demonstration project was done at Santa Cruz Harbor, California, to determine if 450 m3/day of predominantly (71 percent) mud-sized sediment could be dredged from the inner portion of the harbor and discharged to the coastal ocean without significant impacts to the beach and inner shelf. During the project, more than 7600 m3 of sediment (~5400 m3 of fine-gra
Authors
Curt D. Storlazzi, Christopher H. Conaway, M. Katherine Presto, Joshua B. Logan, Katherine Cronin, Maarten van Ormondt, Jamie Lescinski, E. Lynne Harden, Jessica R. Lacy, Pieter K. Tonnon
An inexpensive instrument for measuring wave exposure and water velocity
Ocean waves drive a wide variety of nearshore physical processes, structuring entire ecosystems through their direct and indirect effects on the settlement, behavior, and survivorship of marine organisms. However, wave exposure remains difficult and expensive to measure. Here, we report on an inexpensive and easily constructed instrument for measuring wave-induced water velocities. The underwater
Authors
J.D. Figurski, D. Malone, J.R. Lacy, M. Denny
The influence of current speed and vegetation density on flow structure in two macrotidal eelgrass canopies
The influence of eelgrass (Zostera marina) on near-bed currents, turbulence, and drag was investigated at three sites in two eelgrass canopies of differing density and at one unvegetated site in the San Juan archipelago of Puget Sound, Washington, USA. Eelgrass blade length exceeded 1 m. Velocity profiles up to 1.5 m above the sea floor were collected over a spring-neap tidal cycle with a downward
Authors
Jessica R. Lacy, Sandy Wyllie-Echeverria
Wind-enhanced resuspension in the shallow waters of South San Francisco Bay: Mechanisms and potential implications for cohesive sediment transport
We investigated the driving forces of sediment dynamics at the shoals in South San Francisco Bay. Two stations were deployed along a line perpendicular to a 14 m deep channel, 1000 and 2000 m from the middle of the channel. Station depths were 2.59 and 2.19 m below mean lower low water, respectively. We used acoustic Doppler velocimeters for the simultaneous determination of current velocities, tu
Authors
Andreas Brand, Jessica R. Lacy, Kevin Hsu, Daniel Hoover, Steve Gladding, Mark T. Stacey
Evaluation of a Single-Beam Sonar System to Map Seagrass at Two Sites in Northern Puget Sound, Washington
Seagrass at two sites in northern Puget Sound, Possession Point and nearby Browns Bay, was mapped using both a single-beam sonar and underwater video camera. The acoustic and underwater video data were compared to evaluate the accuracy of acoustic estimates of seagrass cover. The accuracy of the acoustic method was calculated for three classifications of seagrass observed in underwater video: bare
Authors
Andrew W. Stevens, Jessica R. Lacy, David P. Finlayson, Guy Gelfenbaum
Seabed ripple morphology and surficial sediment size at the SAX04 experiments near Fort Walton Beach, Florida, fall 2004
Data presented in this report originates from measurements obtained off the Florida coast (fig. 1) as part of the Sediment Acoustics Experiment (SAX04) and Ripples Department Research Initiative (DRI) (Office of Naval Research (ONR), Critical Benthic Environmental Processes and Modeling, Long Range BAA 04-001, Sept. 10, 2003). The aim of this document is to present methods employed to extract data
Authors
Daniel M. Hanes, Li H. Erikson, Jamie M.R. Lescinski, Jodi N. Harney, Carissa L. Carter, Gerry A. Hatcher, Jessica R. Lacy, David M. Rubin
Bed forms created by simulated waves and currents in a large flume
The morphology and evolution of bed forms created by combinations of waves and currents were investigated using an oscillating plate in a 4-m-wide flume. Current speed ranged from 0 to 30 cm/s, maximum oscillatory velocity ranged from 20 to 48 cm/s, oscillation period was 8 s (except for one run with 12 s period), and the median grain size was 0.27 mm. The angle between oscillations and current wa
Authors
Jessica R. Lacy, David M. Rubin, Hiroshi Ikeda, Kuniyasu Mokudai, Daniel M. Hanes
Shear velocity estimates on the inner shelf off Grays Harbor, Washington, USA
Shear velocity was estimated from current measurements near the bottom off Grays Harbor, Washington between May 4 and June 6, 2001 under mostly wave-dominated conditions. A downward-looking pulse-coherent acoustic Doppler profiler (PCADP) and two acoustic-Doppler velocimeters (field version; ADVFs) were deployed on a tripod at 9-m water depth. Measurements from these instruments were used to estim
Authors
C. R. Sherwood, J.R. Lacy, G. Voulgaris
Estimating hydrodynamic roughness in a wave-dominated environment with a high-resolution acoustic Doppler profiler
Hydrodynamic roughness is a critical parameter for characterizing bottom drag in boundary layers, and it varies both spatially and temporally due to variation in grain size, bedforms, and saltating sediment. In this paper we investigate temporal variability in hydrodynamic roughness using velocity profiles in the bottom boundary layer measured with a high-resolution acoustic Doppler profiler (PCAD
Authors
J.R. Lacy, C. R. Sherwood, D.J. Wilson, T.A. Chisholm, G.R. Gelfenbaum
Accuracy of a pulse-coherent acoustic Doppler profiler in a wave-dominated flow
The accuracy of velocities measured by a pulse-coherent acoustic Doppler profiler (PCADP) in the bottom boundary layer of a wave-dominated inner-shelf environment is evaluated. The downward-looking PCADP measured velocities in eight 10-cm cells at 1 Hz. Velocities measured by the PCADP are compared to those measured by an acoustic Doppler velocimeter for wave orbital velocities up to 95 cm s-1 and
Authors
J.R. Lacy, C. R. Sherwood
Interaction of lateral baroclinic forcing and turbulence in an estuary
Observations of density and velocity in a channel in northern San Francisco Bay show that the onset of vertical density stratification during flood tides is controlled by the balance between the cross-channel baroclinic pressure gradient and vertical mixing due to turbulence. Profiles of velocity, salinity, temperature, and suspended sediment concentration were measured in transects across Suisun
Authors
J.R. Lacy, M.T. Stacey, J.R. Burau, Stephen G. Monismith
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Wave exposure of Corte Madera Marsh, Marin County, California: A field investigation
Tidal wetlands provide valuable habitat, are an important source of primary productivity, and can help to protect the shoreline from erosion by attenuating approaching waves. These functions are threatened by the loss of tidal marshes, whether due to erosion, sea-level rise, or land-use practices. Erosion protection by wetlands is expected to vary geographically, because wave attenuation in marsheAuthorsJessica R. Lacy, Daniel J. HooverThe dynamics of fine-grain sediment dredged from Santa Cruz Harbor
In the fall and early winter of 2009, a demonstration project was done at Santa Cruz Harbor, California, to determine if 450 m3/day of predominantly (71 percent) mud-sized sediment could be dredged from the inner portion of the harbor and discharged to the coastal ocean without significant impacts to the beach and inner shelf. During the project, more than 7600 m3 of sediment (~5400 m3 of fine-graAuthorsCurt D. Storlazzi, Christopher H. Conaway, M. Katherine Presto, Joshua B. Logan, Katherine Cronin, Maarten van Ormondt, Jamie Lescinski, E. Lynne Harden, Jessica R. Lacy, Pieter K. TonnonAn inexpensive instrument for measuring wave exposure and water velocity
Ocean waves drive a wide variety of nearshore physical processes, structuring entire ecosystems through their direct and indirect effects on the settlement, behavior, and survivorship of marine organisms. However, wave exposure remains difficult and expensive to measure. Here, we report on an inexpensive and easily constructed instrument for measuring wave-induced water velocities. The underwaterAuthorsJ.D. Figurski, D. Malone, J.R. Lacy, M. DennyThe influence of current speed and vegetation density on flow structure in two macrotidal eelgrass canopies
The influence of eelgrass (Zostera marina) on near-bed currents, turbulence, and drag was investigated at three sites in two eelgrass canopies of differing density and at one unvegetated site in the San Juan archipelago of Puget Sound, Washington, USA. Eelgrass blade length exceeded 1 m. Velocity profiles up to 1.5 m above the sea floor were collected over a spring-neap tidal cycle with a downwardAuthorsJessica R. Lacy, Sandy Wyllie-EcheverriaWind-enhanced resuspension in the shallow waters of South San Francisco Bay: Mechanisms and potential implications for cohesive sediment transport
We investigated the driving forces of sediment dynamics at the shoals in South San Francisco Bay. Two stations were deployed along a line perpendicular to a 14 m deep channel, 1000 and 2000 m from the middle of the channel. Station depths were 2.59 and 2.19 m below mean lower low water, respectively. We used acoustic Doppler velocimeters for the simultaneous determination of current velocities, tuAuthorsAndreas Brand, Jessica R. Lacy, Kevin Hsu, Daniel Hoover, Steve Gladding, Mark T. StaceyEvaluation of a Single-Beam Sonar System to Map Seagrass at Two Sites in Northern Puget Sound, Washington
Seagrass at two sites in northern Puget Sound, Possession Point and nearby Browns Bay, was mapped using both a single-beam sonar and underwater video camera. The acoustic and underwater video data were compared to evaluate the accuracy of acoustic estimates of seagrass cover. The accuracy of the acoustic method was calculated for three classifications of seagrass observed in underwater video: bareAuthorsAndrew W. Stevens, Jessica R. Lacy, David P. Finlayson, Guy GelfenbaumSeabed ripple morphology and surficial sediment size at the SAX04 experiments near Fort Walton Beach, Florida, fall 2004
Data presented in this report originates from measurements obtained off the Florida coast (fig. 1) as part of the Sediment Acoustics Experiment (SAX04) and Ripples Department Research Initiative (DRI) (Office of Naval Research (ONR), Critical Benthic Environmental Processes and Modeling, Long Range BAA 04-001, Sept. 10, 2003). The aim of this document is to present methods employed to extract dataAuthorsDaniel M. Hanes, Li H. Erikson, Jamie M.R. Lescinski, Jodi N. Harney, Carissa L. Carter, Gerry A. Hatcher, Jessica R. Lacy, David M. RubinBed forms created by simulated waves and currents in a large flume
The morphology and evolution of bed forms created by combinations of waves and currents were investigated using an oscillating plate in a 4-m-wide flume. Current speed ranged from 0 to 30 cm/s, maximum oscillatory velocity ranged from 20 to 48 cm/s, oscillation period was 8 s (except for one run with 12 s period), and the median grain size was 0.27 mm. The angle between oscillations and current waAuthorsJessica R. Lacy, David M. Rubin, Hiroshi Ikeda, Kuniyasu Mokudai, Daniel M. HanesShear velocity estimates on the inner shelf off Grays Harbor, Washington, USA
Shear velocity was estimated from current measurements near the bottom off Grays Harbor, Washington between May 4 and June 6, 2001 under mostly wave-dominated conditions. A downward-looking pulse-coherent acoustic Doppler profiler (PCADP) and two acoustic-Doppler velocimeters (field version; ADVFs) were deployed on a tripod at 9-m water depth. Measurements from these instruments were used to estimAuthorsC. R. Sherwood, J.R. Lacy, G. VoulgarisEstimating hydrodynamic roughness in a wave-dominated environment with a high-resolution acoustic Doppler profiler
Hydrodynamic roughness is a critical parameter for characterizing bottom drag in boundary layers, and it varies both spatially and temporally due to variation in grain size, bedforms, and saltating sediment. In this paper we investigate temporal variability in hydrodynamic roughness using velocity profiles in the bottom boundary layer measured with a high-resolution acoustic Doppler profiler (PCADAuthorsJ.R. Lacy, C. R. Sherwood, D.J. Wilson, T.A. Chisholm, G.R. GelfenbaumAccuracy of a pulse-coherent acoustic Doppler profiler in a wave-dominated flow
The accuracy of velocities measured by a pulse-coherent acoustic Doppler profiler (PCADP) in the bottom boundary layer of a wave-dominated inner-shelf environment is evaluated. The downward-looking PCADP measured velocities in eight 10-cm cells at 1 Hz. Velocities measured by the PCADP are compared to those measured by an acoustic Doppler velocimeter for wave orbital velocities up to 95 cm s-1 andAuthorsJ.R. Lacy, C. R. SherwoodInteraction of lateral baroclinic forcing and turbulence in an estuary
Observations of density and velocity in a channel in northern San Francisco Bay show that the onset of vertical density stratification during flood tides is controlled by the balance between the cross-channel baroclinic pressure gradient and vertical mixing due to turbulence. Profiles of velocity, salinity, temperature, and suspended sediment concentration were measured in transects across SuisunAuthorsJ.R. Lacy, M.T. Stacey, J.R. Burau, Stephen G. Monismith - News