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Pacific Coastal & Marine Science Center

Sediment Transport in Coastal Environments: Current Research

Joanne Ferriera and Tim Elfers position an instrument-laden tripod for deployment in Corte Madera Marsh; from USGS Open-File Report 2011-1183.Drag and sediment transport: conditions at the bottom boundary

Task lead: Jessica R. Lacy
Research Oceanographer

Objectives:

  1. Investigate the influence of seafloor properties, including bed sediment grain size, bedform morphology, and vegetation characteristics, on sediment resuspension and transport.
  2. Develop parameterizations of the influence of seafloor properties on sediment transport for inclusion in numerical models.
  3. Investigate the temporal variability of bed-sediment grain size on event and seasonal time scales, and investigate the response of bedform morphology to changes in bed sediment grain size.
  4. Collaborate with Team members in collecting oceanographic and sediment transport data to advance understanding of coastal ecosystems and coastal hazards.

Elkhorn Slough from Elena Nilsen.Coastal watershed and estuary restoration in the Monterey Bay area

Task lead: Amy Draut
Research Geologist

This task will support and further work by the USGS and collaborating federal, state, and local agencies, and academic partners, in analyzing the effectiveness of restoration work in coastal watersheds and estuaries in the Monterey Bay area. The USGS will play a supporting role in field efforts led by NOAA and California State University - Monterey Bay to measure physical and ecological changes in the Carmel River watershed resulting from the largest dam removal in California.


Monterey Submarine Canyon map showing three USGS mooring locations; from Xu, 2014.Sediment transport in submarine canyons

Task lead: Katie Maier
Research Geologist

The over-arching aim of the task is to produce a step-change in understanding of submarine turbidity currents by (i) measuring their two key features (synchronous velocity and concentration profiles) in detail (every 2-to-30 seconds) for the first time, and (ii) documenting spatial changes in their flow velocity from source-to-sink for the first time. The following specific questions will be answered:

  1. Do turbidity currents contain distinct near-bed layers with elevated sediment concentration that damps turbulence, and what is the relative importance of dense or dilute layers for overall momentum transfer?
  2. Do turbidity currents either accelerate and erode (ignite) or decelerate and deposit (dissipate), or can they existing in an equilibrium-state with near uniform velocity?
  3. What is the quantitative relationship between mean flow velocity and sediment carrying capacity?

Columbia River Estuary; from USGS Open-File Report 2011-1228Columbia River estuary

Task lead: Guy Gelfenbaum
Research Oceanographer

USGS PCMSC is working closely with the states of Washington and Oregon, the U.S. Army Corps of Engineers, and others to bring the best available scientific information on sediment management to decision makers.

USGS PCMSC has developed a state-of-the-art process-based numerical model of hydrodynamics and sediment transport for the lower Columbia River, Columbia River Estuary, and adjacent coast, and works closely with partners to develop, calibrate and verify the model.

Because of the expertise developed over the years, USGS is sought by others to perform field work and modeling at the mouth of the Columbia River.


USGS sample locations of sediment samples, collected in winter 2008, within the study area and used to groundtruth acoustic data interpretations.San Francisco Bay geomorphology

Task lead: Bruce Jaffe
Research Oceanographer

The primary objective of this task is to develop tools for predicting the long-term geomorphic evolution of estuaries.

Sediment core and historical change analysis will be used in combination with interpretation of high-resolution seismic profiles to develop tools for predicting geomorphic evolution of estuaries. Historical change analysis will use hydrographic and lidar data. Longer-term data will be derived from sediment cores.


USGS scientists from the Pacific Coastal and Marine Science Center explore how sediment moves across San Francisco Bay tidal flats.Sediment transport between estuarine habitats in San Francisco Bay

Task lead: Jessica R. Lacy
Research Oceanographer

Objectives:

  1. Investigate mechanisms of sediment transport from shoals to channels
  2. Investigate resuspension dynamics in subtidal and intertidal shoals, and determine critical shear stresses for these environments
  3. Investigate wave evolution in the shallows, because of its critical importance to sediment resuspension
  4. Investigate wave attenuation in marshes
  5. Investigate transport of sediment between mudflats and marshes
  6. Produce data sets for calibration of and comparison with sediment transport models, including wave parameters, suspended sediment concentration, and sediment flux.

Accomplishments:

Four large deployments (30-40 instruments at 5-8 stations) measuring waves, currents, turbulence, and suspended sediment concentration have been completed: two in South San Francisco Bay, focused on exchange between shoal and channel, in collaboration with UC Berkeley; and two in San Pablo Bay, focused on transport between intertidal and subtidal regions, as part of a post-doctoral research project. See a video on this project at http://gallery.usgs.gov/videos/369. A smaller deployment in Corte Madera Bay was also completed, focused on wave attenuation in the shallows, as part of a larger San Francisco Bay Conservation and Development Commission project.


Drawings and light micrographs of Trochammina hadai and T. pacifica.Transport of invasive microorganisms

Task lead: Mary McGann
Research Geologist

The objectives of his project are to investigate the vectors and timing of microbiological invasions and the subsequent dispersal of these non-native organisms due to sediment transport.

We will attempt to confirm the identification of specific invasives encountered with molecular sequencing, monitor the spread of the invading populations through their recent distribution and the historic sedimentologic record, and document the impact of the invasions on native populations.

The information we gain in this study will also aid port managers in developing plans for reducing the introduction of invasives in our nation's ports by understanding potential pathways of introductions and the temporal survival capability of these organisms during transport.

 

 

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