Bathymetry, topography, and sediment grain-size data from the Elwha River delta, Washington, April and May 2014
Dates
Publication Date
2017-04-18
Start Date
2014-04-26
End Date
2014-05-12
Citation
Stevens, A.W., Gelfenbaum, G., Warrick, J.A., Miller, I.M., and Weiner, H.M., 2017, Bathymetry, topography, and sediment grain-size data from the Elwha River delta, Washington, April and May 2014: U.S. Geological Survey data release, http://dx.doi.org/10.5066/F76T0JSP.
Summary
Two dams on the Elwha River, Washington State, USA trapped over 20 million m3 of sediment, reducing downstream sediment fluxes and contributing to erosion of the river's coastal delta. The removal of the Elwha and Glines Canyon dams between 2011 and 2014 induced massive increases in river sediment supply and provided an unprecedented opportunity to examine the response of a delta system to changes in sediment supply. The U.S. Geological Survey (USGS) developed an integrated research program aimed at understanding the ecosystem responses following dam removal. The research program included repeated surveys of beach topography, nearshore bathymetry, and surface sediment grain size to quantify changes in delta morphology and texture following [...]
Summary
Two dams on the Elwha River, Washington State, USA trapped over 20 million m3 of sediment, reducing downstream sediment fluxes and contributing to erosion of the river's coastal delta. The removal of the Elwha and Glines Canyon dams between 2011 and 2014 induced massive increases in river sediment supply and provided an unprecedented opportunity to examine the response of a delta system to changes in sediment supply. The U.S. Geological Survey (USGS) developed an integrated research program aimed at understanding the ecosystem responses following dam removal. The research program included repeated surveys of beach topography, nearshore bathymetry, and surface sediment grain size to quantify changes in delta morphology and texture following the dam removals. For more information on the USGS role in the Elwha River Restoration Project, please visit http://walrus.wr.usgs.gov/elwha/.
This USGS data release presents data collected during surveys of nearshore bathymetry, beach topography, and surface sediment grain size from the Elwha River delta, Washington. Bathymetry and topography data were collected between April 26 and April 29, 2014, and surface sediment samples were collected on May 12, 2014 (USGS Field Activity Number 2014-620-FA). The survey team included scientists from the U.S. Geological Survey Pacific Coastal and Marine Science Center (PCMSC), Washington State Department of Ecology (WA DOE), Washington Sea Grant, and University of Washington (table 1).
Nearshore bathymetry data were collected using two personal watercraft (PWCs), each equipped with single-beam echosounders and survey-grade global navigation satellite system (GNSS) receivers. Topography data were collected on foot with GNSS receivers mounted on backpacks. Positions of the survey platforms were referenced to a GNSS base station placed on a nearby benchmark with known horizontal and vertical coordinates. Depths from the echosounders were computed using sound velocity profiles measured with a conductivity-temperature-depth (CTD) sensor during the survey. A total of 150 km of nearshore bathymetric survey lines and 130 km of topographic survey lines were collected during the 4 days of survey operations. Swift currents resulting from high river discharge during the survey limited access to portions of the river mouth that have normally been sampled by topographic surveyors on foot. Despite the challenge of high river flow, good coverage of the beach and nearshore region was achieved using the combination of methods described above. Surface sediment was sampled using a small ponar, or 'grab', sampler on May 12, 2014 from a small boat at a total of 43 locations in water depths between about 1 and 12 m around the delta. Figure 1 (top) shows the locations of bathymetric- and topographic-survey lines, sediment samples, CTD samples, and GNSS base stations. A continuous DEM surface of the primary survey area was produced from all available bathymetry and topography data using linear interpolation and a grid-spacing of 5 m. Figure 1 (bottom) shows the bathymetry and topography data for areas adjacent to the river mouth color-coded by elevation. An additional DEM with 1-m resolution grid-spacing was produced using linear interpolation for this smaller region.
Digital files containing the nearshore bathymetry data, beach topography data, derived DEMs, and grain-size data from this survey are available for download from the child item pages listed below.
Table 1. List of survey personnel
Person
Title
Affiliation
Guy Gelfenbaum
Research Oceanographer
USGS PCMSC
Jackson Currie
Physical Science Technician
USGS PCMSC
Andrew Stevens
Oceanographer
USGS PCMSC
Heather Weiner
Coastal Geomatics Specialist
WA DOE
Diana McCandless
Environmental Specialist
WA DOE
Amanda Hacking
Environmental Specialist
WA DOE
Kasey Bowles
Field Technician
WA DOE
Ian Miller
Coastal Hazards Specialist
Washington Sea Grant
Julia Dolan
Undergraduate Student
University of Washington
Sarra Tekola
Undergraduate Student
University of Washington
Figure 1. Top: Map showing locations of bathymetric- and topographic-survey lines, sediment samples, CTD casts, and GNSS base stations from the April and May 2014 survey of the Elwha River delta, Washington. Bottom: Zoomed in detail of top map showing bathymetric- and topographic-survey lines color-coded by elevation.
Click on title to download individual files attached to this item.
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Purpose
Data were obtained to assess the coastal geomorphic response following the removal of two dams on the Elwha River. These data are intended for science researchers, students, policy makers, and the general public. These data can be used with geographic information systems or other software to identify topographic and shallow-water bathymetric features.