In situ seafloor images from the lower Columbia River, Washington and Oregon, 2021

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Frequently anticipated questions:

What does this data set describe?

Title:
In situ seafloor images from the lower Columbia River, Washington and Oregon, 2021
Abstract:
In situ seafloor images were acquired at four sites (SKM, SLG, LDB, WLW) in the lower Columbia River, Washington and Oregon, with an underwater camera system between June 5 and June 8, 2021. Between 248 and 427 digital images of the sediment surface were collected at each site with an underwater camera system that was repeatedly lowered to the seabed along a series of 1 km-long transects oriented along the main navigation channel and spaced about 60 m apart. The camera consisted of a FLIR Blackfly BFS-PGE-50S5 camera and 50 mm lens in a waterproof housing that resulted in a field of view of approximately 17 mm and a resolution of 0.00657 mm per pixel when the housing window was flush with the sediment surface. The imagery is provided in .tif format and compressed into .zip archives for each site. Images used for calibration of the automated processing algorithm to determine sediment grain size distributions were different than those used to validate the technique and were provided in separate .zip archives.
Supplemental_Information:
Additional information about the field activity or activities from which these data were derived is available online at: https://cmgds.marine.usgs.gov/fan_info.php?fan=2021-621-FA Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  1. How might this data set be cited?
    Hatcher, Gerald A., Stevens, Andrew W., and Ferro, Peter Dal, 20230808, In situ seafloor images from the lower Columbia River, Washington and Oregon, 2021: data release DOI:10.5066/10.5066/P92U1KPY, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Stevens, Andrew W., Hatcher, Gerald A., Ferro, Peter Dal, Dartnell, Peter, Warrick, Jonathan A., Cohn, Nicholas, and Moritz, Hans R., 2023, Digital seafloor images, sediment grain size, bathymetry, and water velocity data from the lower Columbia River, Washington and Oregon, 2021: data release DOI:10.5066/P92U1KPY, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

    Other_Citation_Details:
    Suggested Citation: Suggested Citation: Stevens, A.W., Hatcher, G.A., Dal Ferro, P., Warrick, J.A., Cohn, N., and Moritz, H.R., 2023, Digital seafloor images, sediment grain size, bathymetry, and water velocity data from the lower Columbia River, Washington and Oregon, 2021: U.S. Geological Survey data release, https://doi.org/10.5066/P92U1KPY.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -123.442574
    East_Bounding_Coordinate: -122.762951
    North_Bounding_Coordinate: 46.250242
    South_Bounding_Coordinate: 45.712673
  3. What does it look like?
    eyeball_field_data.png (PNG)
    Photographs showing equipment used to acquire seafloor images and example images collected with the camera system
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 05-Jun-2021
    Ending_Date: 08-Jun-2021
    Currentness_Reference:
    ground condition at time data were collected
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: comma-delimited text
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Raster data set. It contains the following raster data types:
      • Dimensions 2048 x 2448, type Pixel
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    There are no additional attributes besides the tags described in data quality section associated with these images.
    Entity_and_Attribute_Detail_Citation: USGS Field Activity 2021-621-FA

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Gerald A. Hatcher
    • Andrew W. Stevens
    • Peter Dal Ferro
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Attn: PCMSC Science Data Coordinator
    2885 Mission Street
    Santa Cruz, CA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

Growth of subaqueous sand dunes commonly causes shoaling in engineered river channels that necessitates costly dredging to maintain adequate depths for navigation. The factors that result in sand wave growth are theoretically understood from laboratory experiments, but the capacity to predict sand wave geometries in field settings is limited due to temporal and spatial variability in hydrodynamics and sediment grain size. Detailed measurements of sand wave geometries, hydrodynamics, and grain size are therefore needed to test and improve numerical models and inform efficient management strategies in navigation channels. This data release presents surface sediment grain size distributions, bathymetry and seafloor acoustic backscatter, and water velocity data acquired at four sites with subaqueous sand dunes in the lower Columbia River, Washington and Oregon, between June 4 and June 9, 2021. The four sites were located between 65 km and 127 km upstream from the ocean inlet along a gradient of relative tidal and fluvial influence. The survey was performed during peak annual river discharge when sediment transport processes were likely active. High resolution digital images were collected at each site with an underwater camera system that was repeatedly lowered to the seabed along a series of 1 km-long transects oriented along the main navigation channel and spaced about 60 m apart. The grain size distributions of the seabed images were estimated using an automated image processing technique and tested with observed grain size distributions derived from manual measurements on a subset of 16 images. Swath bathymetry and seafloor acoustic backscatter data were collected repeatedly at each site using a 234.5 kHz phase-differencing sidescan sonar to characterize sand wave geometry and bathymetric change resulting from sand wave migration. Current velocity data were collected from an underway survey vessel equipped with a downward looking 600 kHz ADCP along transects oriented both along- and across the main navigation channel. Combined, these data provide a comprehensive characterization of mobile subaqueous sand dunes that can be used to improve predictions of dune growth in complicated field settings and inform efficient sediment management practices in the lower Columbia River.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 08-Jun-2021 (process 1 of 3)
    High resolution spatial surveys were performed between June 5 and 8, 2021 to quantify surface sediment grain size distributions of mobile subaqueous dunes at four sites in the lower Columbia River, Washington and Oregon. At each site, digital images of the sediment surface were collected with an underwater camera system that was repeatedly lowered to the seabed along a series of 1 km-long transects oriented along the main navigation channel and spaced about 60 m apart. The camera consisted of a FLIR Blackfly BFS-PGE-50S5 camera and 50 mm lens in a waterproof housing that resulted in a field of view of approximately 17 mm and a resolution of 0.00657 mm per pixel when the housing window was flush with the sediment surface. An ethernet cable between the survey vessel and camera provided power to the camera and allowed for real-time viewing of the seafloor imagery on a computer during acquisition. The locations of each seafloor image were determined using an Applanix POSMV Wavemaster global navigation satellite system receiver operating in DGNSS mode.
    Date: 13-Dec-2022 (process 2 of 3)
    Imagery were inspected to remove images that were not suitable for analysis, including blurry images and replicate images. Clear images of the seabed were subjectively classified into three groups including those that were suitable for automated grain size analysis, those that were too coarse (too few grains in the image), and those that were too fine (individual grains not visible) for analysis. The images that were too coarse or too fine for detailed quantitative analysis were retained for the qualitative information contained.
    Date: 15-Mar-2023 (process 3 of 3)
    Images were organized by site zipped for distribution. The sites include Skamokawa (dgs_images_slg.zip), Slaughters Bar (dgs_images_skm.zip), Lower Dobelbower (dgs_images_ldb.zip), and Willow Bar (dgs_images_wlw.zip). Additional zip files are provided that include the images used for calibration (dgs_images_calibration.zip) and validation (dgs_images_validation.zip) of the automated image processing techniques to quantify grain size distributions in the imagery.
  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Information about the acquisition times and positions is recorded to the image metadata (EXIF) header for each image. The positions of the images were determined using an Applanix POSMV Wavemaster operating in DGNSS mode. A shipboard computer running a custom software was used to view and record images from the camera and record the positions from the POSMV resulting in a log file that contained the image file name, acquisition time, and position of the survey vessel at the time of image acquisition. The positions and times in the log file were later written to the EXIF header of each image using the command-line 'exiftool' software. The positions stored in the EXIF are in the WGS84 (G1150) coordinate reference system and times are all in Coordinated Universal Time (UTC).
  2. How accurate are the geographic locations?
    The locations of each seafloor image collected were determined using an Applanix POSMV Wavemaster operating in DGNSS mode. Manufacturer reported accuracy of the horizontal positions while operating in DGNSS mode is between 0.5 and 2 m depending on the quality of the DGNSS corrections received (https://www.applanix.com/downloads/products/specs/posmv/POS-MV-WaveMaster-II.pdf). Additional uncertainty in the horizontal positions of the images due to instrument layback, or non-vertical wire angle between surface vessel and camera at the seafloor, is unknown but assumed to be minimal because of the weight of the camera and slow speed of the vessel relative to the ambient currents during image acquisition.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    No formal logical accuracy tests were conducted.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints None
Use_Constraints USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator(s) of the dataset and in products derived from these data.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - CMGDS
    2885 Mission Street
    Santa Cruz, CA

    1-831-427-4747 (voice)
    pcmsc_data@usgs.gov
  2. What's the catalog number I need to order this data set? The seafloor images from four sites conducted during the survey are available in TIFF format. The images from each site (SKM, SLG, LDB, WLW) as well as images used for calibration and validation of the automated processing technique used to determine the sediment grain size distributions of each image are combined into a zip file with the site identifier in the file name.
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.
  4. How can I download or order the data?
    • Availability in digital form:
      Data format: Zipped files contain geotagged seafloor images collected for calibration of the image processing technique. in format TIFF (version MATLAB Version: 9.13.0.2080170 (R2022b)) Size: 198.3
      Network links: https://doi.org/10.5066/P92U1KPY
      Data format: Zipped files contain geotagged seafloor images collected from the Lower Dobelbower (LDB) site. in format TIFF (version MATLAB Version: 9.13.0.2080170 (R2022b)) Size: 4400.0
      Network links: https://doi.org/10.5066/P92U1KPY
      Data format: Zipped files contain geotagged seafloor images collected from the Skamokawa (SKM) site. in format TIFF (version MATLAB Version: 9.13.0.2080170 (R2022b)) Size: 4600.0
      Network links: https://doi.org/10.5066/P92U1KPY
      Data format: Zipped files contain geotagged seafloor images collected from the Slaughters Bar (SLG) site. in format TIFF (version MATLAB Version: 9.13.0.2080170 (R2022b)) Size: 3200.0
      Network links: https://doi.org/10.5066/P92U1KPY
      Data format: Zipped files contain geotagged seafloor images collected for validation of the image processing technique. in format TIFF (version MATLAB Version: 9.13.0.2080170 (R2022b)) Size: 199.0
      Network links: https://doi.org/10.5066/P92U1KPY
      Data format: Zipped files contain geotagged seafloor images collected from the Willow Bar (WLW) site. in format TIFF (version MATLAB Version: 9.13.0.2080170 (R2022b)) Size: 5400.0
      Network links: https://doi.org/10.5066/P92U1KPY
    • Cost to order the data: None.

Who wrote the metadata?

Dates:
Last modified: 08-Aug-2023
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/DataReleases/CMGDS_DR_tool/DR_P92U1KPY/dgs_images_metadata.faq.html>
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