Peter Dartnell Andrew W. Stevens Gerald A. Hatcher Peter Dal Ferro 20230808 GeoTIFF data release DOI:10.5066/P92U1KPY Pacific Coastal and Marine Science Center, Santa Cruz, California U.S. Geological Survey https://doi.org/10.5066/P92U1KPY Andrew W. Stevens Gerald A. Hatcher Peter Dal Ferro Peter Dartnell Jonathan A. Warrick Nicholas Cohn Hans R. Moritz 2023 data release DOI:10.5066/P92U1KPY Pacific Coastal and Marine Science Center, Santa Cruz, CA U.S. Geological Survey 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. https://doi.org/10.5066/P92U1KPY Bathymetry and seafloor acoustic backscatter data were collected at four sites (SKM, SLG, LDB, WLW) using a SWATHPlus interferometric sonar (234 kHz) pole mounted to the R/V Parke Snavely during a June 2021 survey of the lower Columbia River, Washington and Oregon. Each site was surveyed repeatedly between June 5 and June 9, 2021 to quantify bathymetric changes resulting from migration of subaqueous sand dunes. The bathymetry and seafloor acoustic backscatter data from each site are provided as GeoTIFF images. 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. Additional information about the field activity 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. Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in Esri format, this metadata file may include some Esri-specific terminology. 20210605 20210609 ground condition at time data were collected. Complete None planned -123.443290 -122.761974 46.250887 45.712158 USGS Metadata Identifier USGS:1027a564-805a-4e1f-b05e-8fbd90f6d437 ISO 19115 Topic Category geoscientificInformation elevation USGS Thesaurus bathymetry bathymetry measurement geospatial datasets sea-floor acoustic reflectivity marine geophysics sonar methods Data Categories for Marine Planning Bathymetry and Elevation Substrate Marine Realms Information Bank (MRIB) Keywords field observation none U.S. Geological Survey USGS Coastal and Marine Hazards and Resources Program CMHRP Pacific Coastal and Marine Science Center PCMSC Geographic Names Information System (GNIS) Columbia River State of Oregon State of Washington None 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 originators of the dataset and in products derived from these data. This information is not intended for navigation purposes. U.S. Geological Survey, Pacific Coastal and Marine Science Center PCMSC Science Data Coordinator mailing and physical

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Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov dgs_swath_results.png Image showing maps of bathymetric data collected at each site, color-coded by elevation PNG MATLAB Version: 9.13.0.2080170 (R2022b) Update 1 The SWATHPlus sonar systems depth accuracy reduces with horizontal range. The system has an estimated vertical depth uncertainty ranging from about 0.05 m to 0.34 m over a horizontal range of 0 to 90 m (http://www.bathyswath.com/sites/default/files/documents/ETD_2002_Bathyswath%20information_EN.pdf). Accuracies of final products may be lower due to total propagated uncertainties of the mapping systems, which include sonar system, position and motion compensation system, and navigation, as well as data processing that includes sounding cleaning, gridding, and datum transformations. No formal logical accuracy tests were conducted 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. The Applanix POS-MV post-processed horizontal positional accuracy is about 0.1 m with roll and pitch accuracies of about 0.02 degrees (https://www.applanix.com/downloads/products/specs/posmv/POS-MV-WaveMaster-II.pdf). The SWATHPlus sonar system with 234 kHz transducer has an across track resolution of about 5 cm (http://www.bathyswath.com/sites/default/files/documents/ETD_2002_Bathyswath%20information_EN.pdf). Accuracies of final products may be lower due to total propagated uncertainties of the mapping systems, which include sonar system, position and motion compensation system, and navigation, as well as data processing that includes sounding cleaning, gridding, and datum transformations. A standard deviation grid calculated from the bathymetry data is included in the data release. The Applanix POS-MV post-processed vertical positional accuracy is about 0.2 m (https://www.applanix.com/downloads/products/specs/posmv/POS-MV-WaveMaster-II.pdf). The SWATHPlus sonar system with 234 kHz transducer has a measurement resolution limit of about 0.6 cm and a resolution detection limit of about 3 mm (http://www.bathyswath.com/sites/default/files/documents/ETD_2002_Bathyswath%20information_EN.pdf). Accuracies of final products may be lower due to total propagated uncertainties of the mapping systems, which include sonar system, position and motion compensation system, and navigation, as well as data processing that includes sounding cleaning, gridding, and datum transformations. The data were collected with a SWATHplus-M 234-kHz interferometric side-scan sonar system pole-mounted on the U.S. Geological Survey (USGS) R/V Parke Snavely. During the mapping mission, an Applanix POS-MV (Position and Orientation System for Marine Vessels) was used to position the vessel during data collection, and it also accounted for vessel motion such as heave, pitch, and roll. The POS-MV also recorded position and vessel motion parameters for later post-processing. Sound-velocity profiles were collected throughout the survey days with a Castaway sound velocimeter. Post-processed POS-MV Smoothed Best Estimate of Trajectory (SBET) files were merged with the survey line files using BathySwath software and then the line files were imported into SonarWiz software. Soundings were cleaned for obvious errors and data from each site were gridded into continuous surfaces with resolutions of 0.5 and 1 m for the bathymetric and seafloor acoustic backscatter data, respectively. The base surface was exported as a GeoTiff file in UTM Zone 10, NAD83 (2011) coordinates vertically referenced to the North American Vertical Datum of 1988 (NAVD88) based on National Geodetic Survey Geoid18 offsets. 2023 Raster Universal Transverse Mercator 10 0.9996 -123.00000 0.00000 500000.0 0.00 coordinate pair 0.5 0.5 Meters North American Datum of 1983, 2011 realization (NAD83(2011)) GRS80 6378137.00 298.257222101 North America Vertical Datum 1988 0.1 meters Explicit elevation coordinate included with horizontal coordinates GeoTiff elevation in meters relative to NAVD88 Producer defined N/A Elevation relative to the North American vertical datum of 1988 (NAVD88). Grid cells containing no information were assigned a fill value of -3.40282e+30. Producer defined -20.9 2.4 meters N/A Relative seafloor backscatter intensity. NaN = not a number because no backscatter data are available at this location in the raster grid. Producer defined 0 1 Bathymetric and seafloor backscatter intensity data in raster format. U.S. Geological Survey field activity 2021-621-FA U.S. Geological Survey - CMGDS Mailing and Physical

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Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov Downloadable data in GeoTiff format and compressed into zipped archives. Files were grouped by data type; bathymetry- lcr21_bathy.zip, and seafloor acoustic backscatter- lcr21_backscatter.zip. Individual files within the ZIP archives were named according to the following convention: XXX_YYYYMMDD_Thhmmss_datatype.tif, where XXX denotes the site surveyed; SKM- Skamokawa, SLG - Slaughters Bar, LDB - Lower Dobelbower, WLW - Willow Bar, YYYYMMDD provides the start date of the survey, hhmmss, denotes the start time of the survey, and datatype is either bathy (for bathymetry data) or backscatter (for seafloor acoustic backscatter data). Additional details about the files contained in each zip archive and start and end times of each survey are provided in the Support File, swath_survey_dates_times.csv. 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. GeoTIFF ArcMap (version 10.3.1) Downloadable zip file contains the TIFF (.tif) version of the seafloor acoustic backscatter data. WinZip 10.5 https://doi.org/10.5066/P92U1KPY Data can be downloaded using the Network_Resource_Name link and scrolling down to the Depth Data section. GeoTIFF ArcMap (version 10.3.1) Downloadable zip file contains the TIFF (.tif) version of the bathymetric data. WinZip 43.4 https://doi.org/10.5066/P92U1KPY Data can be downloaded using the Network_Resource_Name link and scrolling down to the Depth Data section. None. The downloadable data file has been compressed with the "zip" command and can be unzipped with Winzip (or other tool) on Windows systems. To utilize these data, the user must have software capable of uncompressing the WinZip file and importing and viewing a GeoTIFF file. 20230808 U.S. Geological Survey, Pacific Coastal and Marine Science Center PCMSC Science Data Coordinator mailing and physical

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Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998