Andrew W. Stevens Guy R. Gelfenbaum Jonathan A. Warrick Ian M. Miller Heather M. Weiner 20220311 comma-delimited text data release DOI:10.5066/P9QMKAEV Pacific Coastal and Marine Science Center, Santa Cruz, California U.S. Geological Survey https://doi.org/10.5066/P9KXA2SI https://www.sciencebase.gov/catalog/file/get/6171e1bad34ea36449a86d6b Andrew W. Stevens Guy R. Gelfenbaum Jonathan A. Warrick Ian M. Miller Heather M. Weiner 2022 data release DOI:10.5066/P9KXA2SI Pacific Coastal and Marine Science Center, Santa Cruz, CA U.S. Geological Survey https://doi.org/10.5066/P9KXA2SI This part of the data release presents topography data from the Elwha River delta collected in July 2018. Topography data were collected on foot with global navigation satellite system (GNSS) receivers mounted on backpacks. 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. Additional information about the field activities from which these data were derived is available online at: https://cmgds.marine.usgs.gov/fan_info.php?fan=2018-648-FA Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 20180723 20180726 Ground condition at time data were collected Complete None planned -123.5880084 -123.469442 48.1517393 48.1317125 ISO 19115 Topic Category elevation Data Categories for Marine Planning Bathymetry and Elevation USGS Thesaurus topography GPS measurement Marine Realms Information Bank (MRIB) keywords Global Positioning System (GPS) observations None U.S. Geological Survey USGS Coastal and Marine Hazards and Resources Program CMHRP Pacific Coastal and Marine Science Center PCMSC USGS Metadata Identifier USGS:6171e1bad34ea36449a86d6b Geographic Names Information System (GNIS) Clallam County Olympic Peninsula Strait of Juan de Fuca Elwha River 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 originator(s) 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

2885 Mission Street

Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov MATLAB Version: 9.8.0.1396136 (R2020a) No formal attribute accuracy tests were conducted. 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. A series of benchmarks with known coordinates were established adjacent to the study area to provide geodetic control for the bathymetric and topographic surveys. The positions of the benchmarks were derived from a minimum of two static GNSS occupations. The equipment for the static occupations consisted of a dual frequency Trimble R7 GNSS receiver, a fixed-height tripod, and Trimble Geodetic Model 2 antenna. The static observations were recorded internally in the receiver and the raw observations were processed using the National Geodetic Survey (NGS) Online Positioning User Service (OPUS, https://www.ngs.noaa.gov/OPUS/). Estimated uncertainties in the horizontal position of the individual GNSS occupations were provided by OPUS and ranged between 0.006 m and 0.06 m with an average horizontal uncertainty of 0.02 m. The processed positions from each occupation were averaged to obtain the final reported position of the benchmark. All final positions of the GNSS backpacks were determined using differential corrections from the base station receivers. Manufacturer reported accuracy for the differentially corrected horizontal positions for the Trimble R7, R8, and R10 receivers used in the survey is 0.8 cm + 0.5 ppm. Baselines from the GNSS base station were typically less than 5 km, suggesting a horizontal accuracy of backpack positions to be 0.825 cm relative to the base station. The combined horizontal uncertainty from the base station coordinate solutions and rover trajectories is therefore approximately 3 cm. Uncertainty in the horizontal positions associated with variable posture during data collection of the surveyors is unknown. The vertical uncertainty of topographic measurements is estimated by combining the uncertainty in the base station coordinate and remote GNSS positions collected in kinematic mode. Uncertainties in the elevation of the base station were provided by NGS OPUS and ranged between 0.02 m and 0.04 m, with an average vertical uncertainty of 0.03 m. Manufacturer reported vertical accuracy in the rover positions is 1.5 cm + 1 ppm for differential corrected kinematic data for the Trimble R7, R8 and R10 receivers used in the surveys. Baseline lengths were typically less than 5 km, suggesting the vertical accuracy of backpack positions to be 2 cm relative to the base station coordinates. Combining the uncertainty in the elevation of the base station coordinates and rover positions yields a total uncertainty in the backpack GNSS positions of approximately 5 cm. Uncertainty in the vertical positions associated with variable posture of the surveyors during data collection is unknown. Topographic data were collected between July 23 and July 26, 2018, on foot with GNSS equipment mounted on backpacks operating primarily in real-time kinematic (RTK) mode. GNSS backpacks were equipped with a dual-frequency GNSS receivers and handheld data collectors. Differential corrections were transmitted at 1-Hz intervals by a VHF radio to the backpack GNSS receivers from a GNSS base station placed on a benchmark with known horizontal and vertical coordinates relative to the North American Datum of 1983 (CORS96 realization) and North American Vertical Datum of 1988. Prior to data collection, vertical distances between the GNSS antenna and the ground were measured using a tape measure for each topographic surveyor. Hand-held data collectors were used to log raw data and display navigational information allowing surveyors to navigate along predefined survey lines spaced at 25- to 50-m intervals along the delta. Profiles were surveyed from the landward edge of the primary dune over the beach foreshore, to wading depth on the same series of transects as the nearshore bathymetry platforms. Additional topography data between transects were collected to better characterize morphologic variability within the study area. 20180726 Raw topography data were reviewed in Trimble Business Center (TBC) to ensure measured antenna offsets were applied properly in the field. Differential post-processing was performed on points collected in autonomous mode where VHF communication with the base station failed. Orthometric elevations relative to the NAVD88 vertical datum were computed assuming a static geoid value of -20.11 m which is based on the NGS Geoid09 offset at the location of the GNSS base stations. The final point data from the PWCs are projected in cartesian coordinates using the Washington State Plane North, meters coordinate system. 20180731 All available topographic data from the survey were compiled into a comma-delimited text file for distribution 20211020 Point Point 291777 0.0000001 0.0000001 Decimal degrees North American Datum of 1983 GRS_1980 6378137.0 298.257222101 North American Vertical Datum of 1988 0.01 meters Explicit elevation coordinate included with horizontal coordinates Attribute Table Table containing attribute information associated with the dataset Producer defined datetime_utc The date and time of data collection in Coordinated Universal Time (UTC). Producer defined 2018-Jul-23 20:00:21.000 2018-Jul-26 18:00:44.000 date and time in yyyy-mmm-dd HH:MM:SS.FFF format longitude Longitude coordinate of data point relative to the North American Datum of 1983 Producer defined -123.5880084 -123.4694421 Decimal degrees latitude Latitude coordinate of data point relative to the North American Datum of 1983 Producer defined 48.1317125 48.1517393 Decimal degrees easting_m East coordinate of data point relative to the North American Datum of 1983, projected in the Washington State Plane North, meters, coordinate system Producer defined 295026.82 303842.32 meters northing_m North coordinate of data point relative to the North American Datum of 1983,projected in the Washington State Plane South, meters, coordinate system Producer defined 129276.32 131642.59 meters ortho_ht_m Height in meters relative to the NAVD88 vertical datum, computed assuming a static geoid value of -20.11 m which is based on the NGS Geoid09 offset at the location of the GNSS base station Producer defined -1.30 5.65 meters The first line of the csv file is a header line. U.S. Geological Survey U.S. Geological Survey - Science Base U.S. Geological Survey mailing and physical

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 USA 1-888-275-8747 sciencebase@usgs.gov Topography data are available as a comma-delimited text file (ew18_topo.csv), along with associated FGDC-compliant metadata. 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. comma-delimited text MATLAB Version: 9.8.0.1396136 (R2020a) comma-delimited text file No compression applied 20.91 https://www.sciencebase.gov/catalog/file/get/6171e1bad34ea36449a86d6b?name=ew18_topo.csv https://www.sciencebase.gov/catalog/item/6171e1bad34ea36449a86d6b https://doi.org/10.5066/P9KXA2SI https://doi.org/10.5066/F72N51GC Data can be downloaded using the Network_Resource_Name links. The first link is a direct link to download the topographic data. The second link points to a landing page with the topographic data and metadata. The third link points to the landing page for the July 2018 data release. The fourth link points to a landing page for all of the Elwha annual surveys. None 20220311 U.S. Geological Survey, Pacific Coastal and Marine Science Center PCMSC Science Data Coordinator mailing and physical

2885 Mission Street

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