{
    "tag": 14344,
    "title": "Nearshore bathymetry of the Columbia River littoral cell, Washington and Oregon, 2020",
    "pubdate": "20211201",
    "sername": null,
    "series_name": null,
    "issue": "DOI:10.5066\/P9W15JX8",
    "publish": null,
    "publisher_name": null,
    "onlink": "https:\/\/cmgds.marine.usgs.gov\/catalog\/pcmsc\/DataReleases\/ScienceBase\/DR_P9W15JX8\/crlc20_bathy_metadata.faq.html",
    "format": null,
    "email": null,
    "descript": "This portion of the USGS data release presents bathymetry data collected during surveys performed in the Columbia River littoral cell, Washington and Oregon, in 2020 (USGS Field Activity Number 2020-622-FA). Bathymetry data were collected using four personal watercraft (PWCs) equipped with single-beam sonar systems and global navigation satellite system (GNSS) receivers. The sonar systems consisted of an Odom Echotrac CV-100 single-beam echosounder and 200 kHz transducer with a 9-degree beam angle. Raw acoustic backscatter returns were digitized by the echosounder with a vertical resolution of 1.25 cm. Depths from the echosounders were computed using sound velocity profiles measured using a YSI CastAway CTD during the survey. Positioning of the survey vessels was determined at 5 to 10 Hz using Trimble R7 GNSS receivers. Output from the GNSS receivers and sonar systems were combined in real time on the PWC by a computer running HYPACK hydrographic survey software. Navigation information was displayed on a video monitor, allowing PWC operators to navigate along survey lines at speeds of 2 to 3 m\/s. Survey-grade positions of the PWCs were achieved with a single-base station and differential post-processing. Positioning data from the GNSS receivers were post-processed using Waypoint Grafnav to apply differential corrections from a GNSS base station with known horizontal and vertical coordinates relative to the North American Datum of 1983. Orthometric elevations relative to the NAVD88 vertical datum were computed using National Geodetic Survey Geoid12a offsets. Bathymetric data were merged with post-processed positioning data and spurious soundings were removed using a custom Graphical User Interface (GUI) programmed with the computer program MATLAB. The average estimated vertical uncertainty of the bathymetric measurements is 10 cm. The final point data from the PWCs are provided in a comma-separated text file and are projected in cartesian coordinates using the Washington State Plane South, meters coordinate system. Due to equipment and staffing issues associated with the global pandemic, bathymetric surveys performed at the southern portion of the Clatsop Plains sub-cell (survey lines 71 to 101) and North Beach sub-cell were performed several weeks after the corresponding topographic surveys. The CTD was not available for bathymetric surveys at these locations and an assumed speed of sound of 1,500 and 1,490 m\/s was applied to soundings collected in the North Beach sub-cell and southern portion of the Clatsop sub-cell, respectively.",
    "lang": null,
    "journal": null,
    "pwid": null,
    "originator": [
        {
            "name": "Stevens, Andrew W.",
            "role": "Author"
        },
        {
            "name": "Wood, Jeffrey M.",
            "role": "Author"
        },
        {
            "name": "Ruggiero, Peter",
            "role": "Author"
        },
        {
            "name": "Gelfenbaum, Guy R.",
            "role": "Author"
        },
        {
            "name": "Weiner, Heather M.",
            "role": "Author"
        },
        {
            "name": "Kaminsky, George M.",
            "role": "Author"
        }
    ],
    "index_term": [
        {
            "thcode": 2,
            "code": "80",
            "name": "bathymetry",
            "scope": "The elevation of the earth's surface beneath a body of water, especially the ocean, typically determined by measurements of depth from the water surface."
        },
        {
            "thcode": 2,
            "code": "82",
            "name": "bathymetry measurement",
            "scope": "Means of determining the depth to the floor of a body of water, especially the ocean."
        },
        {
            "thcode": 2,
            "code": "492",
            "name": "GPS measurement",
            "scope": "Determination of distance and location using instruments receiving signals from the Global Positioning System, a system of satellites for identifying earth locations."
        },
        {
            "thcode": 2,
            "code": "707",
            "name": "marine geophysics",
            "scope": "Branch of earth sciences concerned with the physical processes of the oceans and continental margins.  We include here studies of large bodies of brackish and fresh water, such as lakes and rivers."
        },
        {
            "thcode": 2,
            "code": "1025",
            "name": "sea-floor characteristics",
            "scope": "Geomorphic features and geographic, compositional, and textural variation in the materials composing the ocean floor. Includes both large-scale structures (such as seamounts and rises) and fine-scale variations in rocks and deposits on the sea floor."
        },
        {
            "thcode": 2,
            "code": "2035",
            "name": "single-beam echo sounder",
            "scope": "Acoustic technique for determining seafloor or lakebed depth directly below the instrument platform."
        },
        {
            "thcode": 15,
            "code": "006",
            "name": "elevation",
            "scope": "Height above or below sea level, for example altitude, bathymetry, digital elevation models, slope, derived products, DEMs, TINs"
        },
        {
            "thcode": 23,
            "code": "22",
            "name": "Bathymetry and Elevation",
            "scope": "Includes measures of the height of a location above or below a reference surface. Bathymetry is the elevation of the Earth's surface beneath a body of water, especially the ocean, typically determined by measurements of depth from the water surface at mean lower low water. Distributions are topographic maps and bathymetric charts based on collected data and also include smoothed or gridded maps of bathymetry and elevation from observational data or other associated factors. Assessment data types include models of ecological value, economic value, or current rates of alterations due to erosion, accretion, climate change, and other stressors (for example, wetland habitat loss). Predictions are the results of models or projections of future distributions, values, or ecological impacts of bathymetry, including predicted changes due to natural and human forces such as erosion, deposition, sea-level rise, and dredging activities; predictions also include the results of scenario-based models of bathymetry changes under different management strategies."
        },
        {
            "thcode": 61,
            "code": "417",
            "name": "Global Positioning System (GPS) observations",
            "scope": "the use of satellite signals from the Global Positioning System to determine the precise location of a terrestrial receiver."
        }
    ],
    "place_term": [],
    "image": [],
    "fan": [
        "2020-622-FA"
    ]
}