Topography data collected in the Liberty Island Conservation Bank portion of the Cache Slough Complex, Sacramento-San Joaquin Delta, California, during USGS field activity 2017-649-FA

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Frequently anticipated questions:

What does this data set describe?

Title:
Topography data collected in the Liberty Island Conservation Bank portion of the Cache Slough Complex, Sacramento-San Joaquin Delta, California, during USGS field activity 2017-649-FA
Abstract:
This portion of the USGS data release presents topography data acquired in the Liberty Island Conservation Wildlands restoration site in 2017 (USGS Field Activity Number 2017-649-FA). Topographic data were collected on June 26 and 27, 2017 by walking with global navigation satellite system (GNSS) receivers mounted on backpacks. Hand-held data collectors were used to log raw data and display navigational information as the surveyors traversed the landscape. The final point data are provided in a comma-separated text file and are projected in cartesian coordinates using the Universal Transverse Mercator (UTM) Zone 10 North, meters coordinate system.
Supplemental_Information:
Additional information about the field activity from which these data were derived are available online at:
https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-649-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?
    Stevens, Andrew W., Dartnell, Peter, Fregoso, Theresa A., Lacy, Jessica R., and Dailey, Evan T., 20200224, Topography data collected in the Liberty Island Conservation Bank portion of the Cache Slough Complex, Sacramento-San Joaquin Delta, California, during USGS field activity 2017-649-FA: data release DOI:10.5066/P9AQSRVH, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Fregoso, Theresa A., Stevens, Andrew W., Wang, Rueen-Fang, Handley, Thomas, Dartnell, Peter, Lacy, Jessica R., Ateljevich, Eli, and Dailey, Evan T., 2020, Bathymetry, topography, and acoustic backscatter data, and a digital elevation model (DEM) of the Cache Slough Complex and Sacramento River Deep Water Ship Channel, Sacramento-San Joaquin Delta, California: data release DOI:10.5066/P9AQSRVH, U.S. Geological Survey, Santa Cruz, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -121.6742286
    East_Bounding_Coordinate: -121.6678300
    North_Bounding_Coordinate: 38.3359344
    South_Bounding_Coordinate: 38.3267719
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/cs17_backpack_topo.png (PNG)
    Map showing tracklines for topography data collected in 2017
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 26-Jun-2017
    Ending_Date: 27-Jun-2017
    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 Point data set. It contains the following vector data types (SDTS terminology):
      • Point (2950 6)
    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 0.0000001. Longitudes are given to the nearest 0.0000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is GRS_1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988
      Altitude_Resolution: 0.01
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates
  7. How does the data set describe geographic features?
    Attribute Table
    Table containing attribute information associated with the dataset (Source: Producer defined)
    area
    Designation of sub-area within the Cache Slough Complex survey area (Source: producer defined)
    ValueDefinition
    WildlandsWildlands sub-area
    datetime_utc
    The date and time of data collection in Coordinated Universal Time (UTC). (Source: Producer Defined)
    Range of values
    Minimum:2017-06-26 19:19:13.000
    Maximum:2017-06-27 22:41:28.000
    Units:date and time in mm/dd/yyyy HH:MM:SS.FFF format
    longitude
    Longitude coordinate of data point relative to the North American Datum of 1983 (Source: Producer defined)
    Range of values
    Minimum:-121.6742286
    Maximum:-121.6678300
    Units:Decimal degrees
    latitude
    Latitude coordinate of data point relative to the North American Datum of 1983 (Source: Producer defined)
    Range of values
    Minimum:38.3267719
    Maximum:38.3359344
    Units:Decimal degrees
    easting_m
    East coordinate of data point relative to the North American Datum of 1983, projected in the Universal Transverse Mercator (UTM) Zone 10 North, meters, coordinate system (Source: Producer defined)
    Range of values
    Minimum:615883.05
    Maximum:616432.49
    Units:meters
    northing_m
    North coordinate of data point relative to the North American Datum of 1983, projected in the Universal Transverse Mercator (UTM) Zone 10 North, meters, coordinate system (Source: Producer defined)
    Range of values
    Minimum:4242906.96
    Maximum:4243922.26
    Units:meters
    ellipsoid_ht_m
    Height in meters of data point with reference to the reference ellipsoid (Source: Producer defined)
    Range of values
    Minimum:-32.24
    Maximum:-26.08
    Units:meters
    ortho_ht_m
    Height in meters of data point with reference to the North American Vertical Datum of 1988. (Source: Producer defined)
    Range of values
    Minimum:-0.42
    Maximum:5.73
    Units:meters

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Andrew W. Stevens
    • Peter Dartnell
    • Theresa A. Fregoso
    • Jessica R. Lacy
    • Evan T. Dailey
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    PCMSC Science Data Coordinator
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    2885 Mission Street
    Santa Cruz, CA

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

Why was the data set created?

These data were collected in support of ongoing field experiments and numerical modeling with the U.S. Bureau of Reclamation to improve our understanding of habitat quality, the influence on various landscape features on ecosystem function, and the effects of restoration actions in the Sacramento-San Joaquin Delta. These data are intended for science researchers, students, policy makers, and the general public.

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: 28-Jun-2017 (process 1 of 5)
    Topography data were collected between June 26 and June 27, 2017 on foot with GNSS equipment mounted on backpacks. A total of 3 GNSS backpacks, each equipped with a dual-frequency GNSS receiver and handheld data collector, were used during the survey. 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 as the surveyors traversed the landscape.
    Date: 31-Aug-2017 (process 2 of 5)
    Positioning data from the survey platforms were post-processed to apply differential corrections from a GNSS base station with known horizontal and vertical coordinates relative to the North American Datum of 1983 (2011 realization). Post-processing of raw GNSS data was performed with Trimble Business Center software. Orthometric elevations relative to the NAVD88 vertical datum were computed using National Geodetic Survey Geoid12a offsets. The final point data from the topographic surveyors are projected in cartesian coordinates using the Universal Transverse Mercator (UTM), Zone 10 North, meters coordinate system.
    Date: 11-Sep-2019 (process 3 of 5)
    All available topographic data from the survey were compiled into a comma-delimited text file for distribution
    Date: 19-Oct-2020 (process 4 of 5)
    Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 13-Oct-2021 (process 5 of 5)
    Performed minor edits to the metadata to correct typos. No data were changed. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Susan A. Cochran
    Geologist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7545 (voice)
    scochran@usgs.gov
  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?
    No formal attribute accuracy tests were conducted.
  2. How accurate are the geographic locations?
    Survey-grade positions during the topographic surveys were achieved with global navigation satellite system (GNSS) receivers and a GNSS base station placed on a benchmark with coordinates relative to the North American Datum of 1983 (2011 realization). The position and elevation of the benchmark was derived from three static GNSS occupations on June 26-28, 2017 with durations between 4 and 8 hours. The equipment for the static occupations consisted of a Trimble R7 GNSS receiver, a fixed-height tripod, and Trimble Geodetic Model 2 antenna. The static observations were processed using the National Geodetic Survey Online Positioning User Service (OPUS). The processed positions from each occupation were averaged (standard deviation individual horizontal positions were less than 1 cm) to derive the final position of the benchmark. Positioning data from the topographic surveyors were post-processed using Trimble Business center software to apply differential corrections from the GNSS base station. Manufacturer reported accuracy for the differentially corrected horizontal positions for the GNSS rover trajectories is 0.8 cm + 0.5 ppm. The maximum baseline from the GNSS base stations was approximately 3 km, suggesting the minimum horizontal accuracy of survey vessel positions to be about 1 cm. Uncertainty in the horizontal positions associated with surveyor posture are unknown.
  3. How accurate are the heights or depths?
    Survey-grade positions during the topographic surveys were achieved with global navigation satellite system (GNSS) receivers referenced to a GNSS base station placed on a benchmark with coordinates relative to the North American Datum of 1983 (2011 realization). The uncertainty of the elevation of the benchmark, derived as described above, is estimated to be 1 cm. Positioning data from the topographic surveyors were post-processed using Trimble Business center software to apply differential corrections from the GNSS base station. Manufacturer reported accuracy for the differentially corrected vertical positions for the GNSS rover trajectories is 1.5 cm + 1 ppm. The maximum baseline from the GNSS base stations was approximately 3 km, suggesting the vertical accuracy of the survey platforms to be 1.8 cm relative to the benchmark elevation. Combining the uncertainty in the base station elevation (1 cm) and rover positions yields a total estimated vertical uncertainty of 3 cm. Uncertainty in the vertical positions associated with sinking into the substrate or variable posture during data collection of the surveyors is unknown.
  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?
    All data falls within expected ranges.

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. This information is not intended for navigational purposes.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - Science Base
    U.S. Geological Survey
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO
    USA

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? Bathymetry data are available as a comma-delimited text file (cs17_backpack_topo.csv), along with associated FGDC-compliant metadata.
  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?

Who wrote the metadata?

Dates:
Last modified: 13-Oct-2021
Metadata author:
PCMSC Science Data Coordinator
U.S. Geological Survey, Pacific Coastal and Marine Science Center
2885 Mission St.
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/ScienceBase/DR_P9AQSRVH/cs17_backpack_topo_metadata.faq.html>
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