Topographic measurements of Little Holland Tract, Sacramento-San Joaquin Delta, California, 2015, using backpack GPS

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Frequently anticipated questions:

What does this data set describe?

Title:
Topographic measurements of Little Holland Tract, Sacramento-San Joaquin Delta, California, 2015, using backpack GPS
Abstract:
Topographic data were collected by the U.S. Geological Survey (USGS) in 2015 for Little Holland Tract in the Sacramento-San Joaquin River Delta, California. The data were collected on foot using a global positioning system (GPS) backpack platform that consisted of survey-grade Trimble R10 and R7 global navigation satellite system (GNSS) receivers with Zephyr 2 antennas. Orthometric elevations relative to NAVD88 were computed using the National Geodetic Survey Geoid12a, and the final data were projected in Cartesian coordinates using the UTM Zone 10 North (meters) (NAD83[2011]) coordinate system. The mean estimated vertical uncertainty of the 2015 USGS GPS backpack survey is 3.5 cm. 
Supplemental_Information:
Additional information about the field activities from which these data were derived are available online at: http://cmgds.marine.usgs.gov/fan_info.php?fan=2015-642-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.
  1. How might this data set be cited?
    Snyder, Alexander G., Stevens, Andrew W., Carlson, Emily, and Lacy, Jessica R., 2016, Topographic measurements of Little Holland Tract, Sacramento-San Joaquin Delta, California, 2015, using backpack GPS: data release DOI:10.5066/F7RX9954, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.

    Online Links:

    This is part of the following larger work.

    Snyder, Alexander G., Stevens, Andrew W., Carlson, Emily, and Lacy, Jessica R., 2016, Digital elevation model of Little Holland Tract, Sacramento-San Joaquin Delta, California, 2015: data release DOI:10.5066/F7RX9954, U.S. Geological Survey, Santa Cruz, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -121.666347272
    East_Bounding_Coordinate: -121.64879356
    North_Bounding_Coordinate: 38.350117093
    South_Bounding_Coordinate: 38.310742125
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 22-May-2015
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: comma-delimited text and shapefile
  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):
      • Entity point (57264)
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 10
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -123.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.6096
      Ordinates (y-coordinates) are specified to the nearest 0.6096
      Planar coordinates are specified in Meter
      The horizontal datum used is D_North_American_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.
  7. How does the data set describe geographic features?
    Attribute Table
    Table containing attribute information associated with the data set. (Source: Producer defined)
    Date_Time
    Date and time that data point was collected in Pacific Standard Time, yyyy-mm-dd hh:mm:ss.sss. (Source: Producer defined) Unknown
    Longitude
    Longitude coordinate of data point (NAD83 (2011)). (Source: Producer defined)
    Range of values
    Minimum:121.64887
    Maximum:121.66628
    Units:Decimal Degrees
    Latitude
    Latitude coordinate of data point (NAD83 (2011)). (Source: Producer defined)
    Range of values
    Minimum:38.31092
    Maximum:38.35001
    Units:Decimal Degrees
    Easting_m
    Easting projected coordinate of data point - NAD83(2011), UTM Zone 10. (Source: Producer defined)
    Range of values
    Minimum:616597.494
    Maximum:618068.94
    Units:meters
    Northing_m
    Easting projected coordinate of data point - NAD83(2011), UTM Zone 10. (Source: Producer defined)
    Range of values
    Minimum:4241156.111
    Maximum:4245504.909
    Units:meters
    Ellip_Ht_m
    Height of data point with reference to the ellipsoid. (Source: Producer defined)
    Range of values
    Minimum:-32.203
    Maximum:-27.859
    Units:meters
    Ortho_Ht_m
    Elevation with reference to Geoid 12A. (Source: Producer defined)
    Range of values
    Minimum:-0.434
    Maximum:3.858
    Units:Meters
    Hor_Acc_m
    Estimate of horizontal accuracy based on 'H. Precision' measurements computer in Trimble Business Center. (Source: Producer defined)
    Range of values
    Minimum:0
    Maximum:0.103
    Units:meters
    Vert_Acc_m
    Estimate of vertical accuracy based on 'V. Precision' measurements computer in Trimble Business Center. (Source: Producer defined)
    Range of values
    Minimum:0
    Maximum:0.194
    Units:Meters
    Entity_and_Attribute_Overview:
    The entity and attribute information provided here describes the tabular data associated with the data set. Please review the detailed descriptions that are provided (the individual attribute descriptions) for information on the values that appear as fields/table entries of the data set.
    Entity_and_Attribute_Detail_Citation:
    The entity and attribute information was generated by the individual and/or agency identified as the originator of the data set. Please review the rest of the metadata record for additional details and information.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Alexander G. Snyder
    • Andrew W. Stevens
    • Emily Carlson
    • Jessica R. Lacy
  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
    US

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

Why was the data set created?

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.

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: 22-May-2015 (process 1 of 6)
    Established base station and collected data using GPS Backpack survey method with survey grade Trimble R10 and R7 GNSS receiver mounted backpacks. Survey design involved 4 people equipped with backpacks walking predesigned transect lines and outlining the edge of water, where accessible. A small area of the northern-most, low-lying topography was also measured using this method, although tall brush made most areas inaccessible or impractical.
    Date: 19-Jun-2015 (process 2 of 6)
    Collected data using GPS Backpack survey method with survey grade Trimble R10 and R7 GNSS receivers mounted backpacks. Survey design involved 4 people equipped with backpacks walking predesigned transect lines and outlining the edge of water, where accessible. A small area of the northern-most, low-lying topography was also measured using this method, although tall brush made most areas inaccessible or impractical.
    Date: 19-Jun-2015 (process 3 of 6)
    Backpack survey data were post-processed using Trimble Business Center (version 3.21) referenced to the static base station, set up on a temporary benchmark established for this survey.
    Date: 17-Nov-2015 (process 4 of 6)
    All data were compiled into a single shapefile.
    Date: Nov-2025 (process 5 of 6)
    Edits were made as needed to bring the metadata up to current PCMSC standards including standardizing doi# links, correcting typos, adding disclaimers, and refining keywords. Point of Contact and Metadata Contact information sections were changed to static PCMSC contact information. No data were changed. Users are advised to compare the metadata date of this file to any similar file to ensure they are using the most recent version. Person who carried out this activity:
    Susan A Cochran
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    2885 Mission St.
    Santa Cruz, CA
    United States

    831-460-7545 (voice)
    scochran@usgs.gov
    Date: 19-Oct-2020 (process 6 of 6)
    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
  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?
    Accuracy estimates were based on horizontal and vertical precision values calculated in Trimble Business Center, but no comparisons to "true" values were conducted.
  2. How accurate are the geographic locations?
    Accuracy estimates were based on horizontal precision values calculated in Trimble Business Center, but no comparisons to "true" values were conducted. Horizontal precision values for each point are included in the dataset, but overall the minimum, maximum, mean and standard deviation precision calculations were 0.009, 0.103, 0.0239, and 0.006 meters, respectively.
  3. How accurate are the heights or depths?
    Accuracy estimates were based on vertical precision values calculated in Trimble Business Center, but no comparisons to "true" values were conducted. Vertical precision values for each point are included in the dataset, but overall the minimum, maximum, mean and standard deviation precision calculations were 0.194, 0.014, 0.0351, and 0.011 meters, respectively.
  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?
    Data falls within expected ranges, efforts were made during digital elevation modeling to best represent reality.

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
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? Topography data are available as both a comma-delimited text file and a shapefile, and include the associated 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. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 19-Oct-2020
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA
US

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_F7RX9954/LHT15_BackpackGPS_FGDC.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:17:20 2021