Elevation Data Collected in 2010 from Sabine National Wildlife Refuge, Louisiana

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Frequently anticipated questions:

What does this data set describe?

Title:
Elevation Data Collected in 2010 from Sabine National Wildlife Refuge, Louisiana
Abstract:
Data release doi:10.5066/F7BR8QBH associated with this metadata record serves as an archive of elevation data collected in August 2010 from Sabine National Wildlife Refuge (SNWR), Louisiana (U.S. Geological Survey [USGS] Field Activity Number [FAN] 10SWL01). Point (xyz) elevations were collected from historically formed open-water bodies and the surrounding emergent marsh using a combination of stop-and-go (semi-kinematic) and kinematic differential Global Positioning System (DGPS) surveying techniques. These data were collected as part of the U.S. Geological Survey’s Gulf Coast Subsidence project https://coastal.er.usgs.gov/gc-subsidence/) and provide more extensive spatial coverage than water depths and marsh-surface elevations collected along coring transects in 2008 (Bernier and others, 2011). All elevation data use the projected coordinate system North American Datum of 1983 (NAD83), Universal Transverse Mercator (UTM) Zone 15 North (15N) and all elevations are North American Vertical Datum of 1988 (NAVD88) orthometric heights, derived using the GEOID09 geoid model.
Supplemental_Information:
A limited number of water depths were collected along coring transects at four study areas in 2008 (Bernier and others, 2011). During this survey, DGPS position and elevation data were collected at two of the 2008 study areas (study areas 2 and 3) and also at two additional study areas (study areas 5 and 6). DGPS position data were not collected at study areas 1 and 4 due to time constraints and the fragmented nature of the emergent marshes and small open-water bodies at these sites. These data are scientific in nature and are not to be used for navigation. Bathymetric grids interpolated from these point elevations should be used with caution because data density varied between study areas and did not provide full coverage, especially within irregular embayments at the study-area margins.
  1. How might this data set be cited?
    Bernier, Julie C., 2017, Elevation Data Collected in 2010 from Sabine National Wildlife Refuge, Louisiana: U.S. Geological Survey Data Release doi:10.5066/F7BR8QBH, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -93.66202
    East_Bounding_Coordinate: -93.43298
    North_Bounding_Coordinate: 29.96446
    South_Bounding_Coordinate: 29.88808
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 04-Aug-2010
    Ending_Date: 13-Aug-2010
    Currentness_Reference:
    Ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: Tabular digital data, vector digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • Point (1120)
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 15
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: 93.0
      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 0.001
      Ordinates (y-coordinates) are specified to the nearest 0.001
      Planar coordinates are specified in Meters
      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.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988
      Altitude_Resolution: 0.001
      Altitude_Distance_Units: Meters
      Altitude_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    snwr_mu1_sa2_elev2010.csv
    Comma-separated values text file containing the processed point location and elevation data for study area 2 located in SNWR Management Unit 1. (Source: USGS)
    snwr_mu1_sa6_elev2010.csv
    Comma-separated values text file containing the processed point location and elevation data for study area 6 located in SNWR Management Unit 1. (Source: USGS)
    snwr_mu3_sa5_elev2010.csv
    Comma-separated values text file containing the processed point location and elevation data for study area 5 located in SNWR Management Unit 3. (Source: USGS)
    snwr_mu5_sa3_elev2010.csv
    Comma-separated values text file containing the processed point location and elevation data for study area 3 located in SNWR Management Unit 5. (Source: USGS)
    snwr_elev2010_all.csv
    Comma-separated values text file containing all processed point location and elevation data for SNWR study areas 2, 3, 5, and 6. (Source: USGS)
    snwr_elev2010_all.shp
    Esri shapefile containing all processed point location and elevation data for SNWR study areas 2, 3, 5, and 6. (Source: USGS)
    snwr_elev2010_all.kml
    Keyhole Markup Language (KML) file containing all processed point location and elevation data for SNWR study areas 2, 3, 5, and 6. (Source: USGS)
    FID
    Internal feature number (Source: Esri) Sequential unique whole numbers that are automatically generated
    Shape
    Feature geometry (Source: Esri) Geometry type defining the features
    NAD83_X
    X-coordinate (easting) of sample point, in meters (NAD83, UTM zone 15N) (Source: USGS)
    Range of values
    Minimum:436125.681
    Maximum:458193.103
    Units:Meters
    Resolution:0.001
    NAD83_Y
    Y-coordinate (northing) of sample point, in meters (NAD83, UTM zone 15N) (Source: USGS)
    Range of values
    Minimum:3306567.886
    Maximum:3314926.203
    Units:Meters
    Resolution:0.001
    NAD83_Z
    Ellipsoid height of sample point, in meters (NAD83) (Source: USGS)
    Range of values
    Minimum:-27.801
    Maximum:-26.662
    Units:Meters
    Resolution:0.001
    NAVD88_G09
    Elevation (orthometric height) of sample point, in meters (NAD83, GEOID09) (Source: USGS)
    Range of values
    Minimum:-0.661
    Maximum:0.468
    Units:Meters
    Resolution:0.001
    SOURCE
    Elevation data collection method used (Source: USGS)
    ValueDefinition
    StaticReported position and elevation data are the processed stop-and-go static site coordinates
    RodReported position and elevation data are the rod-corrected processed kinematic site coordinates
    LOCATION1
    Study area where data was collected (Source: USGS) Character string
    LOCATION2
    SNWR management unit where data was collected (Source: USGS) Character string
    COMMENT
    Additional site information (Source: USGS) Character string

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Julie C. Bernier
  2. Who also contributed to the data set?
    U.S. Geological Survey, Coastal and Marine Geology Program, St. Petersburg Coastal and Marine Science Center
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Julie C. Bernier
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    jbernier@usgs.gov

Why was the data set created?

Dissemination of processed emergent-marsh and open-water sediment-surface elevation data collected from Sabine National Wildlife Refuge, Louisiana in August 2010 (USGS FAN 10SWL01). The elevation data were used to estimate magnitudes of one-dimensional (vertical) and three-dimensional (volume) accommodation that formed as a result of extensive historical wetland loss in the western chenier plain of coastal Louisiana.

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: 2010 (process 1 of 4)
    Position and elevation data were recorded with an Ashtech DGPS receiver and antenna. GPS base stations were erected at temporary USGS benchmarks located within 13 km of the farthest data-collection site. An Ashtech Z-Xtreme GPS receiver recorded the 12-channel full-carrier-phase positioning signals (L1/L2) from satellites via a Thales choke-ring antenna at the base station. A similar GPS instrument combination was used for the rover GPS. The base receiver and the rover receiver recorded their positions concurrently at 1-second (s) recording intervals throughout the survey. Because the SNWR open-water bodies are very shallow (generally less than 50 cm) and commonly have fluid muddy or peaty bottom sediments, an airboat was required to access the study areas, and a combination of stop-and-go (semi-kinematic) and fully kinematic differential GPS (DGPS) surveying techniques were used. At pre-selected sites along the transects, the airboat was brought to a complete stop, spudded onsite, and the rover antenna was lowered to the sediment surface. At these "stop" sites, data recorded in static mode for 2 minutes. Between stop sites, the antenna was pinned in the up position while data continued to record in kinematic mode and the real-time position data from the rover GPS receiver was streamed to a laptop computer running HYPACK 2010 hydrographic survey software. At approximately equal distances between stop sites, the distance from the antenna foot to the sediment surface was measured with a graduated rod and the time and approximate (raw) position of each measurement were marked simultaneously in the HYPACK data file. After post processing, the vertical position of each kinematic epoch with a corresponding HYPACK timestamp was corrected to account for the measured distance between the antenna foot and the sediment surface. As a quality-control check, rod measurements were also made at each of the stop sites before the rover antenna was lowered to the sediment surface, and the corrected kinematic elevation was compared with the static elevation from the same site. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Julie C. Bernier
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    jbernier@usgs.gov
    Date: 2011 (process 2 of 4)
    The coordinate values of the GPS base stations are the time-weighted average of values obtained from OPUS. The base station coordinates were imported into GrafNav, version 8.30 (Waypoint Product Group) and the data from the rover GPS were post-processed to the concurrent base-station session data; baseline distances were less than 13 km. The DGPS data were acquired and processed in the North American Datum of 1983 (NAD83) (CORS96) geodetic datum. Processed ellipsoid elevations were transformed in GrafNav to North American Vertical Datum of 1988 (NAVD88) orthometric elevations using the National Geodetic Survey geoid model of 2009 (GEOID09). Person who carried out this activity:
    U.S. Geological Survey
    Attn: Julie C. Bernier
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    jbernier@usgs.gov
    Date: 2011 (process 3 of 4)
    The processed stop-and-go and kinematic point data were imported into Esri ArcGIS version 9.3, the kinematic elevations were corrected to account for the measured distance between the antenna foot and the sediment surface, and the differences between the processed static and kinematic elevations at all stop sites were compared. The average kinematic-minus-static difference for all stop sites (N=271) was 0.5 plus-or-minus 8.3 cm (2-sigma), which is comparable to the maximum error (plus-or-minus 10 cm) at line crossings for single-beam acoustical bathymetric surveys in the delta plain (Morton and others, 2010). The stop-and-go and kinematic datasets were then merged; the final point data are the stop-and-go static positions where applicable or the corrected kinematic elevations. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Julie C. Bernier
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    jbernier@usgs.gov
    Data sources produced in this process:
    • snwr_mu1_sa2_elev2010.csv
    • snwr_mu1_sa6_elev2010.csv
    • snwr_mu3_sa5_elev2010.csv
    • snwr_mu5_sa3_elev2010.csv
    • snwr_elev2010_all.csv
    • snwr_elev2010_all.shp
    • snwr_elev2010_all.kml
    Date: 13-Oct-2020 (process 4 of 4)
    Added keywords section with USGS persistent identifier as theme keyword. 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?
    Bernier, J.C., Morton, R.A., and Kelso, K.W., 2011, Trends and Causes of Historical Wetland Loss, Sabine National Wildlife Refuge, Southwest Louisiana: U.S. Geological Survey Open-File Report 2011-1169.

    Online Links:

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    The positional accuracy of the processed data is determined by the accuracy of the raw position data recorded during data collection. DGPS coordinates were obtained using post-processing software packages (National Geodetic Survey On-Line Positioning User Service, OPUS, and Waypoint Product Group GrafNav, version 8.30).
  2. How accurate are the geographic locations?
    All static base station sessions were processed through the On-Line Positioning User Service (OPUS) maintained by the National Geodetic Survey (NGS). The OPUS base-station solutions were entered into a spreadsheet to compute a final, time-weighted positional coordinate (latitude, longitude, and ellipsoid height). Base-station positional error was calculated as the absolute value of the final weighted solution minus the session position value. The maximum horizontal error of the base station coordinates used for post-processing was 0.0028 seconds latitude and 0.0040 seconds longitude.
  3. How accurate are the heights or depths?
    All static GPS base station sessions were processed through OPUS. The OPUS base-station solutions were entered into a spreadsheet to compute a final, time-weighted positional coordinate (latitude, longitude, and ellipsoid height). Base-station positional error for each GPS session was calculated as the absolute value of the final weighted solution minus the session position value. For this survey, the standard deviation of the base station ellipsoid height was 0.005 m and the maximum vertical error for the base station was +/- 0.016 m.
  4. Where are the gaps in the data? What is missing?
    Data release doi:10.5066/F7BR8QBH associated with this metadata record includes the processed elevation data for 1120 point locations collected from Sabine National Wildlife Refuge, Louisiana in August 2010 (USGS FAN 10SWL01).
  5. How consistent are the relationships among the observations, including topology?
    Position and elevation data were recorded with an Ashtech DGPS receiver and choke-ring antenna. A combination of stop-and-go (semi-kinematic) and fully kinematic differential GPS (DGPS) surveying techniques were used to measure the emergent-marsh and open-water sediment-surface elevations. DGPS data were recorded concurrently throughout the survey at nearby base stations using a similar instrument combination. The final point (xyz) data, including elevation, are the post-processed DGPS coordinates; baseline distances were less than 13 km.

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:
The U.S. Geological Survey requests that it be acknowledged as the originator of this dataset in any future products or research derived from these data.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center
    Attn: Julie C. Bernier
    Geologist
    600 4th Street South
    St. Petersburg, FL
    USA

    727-502-8000 (voice)
    jbernier@usgs.gov
  2. What's the catalog number I need to order this data set? Downloadable data
  3. What legal disclaimers am I supposed to read?
    This publication was prepared by an agency of the United States Government. Although these data have been processed successfully on a computer system at the U.S. Geological Survey, 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 imply any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and (or) contained herein. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.
  4. How can I download or order the data?
    • Availability in digital form:
      Data format: This zip archive includes comma-separated values text files (.csv), GIS data files in Esri shapefile (.shp) and Keyhole Markup Language (KML) format, and accompanying metadata for elevation data collected in 2010 from Sabine National Wildlife Refuge, Louisiana (USGS FAN 10SWL01). in format Compressed (zip) archive Multimedia presentation Size: 0.2
      Network links: https://coastal.er.usgs.gov/data-release/doi-F7BR8QBH/data/snwr_elev2010.zip
    • Cost to order the data: None, if obtained online

  5. What hardware or software do I need in order to use the data set?
    GIS files can be opened using the free ArcGIS Explorer or Google Earth GIS viewers.

Who wrote the metadata?

Dates:
Last modified: 13-Oct-2020
Metadata author:
U.S. Geological Survey
Attn: Julie C. Bernier
Geologist
600 4th Street South
St. Petersburg, FL
USA

727-502-8000 (voice)
jbernier@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/snwr_elev2010-met.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:18:56 2021