Elevation data for four sites in the coastal marsh at Grand Bay National Estuarine Research Reserve, Mississippi, from October 2016 through October 2017

Frequently anticipated questions:

• What does this data set describe?
  1. How might this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  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?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

What does this data set describe?

1. How might this data set be cited?
   Smith, Kathryn E.L., Terrano, Joseph F., Khan, Nicole, and Stalk, Chelsea A., 20200226, Elevation data for four sites in the coastal marsh at Grand Bay National Estuarine Research Reserve, Mississippi, from October 2016 through October 2017: U.S. Geological Survey Data Release doi:10.5066/P9BFR2US, U.S. Geological Survey, St. Petersburg, FL.

   Online Links:

   • https://doi.org/10.5066/P9BFR2US

   This is part of the following larger work.
   Smith, Kathryn E.L., Terrano, Joseph F., Khan, Nicole, and Stalk, Chelsea A., 20200226, Shore proximal sediment deposition, elevation, turbidity, and water level data in a coastal marsh at Grand Bay National Estuarine Research Reserve, Mississippi, from October 2016 through October 2017: U.S. Geological Survey Data Release doi:10.5066/P9BFR2US, U.S. Geological Survey, St. Petersburg, FL.

   Online Links:

   • https://doi.org/10.5066/P9BFR2US

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -88.41443
   East_Bounding_Coordinate: -88.39625
   North_Bounding_Coordinate: 30.38386
   South_Bounding_Coordinate: 30.36241
   

3. What does it look like?
4. Does the data set describe conditions during a particular time period?

   Beginning_Date: 20-Oct-2016

   Ending_Date: 18-Oct-2017

   Currentness_Reference:

   ground condition

5. What is the general form of this data set?

   Geospatial_Data_Presentation_Form: Tabular digital data (CSV)
   

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.
   2. What coordinate system is used to represent geographic features?
      

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:

      UTM_Zone_Number: 16
      Transverse_Mercator:

      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -87.0
      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?

   Grand_Bay_Elevation_Data.csv

   CSV file containing attribute information associated with location and elevation data collected in Grand Bay, Mississippi during 2016 and 2017. (Source: USGS)

   Sample_ID

   Sample identification number (Source: USGS) Character string. Sample IDs listed within the table used the naming convention FAN-GBXYY-ZZ, where FAN represents the USGS abbreviated field activity number (17CCT01, 17CCT02, 17CCT03, 17CCT04 and 17CCT05), the last number denoting what trip number it was, GB denotes samples are from Grand Bay, X is the site number (1,2,3, or 4), YY is the sample number, ZZ denotes the code where the elevation was collected from (see "type" field). For example, sample ID 17CCT01_GB100_WLT is from the first trip of the year (17CCT01) from site 1 measuring the elevation of the top of the water level logger well. Some samples have further specified sample numbers that follow ZZ. These sample numbers are used to distinguish samples of the same type collected at a specific site. For example "17CCT01-GB100-SL-01" is from the first trip of the year (17CCT01) from site 1 measuring shoreline elevations, with this specific point being the first point collected. Another example is "17CCT04-GB101-R170E". This sample is from the fourth trip of the year (17CCT04) from site 1 measuring the elevation of the random surface sample (sample number 170) from the estuary.

   FAN

   USGS field activity number (FAN) assigned to each sample collection trip. (Source: USGS) Field activity numbers were assigned by the USGS to track field collection of samples. The FAN number consists of YYYY-XXX-FA, with YYYY being the 4-digit year, XXX being the trip number, and FA representing that it is a field activity.

   Alt_FAN

   Alternate (abbreviated) FAN number assigned each collection trip. (Source: USGS) FAN numbers were assigned by the USGS and are YYCCTXX, where YY is the 2-digit year, CCT stands for coastal change and transport, and XX is the trip number. For example, 17CCT01 was from 2017 sample collection trip 01.

   Site

   Site number (Source: USGS)

   Range of values
   Minimum:	1
   Maximum:	4

   Date

   Date the elevations were collected from Grand Bay in M/DD/YYYY or MM/DD/YYYY format. (Source: USGS)

   Range of values
   Minimum:	20161020
   Maximum:	20171018

   Type

   Codes used to identify what object was measured for elevation. (Source: USGS)

   Value	Definition
   BM	Elevation benchmark
   WLT	Elevation at the top of the water level logger well
   WLS	Sediment surface elevation at base of water level logger well
   05T	Elevation at the 5-meter net sedimentation tile plot
   10T	Elevation at the 10-meter net sedimentation tile plot
   15T	Elevation at the 15-meter net sedimentation tile plot
   20T	Elevation at the 20-meter net sedimentation tile plot
   05F	Elevation at the 5-meter feldspar plot
   10F	Elevation at the 10-meter feldspar plot
   15F	Elevation at the 15-meter feldspar plot
   20F	Elevation at the 20-meter feldspar plot
   BP	Elevation at the net sedimentation tile bead plot
   NTU	Elevation of the EcoNTU turbidity sensor
   SL	Elevation of the shoreline
   R0	Random surface samples collected at the bead plot
   R05	Random surface samples collected between 0 to 5-meters from the bead plot
   R10	Random surface samples collected between 6 to 10-meters from the bead plot
   R15	Random surface samples collected between 11 to 15-meters from the bead plot
   R20	Random surface samples collected between 16 to 20-meters from the bead plot

   Occ_time

   Occupation time for the elevation data collection in seconds (s) (Source: USGS)

   Range of values
   Minimum:	29
   Maximum:	10160

   Time_UTC

   Time in Coordinated Universal Time (UTC) the elevation were collected from Grand Bay in HH:MM:SS format. (Source: USGS) Time the elevations were collected from Grand Bay in HH:MM:SS format.

   East

   Easting coordinate of the elevation collection location in the North American Datum of 1983 (NAD83) Universal Transverse Mercator (UTM) Zone 16N (Source: USGS)

   Range of values
   Minimum:	364089.058
   Maximum:	365849.136

   North

   Northing coordinate of the elevation collection location in the North American Datum of 1983 (NAD83) Universal Transverse Mercator (UTM) Zone 16N (Source: USGS)

   Range of values
   Minimum:	3359793.467
   Maximum:	3362148.392

   Lat

   Latitude of the elevation collection location in the North American Datum of 1983 (NAD83) (Source: USGS)

   Range of values
   Minimum:	30.36241
   Maximum:	30.38386

   Long

   Longitude of the elevation collection location in the North American Datum of 1983 (NAD83) (Source: USGS)

   Range of values
   Minimum:	-88.41443
   Maximum:	-88.39625

   Elev

   Elevation, in meters, in the North American Vertical Datum of 1988 (NAVD88) GEOID 12A (Source: USGS)

   Range of values
   Minimum:	-1.0462
   Maximum:	1.9287

   Ver_elev

   Vertical elevation, in meters, in the North American Vertical Datum of 1988 (NAVD88) (Source: USGS)

   Range of values
   Minimum:	-0.4366
   Maximum:	1.3858

   Vert_error

   Vertical elevation error, in meters (Source: USGS)

   Range of values
   Minimum:	0.0143
   Maximum:	3.5031

   Horiz_error

   Horizontal elevation error, in meters (Source: USGS)

   Range of values
   Minimum:	0.001
   Maximum:	1.130

   Method

   Codes used to identify what method was used to measure elevation (Source: USGS)

   Value	Definition
   DGPS	Elevation collected using a differential GPS
   TS	Elevation collected using a total station

   Flag

   Codes used to identify potential errors in the data (Source: USGS)

   Value	Definition
   V	Verified acceptable data
   E	High vertical error; Recommend not using these data or using extreme caution taking into consideration the vertical error
   X	Elevation measurement is subject to extreme error and should not be used
   A	Elevation was adjusted due to sampling or processing error; Recommend using adjusted elevation only

   Notes

   Notes about the GPS data collection (Source: USGS) Values are errors or written locations of where the elevation measurement was collected. Shorelines are represented as a series of continuous sequential numbers. Random surface samples (R) have an angle and distance. The angle and distance were used to determine where to collect the sample from a fixed point (bead plot at shoreline (0,0)).

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • Kathryn E.L. Smith
   • Joseph F. Terrano
   • Nicole Khan
   • Chelsea A. Stalk
2. Who also contributed to the data set?

   Acknowledgment of the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, as a data source would be appreciated in products developed from these data, and such acknowledgment as is standard for citation and legal practices. Sharing of new data layers developed directly from these data would also be appreciated by the U.S. Geological Survey staff. These data are not legal documents and are not to be used as such.

3. To whom should users address questions about the data?
   U.S. Geological Survey St Petersburg Coastal and Marine Science Center

   Attn: Kathryn Smith

   Research Ecologist

   600 4th Street South

   St. Petersburg, FL
   

   727-502-8073 (voice)

   727-502-8182 (FAX)

   kelsmith@usgs.gov

Why was the data set created?

This data release contains elevation data for shorelines, net sedimentation tile plots, elevation benchmarks, and water level logger wells. Elevation data can be used in conjunction with in-situ sedimentation data to track lateral erosion and accretion of the marsh and estuary surface. Elevation data were collected using a total station and differential Global Positioning System (DGPS). Data should not be used for navigational purposes.

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: 2017 (process 1 of 5)

   GPS base stations were erected on two NGS benchmarks located within the Grand Bay National Estuarine Research Reserve (GBNERR), B166 (PID DO5987) and 189A (PID DO5977). Ashtech Z-Xtreme DGPS receivers recorded the 12-channel full-carrier-phase positioning signals (L1/L2) from satellites via a Thales choke-ring antenna at the base stations. A similar instrument combination (Ashtech Z-Xtreme receiver and Ashtech GNSS antenna) was used for the rover GPS systems. The base receiver and the rover receiver record their positions concurrently at 1 s recording intervals throughout the survey. A stop-and-go rapid-static survey technique was used, with a static occupation. For FAN 17CCT01, total station measurements were collected instead of using DGPS . The total station measures the sloping distance of an object to the instrument. A temporary USGS-installed benchmark was surveyed before collecting marsh data to get a static reference point. This reference point was then used to determine elevation for the rest of the samples. Person who carried out this activity:
   

   Chelsea A. Stalk

   Researcher III

   600 4th Street South

   St.Petersburg, FL
   

   USA

   727-502-8000 (voice)

   cstalk@contractor.usgs.gov

   Date: 2017 (process 2 of 5)

   The final, time weighted coordinates from 16CCT07 for the GPS base stations were imported into GrafNav, versions 8.6 (Novatel Waypoint Product Group) and the data from the rover GPS were post-processed to the concurrent GPS session data from the nearest base station; baseline distances for all sample sites were less than 9 km and dependent upon site location. The GPS data were acquired in the NAD83 geocentric datum. Due to a local base station malfunction, data from survey 17CCT05 were post-processed using concurrent CORS data from the neared station, ALDI (baseline distance 30 km). Person who carried out this activity:
   

   Chelsea A. Stalk

   Researcher III

   600 4th Street South

   St.Petersburg, FL
   

   USA

   727-502-8000 (voice)

   cstalk@contractor.usgs.gov

   Date: 2017 (process 3 of 5)

   The exported file from GrafNav was converted using the NOAA VDatum software conversion tool version 3.6 (http://vdatum.noaa.gov/). The sample locations were transformed from the GPS acquisition datum of NAD83 horizontal and vertical, to NAD83, Universal Transverse Mercator (UTM) Zone 16 North (16N) horizontal reference frame and the NAVD88 orthometric elevation, using the NGS geoid model 2012A (GEOID 12A). Person who carried out this activity:
   

   Chelsea A. Stalk

   Researcher III

   600 4th Street South

   St.Petersburg, FL
   

   USA

   727-502-8000 (voice)

   cstalk@contractor.usgs.gov

   Date: 2018 (process 4 of 5)

   Elevation data from all trips were compiled into tabular digital datasets (Comma separated values [CSV] format). Data with errors in collection or processing were flagged and noted as such in the published data file. Person who carried out this activity:
   

   Kathryn Smith

   Researcher III

   600 4th Street South

   St.Petersburg, FL
   

   USA

   727-502-8073 (voice)

   kelsmith@usgs.gov

   Date: 13-Oct-2020 (process 5 of 5)

   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?
   Terrano, Joseph F., 2018, An Evaluation of Marsh Shoreline Erosion and Sediment Deposition in the Grand Bay National Estuarine Research Reserve, Mississippi, USA: University of South Florida Scholar Commons, Tampa, Florida.

   Online Links:

   • https://scholarcommons.usf.edu/etd/7371/

   Other_Citation_Details:

   Contains detailed process descriptions for net sedimentation tile construction, deployment, collection, and laboratory processing.

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 sample locations is determined by the accuracy of the raw position data recorded by the GPS and antenna 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 8.6. Water level readings were corrected to NAVD88 and compared to a nearby National Oceanic and Atmospheric Administration (NOAA) water level station. The total station only provides elevation measurements and does not produce positional data; therefore, no positional data were reported for those samples. The random surface samples (R) were collected using an angle and distance from the bead plot. The angles and distances were reported in the notes section and were approximate locations and should not be considered precise positions. If positions are desired the reader is requested to contact the authors for more information.
2. How accurate are the geographic locations?
   All static GPS base station sessions were processed through the OPUS maintained by NGS. The OPUS base station solutions were entered into a spreadsheet to compute a final, time-weighted positional coordinate (latitude, longitude, and ellipsoid height) for each base station. Base station positional error was calculated as the absolute value of the final position minus the session position value. The maximum horizontal error of the base station coordinates used for post-processing the sample locations were 0.00081 s latitude and 0.00063 s longitude for B166, and 0.00054 s latitude and 0.00036 s longitude for 189A. The time-weighted positions for both base stations were compared against the derived coordinates from the first survey (16CCT07). All subsequent survey occupations (17CCT01-17CCT05 produced time weighted averages that were within 3 standard deviations of the first occupation and therefore, for consistency, the 16CCT07 coordinates were used in all post-processing.
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) for each base station. Base station positional error for each GPS session was calculated as the absolute value of the final position minus the session position value. For all base station occupations, the maximum standard deviations of the base station ellipsoid heights were 0.021 m for B166, 0.012 m for 189A and the maximum vertical errors for the base stations were 0.028 m and 0.029 m, respectively. The time-weighted positions for both base stations were compared against the derived coordinates from the first survey (16CCT07), which individually has a standard deviation of 0.007 m (B166) and 0.011 m (189A). All subsequent survey occupations (17CCT01-17CCT04) produced time weighted averages that were within 3 standard deviations of the first occupation and therefore, for consistency, the 16CCT07 coordinates were used in post-processing. Data acquired during survey 17CCT05 was post-processed using data downloaded from the NGS website for CORS station ALDI (https://www.ngs.noaa.gov/CORS/Sites/aldi.html). The station is located approximately 30 km away from the survey location, causing significant errors due to extended baseline distance. Total station samples are referenced to a benchmark at each of the study sites.
4. Where are the gaps in the data? What is missing?
   This dataset includes the locations of 1,236 elevation points collected from shorelines, water level logger wells, elevation benchmarks, random surface samples, and net sedimentation tile study sites that were collected from Grand Bay Mississippi from October 2016 to October 2017 (USGS FANs 16CCT07, 17CCT01, 17CCT02, 17CCT03, 17CCT04, and 17CCT05). This dataset is considered complete for the information presented, as described in the abstract section. Users are advised to read the rest of the metadata record carefully for additional details. In some cases, sensor malfunctions or significant errors caused data loss for some sites or FANs. During 17CCT01 a total station was used in some cases and there is no occupation time, collection time, easting, northing, latitude, longitude, verified elevations, or horizontal error.
5. How consistent are the relationships among the observations, including topology?
   Position and elevation data at each sample site were recorded with Ashtech DGPS receivers and GNSS antennas. Additionally, DGPS data were recorded concurrently throughout the survey at two NGS benchmarks using a similar instrument combination. Due to a local base station malfunction during survey 17CCT05, the nearest Continually Operating Reference Station (CORS) ALDI (PID=DL3486), located on the east end of Dauphin Island, Alabama, was utilized for post-processing. The final sample locations, including elevation, are the post-processed DGPS coordinates processed to the nearest base station; baseline distances for all sample sites were approximately less than 9 kilometers (km), sample elevations from survey 17CCT05 have a baseline upwards of 30 km. Total station samples do not include occupation times, collection times, positional data, or horizontal errors. The random surface samples (R) collected with the total station do not include verified elevations and should be used with caution.

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 to be acknowledged as originator of the data in future products or derivative research. This metadata record should be reviewed in its entirety to ensure specific data are suitable for other studies. These data should not be used for navigational purposes.

1. Who distributes the data set? (Distributor 1 of 1)
   
   U.S. Geological Survey St Petersburg Coastal and Marine Science Center

   Attn: Kathryn Smith

   Research Ecologist

   600 4th Street South

   St. Petersburg, FL
   

   727-502-8073 (voice)

   727-502-8182 (FAX)

   kelsmith@usgs.gov
2. What's the catalog number I need to order this data set? Grand_Bay_Elevation_Data.csv
3. What legal disclaimers am I supposed to read?

   This digital 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, 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:	comma-delimited text .csv Size: 0.048
     Network links:	https://coastal.er.usgs.gov/data-release/doi-P9BFR2US/data/Grand_Bay_Elevation_Data.zip

   • Cost to order the data: None. No fees are applicable for obtaining the dataset.

Who wrote the metadata?

Dates:

Last modified: 13-Oct-2020

Metadata author:

U.S. Geological Survey St Petersburg Coastal and Marine Science Center

Attn: Joseph F. Terrano

Researcher III

600 4th Street South

St. Petersburg, FL

727-502-8047 (voice)

727-502-8182 (FAX)

jterrano@contractor.usgs.gov

Metadata standard:

Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)