Bathymetric Grid for a Wave Exposure Model of Grand Bay, Mississippi

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Frequently anticipated questions:

What does this data set describe?

Title:
Bathymetric Grid for a Wave Exposure Model of Grand Bay, Mississippi
Abstract:
Coastal marshes are highly dynamic and ecologically important ecosystems that are subject to pervasive and often harmful disturbances, including shoreline erosion. Shoreline erosion can result in an overall loss of coastal marsh, particularly in estuaries with moderate- or high-wave energy. Not only can waves be important physical drivers of shoreline change they can also influence shore-proximal vertical accretion through sediment delivery. For these reasons, estimates of wave energy can provide a quantitative measure of wave effects on marsh shorelines. Since wave energy is difficult to measure at all locations, scientists and managers often rely on hydrodynamic models to estimate wave properties at different locations. The Wave Exposure Model (WEMo) is a simple tool that uses linear wave theory to estimate wave energy characteristics for enclosed and semi-enclosed estuaries (Malhotra and Fonseca, 2007). The interpretation of hydrodynamic models is improved if model results can be validated against measured data. The data presented in this publication are input and validation data for modeled and observed mean wave height for two temporary oceanographic stations established by the U.S. Geological Survey (USGS) in the Grand Bay National Estuarine Research Reserve, Mississippi.
Supplemental_Information:
Oceanographic and water quality measurements were collected in Grand Bay by the U.S. Geological Survey (USGS) from August 2016 to January 2017 under Field Activity Numbers (FAN) 2016-046-FA and 2017-006-FA. This data release only presents data from October 2016 to January 2017 for model validation purposes. For additional information see https://cmgds.marine.usgs.gov/fan_info.php?fan=2017-0406-FA. The bathymetric digital elevation model (DEM) was compiled through depth measurements obtained from multiple National Oceanic and Atmospheric Administration (NOAA) hydrographic surveys (H08647, H08648, H09118, F11621, H11620, and F00588) and single-beam bathymetry data collected by USGS under the FAN 2015-315-FA. For additional information see https://cmgds.marine.usgs.gov/fan_info.php?fan=2015-315-FA. Wind data were obtained from NOAA National Data Buoy (GDXM6) Crooked Bayou, Grand Bay Reserve, MS.
  1. How might this data set be cited?
    Smith, Kathryn E.L., and Terrano, Joseph F., 20190430, Bathymetric Grid for a Wave Exposure Model of Grand Bay, Mississippi: U.S. Geological Survey Data Release doi:10.5066/P9Z4ZPU3, U.S. Geological Survey, St. Petersburg, Florida.

    Online Links:

    This is part of the following larger work.

    Smith, Kathryn E.L., and Terrano, Joseph F., 20190430, Wave Exposure Model for Grand Bay, Mississippi: Input and Validation Datasets: U.S. Geological Survey Data Release doi:10.5066/P9Z4ZPU3, U.S. Geological Survey, St. Petersburg, Florida.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -88.486411
    East_Bounding_Coordinate: -88.271674
    North_Bounding_Coordinate: 30.407174
    South_Bounding_Coordinate: 30.185720
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 26-Sep-1961
    Ending_Date: 03-Jun-2015
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: raster digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Raster data set. It contains the following raster data types:
      • Dimensions 2430 x 2036 x 1, type Grid Cell
    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 row and column
      Abscissae (x-coordinates) are specified to the nearest 10
      Ordinates (y-coordinates) are specified to the nearest 10
      Planar coordinates are specified in meter
      The horizontal datum used is NAD83 North American Datum 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:
      Depth_System_Definition:
      Depth_Datum_Name: MLLW
      Depth_Resolution: 0.10
      Depth_Distance_Units: meter
      Depth_Encoding_Method: Implicit coordinate
  7. How does the data set describe geographic features?

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
  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. Users should be aware that comparisons with other datasets for the same area from other time periods may be inaccurate due to inconsistencies resulting from changes in photointerpretation, mapping conventions, and digital processes over time. 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, Florida

    727-502-8073 (voice)
    727-502-8182 (FAX)
    kelsmith@usgs.gov

Why was the data set created?

The publication includes model input data (bathymetry, shorelines, and wind data) and values for both observed and modeled mean wave heights for 13 weeks from October 2016 to January 2017. The primary goal is to develop a model that examines the relationships between wave energy, shoreline erosion, and marsh sediment delivery and deposition.

How was the data set created?

  1. From what previous works were the data drawn?
    RBR (source 1 of 5)
    U.S. Geological Survey, 2018, Oceanographic and water quality measurements collected in Grand Bay, Alabama/Mississippi - August 2016 - January 2017: U.S. Geological Survey, Woods Hole, Massachusetts.

    Online Links:

    Type_of_Source_Media: digital data
    Source_Contribution: Source of observed wave measurements
    NGDC_bathy (source 2 of 5)
    NOAA National Centers for Environmental Information, Unknown, Bathymetric Data Viewer: National Oceanic and Atmospheric Administration, Unknown.

    Online Links:

    Type_of_Source_Media: digital data
    Source_Contribution: Bathymetry for wave model
    USGS_bathy (source 3 of 5)
    U.S. Geological Survey, 20171201, Single-beam bathymetry data collected in 2015 from Grand Bay, Alabama-Mississippi: U.S. Geological Survey, St Petersburg, Florida.

    Online Links:

    Type_of_Source_Media: digital data
    Source_Contribution: Bathymetry for wave model
    GNDCRMET (source 4 of 5)
    Grand Bay National Estuarine Research Reserve, Unknown, Grand Bay (GND) National Estuarine Research Reserve System-wide Monitoring Program: Crooked Bayou: Centralized Data Management Office, Columbia, South Carolina.

    Online Links:

    Type_of_Source_Media: digital data
    Source_Contribution:
    Meteorological station provided wind speed and direction for wave model
    2012_shoreline (source 5 of 5)
    U.S. Geological Survey, 2018, A GIS Compilation of Vector Shorelines Derived from Aerial Imagery for the Grand Bay Region of Mississippi and Alabama: 2010 and 2012: U.S. Geological Survey, St Petersburg, Florida.

    Online Links:

    Type_of_Source_Media: digital data
    Source_Contribution: Shoreline used to create raster mask
  2. How were the data generated, processed, and modified?
    Date: 2018 (process 1 of 5)
    Bathymetric data covering Grand Bay and Mississippi Sound were compiled and rasterized for wave model input. Data from hydrographic charts were downloaded from the NOAA Bathymetry Data Viewer. The following hydrographic surveys (with collection year) covered the study area: F00588 (2010), H11620 (2007), F11621 (2006), H09118 (1970), H08647 (1962), and H08648 (1962). In addition, the USGS single-beam bathymetry data collected in 2015 was included. The data were converted to a consistent tidal datum (Mean Lower Low Water (MLLW)) using Vdatum software (https://vdatum.noaa.gov/). Using latitude and longitude coordinates from each file, data were imported into ArcGIS (version 10.6) as shapefiles and merged into one file. Data were weighted based on date of survey, with recent surveys given a weight of 10 (2015 and 2010), recent past surveys a weight of 5 (2007 and 2006) and historical surveys a weight of 1 (1970 and 1962). Using the Inverse Distance Weighted tool in ArcGIS, a raster was created using the vertical elevation as the Z value input, a standard search radius of 50 to 100 nearest neighbors, and the weight field. The Focal Statistics tool was used to smooth the dataset using a circle radius of 20 cells. A raster mask was created by buffering the 2012 shoreline and enclosing the Grand Bay estuary and Mississippi Sound, out to the landward side of Petit Bois and Dauphin Islands. Person who carried out this activity:
    Kathryn Smith
    Research Ecologist
    600 4th Street South
    St.Petersburg, FL
    USA

    727-502-8073 (voice)
    kelsmith@usgs.gov
    Data sources used in this process:
    • NGDC_bathy
    • USGS_bathy
    • 2012_shoreline
    Data sources produced in this process:
    • bathy_grid
    • raster_mask
    Date: 2018 (process 2 of 5)
    Wind data for 2016 and 2017 were downloaded for the Crooked Bayou meteorological station from the National Estuarine Research Reserve's Centralized Data Management Office (CDMO). Using Excel (version 1803), the data for both years were appended. Wind speed was corrected for gauge height using the Power Law Method (described here: https://www.ndbc.noaa.gov/adjust_wind.shtml) and processed for model input using the WEMo Wind Analysis tool. WEMo calculates the wind speed and corresponding frequency for every 6.43 degrees (56 rays) angular resolution and is resampled or linearly interpolated for any other angular resolution. Wind frequency for a direction is defined as the ratio of the number of hours the wind blows from that direction and the total number of hours of wind data. Wind data for each week (beginning with October 24th, 2016 and ending on January 24th, 2017) are exported as representative wind energy (RWE) wind files for model input. Files were named "GB_wind_<start date>_<end date>_corr.Wind_RWE". RWE files are formatted specifically for WEMo input but can be viewed in any text editing software. For more information, see WEMo documentation (Malhotra and Fonseca 2007). Person who carried out this activity:
    Kathryn Smith
    Research Ecologist
    600 4th Street South
    St.Petersburg, FL
    USA

    727-502-8073 (voice)
    kelsmith@usgs.gov
    Data sources used in this process:
    • GNDCRMET
    Data sources produced in this process:
    • RWE_wind
    Date: 2018 (process 3 of 5)
    Mean wave height was calculated for the same location as two USGS observational wave stations in Grand Bay. A shapefile of the station locations was created in ArcGIS by obtaining latitude and longitude coordinates from the KML file located on the data publication (Nowacki and others, 2018). Stations used in this study include 1078 and 1076. Several stations were excluded because they were either located within a river mouth and lack bathymetry data or adjacent to the shoreline and may be impacted by refractive waves. Wave height is estimated by the model through a series of wave propagation and dissipation steps, using the wind speed and direction data (RWE wind), along with depth (bathy grid) and shoreline (2012 shoreline). Wave generation equations are modified to account for limited fetch and wave dissipation factors that account for wave friction, shoaling and breaking due to shallow water. For details on model parameterization and calculations, see Malhotra and Fonseca (2007). Mean wave height for each weekly model run was populated in an Excel file. Person who carried out this activity:
    Kathryn Smith
    Research Ecologist
    600 4th Street South
    St.Petersburg, FL
    USA

    727-502-8073 (voice)
    kelsmith@usgs.gov
    Data sources used in this process:
    • RWE_wind
    • 2012_shoreline
    • bathy_grid
    Data sources produced in this process:
    • Mean_Hs
    Date: 2018 (process 4 of 5)
    Mean wave height was calculated from the observational wave data for two wave sensors. NetCDF datasets containing wave height data were downloaded from the data publication (Nowacki and others, 2018). Only data for the RBR virtuoso D|wave sensor at sites 1076 and 1078 was used (data file '10763Bdws-a.nc' and '10781Baqd-a.nc') because (1)the sensor provides the most accurate wave height data, (2) bathymetry data was available for those locations, and (3) the sensor is located far enough from the shoreline to reduce impact of refractive waves. The datasets were imported into R version 3.5.1 (https://www.r-project.org/about.html) and weekly mean wave height were calculated from observational measurements. Data was entered into the Excel spreadsheet containing modeled mean wave height. The Excel spreadsheet was exported as a non-proprietary, tab-delimited text file for publication purposes. Person who carried out this activity:
    Kathryn Smith
    Research Ecologist
    600 4th Street South
    St.Petersburg, FL
    USA

    727-502-8073 (voice)
    kelsmith@usgs.gov
    Data sources used in this process:
    • RBR
    • Mean_Hs
    Data sources produced in this process:
    • Mean_Hs.txt
    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?
    Malhotra, A., and M.S. Fonseca, 2007, WEMo (Wave Exposure Model): Formulation, Procedures and Validation: NOAA Technical Memorandum NOS NCCOS #65, National Oceanic and Atmospheric Administration, Beaufort, North Carolina.

    Online Links:

    Other_Citation_Details: Publication describing the wave model and parameterization
    Nowacki, D.J., Suttles, S.E., Ganju, N.K., Montgomery, E.T. and Martini, M.A., 2018, Oceanographic and water quality measurements collected in Grand Bay, Alabama/Mississippi August 2016-January 2017: U.S. Geological Survey, Woods Hole, Massachusetts.

    Online Links:

    Other_Citation_Details: Source of oceanographic data

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?
    A formal accuracy assessment of the horizontal positional information in the dataset has not been conducted. For additional information on data collection techniques see the source metadata.
  3. How accurate are the heights or depths?
    A formal accuracy assessment of the vertical positional information in the dataset has not been conducted. For additional information on data collection techniques see the source metadata.
  4. Where are the gaps in the data? What is missing?
    Dataset is considered complete for the information presented. Some oceanographic data were not used as the full data record (August 4th, 2016 to January 26th, 2017) was longer than required for model validation. 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?
    Model and observed wave information were checked for completeness and accuracy.

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:
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. 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 data is used appropriately. Bathymetry data were developed exclusively for the development of a wave model and scientific research and should not be used for navigation 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? bathy_grid.img
  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?
  5. What hardware or software do I need in order to use the data set?
    The bathymetry grid is provided as a .img file, which is proprietary format; however, ERDAS Imagine files can be read and written by ArcGIS Desktop and other Esri applications. It is also supported by Safe Software's FME engine for format conversion and can be viewed in GeoViewer, freely downloadable from LizardTech. A free desktop viewer, ERDAS ER Viewer, is available from Hexagon Geospatial or ERDAS_IMG files.

Who wrote the metadata?

Dates:
Last modified: 13-Oct-2020
Metadata author:
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
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/spcmsc/Bathy_grid_metadata.faq.html>
Generated by mp version 2.9.50 on Tue Sep 21 18:18:33 2021