Hillshade of Swath Bathymetry collected by the USGS offshore of the Grand Strand, South Carolina, 1999-2003 (BATHY_HILLSH, grid)

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Frequently anticipated questions:


What does this data set describe?

Title:
Hillshade of Swath Bathymetry collected by the USGS offshore of the Grand Strand, South Carolina, 1999-2003 (BATHY_HILLSH, grid)
Abstract:
In 1999, the U.S. Geological Survey (USGS), in partnership with the South Carolina Sea Grant Consortium, began a study to investigate processes affecting shoreline change along the northern coast of South Carolina, focusing on the Grand Strand region. Previous work along the U.S. Atlantic coast shows that the structure and composition of older geologic strata located seaward of the coast heavily influences the coastal behavior of areas with limited sediment supply, such as the Grand Strand. By defining this geologic framework and identifying the transport pathways and sinks of sediment, geoscientists are developing conceptual models of the present-day physical processes shaping the South Carolina coast. The primary objectives of this research effort are: 1) to provide a regional synthesis of the shallow geologic framework underlying the coastal upland, shoreface and inner continental shelf, and define its role in coastal evolution and modern beach behavior; 2) to identify and model the physical processes affecting coastal ocean circulation and sediment transport, and to define their role in shaping the modern shoreline; and 3) to identify sediment sources and transport pathways; leading to construction of a regional sediment budget.
  1. How might this data set be cited?
    U.S. Geological Survey, 2007, Hillshade of Swath Bathymetry collected by the USGS offshore of the Grand Strand, South Carolina, 1999-2003 (BATHY_HILLSH, grid): Open-File Report 2005-1346, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Coastal and Marine Science Center, Woods Hole, MA.

    Online Links:

    This is part of the following larger work.

    Baldwin, W.E., Denny, J.F., Schwab, W.C., Gayes, P.T., Morton, R.A., and Driscoll, N.W., 2007, Geologic Framework Studies of South Carolina's Long Bay from Little River Inlet to Winyah Bay, 1999-2003; geospatial data release: Open-File Report 2005-1346, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -79.177101
    East_Bounding_Coordinate: -78.502832
    North_Bounding_Coordinate: 33.876654
    South_Bounding_Coordinate: 33.144166
  3. What does it look like?
    http://pubs.usgs.gov/of/2005/1346/images/bathy_hillsh.jpg (JPEG)
    hillshade of bathymetry
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 29-Oct-1999
    Ending_Date: 21-May-2003
    Currentness_Reference:
    ground condition of several individual surveys: 19991029 to 19991112, 20000313 to 20000330, 20010501 to 20010515, 20020502 to 20020508, 20020603 to 20020618, 20030501 to 20030521.
  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 800 x 610 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: 17
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -81.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 100.000000
      Ordinates (y-coordinates) are specified to the nearest 100.000000
      Planar coordinates are specified in meters
      The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257224.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: Mean lower low water
      Depth_Resolution: 100
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Implicit coordinate
  7. How does the data set describe geographic features?
    bathy_hillsh
    ESRI GRID (Source: ESRI)
    COUNT
    Internal (Source: ESRI) Sequential unique whole numbers that are automatically generated.
    Rowid
    Internal feature number. (Source: ESRI) Sequential unique whole numbers that are automatically generated.
    VALUE
    Hillshade Value (digital number) (Source: ESRI) Sequential unique whole numbers that are automatically generated.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • U.S. Geological Survey
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    U.S. Geological Survey
    Attn: Jane Denny
    Geologist
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 x2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov

Why was the data set created?

This data set contains a hillshade of the swath bathymetric data collected between 1999 and 2003. These data are used to define the sea-floor morphology offshore of the Grand Strand, South Carolina.

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: 2004 (process 1 of 10)
    Bathymetric data were corrected for variations in the speed of sound throughout the water column; sound velocity profiles were acquired throughout the survey area using an Applied MicroSystems SVPlus Sound Velocimeter. These data were downloaded and reformatted to the required format needed for use within University of New Brunswick's Ocean Mapping Group (OMG) SwathEd multibeam processing software. The raw Submetrix 2000 Series data were "unraveled" and reformatted into the OMG format. This process creates several files on disk: 1) bathymetric soundings 2) raw sidescan-sonar backscatter 3) navigation 4) parameter files describing the configuration of the system (i.e. offsets between motion reference unit and GPS antenna, etc). This process also incorporates the sound velocity profiles in order to properly trace the rays given the structure of the water column. Person who carried out this activity:
    Jane Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 x2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov
    Date: 2004 (process 2 of 10)
    The OMG formatted bathymetric data were then graphically edited using the SwathEd multibeam processing software. This enabled editing on a "ping-by-ping" basis, both in the across- and along-track dimension. Spurious or erroneous data were removed. The navigation data were also graphically examined for each line of data. Person who carried out this activity:
    Jane Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 x2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov
    Date: 2004 (process 3 of 10)
    Navigation data output during the unravel were reformatted for entry into MATLAB. The time of day and position were used to extract the tidal elevation from within the ADCIRC circulation model. The ADCIRC circulation model is referenced to Mean Sea Level. Verified tidal data from the NOAA tidal gauge at SpringMaid Pier, SC were downloaded, referenced to Mean Lower Low Water (MLLW). A low-pass filter was applied to the NOAA tide data; the residual was assumed to represent the wind component of sea surface elevations. Tidal elevation (output from ADCIRC) and wind component (NOAA tide station) represent total variation in surface elevations. These data were then written to an ASCII file and reformatted to OMG format for use within SwathEd. The tidal data were then written into the headers of the OMG formatted files, using the 'mergedTide' command. (SwathEd Commands: binTide -year XXX adcirc_wind.txt tide.bin mergeTide -tide tide.bin *.merged ) SwathEd Software was used to grid the bathymetric data at 20 m grid cell size utilizing the 'weigh_grid' command. weigh_grid -omg -butter -power 2 -cutoff 10 -lambda 2.5 Grid *.merged The gridded data were then viewed using the SwathEd Jview Command. The PatchTool was used to assess the roll misalignment of the data; slight roll misalignment artifacts were visible in the gridded data. The PatchTool is a QC tool to assess the degree to which the head (transducers and MRU) needs to be 'rolled' to achieve the proper alignment. QC was also preformed on the navigation. Edits were made as necessary. After the needed adjustments were recorded, the configuration and navigation were remerged with the OMG bathymetric data using the mergeNav and mergeAtt commands. mergeNav -use_params 0 -nav *.nav -swath *.merged) The remerged data were regridded for a second round of QC. The roll misalignment artifacts were no longer visible in the gridded data. The bathymetric data to this point have been edited, navigation, edited, tidal elevations relative to MLLW incorporated in the data, sound velocity corrections applied, and roll misalignment rectified. Next the data need to be interpolated to generate a continuous bathymetric surface. The SwathEd 'make_blank' command was used to generate a 20 meter grid for the survey area. The OMG formatted bathymetric files were then written into the 20 meter grid using the 'weigh_grid' command. Due to noise within the far range of the sonar signal, the 'max_incidence' parameter was used. This essentially limits the across track data range of the data; thus elimination noise. (weigh_grid -omg -butter -power 2 -cutoff 20 -lambda 10 -max_incidence 60 Grid *.merged) The 20 meter gridded data were then exported to an xyz ASCII file. (r4toASCII -utm -merid -81 20m_grd 20m.xyz) Person who carried out this activity:
    Jane Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 x2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov
    Date: 2004 (process 4 of 10)
    The 20m xyz ASCII data were then imported into Geographic Resources Analysis Support System (GRASS). A spline with tension and directionality interpolation routine was used in order to generate a continuous bathymetric surface from the interferometric sonar data. After many iterations, the gridding parameters resulting in a gridded dataset with the least amount of visible artifacts were as follows: s.surf.rst input=20m.xyz elev=grid100m field=1 tension=200 dmin=20 theta=45 scalex=0.5 smooth=2 A smoothing filter (comparable to a median/mean filter) was applied to the dataset. Person who carried out this activity:
    Jane Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 x2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov
    Date: 2004 (process 5 of 10)
    The final grid was then exported as an ESRI Binary Grid. r.out.arc in=grid100m out=grid100m.asc The exported data were then imported to ArcGIS 9.0 using the ASCIItoGRID command. The projection was then defined: UTM, zone 17 projection, WGS84 Ellipsoid. Person who carried out this activity:
    Jane Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 x2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov
    Date: 2004 (process 6 of 10)
    Hillshade was applied to bathymetric grid using an elevation of 45, vertical exaggeration of 5x, and sun angle of 45 within Spatial Analysis Tools within ArcGIS 9.1. Person who carried out this activity:
    Jane Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 x2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov
    Date: 27-Jun-2016 (process 7 of 10)
    Edits to the metadata were made to fix any errors that MP v 2.9.32 flagged. This is necessary to enable the metadata to be successfully harvested for various data catalogs. In some cases, this meant adding text "Information unavailable" or "Information unavailable from original metadata" for those required fields that were left blank. Other minor edits were probably performed (title, publisher, publication place, etc.). An online link was changed to point to pubs.usgs.gov. Date range format had to be fixed. The distribution format name was modified in an attempt to be more consistent with other metadata files of the same data format. The metadata date (but not the metadata creator) was edited to reflect the date of these changes. The metadata available from a harvester may supersede metadata bundled within a download file. Compare the metadata dates to determine which metadata file is most recent. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Rd.
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
    Date: 20-Jul-2018 (process 8 of 10)
    USGS Thesaurus keywords added to the keyword section. 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: 18-Nov-2019 (process 9 of 10)
    Crossref DOI link was added as the first link in the metadata. 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: 08-Sep-2020 (process 10 of 10)
    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?

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

  1. How well have the observations been checked?
    These data are internally consistent and have been compared to multibeam and single-beam bathymetric surveys to check for accuracy. Any differences between this bathymetric data set and others were determined to be within acceptable error given the inherent differences in the various bathymetric data sets (i.e. acquisition system, mode of navigation, density of point, and or swath bathymetry).
  2. How accurate are the geographic locations?
    DGPS is assumed to be accurate within 1-2 meters. Standard GPS is assumed accurate within 5-10 meters. 99% of the positional data is DGPS. Unless noted, all GPS/DGPS data is referenced to WGS84 (NAD83). The configuration of the fathometer is as follows: The fathometer is mounted on either the port or starboard side of the vessel. Offset between the sidemount and GPS antennae is measured. No measurements were taken of ship's pitch, yaw, heave, or change in draft due to water and fuel usage. Motion of the fathometer is not measured. Horizontal accuracy of the fathometer is assumed to be within 3 meters.
  3. How accurate are the heights or depths?
    Ship motion was recorded with a TSS DMS 2-05 Attitude Sensor, mounted directly above the SEA SwathPlus transducers. Navigation was recorded using a Differential Global Positioning System (DGPS). The interferometric sonar is an angle-measuring system; depth accuracy decreases with increasing horizontal range. The combined angular accuracy of the SwathPlus system and the TSS DMS 2-05 attitude sensor is documented as 0.1 degrees. Assuming a constant angular accuracy, and using the International Hydrographic Standard (IHO) of a required 0.3 meter accuracy in < 30 meter water depth, all data collected within the survey fall within the IHO accuracy standards. However, vertical accuracy is also directly affected by the accuracy of both the navigation system and tidal measurements.
  4. Where are the gaps in the data? What is missing?
    These data represent all bathymetric data collected by the USGS offshore of Myrtle Beach, SC 1999 - 2003. Any spurious data were removed during processing.
  5. How consistent are the relationships among the observations, including topology?
    A hillshade was applied to the final bathymetric grid. Any spurious data were removed during processing.

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:
These data are NOT to be used for navigation purposes. Mariners should refer to the appropriate nautical chart. Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    384 Woods Hole Road
    Woods Hole, MA
    USA

    508-548-8700 (voice)
    508-457-2310 (FAX)
  2. What's the catalog number I need to order this data set? Downloadable Data
  3. What legal disclaimers am I supposed to read?
    Although all data have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and/or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm 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?
    • Availability in digital form:
      Data format: Grid contains a hillshade of swath bathymetry collected offshore of the Grand Strand, SC in format AIG (version ArcGIS 9.0) ESRI Grid Format Size: 0.226
      Network links: http://pubs.usgs.gov/of/2005/1346/arcgis/bathy/bathy_hillsh.zip
      Media you can order: DVD-ROM (Density 4.75 Gbytes) (format UDF)
    • Cost to order the data: None

  5. What hardware or software do I need in order to use the data set?
    These data are available in Environmental Systems Research Institute (ESRI) Raster GRID format. The user must have software capable of importing and processing the data file.

Who wrote the metadata?

Dates:
Last modified: 08-Sep-2020
Metadata author:
Jane Denny
U.S. Geological Survey
Geologist
384 Woods Hole Road
Woods Hole, MA
USA

508-548-8700 x2311 (voice)
508-457-2310 (FAX)
jdenny@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/whcmsc/open_file_report/ofr2005-1346/bathy_hillsh.grd.faq.html>
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