Single-Beam Bathymetry of the Hurricane Sandy Breach at Fire Island, New York, June 2013 (1-Meter Digital Elevation Model)

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Frequently anticipated questions:

What does this data set describe?

Single-Beam Bathymetry of the Hurricane Sandy Breach at Fire Island, New York, June 2013 (1-Meter Digital Elevation Model)
This dataset,, contains a 1-meter (m) grid of June 2013 bathymetry of the breach channel, ebb shoal, and adjacent coast of the Fire Island Wilderness Breach. Scientists from the U.S. Army Corps of Engineers (USACE), in collaboration with the U.S. Geological Survey (USGS), St. Petersburg Coastal and Marine Science Center (SPCMSC), conducted a bathymetric survey from June 22-26, 2013. The survey focused on a breach (Wilderness Breach) created by Hurricane Sandy near Pelican Island, NY, which is located in Great South Bay. A total of 41 shore-perpendicular transects with a 50-meter spacing were collected using a Knudsen 320BP single-beam echosounder, centered on the breach.
Data were collected onboard the LARC-5 survey vehicle, which is 10.6 m (35 ft) long, 3 m (10.2 ft) wide and 3.3 m (11 ft) tall. It has a maximum land speed of 40 kph (25 mph) and approximately 11 kph in water, with a typical survey speed of 7 kph. Data were collected during USGS field activity number (FAN) 13CCH06, additional survey details are available at
  1. How might this data set be cited?
    U.S. Geological Survey, 20150126, Single-Beam Bathymetry of the Hurricane Sandy Breach at Fire Island, New York, June 2013 (1-Meter Digital Elevation Model): U.S. Geological Survey Data Series 914, U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -72.906674728
    East_Bounding_Coordinate: -72.881454869
    North_Bounding_Coordinate: 40.726625604
    South_Bounding_Coordinate: 40.713254033
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 22-Jun-2013
    Ending_Date: 26-Jun-2013
    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 1435 x 2097 x 1, type Grid Cell
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      UTM_Zone_Number: 18
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -75.0
      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 1.0
      Ordinates (y-coordinates) are specified to the nearest 1.0
      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?
    Esri 32 bit floating point raster grid created from outputs of USACE post-processing program; edited in ArcGIS to remove certain errant data points. (Source: USGS)
    Unknown (Source: Producer defined)
    Range of values

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?
    USACE Field Research Facility
    Attn: Nick Spore
    Research Civil Engineer
    Kitty Hawk, NC

    (252) 261-6840 ext 231 (voice)

Why was the data set created?

In October 2012 Hurricane Sandy created a new breach in Fire Island, one of the barrier islands along the southern coast of Long Island, New York. The objective of this study was to create an updated bathymetric map in order to better understand the geomorphological progression of the breach.

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: 2013 (process 1 of 4)
    Single-beam data were collected in the Atlantic Ocean (offshore of Fire Island, NY), through the breached area and in Great South Bay (near Pelican Island, NY) onboard the USACE's LARC-5 amphibious vehicle. The LARC operator used the RTK GPS to follow a pre-defined course of survey lines entered into HYPACK, prior to the start of the survey. The Trimble 4000 RTK GPS software combined with HYPACK 2013 Hydrographic survey software helped ensure the operator stayed on course throughout data acquisition. Person who carried out this activity:
    Nick Spore
    USACE Field Research Facility
    Research Civil Engineer
    Kitty Hawk, NC

    (252) 261-6840 ext 231 (voice)
    Date: 2013 (process 2 of 4)
    HYPACK software was used to merge the GPS and echosounder data to create text files, in .RAW format, which were later analyzed by the custom-built USACE Field Research Facility FORTRAN software. Conductivity, temperature and depth (CTD) were measured at the beginning of the survey (at the -8m isobath) and at the end of the survey (at the -8m isobath) aboard the LARC to determine the speed of sound in the water column. The time-stamp on the echosounder was corrected for 'drift' using the GPS time clock. The custom FRF software was used to remove the motion of the LARC due to waves and changing tide level. It also adjusted the measurements to changes in the speed of sound over the survey area and correctly aligned the time of the echosounder and the GPS data. This was done by dynamically adjusting the time or latency of the GPS data relative to the echosounder data until a best fit was achieved. Person who carried out this activity:
    Nick Spore
    USACE Field Research Facility
    Research Civil Engineer
    Kitty Hawk, NC

    (252) 261-6840 ext 231 (voice)
    Date: 2013 (process 3 of 4)
    Land points were separated from points in the water by first computing the average and standard deviation for all GPS elevations collected when the echosounder data indicated that the LARC was floating. Person who carried out this activity:
    Nick Spore
    USACE Field Research Facility
    Research Civil Engineer
    Kitty Hawk, NC

    (252) 261-6840 ext 231 (voice)
    Date: 2014 (process 4 of 4)
    Post-processed topographic-bathymetric data from USACE were importedinto ArcGIS 10.2.1, converted to a NAD 1983 UTM Zone 18N coordinate system, saved as a point shapefile and used to create a trackline map of the single-beam point data coverage. Errant data points were manually removed from the data. The edited trackline data were exported from ArcGIS into a text file as well as being used to create a 32 bit raster grid and calculate vertical RMSE; the grid was computed using a natural neighbors gridding algorithm with a 1-m grid cell. The raster grid was also used to generate a color-contoured image of the breach. Person who carried out this activity:
    Andrew T Brownell
    U.S. Geological Survey, SOUTHEAST REGION
    Research Assistant
    600 4th Street South
    St. Petersburg, FL

    727-502-8097 (voice)
  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?
    A GPS base station was established on 22 June 2013 by USGS staff and occupied for three consecutive days before submitting the coordinates to the Online Positioning User Service (OPUS) for precise quality control.
  2. How accurate are the geographic locations?
    The LARC's onboard RTK GPS system computes its location from available transmitting GPS satellites. After it determines its location, the correction from the base station is received and applied to that computed position for a more accurate positioning. An accuracy of +/- 2 m in all three dimensions can thus be achieved. Horizontal Coordinate System: North American Datum 1983 (NAD83), meters Projection: New York State Plane Long Island, meters (3104)
  3. How accurate are the heights or depths?
    The Knudsen 320BP echosounder is capable of measuring depths as shallow as 10 cm. The accuracy is determined as three percent of the selectable depth range. The elevations of above water points are based on the height above the ground of the GPS antenna on the LARC. The GPS control monument was located on Fire Island at the National Park Service Visitor Center benchmark, with a latitude of 40 43 58.16252 and a longitude of -72 52 01.04782.
  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?
    This dataset was acquired on one research event over the course of 5 days in 2013 and is therefore internally consistent. Forty-one shore-perpendicular transects with a 50-m spacing were acquired using a single-beam echosounder.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None
These data are not to be used for navigation. The U.S. Geological Survey requests that it be referenced 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, SOUTHEAST REGION
    Attn: Cheryl J Hapke
    Research Geologist
    600 4th Street South
    St. Petersburg, FL

    727-502-8000 (voice)
    727-502-8001 (FAX)
  2. What's the catalog number I need to order this data set?
  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, 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: The data were created with Environmental Systems Research Institute (Esri) ArcGIS version 10.2.1. Shapefiles may also be viewed with other versions of ArcView, ArcGIS, or the free ArcExplorer ( The ArcGIS shapefile of the trackline data is in the folder labeled: 20130620_bathy_points The text file of the trackline data is labeled: 20130626_bathy_xyz The raster grid is the folder labeled: 20130626_bathy_DEM in format DEM (Digital Elevation Model format [U.S. Geological Survey]) Size: 6.58
      Network links:
    • Cost to order the data: None, if obtained online.

Who wrote the metadata?

Last modified: 01-Feb-2016
Metadata author:
Arnell Forde
U.S. Geological Survey
600 4th Street South
St. Petersburg, FL

727-502-8000 (voice)
727-502-8002 (FAX)
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

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