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High Resolution Bathymetric Mapping

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Frequently-anticipated questions:


What does this data set describe?

Title: High Resolution Bathymetric Mapping
Abstract:
The water levels in Lake Okeechobee were at record low levels in the summer of 2001 making hydrographic surveying ideal in that less area must be covered by boat to fully map the lake floor. This condition also allowed the upper elevations of the lake, which were now exposed, to be mapped by traditional survey techniques or airborne topographic LIDAR technology. Conversely, due to the very flat slope of the lake floor, much of the lakebed was less than 0.6m (2') deep making surveying by any method very difficult at best.
  1. How should this data set be cited?

    Mark Hansen Gary W. Hill; Nancy T. DeWitt, 2002, High Resolution Bathymetric Mapping.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -81.125
    East_Bounding_Coordinate: -80.5
    North_Bounding_Coordinate: 27.25
    South_Bounding_Coordinate: 26.625

  3. What does it look like?

    <https://sofia.usgs.gov/publications/maps/lakeokeebathy/index.html> (JPEG)
    satellite image showing Lake Okeechobee bathymetric contours

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: Sep-2001
    Currentness_Reference: ground condition

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

    Geospatial_Data_Presentation_Form: project, maps and data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      Indirect_Spatial_Reference: Lake Okeechobee

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

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.00000001. Longitudes are given to the nearest 0.00000001. Latitude and longitude values are specified in Decimal degrees.

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257.

      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988
      Altitude_Resolution: 1.0, 0.5
      Altitude_Distance_Units: feet, meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates

  7. How does the data set describe geographic features?

    Entity_and_Attribute_Overview:
    Data in the "raw data" files are in the following format:

    Col 1 Longitude Col 2 Latitude Col 3 X State Plane (ft) Florida East Zone Col 4 Y State Plane (ft) Florida East Zone Col 5 VERTCON corrections factor (m) Col 6 Elevation (m) - NAVD88 Col 7 Elevation (ft) - NAVD88 Col 8 Elevation (m) - NGVD29 Col 9 Elevation (ft) - NGVD29

    Entity_and_Attribute_Detail_Citation: USGS personnel


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

    • Mark Hansen

  2. Who also contributed to the data set?

    The South Florida Water Management District (SFWMD) provided partial funding for this project

  3. To whom should users address questions about the data?

    Mark Hansen
    U.S. Geological Survey
    600 Fourth Street South
    St. Petersburg, FL 33701
    USA

    727 803-8747 x 3036 (voice)
    727 803-2030 (FAX)
    mhansen@usgs.gov


Why was the data set created?

High resolution, acoustic bathymetric surveying is a proven method to map sea and lake floor elevations. Of primary interest to the South Florida Water Management District (SFWMD) is the quantification of the present day lakebed in Lake Okeechobee. This information can be used by water management decision-makers to better assess the water capacity of the lake at various levels.


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: 2002 (process 1 of 1)
    The USGS:

    1. Provided equipment and personnel as necessary to conduct high resolution bathymetric surveying for a minimum of 1550 kilometers.

    The USGS has developed a hydrographic survey system specifically designed to map in very shallow water. A survey quality 200 kHz depth sounder was used to acquire water depth measurements and a motion sensor measured heave, pitch, and roll of the boat. A measurement was collected every second or about every 3 m (10 ft) along a survey line. To achieve horizontal accuracy of +/- 4 cm (1.6 in) and vertical accuracy of +/- 8cm (3 in), the boat could not be operated more than 20 km from any one GPS base station. It was anticipated that two GPS base stations would be used. Several new survey benchmarks were established around the lake perimeter for GPS base station occupation.

    Survey track line spacing was 1000 m apart oriented in a north-south direction. A perimeter survey line and several east-west lines were collected also. In addition random crossing lines were collected daily. Crossing lines were used to crosscheck and verify the survey. Soundings were collected along each track line at 3 m (10 ft) spacing. A minimum of 1550 kilometers of survey line were collected. In shallow areas, data were collected in a minimum of 2 feet water depth except where there was potential damage to the bottom environment or the boat/motors.

    2. Provided post processing of the benchmark and hydrographic data.

    3. Stored and maintained all data and provide access to this data for reproduction as needed by the SFWMD.

    4. Provided a final data package that included the following: a. Hard copy plot of locations of surveyed tracklines. b. Digital ASCII XYZ data in UTM Zone 17, GRS80/NAD83 horizontal coordinates, and NAVD88 vertical coordinates in tabular format. c. Copies of raw and processed digital data files on CD-ROM

    Person who carried out this activity:

    Mark Hansen
    U.S. Geological Survey
    600 Fourth Street South
    St. Petersburg, FL 33701
    USA

    727 803-8747 x 3036 (voice)
    727 803-2030 (FAX)
    mhansen@usgs.gov

  3. What similar or related data should the user be aware of?

    Hill, Gary W. DeWitt, Nancy T; Hansen, Ma, 2001, Elevation Contours of Lake Okeechobee: U.S. Geological Survey, St. Petersburg, FL.

    Online Links:

    Other_Citation_Details: accessed as of 12/28/2010


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?

    Boat position measured using precise differential GPS receivers. Horizontal accuracy is +/- 4 cm (1.6in)

  3. How accurate are the heights or depths?

    Dynamic elevation measured using precise differential GPS receivers. Vertical accuracy is +/- 8 cm (3 in).

  4. Where are the gaps in the data? What is missing?

    unknown

  5. How consistent are the relationships among the observations, including topology?

    unavailable


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: none

  1. Who distributes the data set? (Distributor 1 of 2)

    Heather S. Henkel
    U.S. Geological Survey
    600 Fourth St. South
    St. Petersburg, FL 33701
    USA

    727 803-8747 ext 3028 (voice)
    727 803-2030 (FAX)
    hhenkel@usgs.gov

  2. What's the catalog number I need to order this data set?

    raw data file (ptokeemft.xyz)

  3. What legal disclaimers am I supposed to read?

    The data have no explicit or implied guarantees.

  4. How can I download or order the data?


  1. Who distributes the data set? (Distributor 2 of 2)

    Heather S. Henkel
    U.S. Geological Survey
    600 Fourth St. South
    St. Petersburg, FL 33701
    USA

    727 803-8747 ext 3028 (voice)
    727 803-2030 (FAX)
    hhenkel@usgs.gov

  2. What's the catalog number I need to order this data set?

    Elevation Contours of Lake Okeechobee 2001

  3. What legal disclaimers am I supposed to read?

    The data have no explicit or implied guarantees.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 18-May-2011
Metadata author:
Heather Henkel
U.S. Geological Survey
600 Fourth Street South
St. Petersburg, FL 33701
USA

727 803-8747 ext 3028 (voice)
727 803-2030 (FAX)
sofia-metadata@usgs.gov

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


This page is <https://sofia.usgs.gov/metadata/sflwww/hires_bathy_lakeo.faq.html>

U.S. Department of the Interior, U.S. Geological Survey
Comments and suggestions? Contact: Heather Henkel - Webmaster
Generated by mp version 2.8.18 on Wed May 18 09:51:43 2011