Geophysical Surveys of Bear Lake, Utah-Idaho, September 2002 - Bathymetric Grid

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Frequently-anticipated questions:

What does this data set describe?
    Title:
    Geophysical Surveys of Bear Lake, Utah-Idaho, September 2002 - Bathymetric Grid
    Abstract:
    Bear Lake is a tectonic lake that has existed for at least several hundred thousand years. The lake basin is a relatively simple half graben, a spoon-shaped depression tilted toward the main fault on the east side of the lake. The U.S. Geological Survey, in cooperation with researchers from several universities, has been studying the sediments of Bear Lake since 1996. The general purpose of this effort is to reconstruct past limnological conditions and regional climate on a range of timescales, from hundreds of years to hundreds of thousands of years. This research relates to a variety of human concerns, including water usage in the Bear River basin. Past work has included several coring operations, a seismic-reflection survey, sediment-trap deployments, a barge-mounted drilling operation with the GLAD800 drill rig, and a variety of other studies. The objectives of the September, 2002 operations, preliminarily reported here, were (1) to compile a detailed bathymetric map of the lake using swath-mapping techniques, in order to provide baseline data for a variety of applications and studies, and (2) to complete a sidescan-sonar survey of the lake, providing a nearly complete acoustic image of the lake floor. Limited amounts of subbottom acoustic-reflection data (chrip) were also collected, along with samples of lake-floor sediments representative of different kinds of backscatter patterns. These surveys followed an earlier subbottom acoustic-reflection survey (1997), using boomer and 3.5 kHz systems (S. M. Colman, unpublished data).

  1. How should this data set be cited?

    U.S. Geological Survey, 2003, Geophysical Surveys of Bear Lake, Utah-Idaho, September 2002 - Bathymetric Grid.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -111.5
    East_Bounding_Coordinate: -111.17
    North_Bounding_Coordinate: 42.2
    South_Bounding_Coordinate: 41.08

  3. What does it look like?

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

    Beginning_Date: 04-Sep-2002
    Ending_Date: 16-Sep-2002
    Currentness_Reference: Publication Date

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

    Geospatial_Data_Presentation_Form: Raster

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the 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: 12
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: .9996
      Longitude_of_Central_Meridian: -111.000000
      Latitude_of_Projection_Origin: +00.000000
      False_Easting: 500000
      False_Northing: 0

      Planar coordinates are encoded using Coordinate Pair
      Abscissae (x-coordinates) are specified to the nearest 5
      Ordinates (y-coordinates) are specified to the nearest 5
      Planar coordinates are specified in meters

      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: Local Lake Level Datum
      Altitude_Resolution: 1
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method: implicit coordinate
      Depth_System_Definition:
      Depth_Datum_Name: Local Surface
      Depth_Resolution: 1
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Attribute Values

  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)

  2. Who also contributed to the data set?

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

    Jane F. Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA 02543
    USA

    508-457-2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov

Why was the data set created?
The bathymetric contours will be used as a reference for depth information within Bear Lake, Utah-Idaho. No bathymetric surveys have been conducted in the Lake since the 1970's. This dataset represents the most up-to-date bathymetric information for the area.

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: 16-Sep-2002 (process 1 of 4)
    Bathymetric data were corrected for variations in the speed of sound throughout the water column; sound velocity profiles were acquired at locations throughout the lake and throughout the survey period. Attitude sensor and compass information were incorporated into the header of the bathymetric data files using the SEA RTS2000 acquiistion and processing system. The resultant data files were imported into SEA GRID2000 program and gridded to a 10 meter grid cell size.

    Person who carried out this activity:

    Jane F. Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA 02543
    USA

    508-457-2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov

    Date: 16-Sep-2002 (process 2 of 4)
    The SEA GRID2000 file was then exported as x,y,z. The weighgrid command within the University of New Brunswick, Ocean Mapping Group, SwathEd software was used to interpolate the data to fill in between line data gaps. An interpolation of 300 meter radius was used.

    Person who carried out this activity:

    Jane F. Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA 02543
    USA

    508-457-2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov

    Date: 16-Sep-2002 (process 3 of 4)
    The grid file was then converted to an ASCII Raster file and imported to ESRI ArcView 3.2.

    Person who carried out this activity:

    Jane F. Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA 02543
    USA

    508-457-2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov

    Date: 16-Sep-2002 (process 4 of 4)
    That Raster Grid was converted to a TIFF image using an ArcView extension 'image_convert_georef.ave' downloaded from the ESRI website (www.esri.com). The extension coverted the Grid to a TIFF image maintaining the grid legend. A TIFF world file was also generated.

    Person who carried out this activity:

    Jane F. Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA 02543
    USA

    508-457-2311 (voice)
    508-457-2310 (FAX)
    jdenny@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; all data were acquired with an SEA 2000 Series Submetrix interferometric sonar.

  2. How accurate are the geographic locations?

    All navigation data were acquired using the Wide Area Augmentation System (WAAS), a GPS-based navigation and landing system providing precision guidance to aircraft. Horizontal accuracy of the WAAS network is assumed to be accurate < 3 meters.

  3. How accurate are the heights or depths?

    Vertical accuracy is dependant on the navigation system. All navigation data were acquired using the Wide Area Augmentation System (WAAS), a GPS-based navigation and landing system providing precision guidance to aircraft. The Wide Area Augmentation System (WAAS) is assumed to have a vertical accuracy of +/- 5 meters. All ship motion was recorded by a TSS DMS 2-05 Attitude Sensor.

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

    These data are complete.

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

    These data are were checked for consistency by plotting the point data with the contoured surface and eliminating suprious and anomolous soundings.

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:
Bathymetry is not to be used for navigational purposes. The USGS asks to be referenced in any use of these data.

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

    Jane F. Denny
    U.S. Geological Survey
    Geologist
    384 Woods Hole Road
    Woods Hole, MA 02543
    USA

    508-457-2311 (voice)
    508-457-2310 (FAX)
    jdenny@usgs.gov

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

    Bathymetric Grid - TIFF Image Format

  3. What legal disclaimers am I supposed to read?

    Altough this data set and its lineage 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 it's related materials. The act of distribution shall not constitute any such warranty, and no resposibility is assumed by the USGS in the use of these data or related items. Users must assume resposibility for the proper use of this data. This data should not be used at resolutions for which it is not intended. This data has no been reviewed for conformity with U.S. Geological Survey editorial standards, or the North American Strigraphic code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the US Government.

  4. How can I download or order the data?

Who wrote the metadata?
Dates:
Last modified: 19-Jan-2002
Last Reviewed: 2002

Metadata author:
Jane F. Denny
U.S. Geological Survey
Geologist
384 Woods Hole Road
Woods Hole, MA 02543
USA

508-457-2311 (voice)
508-457-2310 (FAX)
jdenny@usgs.gov

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

Generated by mp version 2.7.17 on Wed Jul 02 14:26:25 2003