Interpretation of Sidescan-sonar Imagery in the John Day Reservoir

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Frequently-anticipated questions:


What does this data set describe?

    Title:
    Interpretation of Sidescan-sonar Imagery in the John Day Reservoir
    Abstract:
    A two-week field operation was conducted in the John Day Reservoir on the Columbia River to image the floor of the pool, to measure the distribution and thickness of post-impoundment sediment, and to verify these geophysical data with video photography and bottom sediment samples. The field program was a cooperative effort between the USGS Coastal and Marine Geology Team of the Geologic Division and the USGS Columbia River Research Laboratory of the Biological Resources Division. The data collection was completed aboard the R/V ESTERO during September 13-27, 2000. The interest in sediment accumulation in the reservoir was two-fold. First, it was unknown how effective this reservoir was as a sediment trap to material that otherwise would have been transported down-river to the estuary and eventually to the ocean. The recent erosion of beaches along the Washington coast has been attributed to a decreased contribution of sediment from the Columbia River to the coastal system due to the damming of the river. Second, sediment accumulation on the floors of reservoirs along the Columbia River has been suggested to be diminishing salmon spawning grounds. The extent of changes in habitat since construction of the John Day Dam, however, had not been documented. Common data sets were needed to address both of these questions, and for these reasons this geophysical and sampling program was undertaken.

  1. How should this data set be cited?

    Twichell, David C. , 2004, Interpretation of Sidescan-sonar Imagery in the John Day Reservoir:.

    Online Links:

    This is part of the following larger work.

    Cross, VeeAnn A. , and Twichell, David C. , 2004, Geophysical, Sedimentologic, and Photographic Data from the John Day Reservoir, Washington and Oregon: Data Archive and Preliminary Discussion: Open-File Report 2004-1014, U.S. Geological Survey, Woods Hole Science Center, Woods Hole, MA.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -120.683233
    East_Bounding_Coordinate: -119.327509
    North_Bounding_Coordinate: 45.934511
    South_Bounding_Coordinate: 45.687974

  3. What does it look like?

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

    Beginning_Date: 11-Sep-2000
    Ending_Date: 22-Sep-2000
    Currentness_Reference: ground condition

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

    Geospatial_Data_Presentation_Form: vector digital data

  6. How does the data set represent geographic features?

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

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • G-polygon (195)

    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 0.000000. Longitudes are given to the nearest 0.000000. 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 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.

  7. How does the data set describe geographic features?

    ss_interpretation

    FID
    Internal feature number. (Source: ESRI)

    Sequential unique whole numbers that are automatically generated.

    Shape
    Feature geometry. (Source: ESRI)

    Coordinates defining the features.

    ID
    Automatically generated number during feature creation. (Source: Software generated.)

    BACKSCAT
    Indicator of backscatter intensity. (Source: Scientist.)

    character set

    INTERP
    Interpretation of what is present on the floor of the John Day Reservoir based on the sidescan-sonar imagery. (Source: Scientist.)

    character set

    TIMING
    Indication of whether the interpreted feature was developed pre- or post-impoundment (formation of the John Day Reservoir). (Source: Scientist.)

    character set

    DEP_TYPE
    Indicates whether the interpreted feature is basement, fluvially generated deposit, post-impoundment sand, or post-impoundment mud. (Source: Scientist.)

    character set

    AREA
    Area (square meters calculated using Washington State Plane South, NAD83 projection) of each individual polygon. (Source: Software generated.)

    Range of values
    Minimum:3490.246
    Maximum:14770057.024
    Units:square meters

    PERIMETER
    Perimeter (meters calculated using Washington State Plane South, NAD83 projection) of each individual polygon. (Source: Scientist.)

    Range of values
    Minimum:230.701
    Maximum:104394.129
    Units:meters

    Entity_and_Attribute_Overview:
    Dep_type contains Miocene, Quaternary, and boulders. The boulders are believed to be deposited as a result of the Missoula floods, so the argument could be made that these are fluvial deposits. However, in this case, fluvial deposits refers to more modern deposits formed as a result of the Columbia River pre-impoundment. The Area and Perimeter calculations were done in ArcView 3.3 using the sample script calcapl.ave. The view projection was defined as Washington State Plane South, NAD83 in order to have the units in meters and be consistent with the projected sidescan-sonar imagery.


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?

    David C. Twichell
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2266 (voice)
    (508) 457-2310 (FAX)
    dtwichell@usgs.gov


Why was the data set created?

This shapefile is intended to provide an interpretation of the sidescan-sonar imagery collected in the John Day Reservoir.


How was the data set created?

  1. From what previous works were the data drawn?

  2. How were the data generated, processed, and modified?

    (process 1 of 1)
    Using the mosaicked sidescan-sonar imagery as a backdrop, polygons were digitized in ArcView 3.3 representing different interpreted areas.

    Person who carried out this activity:

    David C. Twichell
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2266 (voice)
    (508) 457-2310 (FAX)
    dtwichell@usgs.gov


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?

  3. How accurate are the heights or depths?

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

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


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:
The U.S. Geological Survey must be referenced as the originator of the dataset in any future products or research derived from these data.

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

    David C. Twichell
    U.S. Geological Survey
    Oceanographer
    384 Woods Hole Rd.
    Woods Hole, MA 02543-1598

    (508) 548-8700 x2266 (voice)
    (508) 457-2310 (FAX)
    dtwichell@usgs.gov

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

    Downloadable Data

  3. What legal disclaimers am I supposed to read?

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 25-Mar-2004

Metadata author:
VeeAnn A. Cross
U.S. Geological Survey
Marine Geologist
384 Woods Hole Rd.
Woods Hole, MA 02543-1598

(508) 548-8700 x2251 (voice)
(508) 457-2310 (FAX)
vatnipp@usgs.gov

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

Metadata extensions used:


Generated by mp version 2.7.3 on Thu Mar 25 09:01:31 2004