Single-beam bathymetry data near Kotlik, Alaska, collected July 2021

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Frequently anticipated questions:

What does this data set describe?

Title:
Single-beam bathymetry data near Kotlik, Alaska, collected July 2021
Abstract:
DGGS Raw Data File 2021-14, Single-beam bathymetry data near Kotlik, Alaska, collected July 2021, presents bathymetric data for the purpose of assessing coastal hazards and for river migration studies. The State of Alaska Division of Geological & Geophysical Surveys (DGGS) used a M2Ocean Hydroball (an integrated echosounder, Global Navigation Satellite System (GNSS) antenna, and inclinometer) to collect bathymetric transects near Kotlik on July 7 and 9, 2021. Bathymetric data were corrected using a coincident water level time series referenced to a vertical datum using GNSS survey. The bathymetric data were processed using CIDCO DepthStar. This data collection is being released as a Raw Data File with an open end-user license. All files are available from the DGGS website: http://doi.org/10.14509/30764.
Supplemental_Information: >hydro-soundings : single-beam bathymetric survey soundings
  1. How might this data set be cited?
    Overbeck, J.R., Christian, J.E., and Buzard, R.M., 2021, Single-beam bathymetry data near Kotlik, Alaska, collected July 2021: Raw Data File RDF 2021-14, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 6 p.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -163.658751
    East_Bounding_Coordinate: -163.455434
    North_Bounding_Coordinate: 63.052017
    South_Bounding_Coordinate: 63.021825
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 07-Jul-2021
    Ending_Date: 09-Jul-2021
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: table
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a point 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: 3
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -165
      Latitude_of_Projection_Origin: 0
      False_Easting: 500000.000000
      False_Northing: 0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest .00000001
      Ordinates (y-coordinates) are specified to the nearest .00000001
      Planar coordinates are specified in Meters
      The horizontal datum used is NAD83.
      The ellipsoid used is GRS 80.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257222101000025.
      Vertical_Coordinate_System_Definition:
      Depth_System_Definition:
      Depth_Datum_Name: NAVD88, GEOID12B
      Depth_Resolution: 0.001
      Depth_Distance_Units: meters
      Depth_Encoding_Method: Attribute values
  7. How does the data set describe geographic features?
    rdf2021-14-hydro-soundings.txt
    single-beam bathymetric survey soundings (Source: DGGS)

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?
    This work was funded by the Bureau of Indian Affairs Tribal Resilience Program through a collaborative project with the Native Village of Bill Moore's Slough. We especially thank the Indian General Assistance Program for the Native Village of Bill Moore's Slough for assistance in carrying out the survey.
  3. To whom should users address questions about the data?
    Alaska Division of Geological & Geophysical Surveys
    Metadata Manager
    3354 College Road
    Fairbanks, AK
    USA

    (907)451-5020 (voice)
    (907)451-5050 (FAX)
    dggspubs@alaska.gov
    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
    Contact_Instructions:
    Please view our website (https://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address provided above when possible.

Why was the data set created?

The goal of the Kotlik survey is to provide bathymetric data for the purpose of assessing coastal hazards and for river migration studies.

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: 09-Jul-2021 (process 1 of 4)
    Bathymetric survey - DGGS used a M2Ocean Hydroball bathymetric sensor, which is composed of a Tallysman TW3972 GNSS antenna, Imagenex 852 single-beam echosounder, and Honeywell HMR3000 inclinometer. The Hydroball was placed in a catamaran configuration and towed behind a small skiff at speeds below 4 knots. A total of 21.7 kilometers of river were surveyed, which included 25 cross-river transects. The survey was completed on July 7 and 9, 2021, from 9:42 AM to 3:00 PM and 10:50 AM to 12:30 PM AKDT, respectively. During the survey, the operator started and stopped collection once each day. The weather throughout the survey was fair with scattered clouds and no rain. No abnormalities were observed during collection.
    Date: 09-Jul-2021 (process 2 of 4)
    Ground survey - DGGS set up a GNSS base station using the Trimble R10 receiver sampling at 1 Hz. The base was installed over a temporary benchmark of unknown position. This provided real-time kinematic (RTK) corrections to the Trimble R8s GNSS receiver (ground rover). DGGS measured the height of a water level sensor with the R8s at installation. The corrected base position was later derived using the Online Positioning User Service (found at http://www.ngs.noaa.gov/OPUS/). The R8s position was updated using post-processing kinematic (PPK) corrections in Trimble Business Center.
    Date: 09-Jul-2021 (process 3 of 4)
    Water level survey - A Solinst Levelogger was installed at Kotlik during the bathymetric survey to provide water level corrections. The Levelogger was configured to collect at 15-minute intervals and installed in a plastic bucket stilling well placed on the seafloor of the Kotlik River near the community water intake pipe. Barometric data were downloaded from Iowa State University Environmental Mesonet website (http://mesonet.agron.iastate.edu/request/download.phtml?network=AK_ASOS) from the airport at Emmonak (airport code PAEM) for the bathymetric survey duration. Water level data were extracted from the Levelogger using Solinst Levelogger 5 Series software and exported as .csv files. Matching of the collection time, as well as a barometric compensation of the water surface, were completed in Matlab. A linear interpolation was applied to the barometric data to match the Levelogger time series and a multiplying correction was used to convert 1 kPa to 0.101972 m depth. The corrected water level time series was converted to coordinated universal time (UTC) and exported as a .tid file for ingestion in DepthStar.
    Date: 2021 (process 4 of 4)
    Bathymetric survey data processing - The Hydroball produces three files for export: .dev, .bin, and 0.852, which are directly imported into CIDCO DepthStar software. Processing steps are to input survey settings, upload .dev and .tid files, filter depth returns based on minimum depth and moving average thresholds, manually add and remove points based on visual quality, georeference the hydroball position, and export as .txt. Since the catamaran configuration was used during the survey, a draft correction 0.115 m and a and a GNSS antenna position reference point to echo sounder acoustic center correction of 0.364 m were applied. The minimum depth (sonar threshold) was set at 0.7 m and moving average threshold at 0.5 m. Data were georeferenced using the water level reference survey (WLRS) sounding reduction method with a sound velocity of 1450 m/s, which is the value used for fresh water. The position source was kept raw.
  3. What similar or related data should the user be aware of?
    Herbst, A.M., and Daanen, R.P., 2020, High-resolution lidar data for Kotlik, Western Alaska: Raw Data File RDF 2020-15, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 7 p
    Overbeck, J.R., Hendricks, M.D., and Kinsman, N.E.M., 2018, Photogrammetric digital surface models and orthoimagery for the continuous coastline, Wales to Platinum, Alaska, segment F: Kotlik to Nunam Iqua: Raw Data File RDF 2017-8F, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 3 p
    Overbeck, J.R., Hendricks, M.D., and Kinsman, N.E.M., 2018, Photogrammetric digital surface models and orthoimagery for the continuous coastline, Wales to Platinum, Alaska, segment E: Stebbins to Kotlik: Raw Data File RDF 2017-8E, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 3 p

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

  1. How well have the observations been checked?
    Not applicable
  2. How accurate are the geographic locations?
    Horizontal accuracy was not evaluated.
  3. How accurate are the heights or depths?
    A quality control report was run in DepthStar to compute vertical offsets of overlapping points (intersections) throughout the survey. There were 55 intersections in total with an offset range between 0.000 m and 0.222 m and a vertical accuracy of 0.138 m at the 95th percentile.
  4. Where are the gaps in the data? What is missing?
    This data release is complete.
  5. How consistent are the relationships among the observations, including topology?
    The bathymetry data have been visually inspected for data errors such as false returns. Erroneous data were removed in the data processing, which may lead to gaps between and along transects. Additional data errors may exist due to increased wave activity during segments of surveys, however, these errors were not evaluated or removed.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints:
This report, map, and/or dataset is available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (see contact information below).
Use_Constraints:
Any hard copies or published datasets utilizing these datasets shall clearly indicate their source. If the user has modified the data in any way, the user is obligated to describe the types of modifications the user has made. The user specifically agrees not to misrepresent these datasets, nor to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys. The State of Alaska makes no express or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.
  1. Who distributes the data set? (Distributor 1 of 1)
    Alaska Division of Geological & Geophysical Surveys
    Metadata Manager
    3354 College Road
    Fairbanks, AK
    USA

    (907)451-5020 (voice)
    (907)451-5050 (FAX)
    dggspubs@alaska.gov
    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
    Contact_Instructions:
    Please view our website (https://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address provided above when possible.
  2. What's the catalog number I need to order this data set? RDF 2021-14
  3. What legal disclaimers am I supposed to read?
    The State of Alaska makes no expressed or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 17-Dec-2021
Metadata author:
Alaska Division of Geological & Geophysical Surveys
Attn: Simone Montayne
Metadata Manager
3354 College Road
Fairbanks, AK
USA

(907)451-5020 (voice)
(907)451-5050 (FAX)
dggspubs@alaska.gov
Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:
Generated by mp version 2.9.50 on Thu Dec 16 17:46:08 2021