Alexander G. Snyder
Cordell D. Johnson
Ann E. Gibbs
Li H. Erikson
20210719
Nearshore bathymetry data from the Unalakleet River mouth, Alaska, 2019
comma-delimited text
data release
DOI:10.5066/P9238F8K
Pacific Coastal and Marine Science Center, Santa Cruz, California
U.S. Geological Survey
https://doi.org/10.5066/P9238F8K
https://www.sciencebase.gov/catalog/item/60c24fbad34e86b9389559b8
This data release presents nearshore bathymetry data collected at the mouth of the Unalakleet River in Alaska, near the city of Unalakleet. The data were collected in August 2019 by the U.S. Geological Survey, Pacific Coastal and Marine Science Center. Nearshore bathymetry was measured along survey lines from the shore to a depth of approximately -7.4 m NAVD88 and in a portion of the estuary closest to the mouth. Bathymetry data were collected using small boat equipped with a single-beam sonar system and global navigation satellite system (GNSS) receiver. The sonar system consisted of an Odom Echotrac CV-100 single-beam echosounder and 200 kHz transducer with a 9-degree beam. Depths from the seafloor to the echosounder were calculated using the digitized acoustic backscatter and sound velocity profiles, measured in multiple locations using a YSI CastAway CTD. The position of the boat and echosounder was recorded at 10 Hz using a Trimble R7 receiver and Zephyr 2 antenna. Survey-grade vertical and horizontal positions were achieved by applying differential corrections from a nearby GNSS base station installed for the purposes of this survey.
Data were collected to create a digital elevation model of the nearshore bathymetry for use in coastal flooding models. These data are intended for science researchers, students, policy makers, and the general public. These data can be used with geographic information systems or other software to identify shallow-water bathymetric features.
Additional information about the field activity from which these data were derived is available online at:
https://cmgds.marine.usgs.gov/fan_info.php?fan=2019-629-FA
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in Esri format, this metadata file may include some Esri-specific terminology.
20190709
20190712
ground condition at time data were collected
None planned
-160.863919
-160.766694
63.881365
63.846674
ISO 19115 Topic Category
elevation
Data Categories for Marine Planning
Bathymetry and Elevation
USGS Thesaurus
bathymetry
bathymetry measurement
GPS measurement
Marine Realms Information Bank (MRIB) keywords
single-beam echo sounder
Global Positioning System (GPS) observations
None
U.S. Geological Survey
USGS
Coastal and Marine Hazards and Resources Program
CMHRP
Pacific Coastal and Marine Science Center
PCMSC
USGS Metadata Identifier
USGS:60c24fbad34e86b9389559b8
Geographic Names Information System (GNIS)
Norton Sound
Pacific Ocean
Unalakleet
City of Unalakleet
Unalakleet River
State of Alaska
Nome Census Area
none
USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator of the dataset and in products derived from these data. This information is not intended for navigation purposes.
U.S. Geological Survey, Pacific Coastal and Marine Science Center
PCMSC Science Data Coordinator
mailing and physical
2885 Mission Street
Santa Cruz
CA
95060
831-427-4747
pcmsc_data@usgs.gov
MATLAB Version: 8.6.6.958874 (R2015b)
International Hydrographic Organization (IHO)
2008
IHO standards for hydrographic surveys (6th ed.)
https://iho.int/uploads/user/pubs/Drafts/S-44_Edition_6.0.0-Final.pdf
No formal attribute accuracy tests were conducted.
All data falls within expected ranges.
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.
Survey-grade positions of the small boat were achieved with global navigation satellite system (GNSS) receivers and a single GNSS base station. The position of the GNSS base station was derived from four static GNSS occupations from July 7 to July 12, 2019, with durations ranging from 3 to 13 hours. The static observations were processed using the National Geodetic Survey Online Positioning User Service (OPUS) and averaged to derive the final base station coordinates relative to the North American Datum of 1983 (2011 realization). Positioning data from the survey vessels were post-processed using Waypoint Grafnav to apply differential corrections from the GNSS base station. Manufacturer reported accuracy for the differentially corrected horizontal positions for the GNSS rover trajectories is 0.8 cm + 0.5 ppm. Baselines from the GNSS base station varied between 0.1 km and 4.5 km with a mean of 1 km, suggesting the average horizontal accuracy of survey vessel positions to be about 1 cm. Uncertainty in the horizontal positions associated with pitch and roll of the survey vessels is unknown.
Uncertainty in the final elevations is derived from the combination of uncertainty in the GNSS positioning and bathymetric sounding measurements. Manufacturer reported accuracy for the differentially corrected vertical positions for the GNSS rover trajectories is 1.5 cm + 1 ppm relative to the benchmark elevation. Baselines from the GNSS base station varied between 0.1 m and 4.5 km with a mean of 1 km, suggesting the average vertical accuracy of survey vessel positions to be about 2.5 cm. The manufacturer of the single-beam echosounder used in this study reports a vertical accuracy of 1 cm. Additional uncertainty in the final computed elevations data is related to unmeasured variability in the speed of sound used to compute depths from bathymetric soundings and, thus, is depth-dependent. Based on analysis of available speed of sound measurements, we estimate uncertainties in the final depth soundings to be no greater than 1 percent of the water depth. The total vertical uncertainty is calculated using the constant- and depth-dependent factors summed in quadrature (International Hydrographic Organization, 2008). The vertical uncertainty in final elevations varied between 3 cm and 8 cm with a mean vertical uncertainty of 4 cm. Uncertainty in the vertical positions associated with pitch and roll of the survey vessels is unknown.
Bathymetry data were collected between July 9 and July 12, 2019, using a single-beam sonar system and global navigation satellite system (GNSS) receiver mounted on a small boat. The sonar system consisted of an Odom Echotrac CV-100 single-beam echosounder and 200 kHz transducer with a 9-degree beam angle. Raw acoustic backscatter returns were digitized by the echosounder with a vertical resolution of 1.25 cm. Depths from the echosounder was computed using sound velocity profiles measured using a YSI CastAway CTD during the survey. Positioning of the survey vessel was determined at 10 Hz using survey-grade GNSS receiver. Output from the GNSS receiver and sonar system were combined in real time on the small boat by a computer running HYPACK hydrographic survey software. Navigation information was displayed on a computer monitor, allowing the boat operator to navigate along survey lines at speeds of 2 to 3 m/s.
20190712
Survey-grade positions were achieved with a single-base station and differential post-processing. The position of the GNSS base station was derived from four static GNSS occupations from July 7 to July 12, 2019, with durations ranging from 3 to 13 hours. The static observations were processed using the National Geodetic Survey Online Positioning User Service (OPUS) and averaged to derive the final base station coordinates relative to the North American Datum of 1983 (2011 realization). Positioning data from the survey vessel’s GNSS receiver were post-processed using Waypoint Grafnav to apply differential corrections from the GNSS base station. Orthometric elevations relative to the NAVD88 vertical datum were computed using National Geodetic Survey Geoid12b offsets. Bathymetric data were merged with post-processed positioning data and spurious soundings were removed using a custom Graphical User Interface (GUI) programmed with the computer program MATLAB. The final point data from the survey vessel was projected in cartesian coordinates using the Universal Transverse Mercator Zone 4 North, meters coordinate system.
20200423
All available bathymetry data from the survey were compiled into a comma-delimited text file for distribution.
20210512
Point
Point
895748
0.00000001
0.00000001
Decimal Degrees
North American Datum of 1983, 2011 realization
GRS_1980
6378137.0
298.257222101
North American Vertical Datum of 1988
0.001
meters
Explicit elevation coordinate included with horizontal coordinates
Attribute Table
Table containing attribute information associated with the dataset.
Producer defined
Survey_Date_Time
The date and time of data collection in Greenwich Mean Time (GMT).
Producer defined
2019-Jul-09 19:55:20.589
2019-Jul-12 20:27:05.249
Date and time in yyyy-mmm-dd hh:mm:ss.fff format
0.001
Longitude
Longitude coordinate of data point relative to the North American Datum of 1983, 2011 realization
Producer defined
-160.8639194
-160.7666941
Decimal degrees
0.0000001
Latitude
Latitude coordinate of data point relative to the North American Datum of 1983, 2011 realization
Producer defined
63.84667372
63.88136471
Decimal degrees
0.0000001
Easting_m
Easting coordinate of data point relative to the North American Datum of 1983, 2011 realization, projected to the Universal Transverse Mercator, Zone 4.
Producer defined
408372.883
413201.097
Meters
0.001
Northing_m
Northing coordinate of data point relative to the North American Datum of 1983, 2011 realization, projected to the Universal Transverse Mercator, Zone 4.
Producer defined
7081260.852
7085018.336
Meters
0.001
Ellip_Ht_m
Height in meters of data point with reference to the reference ellipsoid.
Producer defined
0.324
9.366
Meters
0.001
Ortho_Ht_m
Height in meters of data point with reference to the North American Vertical Datum of 1988.
Producer defined
-7.416
1.598
Meters
0.001
U.S. Geological Survey - ScienceBase
Mailing and Physical
Denver Federal Center, Building 810, Mail Stop 302
Denver
CO
80225
1-888-275-8747
sciencebase@usgs.gov
Bathymetry data are available as a comma-delimited text file (unk19_july_bathymetry.csv), along with associated metadata.
Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.
comma-delimited text
Matlab 8.6.0.958874
text
comma-delimited text file
19.1
https://www.sciencebase.gov/catalog/file/get/60c24fbad34e86b9389559b8
https://doi.org/10.5066/P9238F8K
Data can be downloaded using the Network_Resource_Name links. The first link is a direct link to download the zipped file of data and metadata. The second link points to a landing page for the entire data release.
None.
20210719
U.S. Geological Survey, Pacific Coastal and Marine Science Center
PCMSC Science Data Coordinator
mailing and physical
2885 Mission Street
Santa Cruz
CA
95060
831-427-4747
pcmsc_data@usgs.gov
Content Standard for Digital Geospatial Metadata
FGDC-STD-001-1998