Andrew W. Stevens
Renee K. Takesue
Eric E. Grossman
20200721
Eelgrass distributions and bathymetry derived from an acoustic survey of the Nisqually River delta, Washington, 2012
comma-delimited text
data release
DOI:10.5066/P9N9K2I1
Pacific Coastal and Marine Science Center, Santa Cruz, California
U.S. Geological Survey
https://doi.org/10.5066/P9N9K2I1
https://www.sciencebase.gov/catalog/item/5eb9823682ce25b5135d2618
Andrew W. Stevens
Renee K. Takesue
Eric E. Grossman
2020
Eelgrass distributions and bathymetry of the Nisqually River delta, Washington
data release
DOI:10.5066/P9N9K2I1
Pacific Coastal and Marine Science Center, Santa Cruz, California
U.S. Geological Survey
https://doi.org/10.5066/P9N9K2I1
This portion of the USGS data release presents eelgrass distribution and bathymetry data derived from acoustic surveys of the Nisqually River delta, Washington in 2012 (USGS Field Activity Number D-01-12-PS). Eelgrass and bathymetry data were collected from the R/V George Davidson equipped with a single-beam sonar system and global navigation satellite system (GNSS) receiver. The sonar system consisted of a Biosonics DT-X single-beam echosounder and 420 kHz transducer with a 6-degree beam angle. Depths from the echosounder were computed using sound velocity assuming a salinity of 30 psu and temperature of 10 degrees Celsius. Positioning of the survey vessel was determined at 5 to 10 Hz using a Trimble R7 GNSS receiver and Trimble Zephyr Model 2 antenna operating in real time kinematic (RTK) mode. Differential corrections were transmitted by a VHF radio to the GNSS receiver on the survey vessel at 1-Hz from a GNSS base station placed on a nearby benchmark with known horizontal and vertical coordinates relative to the North American Datum of 1983 (CORS96 realization). Output from the GNSS and sonar systems were combined in real time by the Biosonics DT-X deck unit and output to a computer running HYPACK hydrographic survey software. Navigation information was displayed on a video monitor, allowing the vessel operator to navigate along predefined survey lines spaced at 25-50 m intervals alongshore at speeds of 2 to 3 m/s. Acoustic backscatter data were analyzed using a custom graphical user interface that implements a signal processing algorithm applied to each sonar sounding that differentiates and extracts the location of the seafloor apart from the presence of vegetation (Stevens and others, 2008). Individual acoustic returns along a survey line were grouped into packets of ten, and eelgrass percent cover was calculated as the fractional percent of acoustic returns that were classified as vegetated within each group, resulting in an estimate of percent cover every 4 to 5 m (depending on the vessel speed). Orthometric elevations relative to the NAVD88 vertical datum were computed using National Geodetic Survey Geoid12a offsets. The average estimated vertical uncertainty of the bathymetric measurements is 12 cm. The point data are provided in a comma-separated text file and are projected in Cartesian coordinates using the Universal Transverse Mercator (UTM), Zone 10 north, meters coordinate system.
Data were obtained to document interannual changes in eelgrass distributions and coastal morphology following the removal of a dike that restored tidal processes to over 300 ha of former freshwater wetlands on the Nisqually River delta in 2009. 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 the distributions of eelgrass and shallow-water bathymetric features.
Additional information about the field activities from which these data were derived are available online at:
https://cmgds.marine.usgs.gov/fan_info.php?fan=D0112PS
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
20120215
20120219
ground condition at time data were collected
Not planned
-122.7582570
-122.6743017
47.1236026
47.0861282
USGS Metadata Identifier
USGS:5eb9823682ce25b5135d2618
USGS Thesaurus
bathymetry
bathymetry measurement
aquatic vegetation
GPS measurement
sea-floor characteristics
marine geophysics
single-beam echo sounder
ISO 19115 Topic Category
elevation
Data Categories for Marine Planning
Bathymetry and Elevation
Marine Realms Information Bank (MRIB) keywords
Global Positioning System (GPS) observations
Global Change Master Directory (GCMD)
Water Depth
GPS (Global Positioning System)
Echo Sounders
None
U.S. Geological Survey
USGS
Coastal and Marine Hazards and Resources Program
CMHRP
Pacific Coastal and Marine Science Center
PCMSC
USGS Coastal Habitats in Puget Sound Project (CHIPS)
Geographic Names Information System (GNIS)
Salish Sea
Puget Sound
Pierce County
Thurston County
Nisqually River
Billy Frank Jr Nisqually National Wildlife Refuge
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(s) of the dataset and in products derived from these data. This information is not intended for navigational purposes.
PCMSC Science Data Coordinator
U.S. Geological Survey, Pacific Coastal and Marine Science Center
mailing and physical
2885 Mission Street
Santa Cruz
CA
95060
831-427-4747
pcmsc_data@usgs.gov
https://www.sciencebase.gov/catalog/file/get/5eb9823682ce25b5135d2618?name=nq12_bathy_eelgrass_tracklines.png&allowOpen=true
Top: map showing bathymetry data along 2012 survey tracklines; Bottom: map showing eelgrass distribution and percent coverage along 2012 survey tracklines.
PNG
MATLAB Version: 9.6.0.1214997 (R2019a)
Andrew W. Stevens
Jessica R. Lacy
David P. Finlayson
Guy Gelfenbaum
2008
Evaluation of a single-beam sonar system to map seagrass at two sites in northern Puget Sound, Washington
comma-delimited text
Reston, VA
U.S. Geological Survey
https://pubs.usgs.gov/sir/2008/5009/
International Hydrographic Organization (IHO)
2008
IHO standards for hydrographic surveys (5th ed.)
comma-delimited text
Monaco
International Hydrographic Bureau Special Publication 44, 28p.
https://www.iho.int/iho_pubs/standard/S-44_5E.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 survey vessel were achieved with a global navigation satellite system (GNSS) differentially corrected with data from a single GNSS base station placed on a benchmark with horizontal coordinates relative to the North American Datum of 1983 (CORS96 realization). The position of the GNSS base station was derived from a static GNSS occupation on February 21, 2012 with a duration of approximately 4 hours. The static observations were processed using the National Geodetic Survey Online Positioning User Service (OPUS) to derive the final base station coordinates. The estimated uncertainty derived from the static occupation was 2 cm and 3.5 cm for the latitude and longitude of the benchmark, respectively. Additional uncertainty in the horizontal positions of the survey vessel was estimated based on the distance between survey vessel and 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 50 m and 4.5 km with a mean of 1.75 km, suggesting the average horizontal accuracy of survey vessel positions to be about 1 cm. Combining the uncertainty in the benchmark and survey vessel yields a total uncertainty of 5 cm. Uncertainty in the horizontal positions associated with pitch and roll of the survey vessel is unknown.
Uncertainty in the final elevations is derived from the combination of uncertainty in the GNSS positioning and bathymetric sounding measurements. The vertical position of the benchmark was derived from a static GNSS occupation with an estimated uncertainty of 3.9 cm. The 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 50 m and 4.5 km with a mean of 1.75 km, suggesting the average vertical accuracy of survey vessel positions to be about 1.7 cm. The manufacturer of the single-beam echosounder used in this study reports a vertical accuracy of 1 cm. Most of the vertical uncertainty in the final computed elevations data is related to the unmeasured speed of sound used to compute depths from bathymetric soundings and, thus, is depth-dependent. Based on analysis of nearby buoys, we estimate uncertainties in the final depth soundings to be no greater than 3 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 4 cm and 60 cm with a mean estimated vertical uncertainty of 12 cm. Uncertainty in the vertical positions associated with pitch and roll of the survey vessel is unknown.
Eelgrass and bathymetry data were collected from the R/V George Davidson equipped with a single-beam sonar system and global navigation satellite system (GNSS) receiver. The sonar system consisted of a Biosonics DT-X single-beam echosounder and 420 kHz transducer with a 6-degree beam angle. Depths from the echosounder were computed using sound velocity data measured using a YSI CastAway CTD during the survey. Positioning of the survey vessel was determined at 5 to 10 Hz using a Trimble R7 GNSS receiver and Trimble Zephyr Model 2 antenna operating in real time kinematic (RTK) mode. Differential corrections were transmitted by a VHF radio to the GNSS receiver on the survey vessel at 1-Hz from a GNSS base station placed on a nearby benchmark with known horizontal and vertical coordinates relative to the North American Datum of 1983 (CORS96 realization). Output from the GNSS and sonar systems were combined in real time by the Biosonics DT-X deck unit and output to a computer running HYPACK hydrographic survey software. Navigation information was displayed on a video monitor, allowing the vessel operator to navigate along predefined survey lines spaced at 25-50 m intervals alongshore at speeds of 2-3 m/s.
20120219
Acoustic-backscatter data were analyzed using a custom graphical user interface that implements a signal processing algorithm applied to each sonar sounding to extract the location of the bottom and presence of vegetation (Stevens and others, 2008). Individual acoustic returns along a survey line were grouped into packets of ten, and eelgrass percent cover was calculated as the fractional percent of acoustic returns that were classified as vegetated within each group, resulting in an estimate of percent cover every 4 to 5 m (depending on the vessel speed). Orthometric elevations relative to the NAVD88 vertical datum were computed using National Geodetic Survey Geoid12a offsets. The final point data are provided in a comma-separated text file and are projected in Cartesian coordinates using the Universal Transverse Mercator (UTM), Zone 10 north, meters coordinate system.
20130204
All available eelgrass distribution and bathymetry data from the survey were compiled into a comma-delimited text file for distribution.
20200511
Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed.
20201019
U.S. Geological Survey
VeeAnn A. Cross
Marine Geologist
Mailing and Physical
384 Woods Hole Road
Woods Hole
MA
02543-1598
508-548-8700 x2251
508-457-2310
vatnipp@usgs.gov
Point
Point
593447
0.0000001
0.0000001
Decimal degrees
North American Datum of 1983
GRS_1980
6378137.0
298.257222101
North American Vertical Datum of 1988
0.01
meters
Explicit elevation coordinate included with horizontal coordinates
Attribute Table
Table containing attribute information associated with the dataset
Producer defined
datetime_utc
The date and time of data collection in Coordinated Universal Time (UTC).
Producer Defined
2012-02-15 17:44:49.103
2012-02-19 23:35:02.300
date and time in yyyy-mmm-dd HH:MM:SS.FFF format
longitude
Longitude coordinate of data point relative to the North American Datum of 1983
Producer defined
-122.7582570
-122.6743017
Decimal degrees
latitude
Latitude coordinate of data point relative to the North American Datum of 1983
Producer defined
47.0861282
47.1236026
Decimal degrees
easting_m
East coordinate of data point relative to the North American Datum of 1983, projected in the Universal Transverse Mercator (UTM) Zone 10 North, meters, coordinate system
Producer defined
518338.26
524709.03
meters
northing_m
North coordinate of data point relative to the North American Datum of 1983,projected in the Universal Transverse Mercator (UTM) Zone 10 North, meters, coordinate system
Producer defined
5214771.17
5218929.10
meters
elev_m_navd88
Height in meters of data point with reference to the North American Vertical Datum of 1988
Producer defined
-20.16
0.42
meters
veg_flag
Flag that indicates the presence or absence of eelgrass at each location along the survey track
producer defined
0
eelgrass absent
producer defined
1
eelgrass present
producer defined
veg_cover
Fractional percent of points classified as vegetated grouped into packets of 10 sequential points
Producer defined
0.00
1.00
fractional percent
U.S. Geological Survey - Science Base
U.S. Geological Survey
mailing and physical
Denver Federal Center, Building 810, Mail Stop 302
Denver
CO
80225
USA
1-888-275-8747
sciencebase@usgs.gov
Eelgrass distribution and bathymetry data are available as a comma-delimited text file, along with associated FGDC-compliant metadata and a browse graphic.
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 9.6.0.1214997
text
comma-delimited text file
47
https://www.sciencebase.gov/catalog/file/get/5eb9823682ce25b5135d2618?name=nq12_bathy_eelgrass.csv
https://www.sciencebase.gov/catalog/item/5eb9823682ce25b5135d2618
https://www.sciencebase.gov/catalog/item/5e97383a82ce172707f2a9b7
https://doi.org/10.5066/P9N9K2I1
Data can be downloaded using the Network_Resource_Name links. The first link is a direct link to download the eelgrass distribution and bathymetry data. The second link points to a landing page with the eelgrass distribution and bathymetry data, metadata, and a browse graphic. The third link points to a landing page for the annual survey. The fourth link points to a landing page for the entire data release.
None
20201019
PCMSC Science Data Coordinator
U.S. Geological Survey, Pacific Coastal and Marine Science Center
mailing and physical
2885 Mission St.
Santa Cruz
CA
95060
831-427-4747
pcmsc_data@usgs.gov
Content Standard for Digital Geospatial Metadata
FGDC-STD-001-1998