Stevens, A.W., Lacy, J.R., Finlayson, D.P., an, 2008, Evaluation of a single-beam sonar system to map seagrass at two sites in northern Puget Sound:.This is part of the following larger work.
Stevens, A.W., Lacy, J.R., Finlayson, D.P., an, 2008, Evaluation of a single-beam sonar system to map seagrass at two sites in northern Puget Sound: Scientific Investigations Report 2008-5009, U.S. Geological Survey, Coastal and Marine Geology Program, Menlo Park, CA.Online Links:
This is a Point data set.
Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.00001. Longitudes are given to the nearest 0.00001. 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.
| Range of values | |
|---|---|
| Minimum: | 486997.617 |
| Maximum: | 489962.263 |
| Units: | meters |
| Resolution: | 0.001 |
| Range of values | |
|---|---|
| Minimum: | 5381456.319 |
| Maximum: | 5383932.558 |
| Units: | meters |
| Resolution: | 0.001 |
| Range of values | |
|---|---|
| Minimum: | -10.00 |
| Maximum: | 0.00 |
| Units: | meters |
| Resolution: | 0.01 |
| Range of values | |
|---|---|
| Minimum: | -123.58611 |
| Maximum: | -123.13611 |
| Units: | decimal degrees |
| Resolution: | 0.00001 |
| Range of values | |
|---|---|
| Minimum: | 48.58611 |
| Maximum: | 48.60833 |
| Units: | decimal degrees |
| Resolution: | 0.00001 |
| Range of values | |
|---|---|
| Minimum: | 0.00 |
| Maximum: | 10.00 |
| Units: | meters |
| Resolution: | 0.01 |
Sample of digital surface elevation data XYZ ASCII file, bathy/line95.xyz: X Y Z 487989.879521 5381998.198351 -3.31 487990.116289 5381998.892258 -3.34 487989.943243 5382001.029467 -3.40 Sample of sediment sampling log: Station Local_Time UTC Lon Lat Depth_m Comment 1 6/1/07 20:44 6/2/07 3:44 -123.1430877 48.60642247 2.286 - 2 6/1/07 20:35 6/2/07 3:35 -123.1416559 48.60596625 2.1336 18.6 C 3 6/1/07 20:28 6/2/07 3:28 -123.1396819 48.60476647 2.4384 22.4 C
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astevens@usgs.gov
The goal of the project was two-fold: 1) To quantify eelgrass (Z. marina) habitat at two sites, Possession Point and Browns Bay, in northern Puget Sound and 2) Evaluate the benefits and limitations of using acoustics, specifically single-beam sonar, to map seagrass in Puget Sound.
The combined bathymetric data were merged to create a digital elevation model representing the surface topography of Possession Point and Browns Bay. This surface is referenced to the NAD83 datum in the WA State Plane North, meters projection with a horizontal accuracy of 2.3 cm. Elevations are referenced to NAVD88 with an estimated vertical accuracy ranging 2.6-9.8 cm. This includes error from the RTK-DGPS and Biosonics sonar, and errors introduced in data processing.
Results from the tubes and laser particle analyzer were merged using standard USGS methods found in the USGS particle analysis program pcSedSize.
U.S. Geological Survey, Coastal and Marine Geology Program, 2007, InfoBank.Online Links:
A) Bathymetric mapping
Sixty (60) kilometers of acoustic bathymetry/substrate data were collected with a dual-frequency (200 and 430 kHz) Biosonics system along 163 transects in Possession Point between 1/30/07 and 2/1/07. Eighteen(18) kilometers of acoustic bathymetry/substrate data were collected with the same system along 65 transects in Browns Bay on 2/2/2007. The Biosonics sonar generates a 6-degree cone of sound, which translates into a footprint on the seafloor ranging 0.55 to 55 m^2 area for the water depths surveyed (2 - 20 m). Ship speed generally ranged 4.0-4.5 kts and data were merged with GPS positions at 1 Hz. Track lines were spaced 25 - 50 m apart.
B) Sediment Samples for Grain Size Analyses
Sediment samples were collected using a van veen grab sampler or taken directly during low-tide surveys.
In the field, a sub-sample of the uppermost 1-3 cm of each grab was collected and placed into storage bags, labeled, and logged.
Samples were disaggregated and sieved through 2000 and 62 micron screens to separate gravel, sands and mud after the organic component was removed by treatment with hydrogen peroxide. Sediment grain size of sands was determined using the settling methods and principles of Stokes Law on the USGS 3-m long settling tubes. The fine fraction (silts and clays) were analyzed on a Coulter 230 Laser Particle Analyzer. Three samples had less than 3% intermediate fraction and were analyzed on the Coulter. Single sample runs were made on the tubes, while results from the laser particle analyzer are averages of triplicates with standard deviations around the mean ranging 18 to 24 microns due to instrument errors.
A) Bathymetric mapping
Are there legal restrictions on access or use of the data?
- Access_Constraints: None
- Use_Constraints:
- Public domain data from the U.S. government is freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey (USGS) as the source of this information.
(650) 329-5243 (voice)
(650) 329-5190 (FAX)
astevens@usgs.gov
Although this data set has been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and/or related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials.Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
(650) 329-5243 (voice)
(650) 329-5190 (FAX)
astevens@usgs.gov