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Bathymetry at Pleasure Point

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Frequently-anticipated questions:


What does this data set describe?

Title: Bathymetry at Pleasure Point
Abstract:
The Coastal Profiling System (CPS), a hydrographic surveying system mounted on a Personal Watercraft (PWC) originally designed by Oregon State University (Beach et al., 1996; Côté, 1999; MacMahan, 2001) to collect data in energetic nearshore environments, is now being used in many other areas to collect regional bathymetric data.
Supplemental_Information:
A description of the methodology used to collect data with the Coastal Profiling System is available in the Washington Department of Ecology Report: Beach Monitoring in the Columbia River Littoral Cell, 1997 - 2000.

The following is a list of publications cited in this report:

Beach, R.A.; Holman, R.A.; and Stanley, J., 1996. Measuring nearshore bathymetry on high energy beaches. American Geophysical Union Fall Meeting, 1996, F286.

Cote, J.M., 1999. The measurement of nearshore bathymetry on Intermediate and dissipative beaches. Unpublished Masters Thesis, Oregon State University, Corvallis, Oregon, 102 pp.

Gelfenbaum, G., Sherwood, C.R., Kerr, L.A., and Kurrus, K., 2000, Grays Harbor wave refraction experiment 1999: Data report, U.S. Geological Survey Open File Report, OF 00-44, 132 pp.

MacMahan, J., 2001. Hydrographic surveying from a personal watercraft. Journal of Surveying Engineering, 127(1), 12-24.

Ruggiero, P., and Voigt, B., 2000. Beach monitoring in the Columbia River littoral cell, 1997-2000, Washington Department of Ecology Publication # 00-06-26, Olympia, WA, 112 pp.

Additional information about the data collection field activity, W-1-05-PS, is at URL: <http://walrus.wr.usgs.gov/infobank/w/w105ps/html/w-1-05-ps.meta.html>.

  1. How should this data set be cited?

    U.S. Geological Survey, Coastal and Marine Geology Program, 2007, Bathymetry at Pleasure Point.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -123.5894
    East_Bounding_Coordinate: -123.528
    North_Bounding_Coordinate: 48.1542
    South_Bounding_Coordinate: 48.1377

  3. What does it look like?

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

    Beginning_Date: 15-Mar-2005
    Beginning_Time: 155400
    Ending_Date: 17-Mar-2005
    Ending_Time: 205200
    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 Point data set. It contains the following vector data types (SDTS terminology):

      • Point

    2. What coordinate system is used to represent geographic features?

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 10
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996000000
      Longitude_of_Central_Meridian: 123.000000
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000
      False_Northing: 0

      Planar coordinates are encoded using Coordinate Pair
      Abscissae (x-coordinates) are specified to the nearest 0.05
      Ordinates (y-coordinates) are specified to the nearest 0.05
      Planar coordinates are specified in meters

      The horizontal datum used is D WGS 1984.
      The ellipsoid used is WGS 1984.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257.

      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: North American Vertical Datum of 1988
      Altitude_Resolution: 0.01
      Altitude_Distance_Units: meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates

  7. How does the data set describe geographic features?

    ppdata_raw.xyz
    ASCII text file. (Source: U.S. Geological Survey, Coastal and Marine Geology Program)

    Easting
    Easting coordinate position. (Source: U.S. Geological Survey, Coastal and Marine Geology Program)

    Frequency of measurement: Irregular

    Range of values
    Minimum:590719.29
    Maximum:592729.68
    Units:decimal meters
    Resolution:0.05

    Northing
    Value of the Northing coordinate (Source: U.S. Geological Survey, Coastal and Marine Geology Program)

    Frequency of measurement: Irregular

    Range of values
    Minimum:4089643.98
    Maximum:4091003.41
    Units:decimal meters
    Resolution:0.05

    Elevation
    Elevation measurement of the data point (Source: U.S. Geological Survey, Coastal and Marine Geology Program)

    Frequency of measurement: Irregular

    Range of values
    Minimum:-11.89
    Maximum:-0.01
    Units:decimal meters
    Resolution:0.15

    ppdata_proc.xyz
    ASCII text file. (Source: U.S. Geological Survey, Coastal and Marine Geology Program)

    Entity_and_Attribute_Overview: 2 ASCII text files that include: Easting, Northing, Elevation.
    Entity_and_Attribute_Detail_Citation: U.S. Geological Survey, Coastal and Marine Geology Program


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?

    These data were collected by the U.S. Geological Survey Coastal and Marine Geology Program.

  3. To whom should users address questions about the data?

    Peter Ruggiero
    U.S. Geological Survey, Coastal and Marine Geology
    Coastal Engineer
    345 Middlefield Rd MS-999
    Menlo Park, CA 94025-3561
    USA

    650-329-5433 (voice)
    650-329-5190 (FAX)
    pruggiero@usgs.gov


Why was the data set created?

This data will be combined with other bathymetric data in the area to create a map of the region.


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: 2007 (process 1 of 7)
    A Real Time Kinematic Differential Global Positioning System (RTK DGPS) base station is setup on a control monument. An RTK DGPS base station consists of a Trimble 4400 receiver, a Trimble non-micro centered L1/L2 GPS antenna with a ground plane, a Pacific Crest UHF radio modem, radio antenna, two tripods, and various cables. The GPS antenna is mounted onto a tripod that is leveled over the monument. Once leveled the tripod is secured with sand bags and the antenna is connected to the GPS receiver via a data cable. The radio modem and antenna are attached to the second tripod and connected to the GPS receiver via a data cable. After all connections have been made, the Trimble 4400 receiver is started using a TDC1 or TSC1 handheld data logger and the radio modem is turned on.

    Date: 2007 (process 2 of 7)
    The Third Generation Coastal Profiling System (CPSIII) consists of a personal watercraft equipped with a GPS receiver and antenna, an echo sounder, a monitor for visual aid, a keypad for operator control, and a computer running hydrographic surveying software for navigation, data collection, and data analysis (MacMahan, 2001).

    The PWC used for the CPSIII is a 2003 Honda AquaTrax F-12 chosen because of its stability, compartment space, and relatively low price. The 3-man PWC measures 3.20 m in length, 1.25 m in width, and 1.06 m in height. During normal surveying operation, the wave runner travels at approximately 3 m/s (6 knots) and can operate for approximately 5 hours on one 60-L fuel tank. The instruments are placed on a bracket at the stern of the vessel, and forward upper part of the vessel in front of the handlebars. On the stern bracket are three large watertight cases, which house the GPS, computer, echo sounder electronics and batteries. In the computer case, the echo sounder and the laptop computer are mounted. This case has six external watertight connectors: one is for serial communication with the GPS, one for the echo sounder transducer, one for the external screen, one for the external 17 button keypad, one for power, and one spare. The complete system is powered by two gel cell 12-volt marine batteries, configured in parallel and housed in a Pelican box mounted on the bracket at the stern of the PWC. The system draws 12 volts at approximately 5 amps.

    Horizontal and vertical positioning of the CPSIII is obtained using a Trimble 4700 GPS receiver, which is enclosed in a waterproof Pelican box placed on the bracket at the stern of the PWC. Also within the GPS case is the GPS radio modem (Pacific Crest) that is used to communicate with the shore base station. A small bracket is attached to the topside stern of the vessel for mounting the L1/L2 microcentered GPS antenna and the radio antenna. The GPS antenna is mounted approximately 119 cm directly above the echo sounder transducer.

    The echo sounder is an ESE-50 single frequency echo sounder with a 200 kHz transducer manufactured by Flash Fire Technology, Inc. This echo sounder has adjustable gains, offset, and serial outputs. The sampling rate is a function of water depth with an approximate sampling rate of 8 Hz applied in shallow water (0-10 m). The transducer has a 10 - degree conical beam width and generates a pulse at 200 kHz. The echo sounder transducer is mounted on a removable and adjustable arm at the stern of the vessel. The electronics of the echo sounder were reconfigured along with a Big Bay Technologies Inc. P3 mini PC, placed in a watertight Pelican Case. The CPSIII collects data at 5 Hz and while traveling at 3 m/s generates a depth sounding every 0.6 meters along the sea floor.

    Navigation and surveying are aided by the use of a monitor (12 inch Big Bay Technologies outdoor high bright display) which is mounted in a watertight case on a bracket forward of the handlebars. A small 17-button programmable Logic Controls keypad (24 cm X 8.9 cm X 3.2 cm) is placed in a waterproof radio bag mounted on the handlebars.

    Date: 2007 (process 3 of 7)
    HYPACK hydrographic surveying software is used as the data synchronization software and navigation system. Hypack allows visual observation of trackline, distance offline, depth, latitude, longitude, easting, northing, corrected depth, filename, line number, satellite quality, number of satellites, collection mode, and recording mode. All of this information is useful to the operator when collecting hydrographic data.

    HYPACK allows for surveying within a user-defined coordinate system, in this case NAD83 Washington State Plane (4602) - North and NAVD88. As the GPS base station is set up over a monument and survey accurate data is stored in HYPACK in the appropriate datum.

    The CPSIII has the ability to survey preset track lines and data is collected only when the PWC operator selects a line. The PWC operator maneuvers the vessel to one end of the line and drives along the track until the vessel is in a water depth of approximately 1 m.

    Date: 2007 (process 4 of 7)
    Each nearshore profile is examined, typically using a Perl script, to detect and remove any obvious outliers from the raw files that are either shallower than the echo sounder blanking interval or deeper than a user defined cutoff value.

    Date: 2007 (process 5 of 7)
    Each nearshore profile is viewed using HYPACK’s editor. Here, any obviously bad data points that did not get eliminated by the previous processing step are removed by highlighting the point and deleting it from the record. Individual files are then exported from HYPACK in Easting, Northing, Elevation ASCII triplets with one data file per nearshore profile. These files, which have been run through the Perl script and the HYPACK editor are considered the ‘raw’ data files.

    Date: 2007 (process 6 of 7)
    Since the echo sounders did not measure water temperature and therefore did not correct the speed of sound in water in real time, all data have been corrected to adjust the vertical coordinate for the actual speed of sound based on water temperatures measured by local wave buoys (see Excel file ew_enviro_cond_05.xls). Further, no measurements of salinity were made or were available from local buoys. A sensitivity analysis was performed to investigate the effect of salinity and temperature variations, hence speed of sound adjustment on a profile. The results show that a normal range of water temperature can have a measurable affect on depths. A worst case inducement of error, when the water temperature estimate is approximately 10 degrees C different from the actual water temperature, results in approximately 0.20 m of vertical change at a water depth of 11 m. The temperature chosen to correct each profile is taken as the average of the surface water temperatures recorded at the closest wave buoy to the data collection site over the times when data collection occurred at that particular sub-cell. Two standard deviations of all water temperature estimates chosen to correct the profiles (more than 90 samples) is less than 3 degrees C. Therefore, the majority of nearshore profiles have been vertically adjusted by less than 10-cm.

    The salinity is fixed at 31 psu for all lines as its small variations in the sampling region (Gelfenbaum et al., 2000) had a negligible effect when performing a speed of sound correction to the data.

    Date: 2007 (process 7 of 7)
    Finally, a smoothing operation is performed using a running median filter on the vertical coordinate in the onshore direction to reduce high frequency fluctuations from the nearshore bathymetry data. Varying window sizes are used to obtain a smooth profile while maintaining the integrity of the actual data points. These files, which have been processed through the Perl script, the HYPACK editor, corrected for vertical offsets, speed of sound, and salinity, and smoothed are considered the ‘final’ data files.

    Person who carried out this activity:

    Peter Ruggiero
    U.S. Geological Survey
    Coastal Engineer
    Coastal and Marine Geology Program, MS-999,
    345 Middlefield Road
    Menlo Park, CA 94025
    USA

    650-329-5433 (voice)
    650-329-5190 (FAX)
    pruggiero@usgs.gov

  3. What similar or related data should the user be aware of?


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?

    The survey-grade GPS equipment used in the monitoring program (Trimble 4000 series receivers) have manufacturer reported Root Mean Square (RMS) accuracies of approximately ±3-cm + 2ppm of baseline length (typically 10 km or less) in the horizontal while operating in Real Time Kinematic surveying mode (Trimble Navigation Limited, 1998). These reported accuracies are, however, additionally subject to multi-path, satellite obstructions, poor satellite geometry, and atmospheric conditions. While the horizontal uncertainty of individual data points is approximately 0.05 m, the CPS III operators cannot stay 'on line' at all times to this level of accuracy. Typically, mean offsets are less than 2.0 m from the preprogrammed track lines and maximum offsets along the approximately 2 km long transects are typically less than 10.0 m.

  3. How accurate are the heights or depths?

    The survey-grade GPS equipment used in the monitoring program (Trimble 4000 series receivers) have manufacturer reported RMS accuracies of approximately ±5-cm + 2ppm of baseline length (typically 10 km or less) in the vertical while operating in Real Time Kinematic surveying mode (Trimble Navigation Limited, 1998). These reported accuracies are, however, additionally subject to multi-path, satellite obstructions, poor satellite geometry, and atmospheric conditions that can combine to cause a vertical GPS drift that can be as much as 10-cm. While repeatability tests and merges with topographic data suggest sub-decimeter vertical accuracy (MacMahan, 2001), variability in water temperature (not usually measured) can affect depth estimates by as much as 3 % of the water depth. For fresh water, the speed of sound is probably closer to 1450 m/s and would affect depth estimates by approximately 5 cm, due to the shallow depth in most of the lake.

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

    The data is visually inspected for gross inaccuracies using a variety of software packages including HYPACK (Coastal Oceanographics Inc.) and Matlab (Mathworks Inc.).

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

    The fidelity of the data is ensured via the use of survey grade GPS receivers and a geodetic control monument.


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:
Users must assume liability to determine the appropriate use of these data. This data set is not to be used for legal purposes. The Coastal and Marine Geology Program, U.S. Geological Survey should be acknowledged as the data source in products derived from these data. Please contact the USGS for more detailed information if required.

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

    U.S. Geological Survey, Coastal and Marine Geology
    c/o Peter Ruggiero
    Coastal Engineer
    345 Middlefield Rd MS-999
    Menlo Park, CA 94025-3561
    USA

    650-329-5433 (voice)
    650-329-5190 (FAX)
    pruggiero@usgs.gov

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

  3. What legal disclaimers am I supposed to read?

    Users must assume liability to determine the appropriate use of these data. This data set is not to be used for legal purposes. The Coastal and Marine Geology Program, U.S. Geological Survey should be acknowledged as the data source in products derived from these data. Please contact the U.S. Geological Survey for more detailed information if required.

  4. How can I download or order the data?

  5. Is there some other way to get the data?

    Please contact Peter Ruggiero at the U.S. Geological Survey for ordering information.


Who wrote the metadata?

Dates:
Last modified: 07-Mar-2006
Metadata author:
Peter Ruggiero
U.S. Geological Survey, Coastal and Marine Geology
Coastal Engineer
345 Middlefield Rd MS-999
Menlo Park, CA 94025-3561
USA

650-329-5433 (voice)
650-329-5190 (FAX)
pruggiero@usgs.gov

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


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