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Open-File Report 2013–1225

Bathymetry and Acoustic Backscatter—Estero Bay, California

Survey Outline

The 2012 mapping mission (U.S. Geological Survey) Field Activity ID: S-05-12-SC collected high-resolution bathymetry and coregistered acoustic backscatter data from outer Estero Bay, California (fig. 1). The survey was completed in 11 days, from July 30 to August 9, 2012, and consisted of 117 survey lines covering approximately 165 km2 (64 mi2) in elevations ranging from about -45 to -250 m (-148 to -820 ft) relative to the North American Vertical Datum (NAVD88).

Bathymetric surveys were completed using a RESON SeaBat 7111 multibeam echosounder. The sonar was pole-mounted on the 34-ft USGS mapping vessel R/V Parke Snavely (fig. 2 and 3). Global Navigation Satellite System (GNSS) position and inertial motion and orientation measurement data were recorded using an Applanix Position and Orientation Solutions for Marine Vessels (POS MV) 320 inertial-aided position and orientation system. The sonar head, GNSS antennae, and the inertial motion unit (IMU) were surveyed in place to a common reference frame with a Geodimeter 640 Total Station. The R/V Parke Snavely was outfitted with three networked workstations and a navigation computer for use by the captain and survey crew for data collection and initial processing. See table 1 for the sonar-system specifications.

Table 1. Seabat 7111 Sonar System specifications (Reson, Inc., 2011).
Frequency100k Hz
Pulse length0.08-3.04 ms (selectable)
Typical depth1-900 m
Maximum Water Depth1,000 m
Depth resolution, sector coverage,3 cm, 150°
number of beams101, 201 EA, or 301 ED
Along-track, across-track beamwidth1.9° , 1.5° ± 0.05° (3.0°, 4.5°, 6.0° operator selectable)
Bottom detection methodCenter-of-energy and phase-zero-crossing algorithm
Pitch stabilization± 10° (motion sensor required)
Max update rate20Hz (range selection dependent)
System supply90-260 VAC 50/60 Hz, 350 W
System controlTrackball or from ethernet
Temperature–operating, storage-5°C to +40°C, -30° to +55°C
Data outputGigabit ethernet
Transducer array–weight267x483x489 mm, 13.6 kg
Hydrophone and projector dimensions636x118 mm (diameter/length)
Cable length15 m, 30 m (optional)
For more information, contact the PCMSC team.

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