Summary

Introduction 1, 2
  Study Area
  Previous Studies
  Oceanography
  Seafloor Materials

K1-93 Survey
  Methods
  Scope of Work
  Navigation
  Sidescan Sonar
  Bathymetry
  Profiling

Results
  Bathymetry
  Sonar, 3.5kHz 1, 2, 3

Conclusions

Figures
  1   2   3   4   5
  6   7   8   9 10
11 12 13 14 15
16 17 18 19 20

Plate 1

Apx 1: Statistics 1
Apx 1: Statistics 2
Apx 2: Equipment 1
Apx 2: Equipment 2
Acknowledgments

References 1, 2, 3

GEOPHYSICAL PROFILING SYSTEMS

High-resolution 3.5-kHz Seismic Reflection Profiling System
High-resolution 3.5-kHz subbottom profiles were collected concurrently with sidescan sonar imagery, to determine the acoustic signature and thickness of both the dredged material and natural sedimentary layers (figures 3 and 4). The profiling system comprises an Ocean Data Equipment Corporation Bathy 2000 signal correlator, and a Raytheon PTR transceiver, both driving a 3.5-kHz subbottom profiler housed in a towfish. Pulse repetition rates were 0.25, 0.5 and 1.0 sec. Real-time 3.5 kHz-return signals were displayed on a 16-bit format color monitor and on analog ink-jet color paper records. All data are digital, merged with navigation and archived on optical disc.

Chirp Sonar High-Resolution Profiling System
A Datasonics CAP-6000A chirp sonar subbottom profiling system was also used in an effort to map the thickness and extent of any surficial sedimentary layers associated with dredged material disposal. Operational and theoretical details of the chirp sonar are explained in Appendix 2 and references cited therein. The acoustical data were displayed real time on a super VGA graphics monitor and paper copies were produced on a color-jet printer. All data were archived on Sony digital audio tapes. The monitor and paper copies displayed color acoustic profiles and a variety of system settings. The chirp sonar proved unsuccessful owing to a combination of system noise and possibly the carbonate substrate. The poor quality of the chirp data precludes any detailed description of the profiles and subsequent interpretation. The chirp sonar data are not discussed in the remainder of the report.