[ Link to USGS home page ]

Torresan, M.E., Hampton, M.A., Gowen, M.H., Barber, Jr., J.H., Zink, L.L., Chase, T.E., Wong, F.L., Gann, J.T., and Dartnell, P., 1995, Final report: acoustic mapping of dredged material disposal sites and deposits in Mamala Bay, Honolulu, Hawaii: U.S. Geological Survey Open-file Report 95-17.


Introduction 1, 2
  Study Area
  Previous Studies
  Seafloor Materials

K1-93 Survey
  Scope of Work
  Sidescan Sonar

  Sonar, 3.5kHz 1, 2, 3


  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

References 1, 2, 3

Results of the 1993 acoustic survey (presented herein) and the subsequent May 1994 sampling program (Torresan and others, 1994a and b) provide abundant evidence that the dredged material deposits are more extensive than the area defined by the official disposal site boundaries. Furthermore, preliminary interpretations of samples and photographic data collected in May 1994 indicate that the dredged material is more extensive than the area defined as dredged material deposits on the sidescan sonar mosaic and 3.5-kHz profiles (Torresan and others, 1994a and b).

The bathymetry map presented in figure 5 and plate 1 shows that the disposal sites are located in the broad southeast sloping trough having a slope of about 20 m/km (1:50). Large pinnacles and canyons are absent, but several relatively small canyons and areas of irregular topography exist in the immediate vicinity of the disposal sites. There are no obvious features on the bathymetry that are clearly caused by disposal activities. As seen on the bathymetric map (figure 5, plate 1, and Chase and others, 1994), the seafloor is naturally irregular in texture and slope. It is impossible to identify anomalous features on the bathymetry map that result from dredged material disposal. Relatively large bedforms, possibly sandwaves are evident along portions of 3.5-kHz subbottom profiles (figures 7, 8, and 9) collected form near the eastern edge of the former Honolulu Harbor disposal site. The bedforms extend well beyond both the disposal site boundaries and beyond the high-backscatter blanket interpreted as dredged material deposits, and probably result from natural rather than anthropogenic processes as stated in Torresan and others (1994a). The bathymetric data grid collected during the 1993 survey is too coarse in scale and the features created by disposal activities are apparently to small in relief to allow definition on the bathymetric map produced by Chase and others (1994) and shown in figure 5 and plate 1.


Top of page Beginning of OFR 95-17

|-- [Reports]  -- [Honolulu]  -- [Home]  -- [Search]  --|

URL: https://pubs.usgs.gov/of/1995/of95-017/07results.html
Maintained by: Michael Diggles
Author: Florence L. Wong
Last modified: May 27, 2005 (mfd)

USGS Privacy Statement   |   Disclaimer   |   Feedback   |   Accessibility
Department of the Interior   U.S. Geological Survey   Geologic Division   Western Region Coastal & Marine Geology