USGS Western Coastal and Marine Geology
Pacific Coastal & Marine Science Center

Fate of Dredge Disposal Material and Polluted Sediment, Offshore Honolulu, Hawaii

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Shaded Relief Perspective View of Oahu Southern Shelf with Backscatter Overlay

Computer generated image of the seafloor and coastal area of south Oahu showing seafloor backscatter data draped over bathymetry. The white and gray tones visible on the image are a measure of acoustic energy that was backscattered during a multibeam survey conducted in 1998. The patterns and tones denote geologic character of the seafloor with lighter patterns showing higher levels of backscatter or greater hardness (outcropping rock or dredged material), whereas the darker gray patterns indicate less energy returned from the seafloor indicating areas of muddy sediment and/or sand. The seafloor relief and backscatter data in the image is compiled from georeferenced multibeam data collected by the USGS in 1998. Vertical resolution of the data is on the order of 50 cm; horizontal resolution is dependent upon water depth and varies from 6 to 16 m. The black region of the insular shelf indicates seafloor areas not imaged in 1998. The land image is derived from a USGS digital elevation model (DEM). The scale across the bottom of the image is appx 10.2 km. The vertical exaggeration is 20x.

 

For a more information about the multibeam seafloor mapping project click here.

Perspective View of Mamala Bay with Backscatter Overlay

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For more information, please contact:
Michael E. Torresan

U.S. Geological Survey
345 Middlefield Road MS 999
Menlo Park, CA 94025



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U.S. Department of the Interior | U.S. Geological Survey | Western Coastal & Marine Geology
URL: http://walrus.wr.usgs.gov/mamalabay/products/persp_w_back.html
Maintained by Laura Zink Torresan
Last modified 11 October 2005 (lzt)