other projects - columbia river, oregon (usace)

Columbia River Channel Improvement Project, Dredging Support

Lake Logan Sedimentation, North Carolina

Mouth of Columbia River, USACE, Astoria, OR

NOAA Geospatial Services Contract, Dewberry and Davis, Coastal Service Center

Port Au Prince, Haiti

System Installation, Samcheongpo, South Korea

USACE Portland District Hydrographic and Geodetic Control Contract

Mouth of the Columbia River, USACE, Astoria, OR

The U.S. Army Corps of Engineers, Portland District conducted a study to identify bottom characteristics of existing and potential offshore sites and adjacent areas, relating to the disposal of material dredged from the Columbia River mouth (MCR) navigation channel. GR Sensing was contracted to carry out multibeam surveys to provide precision bathymetry of preestablished priority areas listed below. Backscatter information derived from the multibeam survey was used for quantitative bottom classification. Actual survey ranges (line spacing) were based on 125% to 200% coverage's within each of the priority areas. Individual coverage was determined by depth of area, speed, ping rate and line spacing to obtain complete seafloor coverage along with detailed information of the seafloor.

Area	Descriptor	Distance Offshore	Area km2	Water Depth ft
1A	Deepwater Site	10 to 15 miles	42	180 to 310
1B	Shallow Water Site	1 to 4	8.1	30 to 80
2A	MCR channel north	0 to 5	7.1	10 to 90
2B	MCR channel offshore	0.5 to 5	4.4	50 to 80
2C	Clatsop Spit	0 to 6	5.2	10 to 70
2D	South Jetty	4 to 5	4.7	30 to 60
2E	MCR channel east	5 to 6	2.7	10 to 130
3A	Offshore SWS	5 to 6	4.4	50 to 70
3C	ODMDS A	0 to 5	12.3	30 to 90

Surveys were conducted 15 August 2005 to 16 September 2005. Identical Kongsberg EM3002 multibeam bathymetric systems were mobilized aboard two vessels and operated concurrently; the M/V Oakland Pilot, a 51' retired pilot vessel from the Harbor of Oakland, CA, with a 16.5' beam, weighing 43 gross tons and drawing just over 6-ft of water and the R/V Minotaur, a 29' aluminum vessel with a 8.5' beam, weighing 8 gross tons, with a draft of 2 ft.

Post processing of the data was completed using Caris Hips, GR Sensing proprietary software, and Luciano Fonseca's (Center for Coastal and Ocean Mapping) Geocoder, now implemented by CARIS Hips and IVS Fledermaus. This was the first commercial use of Geocoder, currently one of the most successful and accurate backscatter analysis applications used for bottom type detection. Examples of the imagery from the data are included in Figure 1 and 2.

(Images: Figure 1. Example Sun-illuminated image of Section D. Figure 2. Backscatter image of Seafloor Section D using Fonsecas (CCOM-UNH) Geocoder.)

Global Remote Sensing, LLC 17706 Brickyard Road, Suite 200 Bothell, WA 98011 USA
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