Olympic Coast National Marine Sanctuary Science section includes Seafloor Mapping, Oceanography, Deep Sea Coral and Sponges, Wildlife Research, Coastal Habitats, Citizen Science, Ecosystem Processes, Research Surveys, and Research Assets
Olympic Coast National Marine Sanctuary Science section includes Seafloor Mapping, Oceanography, Deep Sea Coral and Sponges, Wildlife Research, Coastal Habitats, Citizen Science, Ecosystem Processes, Research Surveys, and Research Assets
Olympic Coast National Marine Sanctuary Science section includes Seafloor Mapping, Oceanography, Deep Sea Coral and Sponges, Wildlife Research, Coastal Habitats, Citizen Science, Ecosystem Processes, Research Surveys, and Research Assets Olympic Coast National Marine Sanctuary Science section includes Seafloor Mapping, Oceanography, Deep Sea Coral and Sponges, Wildlife Research, Coastal Habitats, Citizen Science, Ecosystem Processes, Research Surveys, and Research Assets

Seafloor Habitat Mapping
with Sonar & LiDAR

Photo of a sidescan towfish with an attached fixed wing depressor.
A sidescan sonar towfish is used to collect benthic imagery.
Because no single tool provides a comprehensive picture of the habitat, various sensors are being used to effectively map the benthic environment at Olympic Coast National Marine Sanctuary. This mapping process involves collecting, integrating, analyzing, and interpreting several types of data at different spatial scales.

Photo of coral attached to a small boulder on the sea bottom.
Rocks, gravel, and marine life on the seafloor.
At the smallest spatial scale (<= 1:20,000) airborne LiDAR (light detection and ranging) has been used to collect bathymetry (depth) information along the narrow coastal margin that includes the intertidal zone of Northern Washington. The basic principle of bathymetric LiDAR operation involves transmitting light sources from an instrument out to a target (i.e., seabed and sea surface) and measuring the time travel for these light sources to reflect back to the instrument, where time is ultimately transformed into a depth measurement. In 2005, the bathymetry of approximately 40.7 km2 (11.8 nm2) of hazardous shoals and rocky outcrops was collected around Cape Flattery using a SHOALS 100T LiDAR system. download the data here (11Mb .zip). To find out more about LiDAR see the National Geodetic Survey Remote Sensing Division page on LiDARimage indicates that the link leaves this site.

Photo of a multibeam echosounder mounted on the bottom of a boat.
A hull-mounted multibeam echosounder for seafloor mapping.
At a medium sampling scale (1:1,000-1:10,000), various types of shipboard hydro-acoustic sensors (sonar) are being used in the sanctuary to collect bathymetric and backscatter information. Sidescan sonar is a type of sonar that creates an image of the seafloor and may be able to provide some understanding of the type of sediment and texture of the seabed. Multibeam sonar not only provides an image of the seafloor but also determines the depth of the water and the nature of the seabed. Data from a multibeam sonar and interpretation of backscatter data informs a more complex analysis of the seafloor that includes variables such as sediment type, slope, aspect, rugosity, and induration. It is therefore the preferred technology for mapping in the sanctuary.

In past years OCNMS was able to collect affordable sidescan data (download data here) for a large area of the northern sanctuary. There were also occasional opportunities for multibeam surveys (download data here). In 2011 the sanctuary acquired a dedicated Reson 8101 multibeam echosounder for the R/V Tatoosh. In the first field season, the Tatoosh mapped the 13 sites of the oceanographic moorings and three shipwrecks. In future years, the sanctuary will prioritize mapping rocky reefs along the coast and flank of the deep canyons, shipwrecks and ultimately the entire sanctuary.

See Seafloor Mapping Projects.



Contact for page content: Nancy Wright
photo of a buoy on the ocean
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