Data acquisition

The Canadian Hydrographic Service conducts hydrographic surveys to acquire data to create nautical charts or update existing charts, as well as to develop tide and current tables, and other navigational publications.

  • CHS hydrographers working in the ice

    CHS Hydrographer working on the ice

  • temporary positioning station set up for a hydrographic survey

    Temporary positioning station set up for a hydrographic survey.

  • CHS Launch Petrel running survey lines in the Arctic

    CHS Launch Petrel running survey lines in the Arctic.

  • The Shoal Seeker, owned by CHS, is equipped with a multibeam echosounder on a retractable bow mount. The Shoal Seeker can be towed behind a truck, which makes it easy to transport for immediate surveys.

    The Shoal Seeker, owned by CHS, is equipped with a multibeam echosounder on a retractable bow mount.

  • Caption: The Canadian Coast Guard’s Petrel has a hull-mounted Kongsberg EM3002 multibeam echosounder and an MVP-30 profiling winch.

    The Canadian Coast Guard’s Petrel has a hull-mounted Kongsberg EM3002 multibeam echosounder and an MVP-30 profiling winch.

  • The Ponar Grab Sampler is commonly used to obtain samples of the seabed in hydrographic surveys.

    The Ponar Grab Sampler is commonly used to obtain samples of the seabed in hydrographic surveys.

Hydrographic surveys collect three types of data:

  • Depths and heights: The depth of water is measured from a known location, such as a boat. Measurements are also taken of the heights of surrounding land formations, such as rocks, islands or shorelines, clearances under bridges and overhead cables. Equipment to measure depths includes different types of echosounders, or sonars, and bathymetric lidar, while heights may be measured by topographic lidar. Backscatter from sonars and lidars can also reveal information about the make-up of the seabed.
  • Water levels and vertical datums: The level of the tide at the time of the depth measurement, as well as other vertical reference points, or datums, must be measured to calculate the correct water depth, against an established vertical datum. Tide gauges are used to measure water levels.
  • Positioning and orientation: A measurement of the precise location on the surface of the Earth (or below the surface of the ocean) at the exact time of the water depth measurement must also be included in a hydrographic survey. Satellite positioning technologies are used to measure position while motion sensors are used to track vessel orientation at the time of the measurement.

 

Data acquisition is generally carried out by field personnel—surveyors and technicians—using survey platforms that include surface vessels, aircraft and land vehicles. CHS also might use satellites, as well as autonomous or semi-autonomous underwater vehicles, for survey work.