It was a tragedy on Georgian Bay that set in motion the process that led to the creation of the Canadian Hydrographic Service. One hundred and fifty people lost their lives when the steamship Asia went down in those dark Ontario waters in 1883, and calls went out almost immediately for a hydrographic survey of the Great Lakes to make navigation safer.
Six years later, the surveying organization that would eventually become the CHS was born. Its mission soon expanded beyond the Great Lakes to include all Canadian waterways.
Hydrography has changed, of course, over the past 120 years. Traditional leadlines and triangulation methods are used only infrequently, having given way to innovations such as multibeam sounds and the satellite-based Global Positioning System (GPS).
Some important dates in our history:
- The Canadian Hydrographic Service, under the name of the Georgian Bay Survey, was established on August 13, 1883 after the Georgian Bay steamship tragedy.
- The primary focus in 1883 was to survey and chart the navigable waters of Georgian Bay and Lake Huron. This was eventually extended to include all of Canada's inland waterways and coastal regions.
- Hydrographic charting was extended to the Pacific Coast as early as 1891, and in the waters of the St. Lawrence River below Quebec by 1905.
- The tidal and current metering program began in 1893 and the precise water level gauging of the Great Lakes in 1912.
- In 1904 the Georgian Bay Survey became the Hydrographic Survey of Canada (although it soon after was unofficially called the Canadian Hydrographic Service).
- In 1928 the name Canadian Hydrographic Service was officially adopted.
- Charting the long rugged coastlines of Newfoundland and Labrador only became the responsibility of CHS following the Second World War when Newfoundland and Labrador joined the Confederation in 1949.
- The demand for Arctic surveys reached a peak during 1954-57 when the Distant Early Warning (DEW line) system was built across Canada with many stations in the Canadian Arctic.
How Far We've Come:
- Early hydrographers positioned their survey vessels by shore markings while close to the land and by quadrant or sextant when surveying offshore.
- These hydrographers measured water depths by leadline, a long labourious process.
- Today's hydrographer employs a precise DGPS (Differential Global Positioning System) to position the survey vessel and multibeam echo sounders to survey the entire sea floor.
- While paper charts are still in use, the increasing trend for modern shipping is to employ ENCs (Electronic Navigational Charts) that form part of ECDIS (Electronic Chart Display and Information Systems).
Techniques and technologies: from then to now
Traditional approaches to hydrography include:
- the use of lead lines, which are weighted lines lowered into the water to measure depth; and
- triangulation, which uses mathematics based on the points of a triangle to establish coordinates and the distances between points.
These have been displaced by:
- multibeam sounding, which uses highly advanced SONAR technology to provide high-resolution digital views of the ocean environment.
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