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High precision hydrography in Canada, The St. Lawrence River channel, HD Bathymetry, Production, Distribution and Updating

Richard Sanfaçon, Marc Journault (CHS), Louis Maltais (CHS)

The St. Lawrence River channel (Quebec,Canada) is a300 kmlong

navigation channel of which210 kmare maintained at minimun depth of

11.3 m. Hydrographic surveys are conducted to exceed S-44 special

orders requirements. Centimeter level precision is constantly achieved

in depth measurements with the survey boats. They are calibrated and

their measurement of depths over the same seafloor has to be within a

couple centimeters at two sigmas to receive the green light for

surveying. The data used to establish the available water column are

processed, validated and delivered within 24 hours.


The trend in commercial navigation in general is towards bigger, wider

and faster ships. Therefore safely manoeuvering in restricted waters

with limited water depth and limited width brings interesting

challenges. With all the potential environmental impacts, there is a

limit to deepening (dredging) and widening the navigation channel.

Ships’s drafts and widths are increasing but not necessarly the

available depth and width of navigation channels, precise and

up-to-date information is the solution. Forcasted water level and

constant bathymetry updates are now requested by clients.


This paper will briefly describe the intense survey operations taking

place in theSt. Lawrence Riverchannel, every year from April to

December. Based on recent work at CHS-Quebec Region, the paper is also

proposing a new way to produce, distribute and update rapidly High

Definition (HD) bathymetric files using the navigation surface and

S-102 tiles concepts. This leads to a positive influence on the

content of the S-100 standard series being developped and offering a

solution to a fast turn around from surveys to bridge for areas facing

dynamic changes with a limited water column.