Tide gauges

Local tide gauges are routinely installed during hydrographic surveys to correct for local conditions against a vertical reference or datum. The tidal records are also used to develop tidal constituent sets, which can be used later for tidal predictions in these areas.

CHS has a network of permanent tide gauges, which is called the Permanent Water Level Network. Some CHS tide gauges have been collecting tide data for over a century. Other's such as the new laser tide gauge systems, are more recent.

These gauges serve many purposes.

Sea-level monitoring

Because of the permanence of the CHS's network of gauges, long-term trends in mean sea level can be observed over time. CHS shares monthly averages of many of its permanent gauges with other sections within DFO, such as Oceanography; other departments such as Environment Canada; Ports Canada Harbour Masters; other nations for scientific research; etc.

Tsunamis and storm surges

The CHS Permanent Water Level Network is also used for emergency preparedness and emergency response.

On the Pacific coast, tsunamis are a real threat from seismic activity (earthquakes) in areas such as Japan, Chile and Alaska, and more immediately from the Cascadia subduction zone off the coast of Vancouver Island.

On the Atlantic coast, many low-lying areas are prone to flooding from storm surges. Storm surges are rapid and sustained increases in the level of the tide caused by low pressure and strong onshore winds.