Storm Surge

Storm surges occur in coastal areas when strong onshore winds and low atmospheric pressure during passing storms (at times hurricanes), raise water levels along the shore above predicted levels. Severe storm surges that occur during high tides can result in flood damage, evacuation of communities and loss of life. Storm surge is increasing due to sea-level rise due to climate change. 

With approximately 42,000 km of coastline, Atlantic Canada is characterized by diverse coastal systems including sandy beaches, estuaries, intertidal flats, salt marshes, cobble beaches, cliffs, bluffs, and rock shores. Each one of these coastal systems is affected by varying levels of storm surge impacts.

A drawing showing how sea level rise causes an increase in the regular tide elevations (high tide and low tide) over time, which also causes an increased storm surge water level.

Four independent events are required for a “worst case scenario” surge event to occur in Atlantic Canada: a spring tide; a lunar perigee; a daily high tide; a powerful storm. Storm surges can happen quickly, without allowing much time for preparation.

The combination of sea-level rise and storm surges could overtop the system of historic dikes that control lowland flooding and protect the transportation and trade corridor between New Brunswick and Nova Scotia, the Chignecto Isthmus or Tantramar Marshlands, through which a trade value of CAD 50 million passes each day (Dietz & Hoyt, 2016).

A flooded, partially damaged oceanside road with a wave crashing onto it.
Text reads "Figure 15: Effects of storm-wave overwash on Cow Bay Road, Halifax Regional Municipality, NS. Photo courtesy of R.B. Taylor." The image shows an oceanside road that is partially cracked and has rocks scattered across it.