Coastal flooding is a problem wherever development has occurred adjacent to, or
on, beach systems. The problems of maintaining these areas are accentuated by
naturally rising sea levels over most of Newfoundland. Floods usually occur when
storms coincide with high tides and can include overtopping or breaching of
barachois beaches. Flooding of this type can be very destructive. Flood risk maps
(link to these maps shown in the freshwater thread) have been prepared for
flood-prone areas through the Canada - Newfoundland Flood Reduction Damage Program.
The worst geological related hazard in the province's history was one of coastal
flooding associated with the Grand Banks
tsunami. that struck the Burin Peninsula
in 1929. Incidences of coastal flooding in Newfoundland and Labrador are shown on
the map below. The larger version provides pop-up information on locations, dates,
deaths, and injuries, along with other comments and an accompanying table.
||Coastal Flooding Map.
The larger version of this map shows the locations of all recorded
coastal flooding in Newfoundland and Labrador from 1755 to 1992. Moving the
mouse over any location will call up information on the landslide occurring
in that place.
Map adapted by Don Walsh and Tina Riche, 2000.
with more information. (46 kb)
Possibly the most vulnerable area to coastal flooding in the province is
Placentia. The town has a history of flooding, aggravated by urban
development over the past 15 to 25 years into the area directly behind the
|Aerial View of Placentia.
This aerial view of Placentia shows a community built on a beach-ridge
complex, very close to sea- level.
Reproduced by permission of the Government of Newfoundland
and Labrador © 1990.
information (46 kb).
Flooding in Placentia occurs either as a result of high water
levels in the estuary (which may be caused by storm runoff, storm surge, high tides, or a
combination of these) or as a result of storm wave run-up and overtopping along the outer beach,
or both. The most damaging recent flood event occurred in January 1982, when high waves were
superimposed on very high tides. Severe flooding also occurred in December 1983 and (less severe) at
Christmas 1992. The Department of Municipal Affairs has responded to this problem by constructing
shoreline defenses, at a cost of about $3 000 000.
||Sea Wall at Placentia.
To reduce flood damage at Placentia, a sea wall has been built along the
Reproduced by permission of the Government of Newfoundland and
Labrador © 1993.
The Burin Peninsula has numerous communities situated at low elevations behind barrier beaches on a
coast threatened by rising sea levels. Coastal protection measures have been constructed in a number
of vulnerable areas, including the site of recent Provincial Park developments at Frenchman's Cove.
The vulnerability to flooding was emphasized by the disaster associated with the
1929 tsunami. An earthquake on the Grand Banks, measuring 7.2 on the Richter scale
produced a tsunami that radiated out from the epicentre. The earthquake was recorded
in Nova Scotia and New York in the west,
and Portugal in the east, but impacted most severely on the Burin Peninsula. The
tsunami traveled at speeds up to about 500 km/hr through deep water, and about 140
km/hr over the continental shelf, but had slowed to about 40 km/hr upon impact with
the coast. It arrived as three main pulses, causing local sea levels to rise between
3 and 7 m. Twenty-eight lives were lost on the Burin Peninsula. Total
damage to property was estimated at about $1 million (1929 dollars).
|House Washed Out to Sea by Tsunami.
Schooner rides at her mooring after towing a house back into harbour.
The house had been washed out to sea during the Burin Tsunami of 1929.
Image courtesy of Provincial Archives of
Newfoundland and Labrador (PANL A2-149).
information (33 kb).
The frequency of tsunamis is uncertain. Alan Ruffman (Geomarine Associates) suggests that
earthquakes of the magnitude that triggered the 1929 tsunami are 1 per 1000 years, but could be as
low as 1 per 100 years for magnitude 6.0 earthquakes. The province has experienced at least 7 other
earthquakes, mostly of a minor nature. Apart from the Burin tsunami, two others have been reported,
at Bonavista in 1755 as a result of the Lisbon earthquake, and St. Shott's in June 1864. These
caused damage, but no reported loss of life.
The stretch of highway that crosses the mouth of Holyrood Pond on the southern shore of the Avalon
Peninsula is prone to coastal flooding. Despite the unusually high elevation of the barrier crest
(more than 7 m above mean sea level) this road has been washed out at least twice in recent years
(during storms in January 1982 and March 1985), and the community of St. Vincent's has been flooded.
In an effort to raise the barrier crest and limit future flooding, an artificial gravel ridge and
wooden sea wall were constructed. The effectiveness of this structure remains to be
Images and text reproduced by permission of M. Batterson, D.G.E.
Liverman, J. Ryan and D. Taylor, The Assessment of Geological Hazards
and Disasters in Newfoundland: An Update. (St. John's: Government of
Newfoundland and Labrador, Department of Mines and Energy, Geological
Survey, © 1999) unless otherwise noted.