Flood Risk and Vulnerability Analysis Project - Atlantic Climate ...

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addition to hurricane intensity such as spatial extent of tropical storm force winds
(fetch), the continental shelf geometry and local topography which make it extremely
difficult to precisely peg a high water mark which can be considerably lower or higher
in specific communities;
Storm surge is simply water that is pushed toward the shore by the force of the winds
swirling around the storm together with the greatly reduced atmospheric pressures;
In addition, wind generated waves are superimposed on the storm tide above but
again, are exceedingly difficult to quantify precisely as the wave height would be
highly dependent on storm depth, track, age, swath size etc. (e.g., Hurricane Igor,
which tracked right along the eastern shore of the Avalon Peninsula, produced wave
heights to the west of the track (south coast of NL) which reached 4.2 metres while
near the track (south of Avalon) wave heights were 8 to 9 metres and to the east of
the track, 12.5 metres);
The US National Oceanic and Atmospheric Administration (NOAA) indicate that the
greatest potential for loss of life related to a hurricanes is from storm surge, which
historically has claimed, in the US, nine of ten victims;
To complete the Hurricane and Tropical Storm threat for Labrador, the following
thoughts are offered:
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Tropical systems do enter the Gulf of Mexico and from there veer North tracking up
the Mississippi Valley and along the western side of the Appalachians through
Ontario and Québec and into Labrador;
By then, these storms are much weakened and so Labrador would experience storm
remnants only though precipitation could still be significant (remnants of tropical
systems can cause widespread flooding as was seen with the remnants of Hurricane
Rita flooding Stephenville, West WRMD, in September, 2005);
Hurricanes represent the greatest threat to Newfoundland and are the weather
phenomena affecting the island that will most likely produce the highest water levels and
the most severe floods;
Figure 3-28 provides a preliminary estimate of the cumulative effects of the various
factors contributing to increased coastal water levels from Hurricanes (this was all that
could be accomplished within the context of this project);
From the analysis of past Hurricane events in this report and the climatic trends reported
by others, and confirmed by analyses herein, it could be hypothesized that, while
extremely difficult to estimate return periods, themselves changing, for rare events with
data over a little more than the last half century, going forward through this century:
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a Category 1 Hurricane making landfall on the island of Newfoundland appears to be
about a 1 in 10 year event (though not all necessarily as damaging as Igor whose
impact was amplified by other factors);
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