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

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Because winter temperatures show the greatest increases, it is thought that in the
future there may be more frequent sudden winter thaws and rain events which could
lead to increases in rain on snow (Catto and Hickman, 2004) or rain on frozen
ground events leading to flooding with the West and Central WRMD regions most
susceptible to these events.
Intensity Duration Frequency Curves
IDF curves for Gander and Goose Bay were updated, using the same approach as
Environment Canada, to 2011 so that, together with outputs from other projects, at least
one current representative IDF will be available for each WRMD;
Only a few additional years of data were considered in updating Goose Bay IDF values
and so there is almost no noticeable change there;
The new IDF values for Gander are minor but do show increases compared to the
previously published values except for the very short durations (5 minutes) and the
biggest changes (4%) at the longer durations indicating, since this is all based on actual
data, that precipitation intensity is already beginning to trend upward which supports the
argument that global warming is already happening; and
While IDFs characterize only one flood risk factor, precipitation, and do not capture the
seasonality of precipitation, developing projected IDFs for future time frames is a
worthwhile exercise and is recommended especially if a means can be found to
incorporate in that effort, the results of dynamical modeling of hurricanes to 2050 and
beyond. Seasonal IDFs could also be developed and may be useful given that specific
hazards are associated with particular seasons (e.g., hurricanes/tropical storms in the
fall and Weather Bombs in the fall and early winter).
Hurricanes and Tropical Storms
Tropical systems are responsible for the most extreme and costly flooding events (e.g.,
Igor, 2010) in Newfoundland and so a very careful analysis of past hurricanes and
tropical storms was conducted;
Past records show that hurricanes can track on either side of the island of
Newfoundland, that a category 2 storm has already made landfall along the south coast
and that a category 3 storm has already narrowly missed the island;
The analysis of past storms showed that there is a significant upward trend in the
frequency of tropical storms and hurricanes affecting Newfoundland since 1954, and
especially since 2000;
This upward trend in tropical storm activity is associated with the gradual increase in
Atlantic sea surface temperatures though there is no scientifically proven link;
It is thought that tracking cool and warm phases of the Atlantic Multi-decadal Oscillation
(AMO), a long-duration cycle (20-40 years) in sea surface temperatures in the North
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