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

Development of Projected Intensity-Duration-Frequency Curves
for Corner Brook and Goulds/Petty Harbour, Newfoundland May 16, 2012
1.0 INTRODUCTION
This report provides an overview of the development of projected intensity-durationfrequency
curves (IDF curves) for two areas of Newfoundland, Canada; Corner Brook
and Goulds/Petty Harbour. The objective of the work described here is to develop IDF
curves that reflect the changes in the characteristics of precipitation that might be
caused by projected changes in climate. Three time frames were adopted for
projections: 2020, 2050 and 2080.
Over the last four decades, climate scientists have developed a theoretical framework
and have accumulated observational evidence to indicate that the average temperature
of the Earth is increasing, and that part of this increase can be attributed to emissions of
greenhouse gases generated by human activities (IPCC, 2007). Modern climate
simulation models, referred to as global climate models (GCMs, and also referred to as
general circulation models), have been used to develop quantitative projections of future
changes in temperature, precipitation and other climate variables based on estimates of
future emissions of greenhouse gases. These models show a consensus that the
global average temperature will increase, though the amount of the projected
temperature increase varies with latitude and is not evenly distributed seasonally.
Increases in the global average temperature will cause increased evaporation, resulting
in an increase in the global average precipitation. However there is a high degree of
uncertainty regarding the spatial and temporal distribution of those changes in
precipitation, and furthermore, precipitation in some areas of the globe will decrease.
Theory, and analysis of GCM outputs, indicates that warmer temperatures will change
the characteristics of precipitation extremes (Kharin, et al., 2007). This scientific
information along with recent flood events have motivated infrastructure planners to
undertake efforts, like that described herein, to quantify the impact of projected climate
change on the IDF curves used as one basis for design of drainage and flood
infrastructure.
This work focused on two areas, Corner Brook and Goulds/Petty Harbour, in
Newfoundland. Newfoundland is the island portion of the easternmost Canadian
province, Newfoundland and Labrador. It is located between the Gulf of St. Lawrence
and the Atlantic Ocean, and is one hundred kilometers northeast of Cape Breton Island
of Nova Scotia. The climate in Newfoundland has been characterized by observations
at a number of weather stations. The climates in the regions of Corner Brook and Petty
Harbour were based on the Deer Lake station and the St. John’s A weather station,
respectively. Although climate measurements from a third station at Stephenville were
studied, Deer Lake and St. John’s A were determined to have the climate that best
represented the sites in question.
AMEC Environment & Infrastructure 1