Abstracts

Community Vulnerability to Extreme Rainfall in Ontario: Lessons Learned from Recent Years and Implications under Climate Change

Joan Klaassen
Environment Canada
Joan.Klaassen@ec.gc.ca

In recent years, a number of heavy storm rainfall and regional flooding events have been recorded across Ontario. During the spring and summer of 2000, at least 10 events led to significant flooding impacts over southern and central Ontario. Several of these storms were well in excess of 100 year return period frequency of occurrence, and in excess of design standards of water control infrastructure. The May 2000 rainfall was linked as a causative factor in the Walkerton waterborne disease outbreak. In June 2002, a Northwestern Ontario storm dumped close to 400 mm of rain during a 48 hour period and resulted in serious damages to homes, buildings as well as road and rail infrastructure. The summer of 2004 witnessed several extreme rainfall events, including the July 15 Peterborough flooding and September 9 storm over eastern Ontario. A state of emergency was declared by the city of Peterborough as close to 240 mm of rain fell over a 24-hour period, with 150 mm in 2 hours, which was well behind the design capacity of the water control infrastructure. Flood damages associated with all of these storms has totalled in the hundreds of millions of dollars. Although there may still be scientific debate as to whether extreme weather events such as heavy rainfall are on the rise, societal and community vulnerability to these storms does appear to be on the increase. However, scientists project that under climate change, the frequency and intensity of extreme precipitation events will increase, which in turn could lead to increased community vulnerability. By developing and adopting pro-active adaptation options, including comprehensive emergency preparedness, communities will help reduce their impacts and vulnerability to extremes in the current and future climate.

2005-04-05