| Precipitation data for Toronto, Ontario is examined using time series analysis, in order to determine trends in runoff under the impact of climate change. Trend analyses indicate that the annual number of rainfall events is increasing while the mean event duration and inter-event time are decreasing. Further analyses revealed that much of the increase in precipitation exhibited in the historical record was the result of changes in small events (less than 2mm). These finding were further corroborated by the study of extreme events which failed to detect significant trends in extreme weather events. ASTORM analytical probabilistic models were then used to study the impact of the precipitation changes on stormwater design requirements. According to current trends and assuming no change in current design parameters, there will be an increase in runoff control over the next 50 years, although annual runoff will increase due to the increase in rainfall events. |
