Citation | BGC Engineering. 2009. Climate Change (2050) Adjusted IDF Curves: Metro Vancouver Climate Stations. Prepared for Metro Vancouver. |
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Organization | Metro Vancouver |
URL | http://www.metrovancouver.org/services/liquid-waste/LiquidWastePublications/ClimateChange2050AdjustedIDFCurves2009.pdf |
Abstract/Description or Keywords | This study provides adjusted Intensity Duration Frequency curves for ten Metro Vancouver climate stations that consider changes in winter precipitation intensity for the 2050 time horizon (2040’s-2070’s) due to predicted effects of global warming. These adjusted curves form a useful step towards estimating changes in design runoff events used in a variety of applications, including the planning and design of water and wastewater management infrastructure. Predicted changes in future rainfall amount were based on two model runs of the Canadian Regional Climate Model (CRCM), using the A2 emission scenario for the 2050 horizon. The A2 scenario, which uses very conservative (high) emission assumptions, suggests that monthly fall and winter precipitation in the Metro Vancouver area will increase in magnitude by 10% to 21% by approximately the 2050’s. Herein, the more conservative 21% value was used for analysis and presentation of results. Predicted changes in future rainfall intensity were obtained by identifying a statistical relationship between rainfall amount and intensity for existing data, and then using this relation to estimate future rainfall intensity based on a 21% increase in rainfall amount. The estimated fractional changes in rainfall intensity were used to adjust IDF values. Results suggest that the frequency of extreme rainfall intensity events will significantly increase, with forecasted 50 year rainfall intensities approximately equal to or greater than the current 100 year rainfall intensity at most stations. This study is exploratory in nature as it is limited to a single time horizon, one emission scenario, and two model runs of the CRCM that are based on the same Global Circulation Model (GCM). Of the over fifty Metro Vancouver rain gauges in Metro Vancouver, ten gauges were selected for analysis that are active stations with the most complete data record. In a subsequent study, it may be possible to add additional stations if they also show a statistically significant historical relationship between rainfall amount and intensity and if existing analogue precipitation data be transcribed into digital format. Further work is required to address these limitations, quantify uncertainties and to establish regional IDF curves for various zones within the Metro Vancouver area. |
Information Type | report |
Regional Watershed | Lower Fraser |
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Project status | complete |
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