Water Stewardship Information Sources
| Citation | Cole, A. 2013. Annual Unit Runoff in Canada. Agriculture and Agri-Food Canada. |
|---|---|
| Organization | Agriculture and Agri-Food Canada |
| URL | http://www.agr.gc.ca/atlas/supportdocument_documentdesupport/aafcAnnualUnitRunoff2013/en/AUR_Report_Final.pdf |
| Abstract/Description or Keywords | Streamflow and runoff volumes are highly variable across Canada and are influenced by local physiographic and climatic patterns. Many planning activities require the ability to locate, evaluate, and quantify surface water supplies. This study aims to illustrate runoff trends across the country by calculating annual unit runoff for a variety of probabilities of exceedence commonly used by decision makers. Annual unit runoff is a measure of runoff volume per square kilometre. This report uses units of cubic decametres (1000 m 3 ) per square kilometre (dam3 /km2 ), which is equivalent to millimetres depth on the landscape. Three previous unit runoff studies were undertaken by the Prairie Farm Rehabilitation Administration, PFRA (which became the Agri-Environment Services Branch, AESB, and then merged with Research Branch to become the Science and Technology Branch of Agriculture and Agri-Food Canada): 1. “The Distribution and Variability of Runoff in Alberta, Saskatchewan, and Manitoba”, completed in 1964 [1] 2. “Report on Median Annual Unit Runoff for the Prairie Province”, updated in 1978 [2] 3. “Annual Unit Runoff on the Canadian Prairies”, completed in 1994 [3]. The 1964 study included 230 Water Survey of Canada (WSC) hydrometric gauging stations with effective drainage areas (EDA) smaller than 5,180 km2 and examined the study period from 1911 to1956. The second study (1978) used 543 WSC stations without any drainage area limit and examined the study period from 1912 to1972. The third (1994) study included 397 stations with EDA less than 5,000 km2 and examined the study period from 1950 to1989. The most recent two reports (1978 and 1994) included isopleth maps of the median annual unit runoff (MAUR) – the runoff volume with 50% probability of exceedence. The 1994 report also included isopleth maps for the 10%, 25%, 70%, 75%, 80%, and 90% probability of exceedence. Additional hydrometric data and the availability of more sophisticated statistical and mapping methods provide justification for the reworking and updating of these previous reports to provide new isopleth unit runoff maps. Additional years of record also provide an opportunity to expand the dataset that forms the basis for these maps. The Science and Technology (S&T) Branch has also expanded its national presence and thus it is desirable to expand the maps coverage to include as much of the country as the data will allow. This study examines runoff measurements at hydrometric gauging stations for the period 1950 to 2006 (where possible) and reports the same seven probabilities of exceedence as the previous 1994 report: 10%, 25%, 50%, 70%, 75%, 80%, and 90%. Probability of exceedence refers to the chance of a unit runoff value being equaled or exceeded in any one year. For example, an annual unit runoff of 50 dam3 /km2 at a 70% probability of exceedence means that, in any given year, there is a 70% probability that the annual unit runoff will be at least 50 dam3 /km2. streamflow, water yield |
| Information Type | report |
| Regional Watershed | Province |
| Sub-watershed if known | |
| Aquifer # | |
| Comments | |
| Project status | complete |
| Contact Name | |
| Contact Email |