Towards a Stream Classification System for the Canadian Prairie Provinces CWRA-CGU National Conference, Banff, Alberta June 5-8, 2012 Greg MacCulloch and Paul Whitfield

Page 2 – Introduction 1. A step toward the goal of establishing a classification system for streams that is based on observed variability in flowrates. 2. To gain insight into anticipated stream response that will aid in: –Improved design and operation of hydrometric networks –The prediction of streamflow response at ungauged or poorly gauged locations.

Page 3 – Data Set Sites on the Canadian Prairies south of 54 o N Reference Hydrometric Basin Network (RHBN) (Brimley et al., 1999). The sites that populate this network where chosen to be: – characterized by pristine or stable hydrological conditions, –unaffected by developments within the basin, –and having good quality data for at least 20 years. –continuous record –“having less than 10% of the surface area of the basin modified in some fashion” – “basins with structures controlling less than 5% of the area of a basin” –27 sites met the criteria

Page 4 – Parameters Reviewed Average Annual Yield (mm) Range in Annual Yield (mm) Ratio Range to Average Duration of Peak Yield Proportion daily Q to Annual Total Q: Q>= 0.05% Q> 1% Annual Q > 2% Annual Proportion of record with completely dry years Average March to October zero flow days Last Quartile Ratios (monthly) –Avg May to October –Range May to October –Non Zero Minimum –Maximum monthly

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Page 9 – A basic classification for streams on the Canadian Prairies should be separated into two broad categories: 1.Native Prairie Streams: streams that respond to localized water sources i.e., precipitation and snowmelt, proportionally throughout the basin and can be dry from time to time. 2.Exotic Prairie Streams: Streamflow is predominately conveyed from the headwaters and these streams do not experience dry conditions. They respond to localized water sources disproportionally throughout the basin.

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Page 18 – Conclusions It is likely that there are distinct classes of streams. Stream Characteristics can be distinguished from HYDAT data set –Average Annual Yield (mm) 6 vs. 800 –Ratio of Range in Yield to Average 6 vs. 1 –Average number of days per year with flow >2% 6 vs. 1 –Maximum Monthly LQR 500 vs. 2 A reference network is a very important asset and needs to be maintained. A review of operation of the existing Prairie RHBN is warranted.