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In the next 15 minutes…

In the next 15 minutes…. Okanagan Basin Study – Available on Web Overview and Findings from Low Flow Literature Summary. Okanagan Basin Study Website (http://www.sci.ouc.bc.ca/biol/pdill/OkanaganBasin/default.htm).

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In the next 15 minutes…

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  1. In the next 15 minutes… • Okanagan Basin Study – Available on Web • Overview and Findings from Low Flow Literature Summary

  2. Okanagan Basin Study Website(http://www.sci.ouc.bc.ca/biol/pdill/OkanaganBasin/default.htm)

  3. Forest Management Effects on Low Flows in Snowmelt Dominated Hydrologic Regimes Robin Pike and Rob Scherer Watershed Management Extension Program FORREX – Forest Research Extension Partnership June 23, 2003

  4. Focus: Summarize the current state of knowledge regarding forest management effects on water quantity in snowmelt dominated hydrologic regimes with an emphasis on low flows. • Issue: Does forest management have an effect on low flows?

  5. Project Overview • MSRM / FORREX Partnership Agreement Established • Lit synthesis + Workshop = current state of knowledge and identification of research gaps • Peer assisted process (based on reconciling peer reviewed literature) to ensure science-based findings with a minimum of bias • Next Steps

  6. What are low flows? • Low flows: variously defined, e.g. lowest 5, 7 day flow volume; All flow below certain exceedance level • Dry season discharge; flows fed by groundwater • In Okanagan, low flows predominate in time, but are dwarfed in terms of volume

  7. Typical Streamflow Hydrograph in the Okanagan

  8. June May September July Photo Source: Gary VanEmmerik

  9. Literature summary addressed three main questions • How is streamflow modified by forest practices • timber harvest • roads • silviculture activities • What are the current sources of information? • What are the current management approaches?

  10. Literature Relevant to Okanagan • Snowmelt dominated watershed • Predominantly covered in coniferous forest types (i.e. Engelmann spruce, Douglas-fir, subalpine fir, ponderosa pine and grand fir) • Located east of cascades / coast range and east side of the Rockies

  11. Key Conclusions

  12. Changes in low flows after harvesting: difficult to detect • Pike & Scherer (2003) Review: • 7 studies applicable to snow-dominated hydrology of Interior BC • 3 studies: increased low flow volumes (lower number of low flow days) • 4 studies: no or non-significant changes in low flows • Range: from no effect to 3 ±3 mm (43 ±51%) per year. • Confidence limits very broad (when reported).

  13. International review by Austin (1999) • 28 studies of low flow changes following timber harvesting. • 16 of the studies identified an increase in low flows (increased water yield) • 10 studies identified no change or non-significant change in low flows • 2 studies identified a decrease in low flows (lower water quantity)

  14. Johnson (1998) review of low flow studies in UK & Europe • Clearcutting increases low flows • Increases in low flows are related to proportion of catchment that is clearcut.

  15. Hydrologic Cycle (Source: Pike, 1998)

  16. Important Hydrologic Processes • Evapotranspiration • return of water to the atmosphere through the process of evaporation and transpiration • Interception • “loss” of rain or snow that is temporarily stored and evaporates from the vegetation surfaces • Snow Accumulation and Melt

  17. Conclusions • The effects of forest management on water quantity is highly variable in magnitude, time and space. • Low flows may increase in volume as a result of forest management. • The magnitude of the increases in the literature, however, were found to be highly variable. • Longevity of potential increases is relatively short.

  18. AcknowledgementTechnical Workshop Participants Adam Wei, Okanagan University College Brian Guy, Summit Environmental Ltd. Brian Symonds, Land and Water British Columbia Inc. Bruce McFarlane, Ministry of Water, Land and Air Dan Moore, University of British Columbia Dave Scott, Okanagan University College Dave Toews, Forest Hydrologist Dean Watts, Department of Fisheries and Oceans Des Anderson, Ministry of Water, Land and Air Protection Eugene Hetherington, Forest Hydrologist Karen Rothe, Ministry of Sustainable Resource Management Karyn Sutherland, FORREX Paul Whitfield, Environment Canada Phil Epp, Ministry of Water, Land and Air Protection Rita Winkler, Ministry of Forests Rob Scherer, FORREX Robin Pike, FORREX Roger Wysocki, Department of Fisheries and Oceans Ron Smith, Ministry of Sustainable Resource Management Ross Porcheron, Ministry of Sustainable Resource Management Steve Matthews, Ministry of Water, Land and Air Protection Victor Cumming, FORREX (workshop facilitator) Younes Alila, University of British Columbia

  19. Contact InformationWatershed Management Extension Specialists Rob Scherer (250) 762-5445, Ext 7516 rob.scherer@forrex.org Robin Pike (250) 387-5887 robin.pike@forrex.org

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