1 / 18

Impacts of Forest Clearing on Radiation and Snowmelt in Marmot Creek, Alberta, Canada

Impacts of Forest Clearing on Radiation and Snowmelt in Marmot Creek, Alberta, Canada. Chad R. Ellis. Chad Ellis & John Pomeroy Centre for Hydrology. February 21, 2013. Forest snowmelt. Snowmelt timing controlled by energy to snow Forest cover suppresses turbulent energy fluxes

calvin
Download Presentation

Impacts of Forest Clearing on Radiation and Snowmelt in Marmot Creek, Alberta, Canada

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Impacts of Forest Clearing on Radiation and Snowmelt in Marmot Creek, Alberta, Canada Chad R. Ellis Chad Ellis & John Pomeroy Centre for Hydrology February 21, 2013

  2. Forest snowmelt • Snowmelt timing controlled by energy to snow • Forest cover suppresses turbulent energy fluxes • Snowmelt energy dominated by shortwave and longwave radiation exchanges...

  3. dU/dt Forest-snow energy balance Q* = Qm+ dU/dt= K + L + λE+ H+ G K Canopy λE H L Snow G

  4. Radiation to forest snow • Forest cover: ↓ shortwave radiation ↑ longwave radiation • ‘Radiation paradox’

  5. Terrain effects Level terrain Mountain terrain ≠

  6. Forest cover impacts on mountain snowmelt N↑ Model development: • MCRB watershed treatment (Golding & Swanson): total of 28% of the basin cut • 1977-1979: 2103 circular clearings of ¾h → 4h created • …assess impacts on magnitude and timing of snowmelt runoff

  7. Field Observations

  8. Field observations: Opposing Spruce slopes • Large divergence in melt timing between SF and NF forest gaps (clearings) • Close synchronization of melt between SF and NF slopes with intact forest cover • Large divergence in melt timing between opposing slopes with forest gaps attributed to their differing radiation inputs…

  9. Forest gaps on slopes: radiation ‘Hot’ radiation gaps ‘Cold’ radiation gaps Shortwave Longwave

  10. Simulations: Adaptation of CRHM for forest gaps Vgap L`γ L` h θ d Shortwave Longwave Forest gap radiation outputs CRHM

  11. MCRB: Forest effects on snowmelt • Twin Ck & Middle Ck consist mostly of opposing south-facing and north-facing slopes: Model development: • Result: forest cover masks SW radiation differences caused by slope orientation; melt is driven mainly by LW causing synchronized melt across slopes: • Cumulative melt across Twin and Middle Ck under 4 forest cover scenarios: • Scenario 1: intact forest cover across slopes: Fig. 7.15 • Ellis, Pomeroy and Link, WRR (in press)

  12. MCRB: Forest effects on snowmelt Model development: • Result: Cold radiation holes on NF slopes delays melt compared to intact forest cover (as well as increased snowmelt due to lower interception losses): • Scenario 2: remove forest cover on NF slopes (creating gaps): Fig. 7.15 • Ellis, Pomeroy and Link, WRR (in press)

  13. MCRB: Forest effects on snowmelt Model development: • Result: earlier melt on SF slopes advances the melt period compared to intact forest cover • Scenario 3: remove forest cover on SF slopes only (creating gaps) Fig. 7.15 • Ellis, Pomeroy and Link, WRR (in press)

  14. MCRB: Forest effects on snowmelt Model development: • Result: cold radiation hole in NF gaps delays melt • Earlier melt in SF gaps combined with later melt in NF gaps extends the melt period • Scenario 4: remove forest cover on SF & NF slopes (creating gaps on both) Fig. 7.15 • Ellis, Pomeroy and Link, WRR (in press)

  15. MCRB: Effects of Basin Orientation Model development: CRHMforest application • Rotate basin 90o • Sun-track • Sun-track Fig. 7.15

  16. Influence of Basin Orientation on forest cover scenarios • Original basin orientation: topography has much high influence on forest cover effects: • Basin rotated 90o: Topography has little influence on forest cover effects: CRHMforest application Fig. 7.15 • Sun-track Fig. 7.15

  17. Conclusions • Forest cover effects on radiation to snow and snowmelt in mountain environments are highly variable and strongly dependent on: (i) seasonal meteorological conditions (ii) local slope/aspect • With appropriate parameterisation of site characteristics, physically-based modelling approaches may be useful in representing forest-snow processes with changing forest cover and meteorological conditions • Strategic forest harvesting practises may provide an useful management tool for altering the timing and magnitude of snowmelt

  18. Acknowledgments • Supervisor: J. Pomeroy • Tim Link (U of Idaho), R. Essery (U of Edinburgh) • Field assistance from Michael Solohub and fellow grad students • Tom Brown (CRHM) • USDA-ARS & USACE (radiometer array) Thank you

More Related