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Geomorphological and Ecological Functions within a Headwater Channel Network & Implications for Management. Joanna Eyquem (John Parish, Shelley Gorenc, Mike Tilston, Jackie Thomas). Eastern Region Headwater Streams Workshop Ottawa, February 25, 2011. Overview.
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Geomorphological and Ecological Functions within a Headwater Channel Network & Implications for Management Joanna Eyquem (John Parish, Shelley Gorenc, Mike Tilston, Jackie Thomas) Eastern Region Headwater Streams Workshop Ottawa, February 25, 2011 Eastern Region Headwater Stream Workshop, February 2011
Overview - Focus on quantifying physical processes - Evaluation of functions - Hydrology and hydraulics - Sediment movement - Implications for land use management recommendations Eastern Region Headwater Stream Workshop, February 2011
Study Area: NW Brampton • Headwater Streams • Huttonville Creek • Fletchers Creek • Halton Till • Agricultural landuse • Low gradient • Ground-truthing to confirm extent Eastern Region Headwater Stream Workshop, February 2011
Mayfield Road Highway 7 (Bovaird Drive) Eastern Region Headwater Stream Workshop, February 2011
East Central West Eastern Region Headwater Stream Workshop, February 2011
Western Swale Area Huttonville Creek Order 2 Gradient: 0.36% Bed: Soil Drainage Area: 0.036km2 TOB width: 2.3m Landuse: Wheat Eastern Region Headwater Stream Workshop, February 2011
Central Swale Area Huttonville Creek Order 2 Gradient: 0.55% Bed: Gravel Drainage Area: 0.022km2 TOB width: 2.75m Landuse: Wheat Eastern Region Headwater Stream Workshop, February 2011
Eastern Swale Area Fletcher’s Creek Order 2 Site Photos Gradient: 0.43% Bed: Mixed Drainage Area: 0.014km2 TOB width: 1.27m Landuse: Soybean Eastern Region Headwater Stream Workshop, February 2011
Instrumentation • - Three ‘nested’ sites • Two first order swales • Second order swale • 6 monumented cross-sections • 6 in-situ sediment traps • 1 pressure transducer • High resolution sampling (1 min) Eastern Region Headwater Stream Workshop, February 2011
Monitoring • Cross-sectional measurement • Sediment trap content measurement • Bedload traps • Field traps • Continuous flow gauge record • Linked to broader context Eastern Region Headwater Stream Workshop, February 2011
Drainage Patterns & Relationships • Stream order-frequency & stream order-drainage area Eastern Region Headwater Stream Workshop, February 2011
High drainage density Eastern Region Headwater Stream Workshop, February 2011
Cross-sectional change • Changes dominated by agricultural practices. • Seasonal change related to ploughing and flows (e.g. aggradation due to sediment supply) • Difficulties in maintaining sections. Eastern Region Headwater Stream Workshop, February 2011
Ploughing prior to Nov 15, 2006 - aggradation Reset August 30, 2007 Eastern Region Headwater Stream Workshop, February 2011
Stable until Oct 25, 2007 Sedimentation recorded Nov 26, 2007 Eastern Region Headwater Stream Workshop, February 2011
Hydrology • Fast response to rain events • Duration of response shorter Eastern Region Headwater Stream Workshop, February 2011
Fast response Eastern Region Headwater Stream Workshop, February 2011
Hydrology • Larger discharge per unit area than downstream station BUT • Less response to low intensity events SO - Annual flow delivery rates per unit drainage area similar Eastern Region Headwater Stream Workshop, February 2011
Flow delivery Eastern Region Headwater Stream Workshop, February 2011
Sediment delivery mechanism • Estimates of annual soil loss • Field traps (0.07 to 0.34m3/yr) • Revised Universal Soil Loss Equation (RUSLE) (4.00 to 10.49m3/yr) • Estimates of fluvial erosion • Changes in channel cross-section (-359.9 to 85.8m3/yr) Eastern Region Headwater Stream Workshop, February 2011
Sediment transport • Bedload transport well below field and channel erosion • Suspended load likely to be dominant form of transport downstream • Empty traps following rainfall events Eastern Region Headwater Stream Workshop, February 2011
Sediment Sourcing • Bedload coarser – fines transported • Most bedload explained by fields • Coarser material? • Variation in Halton Till • Road runoff Eastern Region Headwater Stream Workshop, February 2011
Management Implications • Geomorphological Functions: • Conveyance of flow • Sediment supply and transport • (particularly fines in suspension) • Form & function not representative of “natural conditions” Eastern Region Headwater Stream Workshop, February 2011
Management Implications • Ecological Functions: • Fish do migrate to drainage features • Limited by flow • Temporary nature of habitat Eastern Region Headwater Stream Workshop, February 2011
Management Implications • Maintenance of: • Open channel • Area contributing flow (& sediment) • Drainage density • Connectivity to downstream reaches Eastern Region Headwater Stream Workshop, February 2011
Thank You Eastern Region Headwater Stream Workshop, February 2011
