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Ecohydrological Study Of The Muskakoski Natural Area

Ecohydrological Study Of TheMuskakoski Natural Area, Edmonton, Alberta

Paul R. Morton, P.Geol., EBASheldon Helbert, R.P.Bio., EBAMartin Fereday, P.Eng., The City of Edmonton


Overview

• Brief study context:– municipal development and natural areas– Muskakoski Natural Area– transit-oriented development (TOD)

• Ecohydrological study objectives• Desktop study and field data collection• Data interpretation to-date• Interim findings


Study Context - Municipal Development and Natural Areas

• 1995 - Conservation of Natural Sites in Edmonton’s Table Lands (City Policy C-467)

• 2001 - Conserving Edmonton's Natural Areas: A Framework for Urban Conservation:– recommended long-term planning to conserve

Edmonton’s remaining natural areas– inventory identified 13 sites with high

conservation potential, including the MuskakoskiNatural Area


Study Context - Muskakoski Natural Area

• Western edge of Edmonton• Tamarack-black spruce fen wetland:

– area is ~7 ha– fen not a bog, as sustained by non-stagnant

water, compared to stagnant acidic waters found in bogs.


Study Context - Transit-oriented Development (TOD)

• Bus transit terminal with park-and-ride facility• Design charrette held in December 2008

4 m

etre

s


Study Context - EcohydrologicObjectives

• Overall objective - assist municipal planners to achieve balance between natural area protection and municipal development, involving:– characterizing water inputs, throughputs and

outputs currently influencing the Natural Area– identifying protective strategies for the

ecohydrology of the Natural Area– identifying potential constraints and

opportunities for integration with the TOD.


Study Context - Ecohydrologic Terms

• precipitation• surface runoff• evapotranspiration• infiltration• recharge• discharge• piezometric level• water table.

Wetland


Desktop Study - Site Local Setting


Desktop Study - Historical Changes (1949-2007)

• Changes in wetland area identified from aerial photographs, 60 year time scale

• 3 broad land categories - wetland, development and upland areas

• Wetland area was 13 ha in 1949, decreased to 7 ha by 2007 by development.


Data Collection - Peat Materials


Data Collection - Surface Water


Data Collection - Groundwater

• Groundwater monitoring wells, 1/2-inch ID with custom screened intake sections 5 cm long

• Water levels measured bi-weekly and monthly for:• horizontal hydraulic gradient, to identify wetland

inflows and outflows• vertical hydraulic gradients to identify wetland

discharge/recharge behaviour.

5 cm screen


Interpretation - Peat Materials

• Distribution and thickness of peaty organics• Saturated peat thickness versus time:

– for change in water storage– to determine the relative proportion of peat

water storage to wetland water balance.


Interpretation - Peat Materials


Interpretation - Surface Water

• Rain gauges (geo-referenced) located in:– wetland– local control 3 kms from study site

• Stage gauges (geo-referenced) located in:– wetland– storm water pond– drainage ditch.


Interpretation - Surface Water


Interpretation - Groundwater Horizontal Gradients

• Piezometric elevations in peat organics and siltyclay mineral soil interpolated to give horizontal groundwater gradients

• From these horizontal gradients interpreted:– peat groundwater direction is north and east– mineral soil groundwater direction is east and

south.


Interpretation - Groundwater Horizontal Gradients


Interpretation - Groundwater Vertical Gradients

• From dual-level wells (peat and upper mineral soil) vertical gradients derived from piezometricelevations

• From these vertical gradients interpreted:– downwards (-ve) gradients north of wetland

indicating this is a recharge area– upwards (+ve) gradients across most of wetland

and area south indicating a discharge area.


Interpretation - Groundwater Vertical Gradients

negative gradients

negative gradients

positive gradients

positive gradients


Interpretation - Historical Water Balance


Summary

• Observed and determined that:– peat organics saturated thickness ranges from

0.5 to 2.5 m, with 1.5 m mean, so far– wetland surface went dry mid-September,

suggesting insufficient water inputs– some correlation between drainage ditch water

and wetland (ditch is dewatering wetland?) – slow decline of storm pond (evaporation only),

no water management transfers out, potential to dewater the south-east.


Summary

• Observed and determined that:– horizontal groundwater gradients show

• peat groundwater moves north and east• mineral soil groundwater moves east and south

– vertical groundwater gradients indicate upward movement across centre and south half of wetland, associated with springs and wetlands

– preliminary water balance from historical data and mineral soil, suggests soil moisture deficits have been significant in the past.


Conclusion


Conclusion

• Next steps include:– quantifying water storage volumes in peat

organics– monitoring surface water for natural and any

water management changes, including TOD construction dewatering

– continuing groundwater monitoring to define directions

– permeability testing (peat and silt clay) for groundwater travel time assessment

– wetland water balance July 2008 to June 2009– identifying if water deficit/surplus can be

mitigated by integration with TOD.


Thank You

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