Abstracts

247 - Subsurface Water Flow from Wetlands to the Riparian Zone
Induced by Evapotranspiration
Masaki Hayashi 1 & Garth van der Kamp 2
1
Department of Geoscience, University of Calgary, Calgary, Alberta, Canada
2
Environment Canada, Saskatoon, Saskatchewan, Canada
Subsurface interaction between wetlands and the surrounding riparian zone has significant
effects on water balance and dissolved mass balance of wetlands. This is particularly important
for relatively small wetlands that are not dominated by inflow and outflow streams,
such as prairie wetlands. Summer water loss from prairie wetlands is strongly dependent
on the ratio of the shoreline length to the area of water surface, suggesting that significant
portion of water loss from the wetlands is due to evapotranspiration in the marginal area,
where the water table within or is close to the root zones of riparian plants. The present
study will examine the factors that control the subsurface flow of water from wetlands to the
riparian zone using a simple numerical model and compare the results to the distribution
of soil types in and around wetlands. The subsurface water flow consists of two processes.
The first is the mostly horizontal flow from the surface water body to the saturated zone
underlying the riparian vegetation. The hydraulic conductivity of saturated sediments is
dominated by fractures and other macropores and is orders of magnitude higher than that
of unsaturated sediments. Therefore, much of horizontal flow takes place in the saturated
region below the water table. The second is the mostly vertical flow from the water table
to plant roots, which is strongly dependent on soil water retention characteristics. The
effective width of the riparian zone is determined by the hydraulic properties of sediments
that control the two processes. In the prairie region, which is covered by clay-rich glacial
tills, the effective width is expected to be in the order of 10 m, which is consistent with field
observation of vegetation zones (i.e. willow ring) and soil type distribution. These results
are quite general and may be used to study, for example, the interaction between streams
and the riparian vegetation in most dry climates.
139 - Detecting Hyporheic Exchange Using Electrical Resistivity
Tomography along a Fractured Sedimentary Bedrock River:
Eramosa River, Guelph, Ontario
Colby M. Steelman 1 , Celia S. Kennedy 2 , Donovan Capes 1 & Beth L. Parker 1,2
1
School of Engineering – University of Guelph, Guelph, Ontario, Canada
2
School of Environmental Sciences – University of Guelph, Guelph, Ontario, Canada
The Eramosa River located within the Grand River Watershed in Ontario, Canada, resides
upon a densely fractured dolostone aquifer with abundant dissolution-enhanced
channel features. While the bedrock aquifer represents a major component of the total water
supply for the surrounding region, potential effects of increased groundwater extraction
on surface water and surrounding ecosystems are not yet fully understood. In general,
little is known about the nature of the interaction between surface water and groundwater
along densely fractured sedimentary bedrock riverbeds. For instance, the timing and magnitude
of groundwater - surface water exchange in a fractured carbonate rock environment
52 IAH-CNC 2015 WATERLOO CONFERENCE