Abstracts

198 - Monitoring of event-based, depression focussed recharge
to a shallow unconfined aquifer near a municipal well in the Alder
Creek Subwatershed, SW Ontario
Paul G. Menkveld, Andrew J. Wiebe, & David L. Rudolph
Department of Earth and Environmental Sciences – University of Waterloo, Waterloo,
Ontario, Canada
Groundwater is a critical resource that is dependent on recharge processes. Contrary to
some conventional modelling practices that rely on annual and aerially averaged recharge
rates, the natural recharge process is often discrete in time and space, which may significantly
influence the dynamics of the groundwater flow system. Events such as snow melts
and major rainfall periods may result in large amounts of infiltration over short time spans.
In addition, depression-focused recharge may lead to anomalously large rates of recharge
in small, local areas. To quantify these localized recharge phenomena, a dense monitoring
network was established in a small (200 m 2 ) depression-focused recharge site, located
within the Alder Creek sub-watershed, in the Regional Municipality of Waterloo. The
site is located on the heavily managed Waterloo Moraine, with a shallow screened public
supply well located within 40 m of the study site. Soil moisture (using TDR and a neutron
probe), soil water tension, temperature, hydraulic head, resistivity, isotopes and pore-water
geochemistry were measured in vertical profiles in the unsaturated zone and shallow
saturated zone by electronic and manual instruments beneath an ephemeral pond formed
during a snow melt event. Photo surveys were used to capture the formation, extents, and
evolution of the pond. Continuous and time sparse (manually collected) data sets were
constructed and compared to assess the value and accuracy of the different instruments.
The combined data sets provide insight into the depression-focused recharge process and
support estimates of recharge rates based on analytical and numerical modeling techniques.
The effectiveness of the different data sets in understanding and quantifying the recharge
process will also be discussed. Considering the close proximity of the public supply well
to this recharge site, the study has implications for water supply security (GUDI) as hydrologic
event-based analysis of the well’s capture zone will affect the well’s vulnerability
to surface water.
281 - Cumulative impacts of groundwater extraction on seasonal
flows of a regulated stream, Cowichan River, BC
Sylvia Barroso, Neil Goeller, & Pat Lapcevic
BC Ministry of Forests, Lands and Natural Resource Operations, Nanaimo, BC, Canada
Cowichan River is an important resource for the Vancouver Island region and North
America’s west coast, providing critical spawning and rearing habitat for salmonid species,
in addition to being a key source of industrial and municipal water supply, effluent dilution,
a destination for recreation and tourism, and possessing cultural and economic significance
to the Coast Salish First Nation. River flows in the lower reaches are linked to the underlying
fluvial and glaciofluvial aquifer complex. Groundwater demands on this aquifer are
substantial, including municipal and aquaculture well fields proximal to the river which
88 IAH-CNC 2015 WATERLOO CONFERENCE