Hydrostratigraphy of the Paris Moraine in the Guelph Area, Ontario, Canada

Abstract

Many growing southern Ontario communities, including Guelph, rely on fractured bedrock aquifers for drinking water. Contamination and overexploitation pose a threat to these water resources, necessitating characterization of vulnerability, risks, and recharge areas. Quaternary sediments southeast of the City of Guelph, including the Paris Moraine, were investigated in order to delineate hydrostratigraphy. This was achieved through study of 9 cored-holes, as well as existing MOE, GRCA, and University of Guelph data. Falling head permeameter measurements and empirical grain-size distribution measurements and analysis were employed for determination of 𝐾𝑠𝑎𝑡 values, which were used to construct a hydrostratigraphy. Of 19 methods evaluated, The Kozeny-Carman empirical grain-size method for determining 𝐾𝑠𝑎𝑡 was found to be more representative of measured values for the study area. The area is dominated by a conductivity regime of 2.72x10-7 – 1.40x10-6 m/s with local heterogeneity present on the scale of 10’s to 100’s of meters. The Paris Moraine, particularly its backslope, is at higher risk due to its relatively high conductivity, greater occurrence of aquifer units, as well as prevalence of small-scale topographic (hummocky topography), and bedrock topographic lows.