Geospatial Analysis of Groundwater Geochemistry and Quaternary Geology of Southern Ontario, Canada: A Study of Regional and Local Trends

Groundwater geochemical data from 515 overburden wells are analyzed with the physiographic map of southern Ontario, and high-resolution cored logs and 3D Quaternary sediment mapping in the Brantford-Woodstock area of southwestern Ontario to examine the possible geological influence on groundwater quality and water-well vulnerability at both regional and local scale. Bored/dug wells in Bevelled Till Plains and drilled wells in Drumlinized Till Plains were found to be relatively vulnerable for arsenic & manganese and nitrate contamination, respectively, across southern Ontario in geospatial and Geographically Weighted Regression analyses. Subsurface sediment analysis at the local scale showed expected sediment pattern at variable shallow depths consistent with each physiography with some sediment heterogeneity that may affect shallow groundwater quality. At greater depths, the variable glacial depositional and erosional events significantly influenced the 3D sediment architecture and internal heterogeneity of hydrostratigraphic units, which in turn can impact the groundwater quality and susceptibility to contamination. ; University of Guelph ; Natural Sciences and Engineering Research Council of Canada