Mapping the Subsurface of Waterloo Region, Ontario, Canada; An Improved Framework of Quaternary Geology for Hydrogeological Applications

Abstract

Please click here to download the map associated with this article. The Ontario Geological Survey (OGS) has embarked on a pilot project of 3-dimensional mapping of Quaternary deposits within the Regional Municipality of Waterloo in southwestern Ontario, Canada. This project is part of a broader OGS initiative designed to provide basic geoscience information for the protection and preservation of the provincial groundwater resource. The main objective of this project is to develop a series of protocols for detailed 3-dimensional mapping of Quaternary deposits. These protocols shall be used as standards for similar surveys to be undertaken in other areas of the province. 3-dimensional mapping involves the characterization of the geometry and inherent properties of subsurface deposits. This information can: 1) aid in studies involving groundwater extraction, protection and remediation; 2) assist with the development of policies surrounding land use and nutrient management; and 3) help to better understand the interaction between surface and groundwater systems. This paper briefly summarizes the main sources of information used for the creation of the 3-dimensional block model and the key processes involved in its generation. The attached map is an exploded representation of the main Quaternary units present within the Regional Municipality of Waterloo. The regionally-based block model is created with cells measuring 100 by 100 m. The structural contour and isopach depictions can: 1) assist with the identification of windows that hydraulically connect upper and lower aquifers; 2) help to define areas where aquifers are intrinsically more susceptible to contamination; and 3) aid in unravelling depositional environments which can ultimately be used to help one predict sediment variability in the subsurface.