TOWARD IMPROVED UNDERSTANDING OF AQUIFER HETEROGENEITY: A CASE STUDY FROM THE LAKE SIMCOE REGIONAL CONSERVATION AUTHORITY, SOUTHERN ONTARIO

Hydrogeological understanding of Southern Ontario will be advanced by study of local elements of the hydrogeological system that can provide regional insight. Most of Southern Ontario is covered by glacial sediment that controls groundwater recharge. Moraines are the most extensive landform in the area and within watersheds commonly form high recharge areas . An effective approach to improved understanding of the hydrogeological characteristics of surficial deposits and landforms is the study of sediment facies and architecture in aggregate pits. Preliminary results are presented from a study of the western part of the Nottawasaga River watershed where much of the landscape is defined by till uplands and tunnel channels of a regional unconformity overlain by a number of stratified moraines. Particular moraines investigated in this study are the Gibraltar, Singhampton, Orangeville and Oak Ridges moraines.

Using provincial aggregate pit licence maps and Google Earth ~155 sites in the area were classified as, active, inactive and worked out. Of 25 sites visited (55 licences) 12 were in Ice-contact-stratified-drift, 12 in glacifluvial and 1 in alluvium map units. Data collected include sediment texture, bed thickness, sedimentary structure types, paleoflow measurements, and photo mosaics for architectural and vertical section analysis. This data from the unsaturated zone is synthesized and provides an analogue for aquifer properties. Architectural analysis yields information on sediment facies that may form preferential flow units. Hydraulic values of units are presented from book values or grain-size analysis. Detailed sedimentological data provides a context for interpretation of other data, particularly Ontario Ministry of Environment water well records. The development of sedimentary depositional models provides a framework for development of predictive models of aquifer location, size, extent, and heterogeneity.