A three-dimensional bedrock hydrostratigraphic model of southern Ontario

Abstract

A hydrostratigraphic framework has been developed for southern Ontario consisting of 15 hydrostratigraphic units and 3 regional hydrochemical regimes. Using this framework, the 54 layer 3-D lithostratigraphic model has been converted into a 15 layer 3-D hydrostratigraphic model. Layers are expressed as either aquifer or aquitard based principally on hydrogeologic characteristics, in particular the permeability and the occurrence/absence of groundwater when intersected by a water well or petroleum well. Hydrostratigraphic aquifer units are sub-divided into up to three distinct hydrochemical regimes: brines (deep), brackish-saline sulphur water (intermediate), and fresh (shallow). The hydrostratigraphic unit assignment provides a standard nomenclature and definition for regional flow modelling of potable water and deeper fluids. Included in the model are: 1) 3-D hydrostratigraphic units, 2) 3-D hydrochemical fluid zones within aquifers, 3) 3-D representations of oil and natural gas reservoirs which form an integral part of the intermediate to deep groundwater regimes, 4) 3-D fluid level surfaces for deep Cambrian brines, for brines and fresh to sulphurous groundwater in the Guelph Aquifer, and the fresh to sulphurous groundwater of the Bass Islands Aquifer and Lucas-Dundee Aquifer, 5) inferred shallow karst, 6) base of fresh water, 7) Lockport Group TDS, and 8) the 3-D lithostratigraphy. The 3-D hydrostratigraphic model is derived from the lithostratigraphic layers of the published 3-D geological model. It is constructed using Leapfrog Works at 400 m grid scale and is distributed in a proprietary format with free viewer software as well as industry standard formats.