Barrie Creeks, Lovers Creek, and Hewitt's Creek Subwatershed Plan

The Barrie Creeks, Lovers Creek and Hewitt’s Creek Subwatershed Plan
2.4.1.4.
Hydrostratigraphy
The geology of the subwatersheds significantly influences the local hydrogeology, which is the
study of groundwater. Hydrogeologists study the geologic formations to understand how much
water infiltrates into the subsurface, where it flows, how quickly it flows and where it re-enters
the surface water system. Changes in groundwater quantity and quality have potential impacts
on natural functions that could affect the surface water flow regime, aquatic ecosystems, and
use of the resource as a viable water supply.
Hydrostratigraphy is the spatial mapping of geologic formations based on their water bearing
properties. The hydrostratigraphy of the surficial deposits within the subwatersheds is complex
as a result of the glacial history. There are a number of ongoing initiatives to understand the
local hydrostratigraphic framework of the Southern Simcoe County and Barrie area. The
following subsections provide a brief overview of relevant and previously completed
stratigraphic studies.
The stratigraphic framework of Quaternary glacial and non-glacial sediments, as shown in
Figure 2-20, was completed by AquaResource et al. (2011) for the City of Barrie Tier 3 Water
Budget and Risk Assessment. The conceptual model builds upon previous models built for the
South Simcoe Groundwater Studies (Golder, 2004). Four regional aquifers have been defined
throughout the City of Barrie and Southern Simcoe County. An aquifer is an underground
saturated permeable geological formation that is capable of transmitting water in sufficient
quantities under ordinary hydraulic gradients to serve as a source of groundwater supply.
Aquifers are typically composed of coarse grained materials such as sands and gravels. The
aquifers are named A1 through A4, from top to bottom. Despite the continuity of the
hydrostratigraphic framework, it is important to note that pinchouts, lenses, and windows do
occur within any given unit (AquaResource et al., 2011). A description of the interpreted
hydrostratigraphic framework is provided below.
Figure 2-22 and 2-23 below show typical cross sections through the City of Barrie depicting the
key features of the geologic and hydrogeologic system. Figure 2-22 shows a southwest to
northeast cross section, whereas Figure 2-23 shows a north-south cross section. Key
components of the geologic system include (1) the Kempenfelt Bay channel extending in an
east-west direction from Kempenfelt Bay towards Angus; (2) thick deposits associated with the
upland areas; and (3) the thinning of confining layer 3 in the City of Barrie core.
Chapter 2: Study Area: The Barrie Creeks, Lovers Creek and Hewitt’s Creek Subwatersheds 46