Karst

Southern Ontario Karst, Red = Known Karst, Orange = Inferred Karst, Yellow = Potential Karst

Karst formations are found in areas along the Niagara Escarpment, including the Bruce Peninsula, the Guelph/Rockwood/Elora area of Wellington County and in portions of eastern Ontario.

Karst formations, in which there are undetected sinkholes, trenches and caverns, can be dangerous

There is no one formula for defining a hazardous area associated with karst formations. Defining the “area of provincial interest” is a site-specific process. The size, extent and severity of the hazards depend on local conditions. Karst formation character and size depends on the pH of the infiltrating water, the rate at which the rock dissolves, number of fractures and fissures in the rock, distance the water will percolate from surface to water table and the presence of impermeable layers above or below the limestone/dolomite layers.

Karst formations can also be significant recharge zones for municipal supply aquifers

For example, the City of Guelph, whose drinking water supply is wholly groundwater, is known to be a direct recipient of significant recharge through the areas karst formations.

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The upper surface of the zone of saturation, except where the surface is formed by an impermeable body.

Subsurface water level which is defined by the level below which all the spaces in the soil are filled with water; The entire region below the water table is called the saturated zone.

The addition of water to ground water by natural or artificial processes.

The infiltration and movement of surface water into the soil, past the vegetation root zone, to the zone of saturation or water table.

Layer of rock or soil that holds or transmits water.