Civil Engineering Reference
In-Depth Information
Fig. 8-15.
Types of aquifers
When a well is drilled through the upper confining layer and into an artesian aquifer,
water rises in the well to a level above the top of the aquifer. The water level in the
well represents the artesian pressure in the aquifer. The hydraulic head, expressed in
depth of water, at any point within the aquifer equals the vertical distance from this
level down to the point in question.
The elevation to which the water level rises in an artesian well is referred to as the
piezometric level.
An imaginary surface representing the artesian pressure throughout
all or part of an artesian aquifer is called the
piezometric surface.
This imaginary
surface is analogous to the real water surface, the water table, in a water-table aquifer.
Fig. 8-16.
Perched water table (Courtesy of US Filter / Johnson Sceeens)
