Technical Note 2: Determination of hydrogeological parameters from pumping of water wells in Alberta
K.U. Weyer Ph.D., P.Geol., P.HG.
WDA Consultants Inc., 4827 Vienna Drive NW, Calgary, Alberta, Canada
© 2003 K. U. Weyer
In Alberta, it has been customary to describe the performance of geologic layers in an area with a procedure which
is said to reflect the hydrogeologic response of the aquifer to pumping: the so-called safe yield for 20 years of
continuous pumping (Q20 or Q20). In the past there have been doubts expressed about the
procedure used and its physical validity. WDA was asked to apply this method in determining the available groundwater
supply in a rural area of Southern Alberta. When examining the history of the 20-year safe yield and its physical
meaning it became evident why this parameter often has little relation to the actual behaviour of the aquifer if
pumped for 20 years. Below we present the results of our investigation and show alternatives to the present use of
the 20-year safe yield.