Hantush's Modification of the Theis Method

View | Hantush Modified Theis Type Curve

 

 

See Also:

Entering Partial Penetration Data


Hantush's modification of the Theis method is used for confined aquifers that are only partially penetrated by the pumping well and observation well. Drawdown must be measured in an observation well. The method is not suitable for single well tests.

 

 

Type Curve Matching for Hantush Modified Theis

 

In Hantush's modification of the Theis method, a site specific type curve is created based on the geometry of the pumping well and the observation well in which the drawdown measurements are made. Infinite Extent also displays the Theis type curve for comparison. Time-drawdown data is then matched to the type curve on a double logarithmic graph.

 

 

Determining Aquifer Thickness

 

Late time data will tend to deviate upward from the site-specific type curve. By selecting the value of 1/u at this departure point, the thickness of the aquifer can be determined. This is useful for thick aquifers where the full stratigraphy has not been determined. Infinite Extent allows the selection of the departure point by moving a dashed line over the departure point. This is done by holding down the shift key and pressing the left or right arrow keys, or dragging the line with the mouse (with the shift-key depressed).

 

 

Testing

 

Infinite Extent implements the Hantush modification of the Theis method as described by Kruseman and de Ridder (1991). The Infinite Extent method has been shown to work with the example provided with that text. Testing of the equations used in Infinite Extent has shown them to be an accurate implementation as described in this reference. However, because of a lack of examples from partially penetrating wells, the method has not been further tested. In addition, published documentation of the accuracy of this method is not widely available whether implemented by Infinite Extent, by hand plotting, or by other pump test software packages.

 

Starpoint Software recommends a qualitative evaluation of the results of any pump test analyzed with this method.