Huisman Method II Drawdown Calculation

 

See Also:

Using the Huisman Calculators

Huisman Assumptions


The Huisman II method calculates the extra drawdown caused by the well not fully penetrating the aquifer. The method is used when there are drawdown measurements in the pumping well only and no observation well measurements are available.

 

The Huisman II Method implemented by Infinite Extent calculates the extra drawdown caused by the well not being fully penetrating. It uses the following equation:

 

image\HUIS2FRM.gif

 

where:

S(full) = steady state drawdown is the well had been fully penetrating

S(partial) = actual drawdown of the partially penetrating well

D = aquifer thickness

P = penetration ratio (screen length/aquifer thickness)

K = aquifer hydraulic conductivity

rew = effective radius of the pumping well

sigma is a parameter automatically determined by Infinite Extent based on tables provided by Kruseman and de Ridder (1991)

 

 

Results:

 

Output from the test includes:

  1. The extra drawdown caused by the well not fully penetrating the aquifer.
  2. The sigma value determined by Infinite Extent
  3. The penetration ratio (screen length/aquifer thickness)
  4. Eccentricity (a measure of how off-center the screen is in the aquifer. It is calculated by dividing the distance between the middle of the well screen and the middle of the aquifer, by the aquifer thickness).
  5. Distance from the middle of the well screen to the middle of the aquifer.