ANSQUICK >

Radius of influence

<< Click to Display Table of Contents >>

Navigation:  Hydrogeologist workbench (ANSQUICK) >

ANSQUICK >

Radius of influence

This dialog window calculates the radius of influence for a pumping test or a slug test. Radius of influence is determined either from drawdowns in two wells or hydraulic diffusivity and time since the start of pumping.

The window is opened by "File > Hydrogeologist workbench > Radius of influence".

 

"Wells" tab of "Radius of influence" dialog box: calculation of radius of influence based on drawdown in two observation wells.

 

Explanatory table for tab "Wells"

Estimation of radius of influence based on drawdown in two observation wells in an infinite aquifer

"R, m" text box

Information field to display the estimated radius of influence

"Confined", "Unconfined", "Confined-unconfined" option

Selection of aquifer type

"s1, m" and "s2, m" text box

Drawdown in the first and the second observation wells

"r1, m" and "r2, m" text box

Distances from the pumping well to the first and the second observation well

"m, m" text box

Thickness of a confined aquifer or initial saturated thickness of an unconfined aquifer

"H, m" text box

Initial Hydraulic Head that is measured from the aquifer bottom. This field is required only for confined-unconfined aquifers

 

For different aquifer types, the following analytical solutions are applied:

а) confined aquifer

б) unconfined aquifer

в) confined-unconfined aquifer

 

"Time" tab of "Radius of influence" dialog box: calculation of radius of influence based on hydraulic diffusivity and time from start pumping.

 

 

Explanatory table for tab "Time"

Estimation of radius of influence based on hydraulic diffusivity and time from start pumping in an infinite aquifer

"t, day" text box

Time from the start of pumping, days

"a, m2/day" text box

Hydraulic diffusivity for confined or unconfined aquifers , m2/day. After entering this value, Storage coefficient is recalculated

"T, m2/day" text box

Transmissivity of aquifer (auxiliary field). After entering this value, the hydraulic diffusivity is recalculated

"S, –" text box

Specific yield or Storage coefficient (auxiliary field). After entering this value, the hydraulic diffusivity is recalculated

"Rq, m" text box

Information field to display the calculated zone of quasi-steady state regime, m

After entering a value in this field, the time when quasi-steady state condition begin at distance r from the pumping well is calculated. This time is automatically input in added to the text box "t, days"

"R, m" text box

Information field to display the calculated radius of influence, m

 

 

"Slug test" tab of "Radius of influence" dialog box: calculation of radius of influence for slug tests

 

 

Explanatory table for tab "Slug test"

Estimation of radius of influence during slug test in an infinite aquifer

"R, m" text box

Information field to display the calculated radius of influence, m

"t (max), min" text box

Information fields to display the time when the maximum radius of influence occurs, minutes

"t, min" text box

Time from start of test, minutes

"k, m/day" text box

Hydraulic conductivity of aquifer, m/day. After entering this value, transmissivity is recalculated.

"S, –" text box

Specific Yield or Storage Coefficient of aquifer (dimensionless). After entering this value, hydraulic diffusivity is recalculated.

"m, m/day" text box

Thickness of aquifer, m. After entering this value, transmissivity is recalculated.

"rw, m" text box

Screen radius of the pumping well

"rc, m" text box

Casing radius of the pumping well

"Accuracy" frame

Required accuracy of radius of influence: 1, 5 or 10%

"T, m^2/day" text box

Transmissivity of aquifer (auxiliary field). After entering this value, hydraulic diffusivity is recalculated

"a, m^2/day" text box

Hydraulic diffusivity (auxiliary field). After entering this value, Storage coefficient is recalculated

"Ss, 1/m" text box

Specific Storage (auxiliary field). After entering this value, Storage Coefficient is recalculated

 

 

References

Справочное руководство гидрогеолога. Под ред. В.М. Максимова. Л.: Гостоптехиздат. 1959.

Guyonnet D., Mishra S., Mccord J. Evaluating the volume of porous medium investigated during slug tests // Ground Water. 1993. Vol. 31, N 4. P. 627–633.