Drawdown during aquifer tests

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Drawdown during aquifer tests

The tool "Drawdown" is used for quick estimates of drawdowns at variable distances from a well being pumped at a constant rate. These assessments can assist, for example, in planning of aquifer tests or interpreting tests with limited data available. The estimates are enabled for the following conceptual models:

1) Confined infinite aquifer;

2) Unconfined infinite aquifer;

3) Leaky aquifer and aquifer system;

4) Two-layer aquifer;

5) Partially penetrating pumping well in infinite confined aquifer;

6) Multilayered systems;

7) Aquifers and aquicludes;

8) Semi-infinite aquifer;

9) Strip aquifer;

10) Rectangular aquifer;

11) Circular aquifer; and

12) Constant head tests in confined or leaky aquifers.


Dialog windows require inputs of hydraulic properties and types of aquifer tests. The tool calculates hydraulic heads and drawdown hydrographs in user-selected locations. There is also a possibility to calculate maximum drawdowns for steady state conditions.

Most of drawdown calculations are conducted for constant rate tests from a single pumping well. Exceptions are: constant head tests, slug tests and infiltrometer tests.

All dialog windows for hydrogeologist workbench have similar views. They usually show a sketch of the selected conceptual model and contain fields to input parameters. Required parameter units are usually shown near corresponding fields. It is possible to enter pumping rates (Q) and times (t) in other units, when pressing simultaneously SHIFT (or CTRL) and mouse button.


Example of hydrogeologist workbench dialog window.


Explanation table for fields and main options

Text box "Q, m^3/day"

Constant pumping rate of a well

Text box "ε, m/day"

Recharge rate

Text box "t, day"

Time at which the drawdown is calculated. When this field is changed, the the drawdown is automatically recalculated (see Field "s, m").

This field is also used to plot drawdown hydrograph. By default, this is the maximum time for drawdown plotting

Text box "s, m"

This field shows the calculated drawdown. In some dialog windows, it is possible to enter a value in this field to calculate pumping rate

Button "Plot"

Opens the dialog window "Plot" and plots drawdown hydrograph for the times between 0.0001 day (or 0.01 min for slug tests) and the time indicated in text box "t, day"

Button "R"

Opens the dialog window "Recovery"

Text box "T, m^2/day"

Transmissivity of aquifer

Text box "S, --"

Storage coefficient of aquifer

Text box "Ss, 1/m"

Specific storage of aquifer

Other options and fields of hydrogeologist workbench are explained in the text below. Any changes in the dialog windows result in the automatic updates of calculated drawdown values.


Some dialog windows contain auxiliary fields, highlighted in yellow color. They show calculated parameters based on other parameter inputs. For example, the transmissivity value is based on thickness and hydraulic conductivity. When values are entered in these highlighted fields, calculations are conducted for other dependent parameters (e.g. hydraulic conductivity based on transmissivity and thickness).


The dialog window "Recovery" is used to calculate water level recovery for specified times and to plot water level recovery hydrographs. This window opens after pressing button "R" (see the table above)


Dialog window "Recovery".


Explanation table

Text box "t, day"

Time for which recovery is calculated. The time is counted from the end of pumping and Its default value corresponds to the time specified for drawdown calculation in the hydrogeologist workbench dialog window. When this field is changed, the recovery value is automatically recalculated (see Field "s, m" below).

This field is also used to plot water level recovery hydrograph. By default, this is the maximum time for recovery plotting

Text box "s, m"

Calculates residual drawdown during recovery process assuming that duration of pumping is equal to time specified for drawdown calculation in ANSQUICK dialog window.

Button "Plot"

Opens dialog window "Plot" and plots drawdown hydrograph for the times between 0.0001 day and the time indicated in text box "t, day".


The dialog window "Plot" is used to plot water level drawdown and recovery hydrographs for selected conceptual models. Several plots can be displayed at the same time. All plots are redrawn after pressing the F5 key, and individual plots are redrawn (with random colors) after the mouse click on the selected plot area.




Dialog window "Plot".


Explanation table

"Plot" tab

Dialog window "Plot"

"Table" tab

Table view of plotted drawdown or recovery hydrographs

Column "N"

Sequential number

Column "Time"

Time in days (for slug tests - in minutes)

Column "Value"

Water level change in metres

Column "lg(X)"

Logarithm of time

Column "lg(Y)"

Logarithm of water level change

Button "Copy"

Copy in clipboard for "Time" and "Value"

"Data" tab

Contains factual data that were input. This allows comparison of factual and calculated drawdown/recovery data for specified parameters of aquifer

Button "Paste"

Pastes "Time" and "Value" data from clipboard. Remaining fields are calculated based on the two inserted columns.

Buttons "N", "Time", "Value", "lg(X)" и "lg(Y)"

See tab "Table"

"Options" tab

Plot options

Frames "Bottom axis" и "Left axis"

Bottom and left axes options

       Text box "Minimum"

Minimum bound for axes

       Field "Maximum"

Maximum bound for axes

       Text box "Decimal digits"

Decimal places for axes labels

       Option "Log scale"

Displays axis in a log scale

       Option "Auto scale"

Default values for Maximum and Minimum axes bounds

Option "Redraw"

New plot replaces the previous plot that is erased. When this option is unchecked, use button F5 on the keyboard to redrow plots.

Button "Apply"

Applies changes in "Options" to plots