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The slug test dialog window calculates drawdown/recovery of water table during slug tests after instantaneous slug removal/input. The dialog window is opened by selecting menu "File > Hydrogeologist workbench > Slug test".
"Slug test" dialog box.
Explanatory table
"so, m" text box |
Initial (instantaneous) change of water level in a test well |
"t, min" text box |
Time of water level recovery (in minutes) |
"s, m" text box |
Information field showing calculated water level during recovery |
"to, min" text box |
Duration of slug removal (in minutes). When the assigned value is higher than 0, the conceptual scheme applies correction for non-instantaneous slugs |
"k, m/day" text box |
Aquifer hydraulic conductivity |
"S, --" text box |
Confined storage coefficient |
"rc, m" text box |
Radius of casing for a test well |
"m, m" text box |
Aquifer thickness |
"rw, m" text box |
Radius of a test well |
"Underdamping" option |
Enables calculation of slug tests with decreasing oscillations of the drawdown function. This oscillations may occur in deep aquifers with high permeability |
"Lc, m" text box |
Hight of water in well casing |
"T, m^2/day" text box |
Transmissivity of aquifer. This is an axillary field. If a value is entered in this field, the hydraulic conductivity is automatically updated |
"a, m^2/day" text box |
Hydraulic diffusivity of aquifer. This is an axillary field. If a value is entered in this field, the storage coefficient is calculated |
"Ss, 1/m" text box |
Specific storage of aquifer. This is an axillary field. If a value is entered in this field, the storage coefficient is calculated |
Key button functions are explained in section "Aquifer tests".
In this dialog window time entry in minutes is required for user's convenience. Hydrographs are also plotted in minutes format.
To calculate the drawdown during slug tests, solutions of Cooper and Picking are applied. Picking solution is used when text box "to, min" contains "0" value.
When the "Underdamping" option box is checked, the following solution is used:
where g – gravity acceleration value.
References
Van der Kamp G. Determining aquifer transmissivity by means of well response tests: The underdamped case // Water Resources Research. 1976. Vol. 12, N 1. P. 71–77.