Parent Command
> OBSERVATION

Subcommand
>>> ELEMENT

Description
This command selects as an observation type the pressure drawdown during a pumping test. This observation type refers to one or more elements. The drawdown is calculated from a reference pressure, which is the pressure at the specified element at the time of the first active calibration point for that data set, i.e., a calibration time greater than zero must be provided, indicating the beginning of the pumping period; the corresponding observation is a drawdown of zero. Note that the sensitivity of this calibration point is zero by definition, i.e., the first data point is not used for calibration. If drawdown is measured in meters, command >>>> FACTOR must be used to convert the units to Pascals. The phase name phase_name or phase number iphase, which depend on the EOS module being used, are listed in the header of the iTOUGH2 output file. They can be specified either on the command line or using subcommand >>>> PHASE. If no phase is specified, iTOUGH2 takes the pressure drawdown of the first phase which is usually the reference pressure.

Example
> OBSERVATION

>> TIMES: 1 in [MINUTES]
10.0 = beginning of pumping

>> TIMES: 20 LOGARITHMICALLY spaced in [MINUTES]
11.0 120.0

>> DRAWDOWN
>>> ELEMENT: AA__1
>>>> ANNOTATION : Pressure drawdown [m]
>>>> FACTOR : 9810. [m] - [Pa]
>>>> LOGARITHM
>>>> DATA [MINUTES]
10.0 0.0 beginning of pumping
11.0 -0.1
15.0 -0.3
25.0 -0.5
.... .....
>>>> VARIANCE : 0.01 [m^2]
<<<<
<<<

See Also
>> PRESSURE