Parent Command
> OBSERVATION

Subcommand
>>> CONNECTION
>>> ELEMENT
>>> MODEL
>>> SOURCE

Description
This command selects a user-specified observation type. This option enables a user to introduce a new observation type, i.e., any type of data can be used for parameter estimation by defining the corresponding model output which is a user-specified function of TOUGH2 variables. The user must program the function in subroutine USEROBS, file it2user.f. Identification of and details about the observation can be given in the iTOUGH2 input file and will be transferred to subroutine USEROBS. The annotation anno (or a substring thereof) will be available in subroutine USEROBS (variable ANNO); it can be used to identify the observation type and data set. The significant part of the string should therefore not be changed by subcommand >>>> ANNOTATION. Multiple grid block names or sink/source code names defined by the appropriate third-level command will be transferred to the subroutine in array GRIDA. The corresponding element numbers are stored in array NECA, with INEC pointing to the currently processed array index. Integer variables read after command >>>> INDEX are provided through array IOBSA. On output, subroutine USEROBS returns the user-specified model result TRESULT. The user must ensure that all TOUGH2 variables used by the function are transferred to subroutine USERPAR via COMMON blocks. If a variable is not predefined in one of the standard COMMON blocks, a new COMMON block must be created and added to the include file usercom.inc.

Example
In this example the pressure difference measured between two points in a laboratory column
is defined as a user-specified observation. Two differential pressures are measured,
referring to the liquid and NAPL phase, respectively. The iTOUGH2 input block is given below.

> OBSERVATION
>> USER-specified observation type: Pres. Diff.
>>> difference between ELEMENTs: A1112 A1152
>>>> ANNOTATION : Pres. Diff. aqueous phase
>>>> PHASE : 2
>>>> DATA FILE : dp_aqu.dat
>>>> DEVIATION : 1000.0
<<<<
>>> difference between ELEMENTs: A1112 A1152
>>>> ANNOTATION : Pres. Diff. NAPL phase
>>>> NAPL PHASE
>>>> DATA FILE : dp_napl.dat
>>>> DEVIATION : 1000.0
<<<<
<<<

See Also
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