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Strike Dip Markov Chain
Vertical Markov Chain

When a T-PROGS simulation TPROGS Simulation Icon.svg has been created, TSIM can be run to generate either material sets on a 3D grid or HUF data for MODFLOW. TSIM is run via the TPROGS | Run TSIM menu command. This brings up the TSIM Wizard.

Step 1

In the first step of the TSIM wizard, choose to run TSIM now from GMS or save the input files in order to run TSIM later. If not running TSIM from GMS, no material sets or HUF arrays will be created.

Step 2

The TSIM Options dialog

Part two of the TSIM model run is the TSIM Options dialog.

Running TSIM from GMS

Option Description
Number of realizations The number of material sets or HUF sets that will be generated.
Seed The random number seed used by TSIM. This is generated by GMS but can be changed. Running TSIM with the same inputs and see will result in identical outputs.
Max. # of quenching iterations A TSIM parameter. "No more than five quenching iterations are usually necessary – too many iterations may produce unrealistic artifacts."[1]
Quenching tolerance A TSIM parameter. "The tolerance limit sets a criteria for terminating quenching based on the value of the objective function as normalized relative to its initial value."
TSIM Output Choose to generate material sets or, if a MODFLOW model exists which uses the HUF package, HUF arrays.
Create material probability datasets This will cause datasets to get created, one per material, where the dataset values equal the probability that that material occurs in the given cell.
Background Grid The dimensions and number of grid ranks of the background grid are determined from the 3D grid in the project. If generating HUF arrays, specify the number of grid layers in the vertical (Z) direction.
Target grid layers Starting at GMS version 8.0, it is possible to target a subset of grid layers. The resulting material sets will have inactive values outside of the targeted area. Specify the min and max layers or the named layer ranges to target.

Saving Files to Run TSIM Later

The option in Step 2 if saving the TSIM files for later use are similar to those for running TSIM in GMS. Specify a file and where it is to be saved. Also, the dimensions and number of ranks of the background grid must be specified. Finally, no material sets or HUF arrays will be generated.


  1. ^ Carle, Steven F. (1999), T-PROGS: Transition Probability Geostatistical Software. Version 2.1, Davis, California, p. 6,