Product:
GeoStudio – SEEP/W, TEMP/W, CTRAN/W, AIR/W
Occurrence:
I am running an analysis in one of the GeoStudio flow products. I would like to run parameter estimation or a sensitivity analysis on one of the material parameters of my problem definition.
Resolution:
Parameter estimation (or inverse modeling) is one of the most important and well-studied subjects in science and engineering. In contrast to conventional modeling, it uses the results to determine the model parameters. To do so, the inverse problem is formulated as an optimisation problem in which the objective function describes the differences between the observed and estimated model responses. Although traditionally found by trial-and-error, the minimum value of the objective function can more efficiently be found using automatic estimation procedures.
Countless books and papers have been devoted to these procedures, and subroutines are available in a number of well-known mathematical libraries and model-independent programs. These programs interact with a model though its own input and output files while providing access to the latest and most advanced parameter estimation techniques. They are thus perfectly suited for conducting parameter estimation analyses when using our flow products.
The industry standard programs in geo-environmental engineering are PEST/PEST++ and UCODE. These programs, or toolboxes, also contain numerous tools for conducting sensitivity and Monte Carlo analyses. All of these tools are started from the command line prompt and configured through answers to a series of command prompt questions and/or configuration files. The following example and associated tutorial video provide the command line prompts, sample files, and results of a typical parameter estimation problem.
Notes:
Further information that can help with parameter estimation and sensitivity analysis in the GeoStudio flow products can be found under the knowledge base articles pertaining to file naming conventions and batch files (automation).