What is FePEST?

About PEST

At the present time, PEST is one of the most common software packages used for calibration of groundwater models.

However, it can provide much more than this. PEST implements methods that embrace the fact that the outcome of a calibration of an environmental model is not unique. The prediction given by this calibrated model is almost always only one out of many possibilities.

PEST aims to analyse these uncertainties. It gives indications for the confidence in the model prediction and the margins of uncertainty which are related to it based on the available knowledge.

Of course, these methods must be learned and understood. Fortunately, good literature is available to do so. See the literature review for more information.

Where to get PEST?

PEST is free software. It is developed by John Doherty (Watermark Numerical Computing) and can be downloaded including all documentation.

www.pesthomepage.org. Also see the installation instructions.

About FePEST

Because PEST is model-independent it can be used with any modelling software that accepts parameters and provides observations as numerical values, if the respective model files are accessible and their format is documented.

This was always true for FEFLOW, even in the past. However there were practical limitations.

PEST requires the user to prepare a set of configuration files, that instruct PEST how to write model input files, read results files, and much more. For complex simulators - like FEFLOW - this exercise can be very time consuming, and often makes a project too expensive to be actually undertaken.

PEST's nature - being mostly a command line driven tool - often posed another obstacle for users to get started with the software.

FePEST eases these problems by generating these configuration files for the user from values supplied through a convenient interface.

After these files are created, FePEST manages the execution of PEST. While PEST runs in the background, FePEST reads and processes its output, and shows the progress to the user in real-time.

If you are new to PEST

  • Most PEST features required for model calibration using PEST are accessible through FePEST. In many cases the user is not required to make changes to the PEST files and it is therefore not necessary to learn the syntax of the files and commands of PEST.

  • However: It is still essential that the results provided by PEST are interpreted correctly! It is suggested that the time saved on understanding PEST's file structure and command line tools is invested in understanding its methods.

If you are an experienced PEST user

  • PEST provides more functionality than FePEST can cover. We have chosen to implement those workflows that will be most relevant for most users. More methods will be implemented in the future.

  • This poses no limitation in using FePEST for other methods. It is developed in such a way that users can still benefit from the rapid creation of configuration files, even if unsupported methods are required.

  • The configuration files created by FePEST are fully accessible and follow the syntax specified in the PEST documentation. The structure of these files, including several batch-files, are designed to allow adaptations for different purposes.

  • Experienced users will use FePEST for the otherwise elaborate common work steps like the definition of observations and parameters (especially if using the pilot-point method), and then adapt the resulting PEST setup for their own particular purpose.

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