PEST - Model-Independent Parameter Estimation and Uncertainty Analysis


Model-Independent Parameter Estimation
and Uncertainty Analysis

Welcome to the PEST web pages.

PEST is the industry standard software package for parameter estimation and uncertainty analysis of complex environmental and other computer models.
PEST is:
  • state-of-the art;
  • comprehensively documented;
  • accompanied by a plethora of utility programs that support its use in conjunction with widely-used groundwater and surface water models;
  • free.
Stroll through these pages to:
  • find out what PEST does;
  • download PEST;
  • download a comprehensive PEST tutorial; 
  • learn about upcoming PEST events;
  • meet other PEST users.
PEST - the Book

This brings together in one place all of the theory on which PEST and its suite of utility software is based. It also covers important issues like how models should be used in the decision-making context, uncertainty analysis, model-based hypothesis testing, and the effects of model defects on calibrat`ion, prediction and uncertainty analysis. This book makes an essential reference text for those engaged in environmental modelling. Find out more about the book.


PEST_HP is can be purchased from this site. “HP” stands for “highly parallelized” or “high performance” (you can choose).

Two facets of PEST_HP design make it different from that of traditional PEST/BEOPEST. These are as follows.

  1. PEST_HP's inversion algorithm is optimized for contexts where a modeler has access to many computing nodes - either through an office network, a cluster, or (as is increasingly common) through the cloud. Generally it out-performs BEOPEST - both in its speed and in its tolerance of model numerical problems.
  2. PEST_HP includes a number of features which are specifically designed to accommodate difficult, complex, highly parameterized models with long run times.

If you use, then you use PEST_HP automatically. Alternatively, PEST_HP can be purchased as a stand-alone item for your own cloud, network or cluster use.

PEST_HP version 16

A beta release is available for existing users of PEST_HP. You can download it from here . It will work with your existing license file. Also, download the new manual.

New features include:

  • CMAES_HP: a version of the CMAES global optimizer that uses TCP/IP for communication between manager and agents; this has been used successfully for optimization of pump and treat well-field design (amongst other things);
  • A number of new control variables that govern inversion efficiency;
  • Simultaneous and random parameter increments; in certain inversion contexts, this can dramatically reduce the number of model runs required for model calibration. is a PEST cloud enabler. It gives a modeller ridiculously easy access to the cloud computing environment for model calibration using PEST_HP. A user does not need to know anything but the barest essentials about cloud computing. Uploading/downloading of PEST and model files, distribution of files to computing nodes, and shutting down of those nodes when the inversion process is finished, is all taken care of. Meanwhile a modeller gets to use PEST_HP for efficient inversion, and has access to run-time statistics generated by PEST_HP while calibration is in progress.

Upcoming PEST courses

Courses are planned for the US, Italy and Chile. See the training page.

New PEST Manuals

At last, documentation for PEST and its Utilities has been completely re-written!

The new PEST manual is detailed and comprehensive. It now comes in two parts.

Part I describes PEST itself (including Parallel PEST and BEOPEST), as well as the two PEST-compatible global optimisers CMAES_P and SCEUA_P. Part II documents over 100 utility support programs whose tasks include the following:

  • Assisting in PEST setup
  • PEST input dataset error checking
  • Manipulation of Jacobian and other matrices
  • Calculation of pre- and post-PEST-run statistics
  • Analysis of information content of existing or yet-to-be-acquired data
  • Linear and nonlinear parameter and predictive error and uncertainty analysis
  • Subspace analysis
For more information on anything to do with PEST contact us.

Here are some downloads that can help you quickly learn more about PEST, its philosophical underpinnings, and implications of PEST technology for model-based decision support:-

See the downloads page for much more.

These pages were last updated on 1st January, 2019. (Added four MODFLOW6 Utilities to Groundwater Data Utilities Suite) 

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