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RETC is a program for analyzing the hydraulic conductivity properties of unsaturated soils. The parametric models of Brooks-Corey and van Genuchten are used to represent the soil water retention curve. The theoretical pore-size distribution models of Mualem and Burdine predict the unsaturated hydraulic conductivity function. The simulation can be generated from observed soil water retention data, assuming that one observed conductivity value (not necessarily at saturation) is available. The program also permits users to fit analytical functions simultaneously to observed water retention and hydraulic conductivity data.


Version 1.1
Release Date November 1994
Development Status general release
Development Information  
Operating System DOS
Development Language  
Intended Audience  
Key Words  
Related Web Sites  

Minimum System Requirements

To run RETC, you will need the following:


Unzipping SoftwareExit EPA disclaimer

You will need unzipping (compression) software to uncompress ZIP files. If you need to load unzipping software on your computer, free software is available for download on the internet at the following sites:

US EPA. (1991) Program files (ZIP)(69 KB)

"The RETC Code for Quantifying the Hydraulic Functions of Unsaturated Soils." Publication No. 600/2-91/065.

Installation Instructions

  1. Go to Windows Explorer and create a directory named RETC.
  2. Download the program files and user's manual to the new directory.
  3. Unzip the program files to the RETC directory.
  4. Review the user’s manual for instruction on running the model.

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See EPA's PDF page to learn more.


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