1. General Model Information
Name: RETention Curve Computer Code
Main medium: terrestrial
Main subject: hydrology
Organization level: ecosystem
Type of model: static-algebraic equations
Main application: simulation/optimisation tool
Keywords: data processing tool, unsaturated, soil, hydraulic properties, hydraulic functions, hydraulic conductivity, retention, characteristic,parameter estimation, prediction, unimodal, pore size distribution, Mualem, Burdine, van Genuchten, parametric models
U.S. Salinity Laboratory
450 West Big Springs Road
Riverside, CA 92507-4716
Email: to email@example.com
Van Genuchten M.Th
The program permits the prediction of the unsaturated soil hydraulic functions
assuming known values of the hydraulic parameters in unimodal retention and hydraulic
conductivity models (the forward or direct problem), or to estimate the hydraulic
functions from observed soil water retention and/or hydraulic conductivity/diffusivity
data. It includes the parametric equations of Brooks-Corey and van Genuchten, which are
used in conjunction with the VAN GENUCHTEN (1980) analytical solutions to the theoretical
pore size distribution models of Mualem and Burdine to predict unsaturated hydraulic
conductivity from observed soil water retention data. Can be used in a forward mode and
in a parameter fitting mode. When fitting analytical models simultaneously to observed
water retention and hydraulic conductivity data, the program permits weighing of
measured data and estimates the parameter l (pore interaction index) in the Mualem model.
Several examples are presented to illustrate a variety of program options.
The program comes with a user manual giving detailed information about the computer
program along with instructions for data input
preparation and listings of sample input and output files.
A listing of the source code is also provided.
II. Technical Information
Operating System(s): DOS The program and manual are available upon request from: Walter Russell ,USDA, ARS, Riverside/CA please mail to firstname.lastname@example.org The DOS-Binaries Ver 1.1 1994( Source code included) can be downloaded from
Programming Language(s): FORTRAN(see Executables)
The Documentation can be downloaded from
III. Mathematical Information
van Genuchten, M.T. 1980. A Closed-form Equation for Predicting the Hydraulic Conductivity of Unsaturated Soils. Soil Sci. Soc. J. 44:892-898.van Genuchten, M. Th., F. J. Leij, and S. R. Yates. 1991
The RETC Code forQuantifying the Hydraulic Functions of Unsaturated Soils, Version 1.0.
EPA Report 600/2-91/065, U.S. Salinity Laboratory, USDA, ARS, Riverside, California.
V. Further information in the World-Wide-Web
VI. Additional remarks
Last review of this document by: T. Gabele: 08. 07. 1997 -
Status of the document:
last modified by
Joachim Benz Tue Nov 19 15:42:11 CET 2002