Order No: FOS 26
Version: 1.1 (10/85)
Price: $50

ONESTEP is a program for estimation of up to five unknown parameters in the van Genuchten soil hydraulic property model. The program require measurements of cumulative outflow with time during one-step outflow experiments. The outflow data can be optionally supplemented with measurements of equilibrium moisture contents and pressure heads. The program combines a nonlinear optimization routine with a Galerkin finite-element model for the one-dimensional flow equation.

The program runs in batch mode. Example data sets are provided, which can be copied and edited with a text editor for individual problems. The program results are output in text files. ONESTEP is distributed on DOS-formatted diskettes containing source code, executable image, and example data sets. The documentation consists of installation instructions, theory, user's instruction and example problems. (see also program RETC).


Authors: J.B. Kool, J.C. Parker, and M. Th. van Genuchten (Virginia Polytechnical Institute)