DISC is a computer software package for analyzing Tension Disc Infiltrometer data by parameter estimation. The software package consists of the simplified HYDRUS2 computer program, and an interactive graphics-based user interface. The DISC code numerically solves the Richards' equation for saturated-unsaturated water flow. Flow occurs in a three-dimensional region exhibiting radial symmetry about the vertical axis. The software includes a Marquardt-Levenberg type parameter optimization algorithm for inverse estimation of soil hydraulic properties (van Genuchten parameters) from measured transient cumulative infiltration and related data. The governing flow equation is solved numerically using Galerkin-type linear finite element schemes. The transport region is discretized automatically by the software into triangular elements using pregenerated files that are scaled directly to the specified size of the tension disc radius. The code is integrated into a Windows based graphics interface that facilitates entering of the input information and display of the parameter estimation results.
Intel Pentium processor, 16 Mb RAM, hard disk with at least 20 Mb free disk space, VGA graphics (SVGA with 256 colors recommended), MS Windows 95 or higher.
?imunek, J., and M. Th. van Genuchten, The DISC computer software for analyzing tension disc infiltrometer data by parameter estimation. Versions 1.0, Research Report No. 145, U.S. Salinity Laboratory, USDA-ARS, Riverside, California, 34pp., 2000.