Department of Hydrology and Water Resources
University of Arizona
Tucson, AZ 85721
Phone: (520) 621-7114
Dr. Reinder Feddes
Dept. of Water Resources
The Netherlands Phone: 31 8370 82875
Fax: 31 8370 84885
UNSAT2 is a two-dimensional finite element model for horizontal, vertical, or axisymmetric simulation
of transient flow in a variably saturated, non-uniform anisotropic porous medium. The governing equation is the Richard's equation expressed in terms of pressure head. Boundary conditions included are Dirichlet and Neumann, and seepage face. UNSAT2 is capable of simulating infiltration and evaporation as head-dependent conditions, determined after the fluid pressure is calculated. Evapotranspiration is simulated through user specified minimum allowed pressure head at the soil surface, maximum evaporation rate, and soil surface geometric data. User supplied input for simulation of evapotranspiration includes root zone geometric data, root effectiveness function, plant species wilting pressure, and maximum transpiration rate. The code can use both quadrilateral and triangular elements. Unsaturated hydraulic properties must be input in table form: internally, the code uses linear slopes between the data points for interpolation. UNSAT2 has a restart feature for simulating changing boundary conditions.
Please note that there are (at least) two other Models named "UNSAT", viz. the one dimensional finite element code UNSAT-1 by M.Th. van Genuchten and the 1D finite difference model UNSAT-H "Unsaturated Soil Water and Heat Flow Model" by M. J. Fayer and T. L. Jones 1990.
Neuman, S.P., R. A. Feddes, and E. Bresler 1974. Finite element simulation of flow in saturated-unsaturated soils considering water uptake by plants, Third Annual Report, Project No. A10-SWC-77, Hydraulic Engineering Lab., Technion, Haifa, Israel.
Neuman, S. P. 1973. Saturated-unsaturated seepage by finite elements. Proc. ASCE, J. Hydraul.Div. 99(HY12):2233-2250.