1. General Model Information
Name: water and heat flow in unsaturated media
Main medium: terrestrial
Main subject: hydrology
Organization level: ecosystem
Type of model: partial differential equations (finite differences,1D)
Keywords: Richardīs equation, water dynamics, unsaturated media, unsaturated soils, waste-disposal, drainage, hydraulic conductivity, heat flow
Michael J. Fayer, K6-77
Battelle, Pacific Northwest Laboratories
P.O. Box 999
Richland, WA 99352
phone: (509) 376-8326
M.J. Fayer, T.L. Jones, G. W. Gee
Pacific Northwest Laboratory
UNSAT-H, Version 2.0 is a model for calculating water and heat flow in unsaturated media.
The model was developed at Pacific Northwest Laboratory to assess water dynamics
of near-surface, waste-disposal sites at the Hanford Site. The code is primarily used to
predict deep drainage as a function of such environmental conditions as climate, soil
type, and vegetation.
UNSAT-H is a one-dimensional model that simulates the dynamics processes of infiltration,
drainage, redistribution, surface evaporation, and uptake of water from soil by
UNSAT-H uses a finite-difference approximation to solve the one-dimensional vertical form
of Richard's equation, which governs unsaturated moisture movement. UNSAT-H was designed
for use in water balance studies and has capabilities to estimate evaporation resulting
from meteorological surface conditions and transpiration from plants.
Parameters required for each material type are saturated hydraulic conductivity
(Ks, cm/hr), volumetric moisture content at saturation ( s), irreducible moisture content
( r), air entry head (he, cm H2O), and inverse pore size distribution index (b).
For all barrier materials except the existing soil, default values tabulated in the
HELP Manual were used. A site-specific curve was developed for the existing soil based on
Predicting the future long-term performance of low-level wastes at any near-surface
burial site in terms of migration of contaminants requires a model capable of simulating
water flow in the unsaturated soils above the buried waste.
UNSAT-H is also used to simulate the effects of various practices to enhance isolation
Sources of abstract:
FAYER and JONES (1990),
R.A. Olson, 1993:
15th Annual US Department of Energy Low-Level Radioactive Waste
Management Conference 1993, and
Hanford Site National Environmental
Policy Act (NEPA) Characterization, PNL-6415. Chapter 5, 1998.
II. Technical Information
Programming Language(s): UNSAT-H Version 2.0 is written in VAX FORTRAN Version 4.7 and runs under the VAX/VMS Version 4.7 Operating System.
The UNSAT-H Version 2.0 code has been modified to run on DOS and UNIX machines also. This extended version is called Version 2.01.
III. Mathematical Information
Fayer, M.J.; Jones, T.L. 1990. UNSAT-H Version 2.0: Unsaturated soil water and heat flow model. PNL-6779, Pacific Northwest Laboratory, Richland, Washington. 281p.
Fayer, M.J.; Gee, G.W.; Jones, T.L. 1986. UNSAT-H Version 1.0: Unsaturated Flow Code Documentation and Applications for the Hanford Site. PNL-5899, Pacific Northwest Labs., Richland, WA. Aug 86. 199p.
Martian, P. 1995.UNSAT-H infiltration model calibration at the Subsurface Disposal Area, Idaho National Engineering Laboratory. Oct 95. 120p.
Fayer, M. J.; M. L. Rockhold and M. D. Campbell. 1992. Hydrologic Modeling of Protective Barriers: Comparison of Field Data and Simulation Results. Soil Sci. Soc. Am. J. 56: 690-700.
Baca, R.G.; Magnuson, S.O. 1990. Independent verification and benchmark testing of the UNSAT-H computer code, Version 2.0. EEG-BEG-8811, Idaho National Engineering Laboratory, Idaho Falls, Idaho. Feb 1990. 70p.
Cawlfield, D.E.; Lindstrom, F.T.; Weaver, H. 1993.Numerical modeling studies on the alternately pulsed infiltration and subsequent evaporation of water in a dry high desert alluvial soil. American Geophysical Union fall meeting, San Francisco, CA (United States), 6-10 Dec 1993. partment of Energy, Washington, DC. 1993. 5p.
Nichols, W.E. 1990. Comparative simulations of a two-layer landfill barrier using the HELP Version 2.0 and UNSAT-H Version 2.0 computer codes. Battelle Pacific Northwest Labs., Richland, WA. Jan 91. 40p.
Simmons, C. S. and C. R. Cole. 1985. Guidelines for Selecting Codes for Ground-Water Transport Modeling of Low Level Waste-Burial Sites. PNL-4980, Vol. 2, Pacific Northwest Laboratory, Richland, Washington.
Gupta, S. K.; K. K. Tanji; D. R. Nielson; J. W. Biggar; C. S. Simmons and J. L. MacIntyre. 1978. Field Simulation of Soil-Water Movement with Crop Water Extraction. Water Science and Engineering Paper No. 4013, Department of Land, Air, and Water Resources, University of California, Davis, California.
V. Further information in the World-Wide-Web
VI. Additional remarks
Last review of this document by: Juergen BierwirthThu Jan 14 15:49:44 CET 1999
Status of the document:
last modified by
Tobias Gabele Wed Aug 21 21:44:51 CEST 2002