sutra(1) U.S. Geological Survey (wrdapp) sutra(1) NAME sutra - Saturated and (or) unsaturated, constant or variable-density fluid flow, and solute or energy transport (2-dimensional finite-element code) ABSTRACT SUTRA is a finite-element simulation model for saturated- unsaturated, fluid-density-dependent ground-water flow with energy transport or chemically-reactive single-species solute transport. SUTRA may be employed for areal and cross-sectional modeling of saturated ground-water flow systems, and for cross-sectional modeling of unsaturated zone flow. Solute transport simulation using SUTRA may be employed to model natural or man-induced chemical species transport including processes of solute sorption, production and decay, and may be applied to analyze ground-water contaminant transport problems and aquifer restoration designs. In addition, solute transport simulation with SUTRA may be used for modeling of variable density leachate movement, and for cross-sectional modeling of saltwater intrusion in aquifers in near-well or regional scales, with either dispersed or relatively sharp transition zones between freshwater and saltwater. SUTRA energy transport simulation may be employed to model thermal regimes in aquifers, subsurface heat conduction, aquifer thermal energy storage systems, geothermal reservoirs, thermal pollution of aquifers, and natural hydrogeologic convection systems. METHOD The model employs a two-dimensional hybrid finite-element and integrated-finite-difference method to approximate the governing equations that describe the two interdependent processes that are simulated: (1) fluid density-dependent saturated or unsaturated ground-water flow, and either (2a) transport of a solute in the ground water, in which the solute may be subject to equilibrium adsorption on the porous matrix, and both first-order and zero-order production or decay, or (2b) transport of thermal energy in the ground water and solid matrix of the aquifer. HISTORY Version V09972D - Second revision in 1997. Addition of option to use Fortran 90 dynamic array dimensioning. Addition of two output files containing simulation results in simple column format. No changes to input data format, except that the two new files and their unit numbers must be specified in the "SUTRA.FIL" Name File. Version V06902D - First revision in 1990. Note that input and output files from the version V12842D are NOT compatible with version V06902D. Minor modifications in old data files are necessary as described in the change notes and the revised pages of the documentation. Version V12842D - Original version distributed in 1984. 28 February 2000 1 sutra(1) U.S. Geological Survey (wrdapp) sutra(1) DATA REQUIREMENTS Two SUTRA data files are required: (1) SUTRA input data and (2) initial conditions of pressure and concentration or temperature for the simulation. See documentation for detailed coding instructions and description of input parameters. Reprogramming of subroutines BCTIME and UNSAT is required to implement time-dependent boundary conditions and unsaturated flow functions, respectively. OUTPUT OPTIONS A graphical postprocessor, SUTRA-PLOT, developed by Souza (1987) is available for use with SUTRA. This postprocessor facilitates interpretation of the simulation results. SYSTEM REQUIREMENTS SUTRA is written in Fortran 77 including optional Fortran 90 statements allowing dynamic array allocation. SUTRA requires that files needed for the simulation be defined prior to execution. A Name File (SUTRA.FIL) is used for this purpose. For each file (up to six), the unit number is specified on one record followed by a record specifying the file name. The format of the Name File is described in the documentation. Generally, the program is easily installed on most computer systems. The code has been used on a wide variety of computers, ranging from UNIX-based computers to DOS- based 386 computers with as little as 640K of RAM. DOCUMENTATION Souza, W.R., 1987, Documentation of a graphical display program for the saturated-unsaturated transport (SUTRA) finite-element simulation model: U.S. Geological Survey Water-Resources Investigations Report 87-4245, 122 p. Voss, C.I., 1984, A finite-element simulation model for saturated- unsaturated, fluid-density-dependent ground-water flow with energy transport or chemically-reactive single-species solute transport: U.S. Geological Survey Water-Resources Investigations Report 84-4369, 409 p. CONTACTS Operation: U.S. Geological Survey Office of Hydrologic Research Clifford I. Voss 431 National Center Reston, VA 20192 cvoss@usgs.gov Distribution: U.S. Geological Survey Hydrologic Analysis Software Support Program 437 National Center Reston, VA 20192 h2osoft@usgs.gov 28 February 2000 2 sutra(1) U.S. Geological Survey (wrdapp) sutra(1) Official versions of U.S. Geological Survey water-resources analysis software are available for electronic retrieval via the World Wide Web (WWW) at: http://water.usgs.gov/software/ and via anonymous File Transfer Protocol (FTP) from: water.usgs.gov (path: /pub/software). The WWW page and anonymous FTP directory from which the SUTRA software can be retrieved are, respectively: http://water.usgs.gov/software/sutra.html --and-- /pub/software/ground_water/sutra See http://water.usgs.gov/software/ordering_documentation.html for information on ordering printed copies of USGS publications. SEE ALSO mgenrad(1) - SUTRA utility program to generate a simple mesh mgenrec(1) - SUTRA utility program to generate a simple mesh pbcgen(1) - SUTRA utility program to generate hydrostatic pressure sutraplt(1) - Graphics postprocessor program for SUTRA Related models: moc(1) - Two-dimensional method-of-characteristics ground-water flow and transport model modfe(1) - Modular finite-element model for areal and axisymmetric ground-water flow problems modflow(1) - Modular three-dimensional ground-water flow model Modflowp(1) - Parameter-estimation version of the modular model vs2di(1) - A graphical software package for simulating fluid flow and solute or energy transport in variably saturated porous media 28 February 2000 3