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Title: THE CHAIN_2D CODE FOR SIMULATING TWO-DIMENSIONAL MOVEMENT OF WATER FLOW, HEAT, AND MULTIPLE SOLUTES IN VARIABLY-SATURATED POROUS MEDIA, VERSION 1.1 USSL RESEARCH REPORT NO. 136

Author
item SIMUNEK, JIRKA - U.C. RIVERSIDE
item Van Genuchten, Martinus

Submitted to: Laboratory Publication
Publication Type: Government Publication
Publication Acceptance Date: 10/15/1994
Publication Date: N/A
Citation: N/A

Interpretive Summary: Even with well-documented multi-dimensional numerical computer models available, one major problem which often prevents the use of such codes is the extensive work required for data preparation, finite element grid design, and graphical presentation of output results. Hence, a more widespread use of multi-dimensional models requires techniques which make it easier to create, manipulate and display large data files, and which facilitate interactive data management. Introducing such techniques will free users from cumbersome manual data processing, and should enhance the efficiency in which programs are implemented for a particular example. To avoid or simplify the preparation and management of relatively complex input data files for multi-dimensional flow problems, and to graphically display the final simulation results, we developed an interactive graphics-based user-friendl lerface for the MS Windows 3.1 environment. The interface is connected to HYDRUS2, a version of SWMS_2D specifically written for use with the graphics interface. This report serves as both a user manual and reference document. Detailed instructions are given for data input preparation. Example input and selected output files are also provided.

Technical Abstract: This report documents version 1.0 of HYDRUS-2D, a software package for simulating water and solute movement in two-dimensional variably saturated media. The software package consists of the HYDRUS2 computer program, and the interactive graphics-based user interface HYDRUS2D. The HYDRUS2 program numerically solves the Richards' equation for saturated-unsaturated water flow and the convection-dispersion equation for solute transport. The flow equation incorporates a sink term to account for water uptake by plant roots. The transport equation includes provisions for linear equilibrium adsorption, zero-order production, and first-order degradation. HYDRUS2 can handle flow regions delineated by irregular boundaries. The flow region itself may be composed of nonuniform soils having an arbitrary degree of local anisotropy. Flow and transport can occur in the vertical plane, the horizontal plane, or in a three-dimensional region exhibiting radial symmetry about the vertical axis. The water flow part of the model can deal with prescribed head and flux boundaries, boundaries controlled by atmospheric conditions, free drainage boundary conditions, as well as a simplified representation of nodal drains using results of electric analog experiments. The software package contain a graphics-based user interface, HYDRUS2D, for easy data preparation and output display in the MS Windows environment. It also includes a structured mesh generator for relatively simple flow domain geometries.