Description

The HYDRUS workshop begins with a detailed conceptual and mathematical description of water flow and solute transport processes in the vadose zone, followed by an overview of the use of finite element techniques for solving the governing flow and transport equations. Special attention is given to the highly nonlinear nature of the governing flow equation. Alternative methods for describing and modeling the hydraulic functions of unsaturated porous media are also described.

"Hands-on" computer sessions will provide participants an opportunity to become familiar with the Windows-based RETC, STANMOD, HYDRUS-1D and HYDRUS-2D software packages. Emphasis will be on the preparation of input data for a variety of applications, including flow and transport in a deep vadose zone, nonlinear nonequilibrium solute transport, variably-saturated flow through a dam, flow and transport to a tile drain, and two-dimensional leachate migration from a landfill through the unsaturated zone into groundwater. Calibration will be discussed and demonstrated using both one-and two-dimensional model inversion.

Course Software

The course introduces a new generation of Windows-based numerical models for simulating water flow and solute transport in variably-saturated porous media. Two numerical models (HYDRUS-1D and HYDRUS-2D for one- and two-dimensional simulations, respectively) will be available during the course. Both models are supported by interactive graphics-based interfaces for data-preprocessing, generation of unstructured as well as structured finite element grid systems, and graphic presentation of the simulation results. The Windows-based versions of the RETC (for quantifying the hydraulic functions of unsaturated soils) and STANMOD (for evaluating solute transport in the subsurface using analytical solutions of the convection-dispersion equation) codes will also be demonstrated in the course. The RETC code will be provided to all participants.

Course Handouts

Course handouts include lecture notes prepared by the instructors, documentation of the RETC (including the software) and STANMOD codes, and documentation of the HYDRUS-1D and HYDRUS-2D numerical models.