Tens of billions of dollars are spent each year in the United States and elsewhere to remediate groundwater pollution, and to limit or prevent future contamination of the subsurface. The unsaturated zone hence provides the best opportunities to limit or prevent groundwater pollution. Once contaminants enter groundwater, pollution is essentially irreversible, or can be remediated only with extreme costs. Numerical modeling is becoming an increasingly important tool for analyzing complex problems involving water flow and contaminant transport in the unsaturated zone. The course 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. The course introduces a new generation of Windows based numerical models for simulating water flow and solute transport in the variably-saturated porous media. The Windows-based version of the RETC code for quantifying the hydraulic functions of unsaturated soils will be used in the course and provided to all participants. Dr. Martinus Th. He received a B.S. and M.S. in irrigation and drainage from the Agricultural University of Wageningen, The Netherlands, and a Ph.D. in soil physics from New Mexico State University.