Course: Septembre 28 - Octobre 2, 2009
Migration of inorganic and organic contaminants in the subsurface is affected by a multitude of complex, interactive physical, geochemical and microbiological processes. Cycles of precipitation and evaporation largely determine if contaminants remain near the soil surface. Changes in the chemical composition or pH of the soil solution may impact the retention of radionuclides and heavy metals on organic matter or iron oxides. Dissolution and precipitation of radionuclide or trace element bearing minerals generally buffer the transport of a solution with a different pH through the soil profile. Simulation of these and related processes requires a coupled reactive transport code that integrates the physical processes of variably-saturated water flow and convective-dispersive solute transport with a range of biogeochemical processes.
Numerical modelling is becoming an increasingly important tool for analyzing such complex problems involving water flow and contaminant transport in the unsaturated zone. This course is designed to familiarize participants with the principles and mathematical analysis of variably-saturated flow, transport processes and coupled multicomponent reactive transport, and the application of state-of-the-art numerical codes to sitespecific subsurface flow and transport problems.
Although participants should have a general background in the principles of soil physics and chemistry, the course gives an introduction to some theoretical aspects of water flow, solute transport, and heat transport in soils, geochemical equilibrium modelling and geochemical processes as cation exchange, surface complexation and kinetic reactions. Most of the time, "Hands-on" computer sessions will familiarize participants with the basic use of
the software packages, as well as with the conceptualization of practical problems for numerical analysis.