3. 5.3 – Advective-Dispersion Equation (ADE) Approach: Conservation of mass in a control volume (just like Richard’s Eqn) Mechanisms: convection, diffusion, dispersion Steps in derivation: 1.Mass balance on REV – solute mass conservation 2.Look at flux terms (macro and micro), and add transport processes into solute mass cons’ 3.Add in rxns – decay and adsorpotion

9. Note: D = Diffusion Coefficient can vary as a function of moisture content http://www.ufaventures.com/ufa_ventures/tech_briefs/diffusion_co.html