Numerical Model for Predicting Two Dimensional Infiltrations and Solute Travel Time in Heterogeneous Layered Soil

Field soils are usually composed of at least two horizons. Different than independent geological layers, soil horizons are spatially dependent on each other as they were formed under pedogenic process acting on the same parent material. Dyck (2008) tested the influence of soil horizon on the hydraulic behavior of the entire soil profile and found that the influence is scale dependent, different for transient and steady infiltrations, and is dependent on the covariance of shape of the interface and soil hydraulic properties. My research project is conducted to increase our understanding and develop methods to predict, the two dimensional infiltration of water and chemicals into field soils for surface line source boundary condition. Numerical models were constructed to predict infiltration process and chemical travel time in a layered soil profile with scale dependent hydraulic properties. Also the model was compared to Philip’s (1971) quasilinear solution and measured data from Dyck’s (2009a) field experiment. The sensitivity of the spatial variability of water flow and solute transport to the spatial correlation of hydraulic properties within each horizon and the spatial cross correlation across the horizon boundary was tested by the model. The model is applicable for designing hydraulic loading rate and quantifying environmental risk of surface at grade (on site) waste water disposal system.