Modeling plot scale dye penetration by a diffusion limited aggregation (DLA) model

Solute transport in the unsaturated zone often occurs in preferential How p aths. There are several reasons for this, e.g., water repellency, the occur rence of fissures and cracks, animal borrows, decomposed root threads etc. The resulting How patterns often display a fractal resemblance which is dif ficult to predict using conventional transport models. A way to preserve th e fractal property of observed data is to use the diffusion limited aggrega tion (DLA) model concept. In the present paper we use dye infiltration data to further develop the DLA model concept as applied to solute movement in soils. The DLA model is first calibrated against detailed field observation s of dye infiltration. The model is shown to give a good description of obs erved mean and variance of dye penetration. After this, the calibrated mode l is verified against independent data from a nearby plot. The model is sho wn to reproduce observed dye patterns in a satisfactory way also at the ver ification plot. (C) 2001 Elsevier Science B.V. All rights reserved.