PORE-SCALE NETWORK MODELING OF COMPACTION AND FILTRATION DURING SURFACE SEALING

Surface sealing increases the probability of runoff and soil erosion, and occurs on a variety of soils worldwide. Filtration (''washing-in'') and compaction have been reported as mechanisms of surface sealing, but the relative importance of each has not been established. We developed a pore-scale network model to simulate these mechanisms, with the objective of determining their relative importance. Filtration was more effective than compaction in reducing soil hydraulic conductivity during seal formation, even though compaction reduced seal porosity more than filtration. Most of the particles available for filtration were deposited on the network surface rather than being washed into the network. This suggests that surface deposition may be more important than compaction or filtration in determining the seal hydraulic conductivity. The network model can predict seal hydraulic conductivity from pore- and particle-size distributions and the initial hydraulic conductivity, and is potentially a useful research tool in understanding pore-scale mechanisms in soil structure research.