Effect of the infiltration of simulated rains on soil organic carbon content and mud rheology

This study examines the effect of simulated rainfall infiltration on the soil organic carbon content and the rheology of mud, focusing on the natural stability of soils in landslide-prone areas. Using soil samples from the Partenio Mountains in Southern Italy, affected by catastrophic debris flows, the infiltration of rainwater was simulated under controlled conditions. Four distinct rainfall events, varying in intensity and duration, were applied to soil samples reconstituted with the moist tamping technique to reproduce field porosity. Observations during infiltration revealed a highly non-linear distribution of water content in time and space, controlled by rainfall intensity and boundary conditions. The rheological properties of the resultant slurries were analyzed, alongside measurements of dissolved organic carbon and total organic carbon contents. The results indicate that rainfall infiltration alters slurry rheology, reducing viscosity and yield stress, despite minimal changes in the soil organic carbon content. Lower-intensity rainfall led to more pronounced changes, probably due to a more uniform and effective water infiltration. These findings underscore the role of dissolved organic carbon in slurry stability and provide insights into mechanisms governing debris flowslides, with possible implications for geohazard assessment.