ABSTRACT
Within the hydrological cycle, infiltration plays the key role in partitioning rainfall into surface runoff and subsurface flows. Fire modifies the soil as well as the vegetation/litter cover on the soil, thus altering the infiltration process on burned lands. Fire effects on the infiltration process and infiltration rates are described and illustrated with data from studies where infiltration was measured before and after wildfires or compared in paired (burned and unburned) plots. Some research shows that immediately after a fire, ash absorbs the rainfall and briefly enhances the infiltration into the mineral soil. As the ash is washed downslope due to raindrop impact and surface runoff, it clogs the soil pores causing surface sealing, and infiltration reaches its lowest values. The extent and degree of fire-induced or enhanced soil water repellency is directly related to the reduction in infiltration. As vegetation recovery enhances the hydrological functioning of the soil and soil water repellency decreases, infiltration recovers approaching its pre-fire infiltration values within a few years.
