Modelling infiltration and infiltration excess: The importance of fast and local processes

Physically based distributed hydrological models aim at an adequate representation of processes, including runoff generation. A significant proportion is generated through the subsurface, i.e. by groundwater flow or unsaturated subsurface stormflow. However, in case high rainfall intensity and/or low soil-surface infiltrability, surface may strongly contribute to total runoff, too, either saturation excess (“Dunne-type runoff”) infiltration (“Hortonian runoff”). Both types can be rather important if antecedent wetness and parts catchment area are saturated (leading excess), maximum rate into soil less than actual (resulting excess). Even though latter process very during high-intensity rainstorms, both for flood generation matter transport linked with appropriate consideration this still challenging. Actually, budgeting between capacity required there a number challenges details: First, ‘real’ vary tremendously time increments much smaller step model. The infiltrability also significantly reduced, e.g. crusting, compaction sealing hydrophobic effects. Otherwise, enhanced as consequence preferential paths / macropores caused bioturbations other voids. Finally, variability such features small spatial scale, below typical modelling unit. We present observational data approaches deal these challenges. show results from combined infiltration/infiltration-excess experiments observations three scales. Then, we model approach on double-porosity enabling rates dampened moisture distribution after termination infiltration, observable field. Furthermore, effects conditions capacity. These improved plausibility explanatory power concerning dynamics. For instance, plot hillslope scales that it possible simulate jointly relatively slow movement within matrix, field phenomena often observed heavy rainfall. non-linear space-time conditions, which This article protected copyright. All rights reserved.