A model which couples the kinematic wave approximation for Hortonian overland flow and the conceptual approach developed by Corradini et al. (1997)[J.Hydrol., 192, 104-124] for local infiltration was used to investigate the effects of random spatial variability of saturated hydraulic conductivity, Ks , on the outflow hydrograph at hillslope scale. The model incorporates a representation of infiltration of overland flow running over pervious downstream areas (“run-on” process). Single rainfall pulses and complex storms over two soils, representative of a silty loam and a sandy loam soil, were considered. Our results suggest that for realistic values of the coefficient of variation of Ks the run-on process cannot be disregarded, because it produces a significant decrease of overland flow during both the rising and the recession limb of the hydrograph. Furthermore, the role of the level of spatial correlation of Ks was found to be typically minor and the run-on process concurred to this result. The possibility of simplifying the stochastic problem by a deterministic approach based on the use of a uniform lumped value of Ks was also examined and rainfall patterns adequate for this simplification were deduced in terms of scaled storm intensity and storm duration.
On the interaction between infiltration and Hortonian runoff
CORRADINI, Corrado;MORBIDELLI, Renato;
1998
Abstract
A model which couples the kinematic wave approximation for Hortonian overland flow and the conceptual approach developed by Corradini et al. (1997)[J.Hydrol., 192, 104-124] for local infiltration was used to investigate the effects of random spatial variability of saturated hydraulic conductivity, Ks , on the outflow hydrograph at hillslope scale. The model incorporates a representation of infiltration of overland flow running over pervious downstream areas (“run-on” process). Single rainfall pulses and complex storms over two soils, representative of a silty loam and a sandy loam soil, were considered. Our results suggest that for realistic values of the coefficient of variation of Ks the run-on process cannot be disregarded, because it produces a significant decrease of overland flow during both the rising and the recession limb of the hydrograph. Furthermore, the role of the level of spatial correlation of Ks was found to be typically minor and the run-on process concurred to this result. The possibility of simplifying the stochastic problem by a deterministic approach based on the use of a uniform lumped value of Ks was also examined and rainfall patterns adequate for this simplification were deduced in terms of scaled storm intensity and storm duration.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
