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| Titel |
A quasi-three-dimensional model for predicting rainfall-runoff processes in a forested catchment in Southern Finland |
| VerfasserIn |
H. Koivusalo, T. Karvonen, A. Lepistö |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 4, no. 1 ; Nr. 4, no. 1, S.65-78 |
| Datensatznummer |
250001519
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| Publikation (Nr.) |
 copernicus.org/hess-4-65-2000.pdf |
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| Zusammenfassung |
| Runoff generation in a forested catchment (0.18 km2)
was simulated using a quasi-three-dimensional rainfall-runoff model. The model
was formulated over a finite grid where water movement was assumed to be
dominantly vertical in the unsaturated soil zone and horizontal in the saturated
soil. The vertical soil moisture distribution at each grid cell was calculated
using a conceptual approximation to the one-dimensional Richards equation. The
approximation allowed the use of a simple soil surface boundary condition and an
efficient solution to the water table elevation over the finite grid. The
approximation was coupled with a two-dimensional ground water model to calculate
lateral soil water movement between the grid cells and exfiltration over
saturated areas, where runoff was produced by the saturation-excess mechanism.
Runoff was an input to a channel network, which was modelled as a nonlinear
reservoir. The proposed approximation for the vertical soil moisture
distribution in unsaturated soil compared well to a numerical solution of the
Richards equation during shallow water table conditions, but was less
satisfactory during prolonged dry periods. The simulation of daily catchment
outflow was successful with the exception of underprediction of extremely high
peak flows. The calculated water table depth compared satisfactorily with the
measurements. An overall comparison with the earlier results of tracer studies
indicated that the modelled contribution of direct rainfall/snowmelt in
streamflow was higher than the isotopically traced fraction of event-water in
runoff. The seasonal variation in the modelled runoff-contributing areas was
similar to that in the event-water-contributing areas from the tracer analysis. |
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