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| Titel |
A modeling approach to assess the hydrological response of small mediterranean catchments to the variability of soil characteristics in a context of extreme events |
| VerfasserIn |
C. Manus, S. Anquetin, I. Braud, J.-P. Vandervaere, J.-D. Creutin, P. Viallet, E. Gaume |
| 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 ; 13, no. 2 ; Nr. 13, no. 2 (2009-02-02), S.79-97 |
| Datensatznummer |
250011752
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| Publikation (Nr.) |
 copernicus.org/hess-13-79-2009.pdf |
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| Zusammenfassung |
| This paper presents a modeling study aiming at quantifying the possible
impact of soil characteristics on the hydrological response of small ungauged
catchments in a context of extreme events. The study focuses on the September
2002 event in the Gard region (South-Eastern France), which led to
catastrophic flash-floods. The proposed modeling approach is able to take
into account rainfall variability and soil profiles variability. Its spatial
discretization is determined using Digital Elevation Model (DEM) and a soil
map. The model computes infiltration, ponding and vertical soil water
distribution, as well as river discharge. In order to be applicable to
ungauged catchments, the model is set up without any calibration and the soil
parameter specification is based on an existing soil database. The model
verification is based on a regional evaluation using 17 estimated discharges
obtained from an extensive post-flood investigation. Thus, this approach
provides a spatial view of the hydrological response across a large range of
scales. To perform the simulations, radar rainfall estimations are used at a
1 km2 and 5 min resolution. To specify the soil hydraulic
properties, two types of pedotransfer function (PTF) are compared. It is
shown that the PTF including information about soil structure reflects better
the spatial variability that can be encountered in the field. The study is
focused on four small ungauged catchments of less than 10 km2, which
experienced casualties. Simulated specific peak discharges are found to be in
agreement with estimations from a post-event in situ investigation. Examining
the dynamics of simulated infiltration and saturation degrees, two different
behaviors are shown which correspond to different runoff production
mechanisms that could be encountered within catchments of less than
10 km2. They produce simulated runoff coefficients that evolve in time
and highlight the variability of the infiltration capacity of the various
soil types. Therefore, we propose a cartography distinguishing between areas
prone to saturation excess and areas prone only to infiltration excess
mechanisms. The questions raised by this modeling study will be useful to
improve field observations, aiming at better understanding runoff generation
for these extreme events and examine the possibility for early warning, even
in very small ungauged catchments. |
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