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| Titel |
Assessing the simple dynamical systems approach in a Mediterranean context: application to the Ardèche catchment (France) |
| VerfasserIn |
M. Adamovic, I. Braud, F. Branger, J. W. Kirchner |
| 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 ; 19, no. 5 ; Nr. 19, no. 5 (2015-05-22), S.2427-2449 |
| Datensatznummer |
250120719
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| Publikation (Nr.) |
 copernicus.org/hess-19-2427-2015.pdf |
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| Zusammenfassung |
This study explores how catchment heterogeneity and variability can be
summarized in simplified models, representing the dominant hydrological
processes. It focuses on Mediterranean catchments, characterized by
heterogeneous geology, pedology and land use, as well as steep topography
and a rainfall regime in which summer droughts contrast with high-rainfall
periods in autumn. The Ardèche catchment (Southeast France), typical of
this environment, is chosen to explore the following questions: (1) can such
a Mediterranean catchment be adequately characterized by a simple dynamical
systems approach and what are the limits of the method under such
conditions? (2) what information about dominant predictors of hydrological
variability can be retrieved from this analysis in such catchments?
In this work we apply the data-driven approach of Kirchner (2009) to
estimate discharge sensitivity functions that summarize the behaviour of four
sub-catchments of the Ardèche, using low-vegetation periods
(November–March) from 9 years of measurements (2000–2008) from operational
networks. The relevance of the inferred sensitivity function is assessed
through hydrograph simulations, and through estimating precipitation rates
from discharge fluctuations. We find that the discharge sensitivity function
is downward-curving in double-logarithmic space, thus allowing further
simulation of discharge and non-divergence of the model, only during
low-vegetation periods. The analysis is complemented by a Monte Carlo
sensitivity analysis showing how the parameters summarizing the discharge
sensitivity function impact the simulated hydrographs. The resulting
discharge simulation results are good for granite catchments, which are
likely to be characterized by shallow subsurface flow at the interface
between soil and bedrock. The simple dynamical system hypothesis works
especially well in wet conditions (peaks and recessions are well modelled).
On the other hand, poor model performance is associated with summer and dry
periods when evapotranspiration is high and low-flow discharge observations
are inaccurate. In the Ardèche catchment, inferred precipitation rates
agree well in timing and amount with observed gauging stations and SAFRAN
climatic data reanalysis during the low-vegetation periods. The model should
further be improved to include a more accurate representation of actual
evapotranspiration, but provides a satisfying summary of the catchment
functioning during wet and winter periods. |
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