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| Titel |
Comparison of catchment grouping methods for flow duration curve estimation at ungauged sites in France |
| VerfasserIn |
E. Sauquet, C. Catalogne |
| 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 ; 15, no. 8 ; Nr. 15, no. 8 (2011-08-02), S.2421-2435 |
| Datensatznummer |
250012917
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| Publikation (Nr.) |
 copernicus.org/hess-15-2421-2011.pdf |
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| Zusammenfassung |
The study aims at estimating flow duration curves (FDC) at ungauged sites in
France and quantifying the associated uncertainties using a large dataset of
1080 FDCs. The interpolation procedure focuses here on 15 percentiles
standardised by the mean annual flow, which is assumed to be known at each
site. In particular, this paper discusses the impact of different catchment
grouping procedures on the estimation of percentiles by regional regression
models.
In a first step, five parsimonious FDC parametric models are tested to
approximate FDCs at gauged sites. The results show that the model based on
the expansion of Empirical Orthogonal Functions (EOF) outperforms the other
tested models. In the EOF model, each FDC is interpreted as a linear
combination of regional amplitude functions with spatially variable
weighting factors corresponding to the parameters of the model. In this
approach, only one amplitude function is required to obtain a satisfactory
fit with most of the observed curves. Thus, the considered model requires
only two parameters to be applicable at ungauged locations.
Secondly, homogeneous regions are derived according to hydrological
response, on the one hand, and geological, climatic and topographic
characteristics on the other hand. Hydrological similarity is assessed
through two simple indicators: the concavity index (IC) representing the shape
of the dimensionless FDC and the seasonality ratio (SR), which is the ratio of
summer and winter median flows. These variables are used as homogeneity
criteria in three different methods for grouping catchments: (i) according
to an a priori classification of French Hydro-EcoRegions (HERs), (ii) by applying
regression tree clustering and (iii) by using neighbourhoods obtained by
canonical correlation analysis.
Finally, considering all the data, and subsequently for each group obtained
through the tested grouping techniques, we derive regression models between
physiographic and/or climatic variables and the two parameters of the EOF
model. Results on percentile estimation in cross validation show that a
significant benefit is obtained by defining homogeneous regions before
developing regressions, particularly when grouping methods make use of
hydrogeological information. |
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