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Spearman rank correlations r s between streamflow model parameters, rainfall model parameters, topographic indices, soil attributes, geology and climate indicators in 428 catchments (Table 1). The streamflow model parameters are λ q (scale parameter representing streamflow variability), ψ q (location parameter representing the magnitude, ceteris paribus) and η q (scaling parameter representing flashiness of catchment response). The rainfall parameters are λ P (scale parameter representing rainfall variability), ψ P (location parameter representing the magnitude, ceteris paribus) and η P (scaling parameter as an indicator of
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The aim of this paper is to explore how rainfall mechanisms and catchment characteristics shape the relationship between rainfall and flood probabilities. We propose a new approach of comparing intensity-duration-frequency statistics of maximum annual rainfall with those of maximum annual streamflow in order to infer the catchment behavior for runo...
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... statistical properties of the streamflow extremes can only be partly explained by the properties of extreme rainfall. Other potential controls include catchment topography, soil properties, geology and long-term climate. All of these controls are assessed by the correlation analysis of Fig. 8. All correlations discussed below are significant at the 5% ...
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... tends to be small, i.e. the rainfall extremes tend to be large with little temporal variability (see Fig. A3a and A3c). The opposite applies to catchments in the lowlands where convective rainfall extremes are more frequent. The relationship between rainfall magnitude and variability is reflected by a high negative correlation between ψ P and λ P (Fig. 4a and Fig. 8, r S = 0.62). The regional rainfall mechanisms also manifest themselves in the spatial distribution of the scaling parameter η P , which tends to be higher in the convective lowlands than in the mountainous regions with dominant orographic rainfall (Fig. A3e). A higher parameter η P implies that the intensity decreases more strongly ...
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... in the case of rainfall, the location parameter of streamflow ψ q is higher in the mountain catchments than in the lowlands (see Fig. A3d), reflected by a strong positive correlation of ψ q with catchment elevation (Fig. 8, r S = 0.77) and mean summer rainfall (Fig. 8, r S = 0.55). This means, the magnitude of floods tends to be higher in the orographic rainfall regions, not only due the higher extreme rainfall magnitudes but also due to high annual rainfall amounts, possibly leading to high soil moisture levels, persistently high runoff coefficients and ...
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... in the case of rainfall, the location parameter of streamflow ψ q is higher in the mountain catchments than in the lowlands (see Fig. A3d), reflected by a strong positive correlation of ψ q with catchment elevation (Fig. 8, r S = 0.77) and mean summer rainfall (Fig. 8, r S = 0.55). This means, the magnitude of floods tends to be higher in the orographic rainfall regions, not only due the higher extreme rainfall magnitudes but also due to high annual rainfall amounts, possibly leading to high soil moisture levels, persistently high runoff coefficients and to a propensity towards saturation excess ...
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... persistently high runoff coefficients and to a propensity towards saturation excess overflow. The variability of streamflow represented by the scale parameter λ q , however, is controlled by catchment topography, soil type and the geology (e.g. correlations with slope r S = 0.33, Rendzina soils r S = 0.21 or Carbonate rock geology r S = 0.28, Fig. 8) and is thus highest along the Alpine ridge (Fig. A3b), while the variability of the rainfall represented by λ P is mainly controlled by elevation (see negative correlation between λ P and elevation in Fig. 8) and is highest in the lowlands (Fig. A3a). Some of the highest values of λ q relate to karstic catchments along the Alpine ...
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... soil type and the geology (e.g. correlations with slope r S = 0.33, Rendzina soils r S = 0.21 or Carbonate rock geology r S = 0.28, Fig. 8) and is thus highest along the Alpine ridge (Fig. A3b), while the variability of the rainfall represented by λ P is mainly controlled by elevation (see negative correlation between λ P and elevation in Fig. 8) and is highest in the lowlands (Fig. A3a). Some of the highest values of λ q relate to karstic catchments along the Alpine divide (see Fig. 1a catchments with crosses, Fig. A3b and positive correlation between λ q and Carbonate rock in Fig. 8). In karstic catchments, during periods of average rainfall events, most of the rainfall may ...
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... by λ P is mainly controlled by elevation (see negative correlation between λ P and elevation in Fig. 8) and is highest in the lowlands (Fig. A3a). Some of the highest values of λ q relate to karstic catchments along the Alpine divide (see Fig. 1a catchments with crosses, Fig. A3b and positive correlation between λ q and Carbonate rock in Fig. 8). In karstic catchments, during periods of average rainfall events, most of the rainfall may be stored in the fractured carbonic rocks, while more extreme rainfall events can saturate the epikarst zone inducing large streamflow extremes ( Li et al., 2017) and thus more variable floods. Such step changes in streamflow extremes may also ...
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... the comparison of rainfall and flood distributions, one can conclude, not surprisingly, that higher rainfall extremes tend to lead to higher floods, as the positive correlation between the location parameters ψ P and ψ q indicates (Fig. 8, r S = 0.69). This relationship is more distinct in regions dominated by orographic rainfall, where runoff coefficients are persistently high (Merz & Blöschl, 2003), such as in the Northern orographic region (r S = 0.70). The relationship is not existent in the Northeastern convective region, where runoff coefficients tend to be lower ...
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... frequency curve is associated with a steeper flood frequency curve, which is in line with previous studies (e.g. Merz & Blöschl, 2003;Smith et al., 2011;Villarini & Smith, 2010). The scale parameter of rainfall is not aligned with that of streamflow, reflected by r S = 0.14 between λ P and λ q and different spatial patterns (Fig. A3a, A3b and Fig. ...
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... spatial patterns of the scaling parameters η P and η q are to some extent aligned (Fig. 8, r S = 0.3) with larger parameters in the North and East and lower in the West. This similarity suggests that the response times of catchments to the storms producing the annual floods tend to be shorter in regions dominated by convective activity (North and Northeast), while the opposite is the case in the West. The similarity is ...
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