Comparison of catchment grouping methods for flow duration curve estimation at ungauged sites in France

Abstract

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 supposed to be known at each site. In particular, this paper discusses the relevance of different catchments grouping procedures on percentiles estimation by regional regression models. <br><br> First, five parsimonious FDC parametric models were tested to approximate FDCs at gauged sites. The results show that the model based on Empirical Orthogonal Functions (EOF) expansion outperforms the other ones. In this model each FDC is interpreted as a linear combination of regional amplitude functions with weights – the parameters of the model – varying in space. Here, only one amplitude function was found sufficient to fit well most of the observed curves. Thus the considered model requires only two parameters to be estimated at ungauged locations. <br><br> Second, homogeneous regions were derived according to hydrological response on one hand, and geological, climatic and topographic characteristics on the other hand. Hydrological similarity was assessed through two simple indicators: the concavity index (<i>IC</i>) that represents the shape of the standardized FDC and the seasonality ratio (<i>SR</i>) which is the ratio of summer and winter median flows. These variables were used as homogeneity criteria in three different methods for grouping catchments: (i) according to their membership in one of an a priori French classification into Hydro-Eco-Regions (HERs), (ii) by applying a regression tree clustering and (iii) by using hydrological neighbourhood obtained by canonical correlation analysis. <br><br> Finally, regression models between physiographic and/or climatic variables and the two parameters of the EOF model were derived considering all the data and thereafter for each group obtained through the tested grouping techniques. Results on percentiles estimation in cross validation show a significant benefit to form homogeneous regions before developing regressions, particularly when grouping methods use hydrogeological information

Flow Regime Classification and Hydrological Characterization: A Case Study of Ethiopian Rivers

“…Perennial streams are large streams with significant contribution of the base flows and relatively less variability throughout the year. This finding is in line with similar studies in France [47] and other tropical regions [36].…”

“…The identified flow regimes are further described with the help of the flow duration curve, which is a graphical representation of cumulative frequency that shows the percent of time specified discharges were equaled or exceeded during a given period [47,48]. It represents the relationship between the magnitude and frequency of stream flow for a particular river basin [49].…”

The soil water characteristic as new class of closed-form parametric expressions for the flow duration curve

“…A detailed review on methods for clustering of homogeneous catchments appears in Sauquet and Catalogne (2011) and Booker and Snelder (2012), and interested readers are referred to these publications for more information. Another approach has been to mimic the empirical (observed) FDC with a mathematical/probabilistic model and to correlate the fitting coefficients of such parametric expressions to physical and climatological characteristics of the watershed using regression techniques, index models, artificial intelligence, and spacial interpolation schemes (Fennessey and Vogel, 1990;Yu and Yang, 1996;Yu et al, 2002;Croker et al, 2003;Castellarin et al, 2004aCastellarin et al, ,b, 2007Li et al, 2010;Sauquet and Catalogne, 2011;Viola et al, 2011;Longobardi and Villani, 2013;Pumo et al, 2013;Mendicino and Senatore, 2013;Shamseldin, 2014;Waseem et al, 2015). Such pedotransfer functions can then be used to predict the FDC of ungauged basins from simple catchment data (e.g.…”

Benefits of riparian forest for the aquatic ecosystem assessed at a large geographic scale

“…We assumed that for areas in which these factors are quite homogeneous, nutrient transfers are similar, and so are temporal patterns of concentration in water courses. The application of hydro-ecoregions as homogeneous spatial units for this kind of analysis has already been successfully demonstrated in several studies (Wasson et al 2010;Sauquet and Catalogne 2011;Gauroy and Carluer, 2011). Preliminary to the selection of survey sites, the main anthropogenic stressors to riparian forest fragmentation were explored over the entire river network to allow the detection of datasets homogeneous in stressor conditions.…”

“…Finally, to test whether the outcomes are not biased by hydrological processes like dilution, a verification of the results with respect to flow regime was executed. The annual peak flow estimation (Q95 annual daily discharge, estimation to bankfull and effective discharge according to Leopold (1994)) was determined for each stretch, based on extrapolation models for the national gauging stations (Snelder, Lamouroux, Leathwick et al, 2009;Sauquet and Catalogne, 2011). A multivariate regression analysis was performed to enable consideration of respective predictive power to nutrient reductions for the riparian forest cover and the flow regime.…”