Are seemingly physically similar catchments truly hydrologically similar?

Abstract

[1] This paper discusses the notion of similarity often used in the regionalization studies of hydrological models. We compare two different visions of similarity: the apparent similarity defined on the basis of observable catchment properties, and behavioral similarity judged through the use of hydrological models. These two visions are generally assumed to be merged in regionalization studies: Catchments having apparently similar physical characteristics are assumed to have a similar hydrological behavior. In this paper, we wished to test the validity of this assumption. To this aim, we defined behavioral (hydrological) similarity on the basis of model parameter transferability. Then pools of hydrologically similar catchments are compared with pools of apparently physically similar catchments, as identified on the basis of physiographic catchment descriptors. The overlap between the two pools of similar catchments is analyzed, making it possible to judge the efficiency of the physical similarity measure and to identify hydrologically similar catchments in an ungauged context. The results show that the overlap between the two pools is significant for only 60% of the catchments. For the other catchments, two major reasons were identified as contributing to the lack of overlap: (1) these catchments often have a quite specific hydrological behavior and (2) the role of the underground properties of the catchment on its hydrological behavior was not found to be accurately described by the available physical descriptors, meaning that more relevant catchment descriptors should be sought to better describe the geological and lithological context in hydrological terms.

Catchment classification based on characterisation of streamflow and precipitation time series

“…The similarity may be evaluated in terms of signatures of catchments' functional responses, quantifying the characteristics of the hydrologic response that provide insight into the behaviour of the catchment (Atkinson et al, 2002;Wagener et al, 2007;Yilmaz et al, 2008;Oudin et al, 2010). A comprehensive set of measures describing all aspects of the catchment hydrology (such as meteorological observations, soil moisture content, vegetation patterns, etc.)…”

Evaluation of Regionalization Methods for Hourly Continuous Streamflow Simulation Using Distributed Models in Boreal Catchments

“…Littlewood and Croke (2013) indicated the importance of a fine temporal resolution also for extraction of the information content of the data for accuracy of calibrated parameters, which would allow more reliable parameter regionalization. Uncertainties related to model structure, parameter calibration and input data affect the performance of the regionalization of precipitation-runoff models for continuous simulation of streamflow (see Wagener and Wheater, 2006;Oudin et al, 2008;Oudin et al, 2010;Kim and Kaluarachchi, 2008;Gupta et al, 2008). Engeland and Gottschalk (2002) noted that structural errors in the model are more important than parameter uncertainties.…”

“…Engeland and Gottschalk (2002) noted that structural errors in the model are more important than parameter uncertainties. Oudin et al (2010) noted that the physical meaning of calibrated model parameters suffers from problems in model identification, model structural errors, and difficulties in finding an appropriate calibration strategy. Several previous studies (e.g.…”

“…Hence, spatially distributed modelling and parameter regionalization are important for the PUB. Regionalization methods have previously been used to transfer knowledge from gauged to ungauged basins (Blöschl and Sivapalan, 1995;Oudin et al, 2010), which require evaluation and identification of the methods.…”

Added-value from a multi-criteria selection of donor catchments in the prediction of continuous streamflow series at ungauged pollution control-sites

“…1. As for a truly ungauged catchment, streamflow hydrograph is unkown, we apply a method that introduces hydrological catchment behaviour in the assessment of catchment physical similarity (Oudin et al, 2010). We compute two catchment classifications (a hydrological one and a physical one) where similarity is defined as an Euclidean distance in the catchment property space: for the hydrological classification we use seven hydrological signatures calculated on the 1990-2002 period (runoff coefficient, lag time, Base Flow Index, slopes of the Flow Duration Curve for the high flow range, the low flow range and the medium flow range, rising limb density); for the physical classification we use 70 catchment attributes related to climate, geology, land cover, hydrology and morphology and a weighted version of the Euclidean distance for estimating the catchment similarity.…”