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International audience; Repeated measures experiments can be conducted to empirically estimate the uncertainty of a stream gauging method, such as the widespread moving‐boat acoustic Doppler current profilers (ADCPs) approach. Previous ADCP repeated measures experiments, also known as interlaboratory comparisons, provided a credible range of uncertainty estimates reflecting the quality of the site conditions. However, the method, which is a one‐way analysis of variance, only addresses the uncertainty of one lumped factor that combines several distinct factors: instrument, operator, procedure, and cross‐section effects. To decompose the uncertainty of ADCP streamflow measurements due to cross‐section selection and team effects, a large repeated measures experiment has been conducted in the Taurion River (France). The experiment design was crossed and balanced, with two sets of 24 teams circulated over two sets of 12 cross sections. A constant flow rate was released from a dam, located immediately upstream of the experimental site. Prior to the statistical analysis, a data quality review was performed using the U.S. Geological Survey QRev software to clean the data set from avoidable errors and to homogenize the discharge computations. A two‐way analysis of variance was applied to quantify the cross‐section effect, the team effect, and their interaction, which was found to dominate the pure cross‐section effect. It was then possible to predict the average uncertainty of multiple‐transect ADCP discharge measurements, depending on the number of teams, cross sections, and repeated transects included in the discharge average. The method opens interesting avenues for documenting difficult‐to‐estimate uncertainty sources of stream gauging techniques in other measuring conditions, especially the most adverse ones.

HMEM, Durham, New Hampshire, USA, 09-/07/2017 - 12/07/2017; International audience; Stage-discharge rating curves are used to relate streamflow discharge to continuously measured river stage readings to create a continuous record of streamflow discharge. The stage-discharge relationship is estimated and refined using discrete streamflow measurements over time, during which both the discharge and stage are measured. There is uncertainty in the resulting rating curve due to multiple factors including the curve-fitting process, assumptions on the form of the model used, fluvial geomorphology of natural channels, and the approaches used to extrapolate the rating equation beyond available observations. This rating curve uncertainty leads to uncertainty in the streamflow timeseries, and therefore to uncertainty in predictive models that use the streamflow data. Many different methods have been proposed in the literature for estimating rating curve uncertainty, differing in mathematical rigor, in the assumptions made about the component errors, and in the information required to implement the method at any given site. This study describes the results of an international experiment to test and compare streamflow uncertainty estimation methods from 7 research groups across 9 institutions. The methods range from simple LOWESS fits to more complicated Bayesian methods that consider hydraulic principles directly. We evaluate these different methods when applied to three diverse gauging stations using standardized information (channel characteristics, hydrographs, and streamflow measurements). Our results quantify the resultant spread of the stage-discharge Quantifying the uncertainty of discharge measurements (or "gaugings") is a challenge in the hydrometric community. A useful tool to empirically estimate the uncertainty of a gauging method is the field inter-laboratory experiment (Le Coz et al., 2016). Previous inter-laboratory experiments conducted in France (in 2009, 2010, 2011 and 2012) showed that the expanded uncertainty (with a probability level of 95%) of an ADCP gauging made of six successive transects is typically around 5% under optimum site conditions (straight reach, uniform and smooth streambed cross-section, homogeneous flow, etc.) and may be twice higher under poorer site conditions. In practice, the selected cross-section does not always match all quality requirements which may result in larger uncertainty. However, the uncertainty due to site selection is very difficult to estimate with predictive equations. From 9 to 10 November 2016, 50 teams from 8 different countries, using 50 ADCPs simultaneously, conducted more than 600 discharge measurements in steady flow conditions (~14 m3/s released by a dam). 26 cross-sections with various shapes and flow conditions were distributed over 500 meters along the Taurion River at Saint-Priest-de-Taurion, France. A specific experiment protocol, which consisted of circulating every team over half of the cross-sections, was implemented in order to quantify the impact of site selection on the discharge measurement uncertainty. Beyond the description of the experiments, uncertainty estimates are presented. The overall expanded uncertainty of a 6-transect ADCP gaugings (duration around 720 seconds) is estimated to be around 6%.The uncertainty of the discharge measurements varies among the cross-sections. These variations are well correlated to the expert judgment on the cross-section quality made by each team. First results seem to highlight a relation between uncertainty computed for each cross-section and criteria such as flow shallowness and measured discharge ratio. Further investigations are necessary to identify the criteria related to error sources that are possibly meaningful for categorizing measurement conditions and site selection. Moreover, experimental uncertainty and the uncertainty predicted by analytical methods such as QRev, QUant, OURSIN, RiverFlowUA or QMSys software will be compared.

Quantifying the uncertainty of discharge measurements (or “gaugings”) is a challenge in the hydrometric community. A useful tool to empirically estimate the uncertainty of a gauging method is the field inter-laboratory experiment (Le Coz et al., 2016). Previous inter-laboratory experiments conducted in France (in 2009, 2010 and 2012) showed that the expanded uncertainty of an ADCP gauging (considering an average discharge over six successive transects) is typically around 5% (with a probability level of 95%), under optimum measurement conditions (straight reach, uniform and smooth streambed cross-section, homogeneous flow, etc.). In practice, the selected cross-section does not always match all quality requirements which may result in larger uncertainty. However, the uncertainty due to site selection is very difficult to estimate with predictive equations. From 8 to 10 November 2016, 50 laboratories or teams (from 8 different countries) with 50 ADCPs, simultaneously conducted more than 600 ADCP discharge measurements in steady flow conditions (around 14 m3=s released by a dam), during three half-days, over 500 m along the Taurion River at Saint-Priest-de-Taurion, France. 26 cross-sections with various shapes and flow conditions, and more or less favourable conditions, were distributed along the river. A specific experiment procedure, which consisted of circulating every team over half of the cross-sections, was implemented in order to quantify the impact of site selection on the discharge measurement uncertainty. Beyond the description of the experiments, uncertainty estimates are presented. The overall expanded uncertainty is estimated to be around 6% at 95% level of confidence for a measurement performed with 6 transects in the given measurement conditions of the experiments. However, the uncertainty of the discharge measurements varies among the cross-sections. These variations are well correlated to the expert judgment on the cross-section quality made by each team. First results seems to highlight a relation between uncertainty computed for each cross-section and criteria such as the shallowness of the flow, the unmeasured discharge ratio. Further investigations are necessary to identify the criteria related to error sources that are possibly meaningful for categorizing measurement conditions and site selection. Moreover, comparison between experimental uncertainty and analytical methods (such as computations recently proposed by QRev, Quant, Oursin or QMSys software) is planned to be done.; Du 8 au 10 novembre 2016, le Groupe Doppler Hydrométrie a organisé sur le Taurion, à l’aval du barrage-usine de Chauvan, une campagne d’essais interlaboratoires de mesures de débit par profileur hydro-acoustique ADCP. En plus de permettre aux équipes participantes de confronter leurs outils et leurs pratiques, les essais interlaboratoires visent à contribuer collectivement à l’amélioration de la maîtrise de ces mesures et de leurs incertitudes. En l’absence de mesure de référence en termes de débit, les intercomparaisons constituent en effet un moyen utile pour quantifier l’incertitude de la technique de mesure dans des conditions de mesure données (Blanquart, 2013; Dramais et al., 2013; Le Coz et al., 2016). Cette 5ème campagne interlaboratoire du Groupe Doppler Hydrométrie (après celles de la Vézère en 2009, de Génissiat en 2010 et 2012 ainsi que celle du canal de la Gentille en 2011) a rassemblé 50 participants (ou équipes de mesure) français et étrangers issus d’organismes publics ou privés, permettant la réalisation de plus de 600 mesures de débit réparties sur 3 demi-journées en profitant de débits stables délivrés par le barrage-usine de Chauvan, de l’ordre de 14 m3=s. Les essais interlaboratoires de Chauvan se distinguent par leur dimension et par l’originalité du protocole d’essai mis en oeuvre. Alors que les campagnes précédentes ont eu lieu sur des sites de mesure plutôt favorables, caractérisés par des géométries de section en travers relativement simples, des sections de mesure plus variées et complexes ont cette fois été choisies (faibles profondeurs, écoulements parfois perturbés par des obstacles). Ainsi des permutations ont été réalisées par 48 participants parmi les 24 sections de mesure présentant des conditions de déploiement plus ou moins favorables pour les ADCP. En parallèle, le débit a été mesuré en continu par deux ADCP (StreamPro et Q-Liner) sur des sections de mesure fixes et les hauteurs d’eau ont été enregistrées par trois capteurs limnimétriques (deux sondes piézométriques relatives (Paratronic) disposées sur deux sections de mesure et un radar (VEGA) au niveau de la station hydrométrique EDF-DTG). Le suivi limnimétrique a permis de confirmer la stabilité du débit du cours d’eau (variations inférieures à 1 cm) au cours des trois sessions de mesure. Les résultats de débit des ADCP sont peu dispersés (écarts-types de l’ordre de 0,400 m3=s) et la valeur de débit moyenne (référence construite) est proche des valeurs fournies par les mesures indépendantes à moins de 5% près (jaugeages par ADCP en continu aux deux sections fixes, jaugeage par la méthode globale de dilution et débit associé à la courbe de tarage selon la méthode de tracé conventionnelle, selon la méthode GesDyn ou selon la méthode BaRatin). Les premiers résultats montrent que la dispersion des valeurs de débit semble nettement corrélée à la qualité des sections de mesure évaluée in situ par les équipes de mesure ainsi qu’au ratio du débit mesuré. Les essais interlaboratoires conduisent à une évaluation d’incertitude de l’ordre de 6% (au niveau de confiance de 95 %, soit un facteur d’élargissement k=2) pour un jaugeage par ADCP comportant 6 transects de mesure (dans les conditions de l’essai). Le nombre important de participants rassemblés permet une évaluation précise de cette incertitude de mesure bien que l’estimation de l’incertitude liée au biais de la technique de mesure reste problématique. Cette estimation reste néanmoins à affiner après homogénéisation des traitements des mesures à l’aide du logiciel QRev (Mueller, 2016). La permutation des équipes au sein des différentes sections de mesure permettra la conduite d’une étude statistique visant à isoler l’incertitude liée à la section de mesure. Les résultats préliminaires tendent à montrer l’utilité de mesurer le débit sur plusieurs sections de mesure afin de réduire l’incertitude sur l’estimation du débit. Enfin nous prévoyons de comparer les estimations d’incertitude par propagation des incertitudes telles que proposées par les logiciels Oursin (CNR), QRev (USGS), RiverFlowUA (South Florida Water management District), QMSys ou encore QUANT (Water Survey of Canada) aux résultats d’incertitude issus de ces essais interlaboratoires.

International audience; While the application of uncertainty propagation methods to hydrometry is still challenging, in situ collaborative interlaboratory experiments are a valuable tool for empirically estimating the uncertainty of streamgauging techniques in given measurement conditions. We propose a simple procedure for organizing such experiments and processing the results according to the authoritative ISO standards related to interlaboratory experiments, which are of common practice in many metrological fields. Beyond the computation and interpretation of the results, some issues are discussed as regards: the estimation of the streamgauging technique bias in the absence of accurate enough discharge references in rivers; the uncertainty of the uncertainty estimates, according to the number of participants and repeated measurements; the criteria related to error sources which are possibly meaningful for categorizing measurement conditions. The interest and limitations of the in situ collaborative interlaboratory experiments are exemplified by an application to the hydro-acoustic profiler (ADCP) streamgauging technique conducted in 2010 at two different sites downstream of Génissiat hydropower plant in the Rhône river, France. Typically, the expanded uncertainty (with a probability level of 95%) of the average discharge over 6 successive transects varied from +/-5% at one site with favourable conditions to +/-9% at the other site due to unstable flow conditions.

International audience; Quantifying the uncertainty of streamflow data is key for hydrological sciences. The conventional uncertainty analysis based on error propagation techniques is restricted by the absence of traceable discharge standards and by the weight of difficult-to-predict errors related to the operator, procedure and measurement environment. Field interlaboratory experiments recently emerged as an efficient, standardized method to ’measure’ the uncertainties of a given streamgauging technique in given measurement conditions. Both uncertainty approaches are compatible and should be developed jointly in the field of hydrometry. In the recent years, several interlaboratory experiments have been reported by different hydrological services. They involved different streamgauging techniques, including acoustic profilers (ADCP), current-meters and handheld radars (SVR). Uncertainty analysis was not always their primary goal: most often, testing the proficiency and homogeneity of instruments, makes and models, procedures and operators was the original motivation. When interlaboratory experiments are processed for uncertainty analysis, once outliers have been discarded all participants are assumed to be equally skilled and to apply the same streamgauging technique in equivalent conditions. A universal requirement is that all participants simultaneously measure the same discharge, which shall be kept constant within negligible variations. To our best knowledge, we were the first to apply the interlaboratory method for computing the uncertainties of streamgauging techniques, according to the authoritative international documents (ISO standards). Several specific issues arise due to the measurements conditions in outdoor canals and rivers. The main limitation is that the best available river discharge references are usually too uncertain to quantify the bias of the streamgauging technique, i.e. the systematic errors that are common to all participants in the experiment. A reference or a sensitivity analysis to the fixed parameters of the streamgauging technique remain very useful for estimating the uncertainty related to the (non quantified) bias correction. In the absence of a reference, the uncertainty estimate is referenced to the average of all discharge measurements in the interlaboratory experiment, ignoring the technique bias. Simple equations can be used to assess the uncertainty of the uncertainty results, as a function of the number of participants and of repeated measurements. The interlaboratory method was applied to several interlaboratory experiments on ADCPs and currentmeters mounted on wading rods, in streams of different sizes and aspects, with 10 to 30 instruments, typically. The uncertainty results were consistent with the usual expert judgment and highly depended on the measurement environment. Approximately, the expanded uncertainties (within the 95% probability interval) were 5% to 10% for ADCPs in good or poor conditions, and 10% to 15% for currentmeters in shallow creeks. Due to the specific limitations related to a slow measurement process and to small, natural streams, uncertainty results for currentmeters were more uncertain than for ADCPs, for which the site-specific errors were significantly evidenced. The proposed method can be applied to a wide range of interlaboratory experiments conducted in contrasted environments for different streamgauging techniques, in a standardized way. Ideally, an international open database would enhance the investigation of hydrological data uncertainties, according to the characteristics of the measurement conditions and procedures. Such a dataset could be used for implementing and validating uncertainty propagation methods in hydrometry.

National audience; En parallèle de la méthode de propagation des incer titudes, méthode de référence (GUM - Guide pour l'expression de l'incertitude de mesure) qui nécessite de modéliser l'ensemble du processus de mesure, la méthode expérimentale des essais interlaboratoires présente un grand intérêt pour quantifier les incertitudes d'une méthode de mesure , dans des conditions données. Cette méthode, très utilisée dans certains domaines (chimie, biologie, essais mécaniques, etc.), est encadrée par des normes ISO compatibles avec le GUM décrivant la méthode de référence. Ainsi, les comparaisons interlaboratoires hydrométriques permettent de quantifier l'incertitude résultant des erreurs de mesure qui s'expriment lor s de la répétition de jaugeages simultanés par plusieurs équipes en conditions de répétabilité et de reproductibilité, et en particulier pour une plage de débit constant. Des formules simples permettent de quantifier, à partir des résultats expérimentaux de variance de répétabilité et de variance interlaboratoire, l'incertitude de la méthode de jaugeage testée, supposée non biaisée. Plusieurs comparaisons interlaboratoires ont été réalisées ces dernières années à l’initiative du groupe Doppler hydrométrie et ce type d’essais se généralise maintenant entre les équipes d’hydrométrie.

International audience; En parallèle de la méthode de propagation des incertitudes, méthode de référence (GUM - Guide pour l'expression de l'incertitude de mesure) qui nécessite de modéliser l'ensemble du processus de mesure, la méthode expérimentale des essais interlaboratoires présente un grand intérêt pour quantifier les incertitudes d'une méthode de mesure, dans des conditions données. Cette méthode, très utilisée dans certains domaines (chimie, biologie, essais mécaniques, etc.), est encadrée par des normes ISO compatibles avec le GUM décrivant la méthode de référence. Ainsi, les comparaisons interlaboratoires hydrométriques permettent de quantifier l'incertitude résultant des erreurs de mesure qui s'expriment lors de la répétition de jaugeages simultanés par plusieurs équipes en conditions de répétabilité et de reproductibilité, et en particulier pour une plage de débit constant. Des formules simples permettent de quantifier, à partir des résultats expérimentaux de variance de répétabilité et de variance interlaboratoire, l'incertitude de la méthode de jaugeage testée, supposée non biaisée. A partir d'exemples récents d'intercomparaisons de jaugeages ADCP, sur perche, par camion et par dilution, des recommandations générales sont proposées pour l'organisation d'intercomparaisons hydrométriques qui soient exploitables pour quantifier des incertitudes conformes aux textes de référence. La méthode normalisée des essais interlaboratoires améliore l’évaluation des incertitudes sur les techniques de jaugeage. / In addition to the uncertainty propagation method provided by the GUM (Guide to the expression of uncertainty in measurement) witch requires the modelling of the measurement process, the inter-laboratory experimental method is a good solution to deal with the uncertainty of a measurement technique, in given conditions. This method is commonly frequently used in some fields (eg. in chemistry); it is managed with ISO standards and technical notes or specifications. Thus, inter-laboratory comparisons in hydrometry allow the quantification of uncertainty due to errors that will be expressed in repeated simultaneous gauging operations. These repetitions have to be done by different teams, at the same time, in stable flow conditions, under repeatability and reproducibility conditions. Simple formulae with repeatability variance and the inter-laboratory variance results assessed to evaluate the gauging technique uncertainty, supposed to be unbiased. The bias or systematic error is linked to the gauging technique; it could be evaluated by comparison with an independent flow measurement technique with a known uncertainty. In this study some suggestions are presented for the hydrometric inter-laboratory comparison organisation. These pieces of advice follow from recent inter-laboratory comparison with ADCP, current meter on wading rod or gauging van, and tracer dilution devices. The inter-laboratory comparison method is a standardised solution for improving the knowledge and the uncertainty evaluation of gauging techniques.

International audience; Stage-discharge hysteresis due to transient flow is often difficult to highlight during floods in natural rivers. Multi-ADCP discharge measurements conducted during a national ADCP intercomparison test in 2010 on the Rhône river downstream Génissiat dam, France, were used to evidence such effect. Indeed, averaging the discharges simultaneously measured by 14 ADCP allowed to reduce the measurement uncertainty, while the uncertainty due to the time-integration of a varying discharge remained low, due to the short duration of an ADCP transect. Applying metrological standards for interlaboratory tests, the combined ADCP uncertainty was computed to be ∼ 2.2%, ignoring the bias related to the ADCP method itself. The application of the Jones (1916) formula provided an acceptable correction of the discharge deviation to steady conditions, which reached 3 − 4% typically. A 1D hydrodynamic model was also applied and confirmed that the observed stage-discharge hysteresis was due to the advance of the velocity signal over the pressure signal.

Comparaison de méthodes de mesure du débit des petits cours d'eau. Journées d'intercomparaison des 17 et 18 mai 2011. Présentation et analyse des résultats.

Comparaison de méthodes de mesure du débit des petits cours d'eau. Journées d'intercomparaison des 17 et 18 mai 2011. Présentation et analyse des résultats.

Quantifying the uncertainty of discharge measurements (or “gaugings”) is a challenge in the hydrometric community. A useful tool to empirically estimate the uncertainty of a gauging method is the field inter-laboratory experiment (Le Coz et al., 2016). Previous inter-laboratory experiments conducted in France (in 2009, 2010 and 2012) showed that the expanded uncertainty of an ADCP gauging (considering an average discharge over six successive transects) is typically around 5% (with a probability level of 95%), under optimum measurement conditions (straight reach, uniform and smooth streambed cross-section, homogeneous flow, etc.). In practice, the selected cross-section does not always match all quality requirements which may result in larger uncertainty. However, the uncertainty due to site selection is very difficult to estimate with predictive equations. From 8 to 10 November 2016, 50 laboratories or teams (from 8 different countries) with 50 ADCPs, simultaneously conducted more than 600 ADCP discharge measurements in steady flow conditions (around 14 m3=s released by a dam), during three half-days, over 500 m along the Taurion River at Saint-Priest-de-Taurion, France. 26 cross-sections with various shapes and flow conditions, and more or less favourable conditions, were distributed along the river. A specific experiment procedure, which consisted of circulating every team over half of the cross-sections, was implemented in order to quantify the impact of site selection on the discharge measurement uncertainty. Beyond the description of the experiments, uncertainty estimates are presented. The overall expanded uncertainty is estimated to be around 6% at 95% level of confidence for a measurement performed with 6 transects in the given measurement conditions of the experiments. However, the uncertainty of the discharge measurements varies among the cross-sections. These variations are well correlated to the expert judgment on the cross-section quality made by each team. First results seems to highlight a relation between uncertainty computed for each cross-section and criteria such as the shallowness of the flow, the unmeasured discharge ratio. Further investigations are necessary to identify the criteria related to error sources that are possibly meaningful for categorizing measurement conditions and site selection. Moreover, comparison between experimental uncertainty and analytical methods (such as computations recently proposed by QRev, Quant, Oursin or QMSys software) is planned to be done.; Du 8 au 10 novembre 2016, le Groupe Doppler Hydrométrie a organisé sur le Taurion, à l’aval du barrage-usine de Chauvan, une campagne d’essais interlaboratoires de mesures de débit par profileur hydro-acoustique ADCP. En plus de permettre aux équipes participantes de confronter leurs outils et leurs pratiques, les essais interlaboratoires visent à contribuer collectivement à l’amélioration de la maîtrise de ces mesures et de leurs incertitudes. En l’absence de mesure de référence en termes de débit, les intercomparaisons constituent en effet un moyen utile pour quantifier l’incertitude de la technique de mesure dans des conditions de mesure données (Blanquart, 2013; Dramais et al., 2013; Le Coz et al., 2016). Cette 5ème campagne interlaboratoire du Groupe Doppler Hydrométrie (après celles de la Vézère en 2009, de Génissiat en 2010 et 2012 ainsi que celle du canal de la Gentille en 2011) a rassemblé 50 participants (ou équipes de mesure) français et étrangers issus d’organismes publics ou privés, permettant la réalisation de plus de 600 mesures de débit réparties sur 3 demi-journées en profitant de débits stables délivrés par le barrage-usine de Chauvan, de l’ordre de 14 m3=s. Les essais interlaboratoires de Chauvan se distinguent par leur dimension et par l’originalité du protocole d’essai mis en oeuvre. Alors que les campagnes précédentes ont eu lieu sur des sites de mesure plutôt favorables, caractérisés par des géométries de section en travers relativement simples, des sections de mesure plus variées et complexes ont cette fois été choisies (faibles profondeurs, écoulements parfois perturbés par des obstacles). Ainsi des permutations ont été réalisées par 48 participants parmi les 24 sections de mesure présentant des conditions de déploiement plus ou moins favorables pour les ADCP. En parallèle, le débit a été mesuré en continu par deux ADCP (StreamPro et Q-Liner) sur des sections de mesure fixes et les hauteurs d’eau ont été enregistrées par trois capteurs limnimétriques (deux sondes piézométriques relatives (Paratronic) disposées sur deux sections de mesure et un radar (VEGA) au niveau de la station hydrométrique EDF-DTG). Le suivi limnimétrique a permis de confirmer la stabilité du débit du cours d’eau (variations inférieures à 1 cm) au cours des trois sessions de mesure. Les résultats de débit des ADCP sont peu dispersés (écarts-types de l’ordre de 0,400 m3=s) et la valeur de débit moyenne (référence construite) est proche des valeurs fournies par les mesures indépendantes à moins de 5% près (jaugeages par ADCP en continu aux deux sections fixes, jaugeage par la méthode globale de dilution et débit associé à la courbe de tarage selon la méthode de tracé conventionnelle, selon la méthode GesDyn ou selon la méthode BaRatin). Les premiers résultats montrent que la dispersion des valeurs de débit semble nettement corrélée à la qualité des sections de mesure évaluée in situ par les équipes de mesure ainsi qu’au ratio du débit mesuré. Les essais interlaboratoires conduisent à une évaluation d’incertitude de l’ordre de 6% (au niveau de confiance de 95 %, soit un facteur d’élargissement k=2) pour un jaugeage par ADCP comportant 6 transects de mesure (dans les conditions de l’essai). Le nombre important de participants rassemblés permet une évaluation précise de cette incertitude de mesure bien que l’estimation de l’incertitude liée au biais de la technique de mesure reste problématique. Cette estimation reste néanmoins à affiner après homogénéisation des traitements des mesures à l’aide du logiciel QRev (Mueller, 2016). La permutation des équipes au sein des différentes sections de mesure permettra la conduite d’une étude statistique visant à isoler l’incertitude liée à la section de mesure. Les résultats préliminaires tendent à montrer l’utilité de mesurer le débit sur plusieurs sections de mesure afin de réduire l’incertitude sur l’estimation du débit. Enfin nous prévoyons de comparer les estimations d’incertitude par propagation des incertitudes telles que proposées par les logiciels Oursin (CNR), QRev (USGS), RiverFlowUA (South Florida Water management District), QMSys ou encore QUANT (Water Survey of Canada) aux résultats d’incertitude issus de ces essais interlaboratoires.