Il est connu qu’avoir un système d’observation de la pluie de haute résolution spatio – temporelle est crucial pour obtenir de bons résultats dans la modélisation pluie – écoulement. Le radar est un outil qui donne des estimations quantitatives de precipitation avec une très bonne résolution. Lorsqu’il est fusionné avec un réseau des pluviomètres les avantages des deux systèmes sont obtenus. Cependant, les estimations fournies par le radar ont des incertitudes différentes à celles qui sont obtenus avec les pluviomètres. Dans le processus de calcul pluie – écoulement l'incertitude des précipitations interagit avec l'incertitude du modèle hydrologique. L’objectif de ce travail est d’étudier les méthodes utilisées pour quantifier l'incertitude dans l'estimation des précipitations par fusion radar – pluviomètres et de l'incertitude dans la modélisation hydrologique, afin de développer une méthodologie d'analyse de leurs contributions individuelles au traitement pluie - écoulement.Le travail est divisé en deux parties, la première cherche à évaluer: Comment peut-on quantifier l'incertitude de l'estimation des précipitations par radar? Pour répondre à la question, l'approche géostatistique par Krigeage avec Dérive Externe (KED) et Génération Stochastique de la précipitation a été utilisée, qui permet de modéliser la structure spatio – temporaire de l’erreur. La méthode a été appliquée dans la région des Cévennes - Vivarais (France), où il y a un système très dense d'observation. La deuxième partie explique: Comment pourrais être quantifiée l'incertitude de la simulation hydrologique qui provient de l'estimation de précipitation par radar et du processus de modélisation hydrologique? Dans ce point, l'outil de calcul hydrologique à Mesoéchelle (HCHM) a été développé, c’est un logiciel hydrologique distribuée et temps continu, basé sur le Numéro de Courbe et l’Hydrographe Unitaire. Il a été appliqué dans 20 résolutions spatio - temporelles allant de 10 à 300 km2 et 1 à 6 heures dans les bassins de l’Ardèche (~ 1971 km2) et le Gardon (1810 km2). Apres une analyse de sensibilité, le modèle a été simplifié avec 4 paramètres et l’incertitude de la chaîne de processus a été analysée: 1) Estimation de precipitation; 2) Modélisation hydrologique; et 3) Traitement pluie - écoulement, par l’utilisation du coefficient de variation de l'écoulement simulé.Il a été montré que KED est une méthode qui fournit l’écart type de l’estimation des précipitations, lequel peut être transformé dans une estimation stochastique de l’erreur locale. Dans la chaîne des processus: 1) L'incertitude dans l'estimation de précipitation augmente avec la réduction de l’échelle spatio – temporelle, et son effet est atténué par la modélisation hydrologique, vraisemblablement par les propriétés de stockage et de transport du bassin ; 2) L'incertitude de la modélisation hydrologique dépend de la simplification des processus hydrologiques et pas de la surface du bassin ; 3) L'incertitude dans le traitement pluie - écoulement est le résultat de la combinaison amplifiée des incertitudes de la précipitation et la modélisation hydrologique. / It is known that having a precipitation observation system at high space - time resolution is crucial to obtain good results in rainfall - runoff modeling. Radar is a tool that offers quantitative precipitation estimates with very good resolution. When it is merged with a rain gauge network the advantages of both systems are achieved. However, radars estimates have different uncertainties than those obtained with the rain gauge. In the modeling process, uncertainty of precipitation interacts with uncertainty of the hydrological model. The objective of this work is: To study methods used to quantify the uncertainty in radar – raingauge merge precipitation estimation and uncertainty in hydrological modeling, in order to develop a methodology for the analysis of their individual contributions in the uncertainty of rainfall - runoff estimation.The work is divided in two parts, the first one evaluates: How the uncertainty of radar precipitation estimation can be quantified? To address the question, the geostatistical approach by Kriging with External Drift (KED) and Stochastic Generation of Precipitation was used, which allows to model the spatio - temporal structure of errors. The method was applied in the Cévennes - Vivarais region (France), where there is a very rich observation system. The second part explains: How can it be quantified the uncertainty of the hydrological simulation coming from the radar precipitation estimates and hydrological modeling process? In this point, the hydrological mesoscale computation tool was developed; it is distributed hydrological software in time continuous, within the basis of the Curve Number and the Unit Hydrograph. It was applied in 20 spatio-temporal resolutions ranging from 10 to 300 km2 and 1 to 6 hours in the Ardèche (~ 1971 km2) and the Gardon (1810 km2) basins. After a sensitivity analysis, the model was simplified with 4 parameters and the uncertainty of the chain of process was analyzed: 1) Precipitation estimation; 2) Hydrological modeling; and 3) Rainfall - runoff estimation, by using the coefficient of variation of the simulated flow.It has been shown that KED is a method that provides the standard deviation of the precipitation estimation, which can be transformed into a stochastic estimation of the local error. In the chain of processes: 1) Uncertainty in precipitation estimation increases with decreasing spatio-temporal scale, and its effect is attenuated by hydrological modeling, probably due by storage and transport properties of the basin; 2) The uncertainty of hydrological modeling depends on the simplification of hydrological processes and not on the surface of the basin; 3) Uncertainty in rainfall - runoff treatment is the result of the amplified combination of precipitation and hydrologic modeling uncertainties.

This thesis provides a novel investigation into rainfall-runoff processes occurring within a unique two-tiered depth-driven overland flow physical modelling environment, as well as within a numerical model context where parameterisation and DEM/building resolution influences have been investigated using an innovative de-coupled methodology. Two approaches to simulating urban rainfall-runoff responses were used. Firstly, a novel, 9 m2 physical modelling environment consisting of a: (i) a low-cost rainfall simulator component able to simulate consistent, uniformly distributed rainfall events of varying duration and intensity, and; (ii) a modular plot surface layer was used. Secondly, a numerical hydroinundation model (FloodMap2D-HydroInundation) was used to simulate a short-duration, high intensity surface water flood event (28th June 2012, Loughborough University campus). The physical model showed sensitivities to a number of meteorological and terrestrial factors. Results demonstrated intuitive model sensitivity to increasing the intensity and duration of rainfall, resulting in higher peak discharges and larger outflow volumes at the model outflow unit, as well as increases in the water depth within the physical model plot surface. Increases in percentage permeability were also shown to alter outflow flood hydrograph shape, volume, magnitude and timing due to storages within the physical model plot. Thus, a reduction in the overall volume of water received at the outflow hydrograph and a decrease in the peak of the flood event was observed with an increase in permeability coverage. Increases in the density of buildings resulted in a more rapid receding limb of the hydrograph and a steeper rising limb, suggesting a more rapid hydrological response. This indicates that buildings can have a channelling influence on surface water flows as well as a blockage effect. The layout and distribution of permeable elements was also shown to affect the rainfall-runoff response recorded at the model outflow, with downstream concentrated permeability resulting in statistically different hydrograph outflow data, but the layout of buildings was not seen to result in significant changes to the outflow flood hydrographs; outflow hydrographs appeared to only be influenced by the actual quantity and density of buildings, rather than their spatial distribution and placement within the catchment. Parameterisation of hydraulic (roughness) and hydrological (drainage rate, infiltration and evapotranspiration) model variables, and the influence of mesh resolution of elevation and building elements on surface water inundation outputs, both at the global and local level, were studied. Further, the viability of crowdsourced approaches to provide external model validation data in conjunction with dGPS water depth data was assessed. Parameterisation demonstrated that drainage rate changes within the expected range of parameter values resulted in considerable losses from the numerical model domain at global and local scales. Further, the model was also shown to be moderately sensitive to hydraulic conductivity and roughness parameterisation at both scales of analysis. Conversely, the parameterisation of evapotranspiration demonstrated that the model was largely insensitive to any changes of evapotranspiration rates at the global and local scales. Detailed analyses at the hotspot level were critical to calibrate and validate the numerical model, as well as allowing small-scale variations to be understood using at-a-point hydrograph assessments. A localised analysis was shown to be especially important to identify the effects of resolution changes in the DEM and buildings which were shown to be spatially dependent on the density, presence, size and geometry of buildings within the study site. The resolution of the topographic elements of a DEM were also shown to be crucial in altering the flood characteristics at the global and localised hotspot levels. A novel de-coupled investigation of the elevation and building components of the DEM in a strategic matrix of scenarios was used to understand the independent influence of building and topographic mesh resolution effects on surface water flood outputs. Notably, the inclusion of buildings on a DEM surface was shown to have a considerable influence on the distribution of flood waters through time (regardless of resolution), with the exclusion of buildings from the DEM grid being shown to produce less accurate results than altering the overall resolution of the horizontal DEM grid cells. This suggests that future surface water flood studies should focus on the inclusion and representation of buildings and structural features present on the DEM surface as these have a crucial role in modifying rainfall-runoff responses. Focus on building representation was shown to be more vital than concentrating on advances in the horizontal resolution of the grid cells which make up a DEM, as a DEM resolution of 2 m was shown to be sufficiently detailed to conduct the urban surface water flood modelling undertaken, supporting previous inundation research.

Neste estudo, foi realizada uma revisão dos problemas observados na modelagem chuva-vazão, que influenciam a incerteza das condições iniciais dos processos de previsão de vazão. Foi realizada, também, uma revisão do estado da arte de alguns dos modelos de previsão de vazão de curto prazo utilizados no Brasil e, por último, uma revisão das metodologias de atualização de dados empregadas em trabalhos passados. Mas o principal enfoque deste estudo foi à elaboração de uma metodologia de atualização de dados de entrada, baseada na correção do desvio entre a vazão de saída de um modelo hidrológico e a vazão observada, por meio da perturbação dos dados de entrada de precipitação. O estudo de caso está composto por três bacias: Bacia do rio Ijuí, Bacia do rio Tesouras e a Bacia do rio Canoas. Estas bacias foram escolhidas, pois apresentam características distintas, tanto físicas quanto climáticas e, além disso, pela existência de estudos prévios com o modelo hidrológico utilizado neste trabalho. O processo de avaliação do método foi realizado em três etapas: 1) utilizando séries sintéticas; 2) utilizando séries reais; 3) previsão de vazões com atualização de dados. As duas primeiras etapas utilizaram o modelo em modo atualização (“off-line”) e, a última, o modelo em modo de previsão (“on-line”). Para a aplicação do método é necessário estabelecer condições de parada, sendo então, propostos dois conjuntos de critérios de parada. Com isto, foi estabelecido um conjunto adequado de critérios para que estes fiquem fixos para possibilitar futuras aplicações em outros modelos ou em outros estudos de casos. A técnica de previsão de vazão de curto prazo utilizada foi com base na chuva prevista, sendo adotada a previsão de chuva conhecida ou perfeita. Foram geradas previsões diárias de até 7 dias, durante 20 dias contínuos, escolhendo-se dois eventos de diferentes características em cada uma das bacias do estudo de caso. Em modo previsão os resultados se mostraram promissores, o objetivo desejado inicialmente foi atingido pelos dois conjuntos de critérios de parada propostos. Conseguiu-se ter um ganho significativo até o quarto dia de previsão, como, também, melhoras nos períodos de subidas do hidrograma, porém nos períodos de estiagens o ganho foi quase nulo. Além disso, este trabalho mostrou a viabilidade da utilização do modelo IPH II para a geração de previsões de vazões baseadas em previsão de chuva. / In this study a review of the problems observed in rainfall-runoff modeling has been made, which influence the uncertainty of initial conditions of flow forecasting processes, as well as a review of the state of the art of some of the short-term flow forecasting models used in Brazil and the data update methodologies used in many past jobs. However the focus of this study has been the development of a data entry update methodology based on the correction of the deviation between the output flow of a hydrological model and the observed flow, by means of the disruption of rainfall input data. The case study is composed of the three river basins: River Ijuí, River Tesouras and Canoas. These basins have been chosen due to their different characteristics, both physical and climate, besides having been used in previous studies of the hydrological model used. The evaluation process of the method is done in three steps: 1) using synthetic series; 2) using real series; 3) stream flow forecasting with data update, the first two with the model in update mode ("off-line") and the last in predict mode ("on-line"). For the application of this method is necessary to establish stopping conditions for application, and for this have been proposed two sets of stop criteria. With this, intended to establish an appropriate set of criteria so that they become fixed to permit future applications in other models. The short-term flow forecasting technique used has been based on the forecast rain, adopted the rain forecast known or perfect. Predictions have been generated daily up to 7 days, for 20 consecutive days, choosing two events of different features in each case study basins. In predict mode the results have been promissory, the desired goal initially achieved by the two sets of proposed stopping criteria. It was possible to have a significant gain until the fourth day forecast also improvements in periods of hydrograph increases but not during periods of drought the gain was almost nil. This work has also showed the ability to generate predictions of rain forecast based flow as the IPH II model in real time.

This thesis deals with the event-based rainfall-runoff modelling of the selected river basin. This thesis is based on my previous work "Factors affecting the water discharge from the river basin during rainfall-runoff events". In that work I described factors, which have effect on water runoff from the river basin. This thesis was solved on basin of Jílecký stream. Water runoff from basin is affected with a number of factors, the most significant are slope of the terrain, soil saturation, geological and pedological conditions, vegetation cover and anthropogenic influence. Calculations of direct runoff were realised with method of CN curves, with using BPEJ map, land use map gained from Corine Land Cover 2006 and maximum daily precipitation sums with 2, 10, 20, 50 and 100 years probabilities recurrence obtained from the rainfall station Netřebice. Calculations were performed in a numerical method using vector data and a raster method performed in ArcMap. In the next step I performed simulations of various scenarios of change in river basic characteristics such as soil saturation change, grassing of arable land with a slope greater than 12°, grassing of all arable land and enlargement the built-up area in the river basin.

Esta pesquisa teve por objetivo geral analisar a relação existente entre as variáveis chuva e vazão na bacia hidrográfica do Rio Paranaíba, abrangendo áreas dos estados de Goiás - (GO), Minas Gerais - (MG), Mato Grosso do Sul - (MS) e do Distrito Federal - (DF), Brasil. A bacia de estudo está inserida na região hidrográfica do Paraná, ocupando parte das regiões Centro- Oeste e Sudeste do país e possui uma área de drenagem de 223.000 km². Para a realização deste trabalho foram utilizados dados pluviométricos e fluviométricos diários, disponibilizados pela Agência Nacional de Águas (ANA) de 52 postos, sendo 26 para cada variável, compreendendo uma série histórica de 38 anos (1975 a 2012). Após a tabulação dos dados, foram desenvolvidas as seguintes etapas que contribuíram para o entendimento da relação chuva-vazão: estatística prévia dos dados, coeficiente de variação, determinação de vazões específicas, Índice Padronizado de Estiagem Pluviométrica (IESP), pluviogramas e fluviogramas, gráficos de dispersão, coeficientes de correlação de Pearson entre as duas variáveis e Decomposição das Séries para análise de tendências. Os resultados demonstraram uma média anual de precipitação de 1.468,4 mm, ocorrendo de forma sazonal, sendo de outubro a março o período chuvoso e de setembro a abril o período de estiagem. O regime de vazões acompanhou o comportamento pluviométrico, apresentando durante a estação chuvosa, um aumento nos valores médios de vazões que foram de 28,4 m³/s em outubro a 88,1 m³/s em março e uma diminuição nos valores médios de vazões dentro do período de estiagem que foram de 69,6 m³/s em abril a 24,6 m³/s em setembro. Diante de todos os postos, os picos e as baixas de precipitações incidiram diretamente no regime de vazões, devendo-se considerar o período de retardo do aumento da vazão em relação ao início das chuvas. Quanto as correlações entre as variáveis chuva e vazão, esta se mostrou positiva e forte, comprovando o fato de que quanto maior o acumulado total de chuvas, maior também é o volume de vazões. A análise de tendências utilizando a Decomposição das Séries evidenciou tendência de redução das vazões em 42,3% dos postos, aumento em 34,6% dos postos, 15,4% primeiramente de redução e a posteriori de aumento e 7,7% inicialmente de aumento e depois de redução do regime fluviométrico. / The main objective of this research was to analyse the association between rainfall and runoff variables in the Paranaíba River Basin which comprehends some areas of the states of Goiás - (GO), Minas Gerais - (MG), Mato Grosso do Sul - (MS) e do Distrito Federal - (DF), Brazil. The study basin is located in the Paraná Hydrographic Region, comprising part of the Midwest and Southeast regions and covering a drainage area of 223.000 km². For the purpose of this research, daily pluviometric and fluviometric data were obtained from the Brazilian Government National Water Agency (ANA) of 52 stations, 26 for each variable, based on a 38 year series (from 1975 to 2012). After tabulating the data, the following methodologies contributed to the understanding of the relationship between rainfall-runoff: preliminary statistical data, coefficient of variation, determination of specific flows, The Standardized Precipitation Index (SPI), rainfall charts and stage hydrographs, dispersion graphs, Pearson Linear Correlation between both variables and Decomposition of Series for trend analysis. The results indicate an annual average of precipitation of 1.468,4 mm in a seasonal regime from October to March (rainy season) and from April to September (dry season). The runoff regime accompanies the rainfall, presenting during the rainy season, an increase in the mean values from 28,4 m³/s in October to 88,1 m³/s in March and a decrease within the dry season from 69,6 m³/s in April to 24,6 m³/s in September. For all the stations, the peaks and low rainfall focused directly on the runoff regime and it should be considered the delay period in the increase of the runoff in relation to the beginning of the rain. With regard to the correlation between rainfall and runoff variables, it was positive and strong, which shows that the higher the total amount of rainfall is, the greater the runoff is. The trend analysis using the Decomposition of Series presented a runoff reduction trend of 42,3% of the stations, an increase of 34,6% of them, firstly 15,4% of reduction and next of increase and initially7,7% of increase and then a reduction of the fluviometric regime. / Dissertação (Mestrado)

Neste estudo, foi realizada uma revisão dos problemas observados na modelagem chuva-vazão, que influenciam a incerteza das condições iniciais dos processos de previsão de vazão. Foi realizada, também, uma revisão do estado da arte de alguns dos modelos de previsão de vazão de curto prazo utilizados no Brasil e, por último, uma revisão das metodologias de atualização de dados empregadas em trabalhos passados. Mas o principal enfoque deste estudo foi à elaboração de uma metodologia de atualização de dados de entrada, baseada na correção do desvio entre a vazão de saída de um modelo hidrológico e a vazão observada, por meio da perturbação dos dados de entrada de precipitação. O estudo de caso está composto por três bacias: Bacia do rio Ijuí, Bacia do rio Tesouras e a Bacia do rio Canoas. Estas bacias foram escolhidas, pois apresentam características distintas, tanto físicas quanto climáticas e, além disso, pela existência de estudos prévios com o modelo hidrológico utilizado neste trabalho. O processo de avaliação do método foi realizado em três etapas: 1) utilizando séries sintéticas; 2) utilizando séries reais; 3) previsão de vazões com atualização de dados. As duas primeiras etapas utilizaram o modelo em modo atualização (“off-line”) e, a última, o modelo em modo de previsão (“on-line”). Para a aplicação do método é necessário estabelecer condições de parada, sendo então, propostos dois conjuntos de critérios de parada. Com isto, foi estabelecido um conjunto adequado de critérios para que estes fiquem fixos para possibilitar futuras aplicações em outros modelos ou em outros estudos de casos. A técnica de previsão de vazão de curto prazo utilizada foi com base na chuva prevista, sendo adotada a previsão de chuva conhecida ou perfeita. Foram geradas previsões diárias de até 7 dias, durante 20 dias contínuos, escolhendo-se dois eventos de diferentes características em cada uma das bacias do estudo de caso. Em modo previsão os resultados se mostraram promissores, o objetivo desejado inicialmente foi atingido pelos dois conjuntos de critérios de parada propostos. Conseguiu-se ter um ganho significativo até o quarto dia de previsão, como, também, melhoras nos períodos de subidas do hidrograma, porém nos períodos de estiagens o ganho foi quase nulo. Além disso, este trabalho mostrou a viabilidade da utilização do modelo IPH II para a geração de previsões de vazões baseadas em previsão de chuva. / In this study a review of the problems observed in rainfall-runoff modeling has been made, which influence the uncertainty of initial conditions of flow forecasting processes, as well as a review of the state of the art of some of the short-term flow forecasting models used in Brazil and the data update methodologies used in many past jobs. However the focus of this study has been the development of a data entry update methodology based on the correction of the deviation between the output flow of a hydrological model and the observed flow, by means of the disruption of rainfall input data. The case study is composed of the three river basins: River Ijuí, River Tesouras and Canoas. These basins have been chosen due to their different characteristics, both physical and climate, besides having been used in previous studies of the hydrological model used. The evaluation process of the method is done in three steps: 1) using synthetic series; 2) using real series; 3) stream flow forecasting with data update, the first two with the model in update mode ("off-line") and the last in predict mode ("on-line"). For the application of this method is necessary to establish stopping conditions for application, and for this have been proposed two sets of stop criteria. With this, intended to establish an appropriate set of criteria so that they become fixed to permit future applications in other models. The short-term flow forecasting technique used has been based on the forecast rain, adopted the rain forecast known or perfect. Predictions have been generated daily up to 7 days, for 20 consecutive days, choosing two events of different features in each case study basins. In predict mode the results have been promissory, the desired goal initially achieved by the two sets of proposed stopping criteria. It was possible to have a significant gain until the fourth day forecast also improvements in periods of hydrograph increases but not during periods of drought the gain was almost nil. This work has also showed the ability to generate predictions of rain forecast based flow as the IPH II model in real time.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / O objetivo geral foi quantificar e avaliar os principais processos hidrol?gicos, incluindo a produ??o de sedimentos, da Bacia Experimental de Aiuaba (BEA) para o per?odo de 2003-2007. A BEA, com ?rea de 12 km2, est? localizada no sert?o dos Inhamus em ?rea de conserva??o ambiental do bioma caatinga na Esta??o Ecol?gica (ESEC) de Aiuaba, Cear?, pertencente ? bacia do Alto Jaguaribe. Realizou-se caracteriza??o da fisiografia, medi??o de vari?veis hidrol?gicas, avalia??o de processos chuva-defl?vio na bacia hidrogr?fica e no reservat?rio que a controla. Conclui-se que: o processo de infiltra??o do a?ude da BEA (capacidade de 59.700 m3) ? relevante e da mesma ordem de grandeza da evapora??o; a recarga subterr?nea direta ao lago ? desprez?vel em rela??o ? evapora??o e ? infiltra??o; durante os eventos chuva-defl?vio a evapora??o, a infiltra??o e a recarga subterr?nea s?o desprez?veis em rela??o ao defl?vio afluente e ? precipita??o direta sobre o lago. Conclui-se, dos eventos chuva-defl?vio e produ??o de sedimentos, que: o coeficiente de runoff (CR) dos eventos ? extremamente baixo, sendo as l?minas d??gua escoadas menores que as l?minas interceptadas pela vegeta??o; o N?mero de Curva (CN) m?dio por evento foi 42, com m?ximo de 59 e m?nimo de 27; a produ??o de sedimentos apresentou valores entre 9 e 291 kg/km2 para eventos de 2006-2007, e m?dia de 97 kg/km2 por evento; o escoamento superficial ? ef?mero: o tempo de defl?vio foi somente 64% maior que o tempo da precipita??o por evento; as perdas elevadas no escoamento superficial ocorrem, em parte, por perdas em tr?nsito no riacho principal; a l?mina escoada na bacia do riacho secund?rio foi oito vezes maior que na bacia do riacho principal em 2007. Inferiu-se que o mecanismo de gera??o de defl?vio superficial predominante ? o hortoniano e que, se relevante, a contribui??o do escoamento subsuperficial deve ocorrer a uma profundidade menor que 15 cm. O CR m?dio anual da BEA foi 6,54% (m?ximo de 31,08% e m?nimo de 0,13%). No ano de 2004 a l?mina escoada na BEA foi 35 vezes maior que a soma das l?minas escoadas nos demais anos. Dos 1543 dias monitorados, em apenas 139 dias ocorreu escoamento (9%), sendo 28 dias de escoamento nos anos n?o-chuvosos (1,8%). A produ??o de sedimentos em 2007 foi cinco vezes maior que em 2006, e para o bi?nio 2006-07 o m?s de maior escoamento (abril de 2007) foi respons?vel por 71% da produ??o de sedimentos. Comparando-se o CR anual da BEA com outras bacias no rio Jaguaribe, a BEA foi uma das que apresentou menor coeficiente de runoff. Formulou-se a hip?tese de a BEA ser uma ?rea de recarga de aq??fero fraturado, que condiciona processos hidrol?gicos superficiais.

The conceptual rainfall-runoff model Hysim is used to estimate the flow in ungauged catchments in Scotland by Scottish Water. However, there are non-quantified uncertainties associated with the outcomes of the modelling strategy used. In order to identify and quantify these uncertainties it was necessary to use the framework of proxy-basin validation in order to evaluate the performance of different modelling strategies.   The proxy-basin validation test requires hydrologically analogous catchments for the evaluation of models, a Region Of Influence regionalisation method was used in order group selected catchments by Q95(%MF). Four groups of four catchments were established, which covered Q95(%MF) 5-7%, 7-9%, 9-11% and 11-13%.   The allocation of “donor catchment” and “target catchment” for each Q95(%MF) group was accomplished through discussion with Scottish Water with respect to existing Scottish Water modelled catchments. A single donor catchment and three target catchments were therefore indicated for each group.   Two modelling strategies were developed by the study; the first full transposition method used the entire optimised parameter-set from the donor catchment with the exception of the target catchment’s “catchment area” parameter. The second partial transposition method used the entire optimal parameter-set with the exception of the target catchment’s “interception storage”, “time to peak”, “rooting depth” and “catchment area” parameters.    It was found that the full transposition method had the least uncertainty associated its use for flow estimation when the parameter-set was derived from a donor catchment calibration that was excellent. Contrarily, it was found that the partial transposition model method had the least uncertainty associated with flow estimation for parameter-sets that were derived from a relatively poor donor catchment calibration.   Encouraged by this testing framework, this study has suggested the use of catalogue of donor parameter-sets that can be used to estimate flow for catchments that are hydrologically similar. This strategy of hydrological modelling has been recommended to improve existing Scottish Water Hysim methodology.

Les modèles hydrologiques sont des outils indispensables pour calculer les débits a l’exutoire des bassins versants, la gestion des aménagements hydrauliques ou encore la prévision et la prévention des inondations. Les précipitations représentent la variable climatique principale à l’origine des débits des cours d’eau qui s’écoulent au sein d’un bassin versant. De ce fait, la réponse hydrologique du bassin est fortement dépendante de la représentativité des données d’entrée de précipitation.Les radars météorologiques, qui permettent aujourd’hui d’accéder a des mesures a haute résolution spatiale et temporelle des champs de précipitation, sont de plus en plus utilises dans le domaine de la prévision, pour le suivi des situations hydrométéorologiques. Cependant, la mesure des précipitations par radar est entachée d’erreurs qui peuvent affecter gravement la qualité des simulations de débit. De ce fait, l’utilisation des données de précipitations a haute résolution spatiale pour la modélisation hydrologique est souvent limitée par rapport a l’utilisation des données pluviométriques.Récemment, Météo-France a développe une réanalyse des lames d’eau au pas de temps horaire, sur une durée de 10 ans, en combinant l’ensemble des données de précipitation radar et pluviométriques : les mesures radars ont été corrigées et étalonnées avec le réseau de mesure au sol horaire et journalier. Dans cette thèse, nous proposons d’étudier l’intérêt de cette nouvelle base de données à haute résolution spatiale pour la modélisation pluie-débit.Dans un premier temps, nous avons développe et valide un modèle hydrologique semi-distribue qui a la capacité de fonctionner pour différentes résolutions spatiales, de la représentation globale jusqu’a une discrétisation spatiale très fine des bassins. Dans un deuxième temps, l’impact de la résolution spatiale des données d’entrée de précipitation sur la simulation des débits a été analysé. L’apport de l’information radar pour l’estimation des précipitations a été évalue par rapport a une utilisation exclusive des pluviomètres, par le biais de la modélisation pluie-débit en termes de précision des débits a l’exutoire des bassins. Enfin, le modèle semi-distribue TGR a été comparé avec le modèle global GRP actuellement opérationnel dans les Services de Prévision des Crues. L’originalité de notre travail réside sur l’utilisation de données d’observation sur un large échantillon de 181 bassins versants français représentant une grande diversité de tailles et conditions climatiques, ce qui nous permet d’apporter un diagnostic robuste et des éléments de réponse sur les problématiques scientifiques traitées. / Hydrologic models are essential tools to compute the catchment rainfall-runoff response required for river management and flood forecast purposes. Precipitation dominates the high frequency hydrological response, and its simulation is thus dependent on the way rainfall is represented. In this context, the sensitivity of runoff hydrographs to the spatial variability of forcing data is a major concern of researchers. However, results from the abundant literature are contrasted and it is still difficult to reach a clear consensus.Weather radar is considered to be helpful for hydrological forecasting since it provides rainfall estimates with high temporal and spatial resolution. However, it has long been shown that quantitative errors inherent to the radar rainfall estimates greatly affect rainfall-runoff simulations. As a result, the benefit from improved spatial resolution of rainfall estimates is often limited for hydrological applications compared to the use of traditional ground networks.Recently, Météo-France developed a rainfall reanalysis over France at the hourly time step over a 10-year period combining radar data and raingauge measurements: weather radar data were corrected and adjusted with both hourly and daily raingauge data. Here we propose a framework to evaluate the improvement in streamflow simulation gained by using this new high resolution product.First, a model able to cope with different spatial resolutions, from lumped to semi-distributed, was developed and validated. Second, the impact of spatial rainfall resolution input on streamflow simulation was investigated. Then, the usefulness of spatial radar data measurements for rainfall estimates was compared with an exclusive use of ground raingauge measurements and evaluated through hydrological modelling in terms of streamflow simulation improvements. Finally, semi-distributed modelling with the TGR model was performed for flood forecasting and compared with the lumped forecasting GRP model currently in use in the French flood forecast services. The originality of our work is that it is based on actual measurements from a large set of 181 French catchments representing a variety of size and climate conditions, which allows to draw reliable conclusions.

Cette thèse vise à explorer la question du changement d'échelle temporelle en modélisation hydrologique conceptuelle. Les principaux objectifs sont : (i) étudier les effets du changement du pas de temps sur les performances, les paramètres et la structure des modèles hydrologiques ; (ii) mettre au point un modèle pluie-débit applicable à différents pas de temps. Notre point de départ est le modèle global journalier GR4J, développé à Irstea. Ce modèle a été choisi comme le modèle de référence à adapter à d'autres résolutions plus fines, jusqu'à des pas de temps infra-horaires, en suivant une approche descendante. Pour nos tests, nous avons construit une base de données de 240 bassins versants non influencés en France, à différents pas de temps allant de 6 minutes à 1 jour, en utilisant: (i) les données pluviométriques à 6 minutes et la réanalyse des lames d'eau journalières à plus haute résolution spatiale ; (ii) les données de température journalière pour le calcul de l'évapotranspiration potentielle ; (iii) les données hydrométriques à pas de temps variable. Nous avons étudié l'impact de la distribution temporelle des entrées sur les performances du modèle en se focalisant sur la simulation de crue, sur la base de 2400 événements. Ensuite, notre évaluation du modèle a porté sur l'analyse de la cohérence des flux internes du modèle à différents pas de temps, afin d'assurer une performance satisfaisante à travers un fonctionnement du modèle cohérent. Notre diagnostic du modèle nous a permis d'identifier une amélioration de la structure du modèle à différents pas de temps infra-journaliers basée sur la complexification de la composante d'interception du modèle. / This thesis aims at exploring the question of temporal scaling in lumped conceptual hydrological modelling. The main objectives of the thesis are to: (i) study the effects of varying the modelling time step on the performance, parameters and structure of hydrological models; (ii) develop a hydrological model operating at different time steps, from daily to sub-hourly, through a unified, robust and coherent modelling framework at different time scales. Our starting point is the chain of conceptual rainfall-runoff models called ‘GR’, developed at Irstea, and in particular the daily ‘GR4J’ lumped model. The GR4J model will be the baseline model to be effectively downscaled up to sub-hourly time steps following a top-down approach. An hourly adaptation of this model had already been proposed in previous research studies, but some questions on the optimality of the structure at sub-daily time steps were still open. This thesis builds on these previous studies on the hourly model and responds to the operational expectations of improving and adapting the model at multiple sub-daily and sub-hourly time steps, which is particularly interesting for flood forecasting applications. For our modelling tests, we built a database of 240 unregulated catchments in metropolitan France, at multiple time steps, from 6-minute to 1 day, using fine time step hydro-climatic datasets available: (i) 6-min rain gauges and higher spatial-density daily reanalysis data for precipitation; (ii) daily temperature data for potential evapotranspiration (making assumptions on sub-daily patterns); (iii) sub-hourly variable time step streamflow data. We investigated the impact of the inputs temporal distribution on model outputs and performance in a flood simulation perspective based on 2400 selected flood events. Then our model evaluation focused on the consistency of model internal fluxes at different time steps, in order to ensure obtaining a satisfactory model performance by a coherent model functioning at multiple time steps. Our model diagnosis led us to identify and test a significant improvement of the model structure at sub-daily time steps based on the complexification of the interception component of the model. Thus, we propose a new version of the model at multiple sub-daily time steps, with the addition of an interception store without extra free parameters. Our tests also confirm the suitability at multiple time steps of a modified groundwater exchange function proposed earlier, leading to overall improved model accuracy and coherence.