A incorporação de novas tecnologias na pecuária, especialmente o confinamento de animais, proporcionou notável aumento da produtividade, otimizando o uso do solo. No entanto, esta técnica tem gerado um problema crucial à sustentabilidade da atividade: o manejo dos dejetos. Estes dejetos são normalmente lançados diretamente nos mananciais, distribuídos inadequadamente no solo, como fertilizante, ou ainda utilizados como complemento alimentar para peixes, bovinos, e até mesmo para suínos, contrariando Instruções Normativas do Ministério da Agricultura Pecuária e Abastecimento (MAPA) Nos. 07/04, 08/04 e 18/04, proibitivas em relação ao assunto. Quando os dejetos de animais são utilizados como fertilizantes em solos com elevado potencial à erosão, o volume de poluentes carreados e disponibilizados aos mananciais torna-se relevante, especialmente em relação aos nutrientes Nitrogênio (N) e Fósforo (P). De notável interesse, por ser um pólo econômico importante e de grande concentração de granjas de aves, o município de Descalvado, situado na parte central do Estado de São Paulo, é alvo deste tipo de poluição por apresentar solo com elevado potencial erosivo. Tendo como referência este problema ambiental, o estudo concentrou-se na quantificação da produção de sedimentos nas diversas áreas da microbacia do Rio Bonito, (Descalvado – SP), relacionando-as com a concentração e a distribuição local de granjas, o manejo dos dejetos e as práticas agrícolas de cada área. A partir dos resultados de simulação, com a utilização do modelo hidrossedimentológico AVSWAT em plataforma ARCVIEW 3.1, foi possível evidenciar regiões da microbacia que mantêm elevada taxa de fornecimento de nitrogênio (N) e fósforo (P) para os mananciais, provenientes dos dejetos animais, demonstrando-se coerentes com os dados de entrada de contaminação. Os resultados das simulações de erosão para os solos da microbacia do Rio Bonito também se demonstraram coerentes com a realidade brasileira, evidenciando ser o estudo de grande aplicabilidade e interesse para os gestores e tomadores de decisão da bacia hidrográfica. / The incorporation of new technologies on livestock, specially the confinement of animals, has brought considerable increase in the productivity, optimizing the use of the soil. However, this technique has been generating a crucial problem to the sustain of the activity: the management of dejects. These dejects are being commonly thrown directly into the water sources, improperly spread onto the soil, as fertilizer or, yet, used as alimentary complement for fish, bovines, and also to pigs, thwarting the Normative Instructions of Agriculture, Livestock and Supply Ministry (MAPA) Nos. 07/04, 08/04 e 18/04 MAPA. When the animal wastes are used as a fertilizer on the soil with high potential of erosion, an important charge of pollutants is then carried and made available to sources, especially in what concerns to Nitrogen (N) and Phosphorus (P). With an remarkable interest, because of being an important economic center and because it concentrates a great amount of chicken granges, the city of Descalvado, located in the center of the State of São Paulo (Brazil) has been a target to this type of pollution because of it’s soil feature that is high potentially erosive. By this environmental problem, the research concentrates itself in the quantification of the production of sediments in the several areas of Bonito’s river watershed (Descalvado – SP), relating them to the concentration and local distribution of the granges, the waste management and the agricultural practices of each areas. Starting from the simulation results, with the use of the mathematical model AVSWAT (Arc View Soil and Water Assessment Tool) in platform ARCVIEW 3.1, it was possible to evidence the critical areas in relation of pollution, mainly those ones that contributes with Phosphorous (P) and Nitrogen (N), provided by animal wastes. The results of erosion simulations for the soils of the Bonito’s river watershed were demonstrated coherent with the Brazilian reality, evidencing to be this research of great interest for the managers and decision makers of the watershed.

A incorporação de novas tecnologias na pecuária, especialmente o confinamento de animais, proporcionou notável aumento da produtividade, otimizando o uso do solo. No entanto, esta técnica tem gerado um problema crucial à sustentabilidade da atividade: o manejo dos dejetos. Estes dejetos são normalmente lançados diretamente nos mananciais, distribuídos inadequadamente no solo, como fertilizante, ou ainda utilizados como complemento alimentar para peixes, bovinos, e até mesmo para suínos, contrariando Instruções Normativas do Ministério da Agricultura Pecuária e Abastecimento (MAPA) Nos. 07/04, 08/04 e 18/04, proibitivas em relação ao assunto. Quando os dejetos de animais são utilizados como fertilizantes em solos com elevado potencial à erosão, o volume de poluentes carreados e disponibilizados aos mananciais torna-se relevante, especialmente em relação aos nutrientes Nitrogênio (N) e Fósforo (P). De notável interesse, por ser um pólo econômico importante e de grande concentração de granjas de aves, o município de Descalvado, situado na parte central do Estado de São Paulo, é alvo deste tipo de poluição por apresentar solo com elevado potencial erosivo. Tendo como referência este problema ambiental, o estudo concentrou-se na quantificação da produção de sedimentos nas diversas áreas da microbacia do Rio Bonito, (Descalvado – SP), relacionando-as com a concentração e a distribuição local de granjas, o manejo dos dejetos e as práticas agrícolas de cada área. A partir dos resultados de simulação, com a utilização do modelo hidrossedimentológico AVSWAT em plataforma ARCVIEW 3.1, foi possível evidenciar regiões da microbacia que mantêm elevada taxa de fornecimento de nitrogênio (N) e fósforo (P) para os mananciais, provenientes dos dejetos animais, demonstrando-se coerentes com os dados de entrada de contaminação. Os resultados das simulações de erosão para os solos da microbacia do Rio Bonito também se demonstraram coerentes com a realidade brasileira, evidenciando ser o estudo de grande aplicabilidade e interesse para os gestores e tomadores de decisão da bacia hidrográfica. / The incorporation of new technologies on livestock, specially the confinement of animals, has brought considerable increase in the productivity, optimizing the use of the soil. However, this technique has been generating a crucial problem to the sustain of the activity: the management of dejects. These dejects are being commonly thrown directly into the water sources, improperly spread onto the soil, as fertilizer or, yet, used as alimentary complement for fish, bovines, and also to pigs, thwarting the Normative Instructions of Agriculture, Livestock and Supply Ministry (MAPA) Nos. 07/04, 08/04 e 18/04 MAPA. When the animal wastes are used as a fertilizer on the soil with high potential of erosion, an important charge of pollutants is then carried and made available to sources, especially in what concerns to Nitrogen (N) and Phosphorus (P). With an remarkable interest, because of being an important economic center and because it concentrates a great amount of chicken granges, the city of Descalvado, located in the center of the State of São Paulo (Brazil) has been a target to this type of pollution because of it’s soil feature that is high potentially erosive. By this environmental problem, the research concentrates itself in the quantification of the production of sediments in the several areas of Bonito’s river watershed (Descalvado – SP), relating them to the concentration and local distribution of the granges, the waste management and the agricultural practices of each areas. Starting from the simulation results, with the use of the mathematical model AVSWAT (Arc View Soil and Water Assessment Tool) in platform ARCVIEW 3.1, it was possible to evidence the critical areas in relation of pollution, mainly those ones that contributes with Phosphorous (P) and Nitrogen (N), provided by animal wastes. The results of erosion simulations for the soils of the Bonito’s river watershed were demonstrated coherent with the Brazilian reality, evidencing to be this research of great interest for the managers and decision makers of the watershed.

L’objectif général de cette thèse est de caractériser la dynamique des transferts des bactéries fécales à l’aide d’une modélisation spatio-temporelle, à l’échelle du bassin versant (BV) dans une région agricole et à l’échelle événementielle. Ce projet vise à mieux comprendre l'influence des processus hydrologiques, les facteurs environnementaux et temporels impliqués dans l’explication des épisodes de contamination microbienne des eaux récréatives. Premièrement, un modèle bayésien hiérarchique a été développé pour quantifier et cartographier les niveaux de probabilité des eaux à être contaminées par des effluents agricoles, sur la base des données spectrales et des variables géomorphologiques. Par cette méthode, nous avons pu calculer les relations pondérées entre les concentrations d’Escherichia coli et la distribution de l’ensemble des paramètres agro-pédo-climatiques qui régissent sa propagation. Les résultats ont montré que le modèle bayésien développé peut être utilisé en mode prédictif de la contamination microbienne des eaux récréatives. Ce modèle avec un taux de succès de 71 % a mis en évidence le rôle significatif joué par la pluie qui est la cause principale du transport des polluants. Deuxièmement, le modèle bayésien a fait l’objet d'une analyse de sensibilité liée aux paramètres spatiaux, en utilisant les indices de Sobol. Cette démarche a permis (i) la quantification des incertitudes sur les variables pédologiques, d’occupation du sol et de la distance et (2) la propagation de ces incertitudes dans le modèle probabiliste c'est-à-dire le calcul de l’erreur induite dans la sortie par les incertitudes des entrées spatiales. Enfin, une analyse de sensibilité des simulations aux différentes sources d’incertitude a été effectuée pour évaluer la contribution de chaque facteur sur l’incertitude globale en prenant en compte leurs interactions. Il apparaît que sur l’ensemble des scénarios, l’incertitude de la contamination microbienne dépend directement de la variabilité des sols argileux. Les indices de premier ordre de l’analyse de Sobol ont montré que parmi les facteurs les plus susceptibles d’influer la contamination microbienne, la superficie des zones agricoles est le premier facteur important dans l'évaluation du taux de coliformes. C’est donc sur ce paramètre que l’attention devra se porter dans le contexte de prévision d'une contamination microbienne. Ensuite, la deuxième variable la plus importante est la zone urbaine avec des parts de sensibilité d’environ 30 %. Par ailleurs, les estimations des indices totaux sont meilleures que celles des indices de premier ordre, ce qui signifie que l’impact des interactions paramétriques est nettement significatif pour la modélisation de la contamination microbienne Enfin, troisièmement, nous proposons de mettre en œuvre une modélisation de la variabilité temporelle de la contamination microbiologique du bassin versant du lac Massawippi, à partir du modèle AVSWAT. Il s'agit d'une modélisation couplant les composantes temporelles et spatiales qui caractérisent la dynamique des coliformes. La synthèse des principaux résultats démontrent que les concentrations de coliformes dans différents sous-bassins versants se révèlent influencées par l’intensité de pluie. La recherche a également permis de conclure que les meilleures performances en calage sont obtenues au niveau de l'optimisation multi-objective. Les résultats de ces travaux ouvrent des perspectives encourageantes sur le plan opérationnel en fournissant une compréhension globale de la dynamique de la contamination microbienne des eaux de surface. / Abstract : The aim of this study was to predict water faecal contamination from a bayesian probabilistic model, on a watershed scale in a farming area and on a factual scale. This project aims to better understand the influence of hydrological, environmental and temporal factors involved in the explanation of microbial contamination episodes of recreational waters. First, a bayesian probabilistic model: Weight of Evidence was developed to identify and map the probability of water levels to be contaminated by agricultural effluents, on the basis of spectrals data and geomorphologic variables. By this method, we were able to calculate weighted relationships between concentrations of Escherichia coli and distribution of key agronomic, pedologic and climatic parameters that influence the spread of these microorganisms. The results showed that the Bayesian model that was developed can be used as a prediction of microbial contamination of recreational waters. This model, with a success rate of 71%, highlighted the significant role played by the rain, which is the main cause of pollution transport. Secondly, the Bayesian probabilistic model has been the subject of a sensitivity analysis related to spatial parameters, using Sobol indications. This allowed (1) quantification of uncertainties on soil variables, land use and distance and (2) the spread of these uncertainties in the probabilistic model that is to say, the calculation of induced error in the output by the uncertainties of spatial inputs. Lastly, simulation sensitivity analysis to the various sources of uncertainty was performed to assess the contribution of each factor on the overall uncertainty taking into account their interactions. It appears that of all the scenarios, the uncertainty of the microbial contamination is directly dependent on the variability of clay soils. Sobol prime indications analysis showed that among the most likely to influence the microbial factors, the area of farmland is the first important factor in assessing the coliforms. Importance must be given on this parameter in the context of preparation for microbial contamination. Then, the second most important variable is the urban area with sensitivity shares of approximately 30%. Furthermore, estimates of the total indications are better than those of the first order, which means that the impact of parametric interaction is clearly significant for the modeling of microbial contamination. Thirdly, we propose to implement a temporal variability model of microbiological contamination on the watershed of Lake Massawippi, based on the AVSWAT model. This is a model that couples the temporal and spatial components that characterize the dynamics of coliforms. The synthesis of the main results shows that concentrations of Escherichia coli in different sub-watersheds are influenced by rain intensity. Research also concluded that best performance is obtained by multi-objective optimization. The results of these studies show the prospective of operationally providing a comprehensive understanding of the dynamics of microbial contamination of surface water.