Estudos hidrológicos são extremamente importantes em projetos de obras lineares, nas quais o traçado deve minimizar o risco de instabilidade tanto na fase de construção como na fase de operação. O escoamento superficial, além de ser um parâmetro fundamental para a definição do traçado e dos projetos subsequentes, influencia diretamente a dinâmica dos processos geológico-geotécnicos na área do empreendimento. A presente pesquisa propõe um método para realizar uma estimativa das vazões máximas nas travessias de obras civis lineares, integrando modelos hidrológicos obtidos com Sistema de Informação Geográfica (SIG) e métodos usuais de cálculo de vazões de cheia. O método foi aplicado em um setor do oleoduto São Paulo – Brasília (OSBRA), entre os municípios de São Simão e Cravinhos (SP). O modelo hidrológico foi obtido no software ArcGIS 9.3, a partir da definição de uma área mínima de contribuição de 5 hectares, adequada para a escala da base cartográfica digital (1:10.000) e para as características da área de estudo. As 29 bacias de contribuição delimitadas foram posteriormente validadas na vistoria de campo. A compatibilidade entre as bacias geradas pelo modelo hidrológico e as bacias identificadas visualmente na área de estudo foi satisfatória. As vazões máximas foram calculadas pelo Método Racional (bacias com área inferior a 2 km²) e pelo Método Racional Modificado (bacias com área superior a 2 km²), que abrangeu o Método de McMath, o Método Racional com expoente redutor de área e o Método Racional com coeficiente de retardo, sendo o último o que apresentou os resultados mais razoáveis. O cálculo das vazões de cheia foi realizado para períodos de retorno de 10 e 50 anos, a partir dos quais foram gerados Mapas de Vazões Máximas, que foram utilizados para inferência de riscos de eventos perigosos de natureza geológico-geotécnica causados pela ação das águas pluviais na região do oleoduto. Como o traçado do oleoduto foi posicionado ao longo dos divisores principais, não foram identificados locais críticos. Posteriormente, o traçado do oleoduto foi utilizado como referência para uma aplicação do método proposto em um projeto de drenagem. As bacias com valores de vazões máximas classificados com muito baixos não foram incluídas devido aos fluxos pouco significativos. Para as bacias com valores de vazões de cheia classificados como baixos e médios, sugeriu-se a utilização de dispositivos de drenagem superficial. Para as bacias com vazões máximas classificadas como altas e muito altas, foi proposta a utilização de dispositivos de drenagem de transposição de talvegues. Os resultados obtidos na pesquisa permitiram a consolidação do método proposto para aplicação em outros tipos de obras lineares e em locais com diferentes características ambientais. / Hydrological studies are extremely important in linear constructions projects, in which the routing must minimize the risk of instability both during construction and in operation phase. The surface runoff, in addition of being a fundamental parameter to routing definition and subsequent projects, directly influences the dynamics of geological-geotechnical processes in the enterprise area. The present research proposes a method to estimate maximum flows in crossing locations in linear civil constructions, integrating hydrological models obtained with Geographic Information System (GIS) and usual methods of peak flows calculation. The method was applied in a sector of São Paulo – Brasília (OSBRA) oil pipeline, between the municipalities of São Simão and Cravinhos (SP). The hydrological model was obtained in ArcGIS 9.3 software, from the definition of a minimal area of contribution of 5 hectares, adequate for the scale of the digital cartographic base (1:10.000) and for the study area characteristics. The 29 delimited watersheds were subsequently validated in the field visit. The compatibility between watersheds generated in the hydrological model and watersheds visually identified in the study area was satisfactory. The maximum flows were calculated by Rational Method (watersheds with area less than 2 km²) e by Modified Rational Method (watersheds with area higher than 2 km²), which included McMath Method, Rational Method with reducing exponent area and Rational Method with retard coefficient, and the latter presented the most reasonable results. Peak flows calculation was performed for return periods of 10 and 50 years, from which were generated Maximum Flows Maps, which were used for inference of risks of hazardous events of geological-geotechnical nature caused by rainwater action in the pipeline region. The pipeline routing was positioned along the main dividers, therefore critical locations were not identified. Subsequently, the pipeline routing was used as a reference for application of the proposed method in a drainage project. Basins with maximum flows classified as very low were not included due to its low significance flows. For basins with peak flows values classified as low and medium, it was suggested the use of surface drainage devices. For basin with maximum flows classified as high and very high, it was proposed the use of thalwegs transposition drainage devices. The results obtained in the research allowed the consolidation of the proposed method to application in other types of linear constructions and in locals with different environmental characteristics.

A partir de setembro de 1999 até novembro de 2000 estudou-se a várzea da margem direita da planície de inundação do Ribeirão do Feijão, com objetivo de verificação da várzea funcionando como filtro natural na contenção de matéria orgânica utilizando-se para esse estudo, um modelo de simulação desenvolvido com o software Stella. Foram coletados dados climatológicos oriundos de estação climatológica automática (temperatura do ar, umidade relativa, precipitação, radiação solar, velocidade e direção do vento e pressão barométrica), em piezômetros instalados na várzea (em número de 9) e coleta de amostras de água no rio, dados limnológicos: físicos (temperatura da água, turbidez, oxigênio dissolvido, condutividade e profundidade); químicos (fósforo total, fósforo total dissolvido, silicato, nitrogênio total, nitrato, nitrito e amônia), além de dados obtidos pelo estudo da literatura e trabalhos próximos da área de estudo já publicados. A partir do estudo da inter-relação dos processos existentes na várzea de inundação do Ribeirão do Feijão, elaborou-se modelo de simulação. As conclusões que se obtiveram indicam bom comportamento do modelo de simulação e, também, que estudos em escala de tempo mais reduzida sejam utilizados em trabalhos futuros para estudos de várzeas. Outra conclusão refere-se ao funcionamento da várzea como filtro natural, onde houve armazenamento de carbono (matéria orgânica). Constatou-se grande amplitude da variação diária da altura da lâmina d\'água devido à evapotranspiração. Recomenda-se a preservação desse rio porque 40% da água de superfície que abastece a cidade de São Carlos é oriunda desse manancial. / From September 1999 up to November 2000 a wetland of the right margin of Feijão river floodplain was studied with the objective to verify its activity as an natural filter to retain organic matter making use of a simulation model constructed with the help of the Stella software. Were collected climatological data from an automatic climatological station (air temperature, air moisture, rain, solar radiation, speed and wind direction and atmospheric pressure), from piezometers installed within the wetland (number of 9) and samples collected of river water, limnological data: physical data (water temperature, turbidity, dissolved oxygen, conductivity and depth); chemical data (total phosphorus, total dissolved phosphorus, silicate, total nitrogen, nitrate, nitrite and ammonium), moreover data obtained from literature and papers published of sites near the study area. From the interrelationship of processes occurring within the Feijão river floodplain wetland was constructed the simulation model. The obtained conclusions indicate the good simulation model behavior and show that time scales should be shorter in future wetland studies. Other conclusion refer to wetland conduction as a natural filter where occurred carbon storage (organic matter). Great amplitude of water table diary variation have been verified within the wetland due to evapotranspiration. Is possible to recommend the river preservation because 40% of the surface city supply is from this site.

Le risque hydrologique associé aux crues rapides survenant en région méditerranéenne est variable dans l'espace et le temps. Des travaux ont montré une vulnérabilité forte des personnes mobiles face aux crues touchant les bassins versants de petite taille (< 20 km²). Le risque hydrologique qui en résulte s'ajoute au risque, mieux connu, associé au débordement des grands cours d'eau. Ce constat définit les enjeux de la modélisation hydrologique régionale mise en place dans ce travail, qui a pour objectif la compréhension des processus de crue de l'échelle du petit bassin versant (1 km²) à l'échelle des bassins régionaux (> 1000 km²). Le modèle utilisé dans cette thèse est construit avec la plate-forme de modélisation LIQUID, qui permet un couplage « à la carte » de modules représentant les processus que l'on souhaite intégrer au modèle. C'est un modèle utilisé sans calibration, dans une démarche de test d'hypothèses de fonctionnement hydrologique des bassins. La zone d'étude est la région Cévennes-Vivarais. Les premières simulations effectuées montrent une sensibilité forte des résultats du modèle aux propriétés des sols (conductivité hydraulique, épaisseurs), ainsi qu'au type de condition limite employée (percolation profonde ou non). Une distinction apparaît entre les comportements en crue des bassins situés sur roche sédimentaire et des bassins schisteux situés sur les reliefs cévenols. Une version du modèle intégrant la représentation des écoulements latéraux de surface et de subsurface est également développée, et déployée sur le bassin expérimental du Cartaou (0.5 km²). Les premiers résultats soulignent l'important rôle joué par ces écoulements à petite échelle. Une méthodologie d'analyse des récessions de débit est mise en place pour l'estimation des propriétés hydrauliques et des épaisseurs des horizons de roche altérée, non-décrits par les bases de données des sols de la région. Les résultats de l'analyse suggèrent une hiérarchie dans les valeurs des paramètres, contrôlée par le type de géologie. Les horizons de roche altérée sont ensuite intégrés dans la version finale du modèle, qui est déployée à l'échelle de la région entière. Les simulations effectuées sur l'année 2008 montrent l'intérêt de la prise en compte de ces épaisseurs de roche altérée, tant pour la simulation des débits en crue que lors des périodes inter-événementielles. Les simulations mettent également en évidence des différences de comportement entre les bassins du nord de la région (Ardèche, Tarn) et ceux du sud (Cèze, Gardon, Vidourle) que l'on peut relier à la géologie. / The hydrological risk associated with flash-floods in the mediteranean area is temporally and spatially variable. Recent works showed the vulnerability of mobile people during floods occurring on small catchments (area < 20 km²). The associated risk, added to the better-known risk related to the overflow of larger rivers, defines the objectives of the present thesis. This work aims at developing a regional distributed hydrological model to study the flood processes over a large range of spatial scales, from small catchments (1 km²) to large regional catchments (> 1000 km²). The model used in this thesis is built within the LIQUID hydrological modeling platform, which allows a modular coupling of the chosen hydrological processes. The model is used without calibration, with the purpose to test different hypotheses on the hydrological functioning of catchments. The studied area is the Cevennes-Vivarais region (south-east of France). The first simulations show a high sensitivity of the model results to soil properties (hydraulic conductivity, thickness), and to the bottom flux boundary condition (deep percolation). A different behavior is observed between catchments located on sedimentary rocks and catchments located in the mountain area, on metamorphic schists. A version of the model which accounts for lateral surface and sub-surface flows is developed, and tested on the Cartaou (0.5 km²) experimental catchment. Preliminary results highlight the importance of lateral flow processes in flood generation at small spatial scales. A streamflow recession analysis is performed to estimate hydraulic and thickness properties of weathered rock horizons, which are not described by regional soil databases. The results show a hierarchy in the estimated parameters, in relation with geology. The weathered rock horizons are implemented in the hydrological model, which is used at the regional scale. Simulations performed over the 2008 year bring out the better results obtained when using the weathered rock layer, for flood events simulations as well as for long-term simulations. The results also show differences between the hydrological behavior of north catchments (Ardèche, Tarn) and south catchments (Cèze, Gardon, Vidourle), which can be linked to the geology.

Made available in DSpace on 2017-07-10T19:24:32Z (GMT). No. of bitstreams: 1 Jose Francisco de Gois.pdf: 2464234 bytes, checksum: 4e76f6a229f6e21ef5dce9e424bf08c2 (MD5) Previous issue date: 2008-07-28 / The use of soil is understood as a space that is being occupied by man, developing a set of activities of production and reproduction of a society, involving both urban and agricultural areas. Due to the economic development of the last few years, this subject has been studied more and more with a common concern: the quality of water. The objective of this paper is based on the elaboration of a diagnosis of the use and occupation of the soil of the São José river basin, in the city of Cascavel, PR, as a subsidy for the evaluation of the landscape, serving as a tool to the management and adequacy of the area for captation of water to human consumption. This study is of great importance, since the area is considered potential future supplying source for the city of Cascavel Pr. No study of the characterization of this hydrographic basin has been carried out so far. Satellite pictures and topographical letters of the area have been used and geoprocessing techniques provided by softwares ArcView and Spring have also been used. Initially, it was carried out the delimitation of the basin, the geomorphologic characterization of the physical factors of the use of the soil and types. The total area of the hydrographic basin is of 143,8 km ². The characteristics and physical indicators of the basin had demonstrated that the studied area presents a dense net of draining with great trend for peaks of overflow. The area presents six geomorphologic types: steep hillsides very soft and plains to alluvial (11%), hillsides (10.9%), very soft hillsides with rectilinear and irregular sources (34.8%), intermediate hillsides with irregular sources (14.8%), steep hillsides (28.9%) and areas of tops of mount (2.1%), all with formations of The Podzolic Latosol and the basalt presence. As to the definition and characterization of the uses of the soil of the basin it was evidenced the existence of five classes: areas of pastures (31.3%), temporary culture (43.5%), which are the predominant types of use, urban activity (1.7%), areas with intense administrative activity in the country property (1.7%) and forest-covered areas (21.6%). With these data, a comparative analysis was build up to compare the classes of use of the soil versus Geomorphology, where it has been verified that the developed activities can jeopardize the quality of the water, therefore maximize the geomorphologic degradation. For the relation Classes of Use of the soil versus Declivity it was verified that where there are areas of bigger declivity there are activities that are not compatible with it, requiring replanning. In the comparison of the Use of the soil with Law number 4771 of 1965, of the Brazilian Forest Code, it was evidenced that the areas of permanent preservation are very degraded, being invaded for the cattle raising activity and temporary culture, increasing the sand accumulation in the riverbed. In such way, as the hydrographic basin is potential future supplying source for human use, there is a need of monitoring and replanning the activities as well as the elaboration of projects that recover the ciliar bush, so that it prevents the sand accumulation of the hydric courses, and guarantees the quality of water, making it possible consumption of water in a safe way. / O uso do solo é um espaço ocupado pelo homem, onde desenvolve-se um conjunto de atividades de uma sociedade, englobando áreas urbanas e rurais. Com o desenvolvimento econômico, este tema é cada vez mais estudado, com o enfoque em comum: a qualidade da água. O objetivo deste trabalho baseiase na elaboração de um diagnóstico do uso e ocupação do solo da bacia do rio São José, município de Cascavel, PR, como subsídio para a avaliação da paisagem, servindo de ferramenta à gestão e adequação da área para captação de água, já que a área é considerada potencial futuro para o abastecimento do município de Cascavel Pr, não existindo nenhum estudo de caracterização da mesma. Utilizou-se imagens de satélites e cartas topográficas da área e aplicando técnicas de geoprocessamento, com os softwares ArcView e Spring, determinou-se a área da bacia hidrográfica (143,8 km²) e as características dos fatores físicos, que demonstraram uma área com densa rede de drenagem com grande tendência para picos de cheias. Ela apresenta seis tipos geomorfológicos: encostas muito suave e planícies aluvionar (11%), encostas escarpadas (10,9%), encostas muito suaves com vertentes retilíneas e irregulares (34,8%), encostas intermediárias com vertentes irregulares (14,8%), encostas íngremes (28,9%) e áreas de topos de morro (2,1%), todos com formações de Latossolo e a presença de basalto. Encontrou-se cinco classes de uso do solo: áreas de pastagens (31,3%), cultivo temporário (43,5%), atividade urbanas (1,7%), áreas com atividade intensas e administrativas na propriedade rural (1,7%) e áreas com cobertura florestal (21,6%). Construiu-se uma análise comparativa entre as Classes de Uso do Solo versus Geomorfologia, onde se verificou que as atividades desenvolvidas podem comprometer a qualidade da água, pois potencializam a degradação geomorfológica. Na relação Classes de Uso do Solo versus Declividade constatou-se que nas áreas de maior declividade se desenvolvem atividades não compatíveis com a mesma, devendo ocorrer um replanejamento. Na comparação do Uso do Solo com a Lei número 4771 (1965), do Código Florestal Brasileiro, vê-se que áreas de preservação permanente estão muito degradadas, sendo invadida pela atividade pecuarista e cultivo temporário, aumentando o assoreamento no leito do rio. Desta forma, como a bacia hidrográfica é potencial futuro para abastecimento humano, existe a necessidade de monitoramento e um replanejamento das atividades e a elaboração de projetos para a recuperação da mata ciliar, evitando o assoreamento dos cursos hídricos e garantindo a qualidade da água, possibilitando o consumo de forma segura.

Os processos de cheias em bacias urbanas vêm sendo agravados devido a uma série de motivos associados à ocupação desordenada do solo urbano. As medidas de controle de enchentes podem ter sua eficiência analisada através da modelagem hidrológica matemática. É neste sentido que o presente trabalho analisa a influência da urbanização sobre os distúrbios no escoamento superficial, por meio de simulações de cenários urbanísticos propostos, com a finalidade de servir como ferramenta de planejamento urbano. Para isso, definiu-se como área de estudo, parte da bacia do Córrego do Gregório, São Carlos - SP. As principais informações da bacia a serem consideradas são: topografia, hidrografia, uso do solo urbano, expansão da área urbana, áreas de proteção ambiental e divisores de microbacias. O modelo hidrológico utilizado é o IPHS-1, do tipo concentrado. Para essa análise são propostos e simulados cenários urbanísticos, baseados na adoção de medidas de controle de inundações não-estruturais, referindo-se principalmente, à conservação de áreas verdes e disciplinamento do uso e ocupação do solo, verificando sua eficiência na redução do volume escoado e atenuação das vazões de pico. / The flooding processes in urban basins have become worse due to many reasons. All of them associated with the disorganized occupancy of the urban area land. The efficiency of flood mitigation measures can be analyzed by mathematical modeling. This study aims to be used as a tool for urban planning and it analyses the influence of the urbanization processes on surface runoff, using simulation of several urbanization scenarios. The case study was undertaken at the Gregório River Basin in São Carlos - SP. The main information considered was topography, hydrology, urban land use, urbanization, protected land and sub-basins. The software used was IPHS-1 which is a lumped hydrologic model. In this research many urbanization scenarios are proposed and simulated. These views are based in many nonstructural flood mitigation alternatives such as land cover conservation, use and occupancy of the land, in order to check their efficiency in reducing the total volume of surface runoff and the peak flow.

Made available in DSpace on 2017-05-12T14:47:53Z (GMT). No. of bitstreams: 1 Jose Francisco de Gois.pdf: 2464234 bytes, checksum: 4e76f6a229f6e21ef5dce9e424bf08c2 (MD5) Previous issue date: 2008-07-28 / The use of soil is understood as a space that is being occupied by man, developing a set of activities of production and reproduction of a society, involving both urban and agricultural areas. Due to the economic development of the last few years, this subject has been studied more and more with a common concern: the quality of water. The objective of this paper is based on the elaboration of a diagnosis of the use and occupation of the soil of the São José river basin, in the city of Cascavel, PR, as a subsidy for the evaluation of the landscape, serving as a tool to the management and adequacy of the area for captation of water to human consumption. This study is of great importance, since the area is considered potential future supplying source for the city of Cascavel Pr. No study of the characterization of this hydrographic basin has been carried out so far. Satellite pictures and topographical letters of the area have been used and geoprocessing techniques provided by softwares ArcView and Spring have also been used. Initially, it was carried out the delimitation of the basin, the geomorphologic characterization of the physical factors of the use of the soil and types. The total area of the hydrographic basin is of 143,8 km ². The characteristics and physical indicators of the basin had demonstrated that the studied area presents a dense net of draining with great trend for peaks of overflow. The area presents six geomorphologic types: steep hillsides very soft and plains to alluvial (11%), hillsides (10.9%), very soft hillsides with rectilinear and irregular sources (34.8%), intermediate hillsides with irregular sources (14.8%), steep hillsides (28.9%) and areas of tops of mount (2.1%), all with formations of The Podzolic Latosol and the basalt presence. As to the definition and characterization of the uses of the soil of the basin it was evidenced the existence of five classes: areas of pastures (31.3%), temporary culture (43.5%), which are the predominant types of use, urban activity (1.7%), areas with intense administrative activity in the country property (1.7%) and forest-covered areas (21.6%). With these data, a comparative analysis was build up to compare the classes of use of the soil versus Geomorphology, where it has been verified that the developed activities can jeopardize the quality of the water, therefore maximize the geomorphologic degradation. For the relation Classes of Use of the soil versus Declivity it was verified that where there are areas of bigger declivity there are activities that are not compatible with it, requiring replanning. In the comparison of the Use of the soil with Law number 4771 of 1965, of the Brazilian Forest Code, it was evidenced that the areas of permanent preservation are very degraded, being invaded for the cattle raising activity and temporary culture, increasing the sand accumulation in the riverbed. In such way, as the hydrographic basin is potential future supplying source for human use, there is a need of monitoring and replanning the activities as well as the elaboration of projects that recover the ciliar bush, so that it prevents the sand accumulation of the hydric courses, and guarantees the quality of water, making it possible consumption of water in a safe way. / O uso do solo é um espaço ocupado pelo homem, onde desenvolve-se um conjunto de atividades de uma sociedade, englobando áreas urbanas e rurais. Com o desenvolvimento econômico, este tema é cada vez mais estudado, com o enfoque em comum: a qualidade da água. O objetivo deste trabalho baseiase na elaboração de um diagnóstico do uso e ocupação do solo da bacia do rio São José, município de Cascavel, PR, como subsídio para a avaliação da paisagem, servindo de ferramenta à gestão e adequação da área para captação de água, já que a área é considerada potencial futuro para o abastecimento do município de Cascavel Pr, não existindo nenhum estudo de caracterização da mesma. Utilizou-se imagens de satélites e cartas topográficas da área e aplicando técnicas de geoprocessamento, com os softwares ArcView e Spring, determinou-se a área da bacia hidrográfica (143,8 km²) e as características dos fatores físicos, que demonstraram uma área com densa rede de drenagem com grande tendência para picos de cheias. Ela apresenta seis tipos geomorfológicos: encostas muito suave e planícies aluvionar (11%), encostas escarpadas (10,9%), encostas muito suaves com vertentes retilíneas e irregulares (34,8%), encostas intermediárias com vertentes irregulares (14,8%), encostas íngremes (28,9%) e áreas de topos de morro (2,1%), todos com formações de Latossolo e a presença de basalto. Encontrou-se cinco classes de uso do solo: áreas de pastagens (31,3%), cultivo temporário (43,5%), atividade urbanas (1,7%), áreas com atividade intensas e administrativas na propriedade rural (1,7%) e áreas com cobertura florestal (21,6%). Construiu-se uma análise comparativa entre as Classes de Uso do Solo versus Geomorfologia, onde se verificou que as atividades desenvolvidas podem comprometer a qualidade da água, pois potencializam a degradação geomorfológica. Na relação Classes de Uso do Solo versus Declividade constatou-se que nas áreas de maior declividade se desenvolvem atividades não compatíveis com a mesma, devendo ocorrer um replanejamento. Na comparação do Uso do Solo com a Lei número 4771 (1965), do Código Florestal Brasileiro, vê-se que áreas de preservação permanente estão muito degradadas, sendo invadida pela atividade pecuarista e cultivo temporário, aumentando o assoreamento no leito do rio. Desta forma, como a bacia hidrográfica é potencial futuro para abastecimento humano, existe a necessidade de monitoramento e um replanejamento das atividades e a elaboração de projetos para a recuperação da mata ciliar, evitando o assoreamento dos cursos hídricos e garantindo a qualidade da água, possibilitando o consumo de forma segura.

Este trabalho buscou quantificar alguns impactos no ciclo hidrológico, especialmente o padrão de precipitação, decorrentes do desmatamento regional nas proximidades da rodovia Cuiabá-Santarém (BR-163), por meio de um experimento numérico de simulação da atmosfera com o modelo RAMS (Regional Atmospheric Modeling System), na versão brasileira (Brazilian RAMS – BRAMS), com alta resolução (célula de 16x16 km). Foi utilizado um cenário de desmatamento, provido por modelos empíricos de desmatamento, para o ano de 2026, numa situação sem governância, com um tempo de simulação de 40 dias entre 20 de Outubro a 30 de Novembro. Os dados de forçamento na fronteira utilizaram a reanálise do NCEP para o ano de 2002. Houve uma redução média de 7% do padrão de chuva na região após o desmatamento, na área perturbada, e não houve efeitos substanciais nas regiões além da fronteira de desmatamento como um todo. Porém, a distribuição heterogênea do uso da terra induziu à formação de uma célula térmica, sobre a região desmatada, que resultou em uma certa variabilidade espacial da chuva próxima ao setor de desmatamento. Uma célula térmica induziu o levantamento de massa (por convergência) aproximadamente acima da região desmatada, carregando vapor d’água proveniente das regiões de floresta nas adjacências, e promovendo a formação de chuva convectiva. A extensão da célula, entre os dois ramos descendentes, foi aproximadamente o dobro da extensão da faixa de desmatamento. Neste caso da BR-163, a célula foi levemente deslocada para oeste, onde ocorreu aumento da precipitação. A leste, e sobre o setor central do desmatamento, houve redução da precipitação. Notou-se uma pequena mudança na distribuição da chuva ao longo do dia no caso do desmatamento, que não mostrou um horário de máxima precipitação bem definido, e também sugeriu um pequeno aumento da chuva no período noturno. As respostas ao desmatamento ocorreram de forma diferenciada conforme a faixa de topografia analisada. Nas áreas além das fronteiras do desmatamento, houve um pequeno sinal de redução da chuva, nos setores de cota superior à 500 m. / This study aim was to evaluate some impacts on the hydrological cycle, specially the precipitation pattern, due to the regional deforestation along the corridor of the Cuiaba-Santarem highway (BR-163), using a high resolution (16x16 km grid) atmospheric model, the Regional Atmospheric Modeling System (RAMS), in its Brazilian version, the Brazilian RAMS or BRAMS. A deforestation scenario for 2026 has been provided by empirical models of deforestation, under no governance conditions (also known as the business-as-usual scenario) and it has been used in this study. The time length of simulation was 40 days, from October 10th to November 30th. The forcing data of 2002 were provided by the NCEP/NCAR Reanalysis Project. Mean rainfall decreased 7% in the region in which the forest was replaced by pasture. There were no substantial changes where the forest land cover was kept undisturbed. However, the rainfall showed spatial variability due to the local circulation (thermal) induced by land cover heterogeneity. Over the pasture area (deforestation), hot air rises by convergence carrying water vapor from the undisturbed forest located close to the pasture increasing the convective precipitation. This local cell is approximately twice as big as the deforestation length. In the BR-163 study case, the cell was located nearest to the west side of the land cover transition area (forest-pasture) where the rainfall rate increased. On the east side and over the deforestation area, the precipitation rate was reduced. The diurnal cycle of the precipitation has been slightly changed in the deforestation case. During the day, it was not possible to identify the rainfall maximum while at night it suggested a slightly increase of precipitation. The response of the fluxes and surface variables may be different depending on its topography level. A small rainfall reduction has been observed where the forest was kept undisturbed over 500 meters.

Coupled Thermal-Hydrological-Mechanical-Chemical (THMC) processes that exist in the development of different geo-resources (e.g. deep geothermal and shale gas) affect the fracture response (i.e. aperture and permeability), which in turn influences the reservoir production. The main goal of this study was to experimentally evaluate the impact of THMC processes on the response of rock specimens relevant for deep geothermal and shale gas formations. The effects of THMC processes were investigated on: (i) success of the hydraulic fracturing/hydro-shearing mechanism during stimulation stage, and (ii) closure of the created network of fractures during production stage. The elastic, cyclic, creep, and failure characteristics of different intact reservoir rocks in both short- and long-term were investigated to evaluate their response in stimulation stage. In addition, a series of flow tests on fractured reservoir cores were conducted to evaluate how THMC processes affect fracture response subjected to different stress levels, temperatures, composition of injected fluid, and injection rate. Moreover, the sensitivity of ultrasonic signatures (i.e. velocity, amplitude, attenuation, and time-frequency content) to (i) microstructural changes in the intact rocks, and (ii) flow-induced alterations of aperture/permeability in the fractured rocks were investigated. Analysis of hydraulic data, chemical composition of the effluent, ultrasonic signatures, and X-Ray micro-CT and SEM images, provided invaluable information that facilitated interpretation of the effects of coupled THMC processes on fracture response.

Malgré des conditions sèches qui prédominent depuis les années 1970, l’Afrique de l’Ouest a subi au cours des deux dernières décennies des épisodes d’inondations sévères qui ont provoqué de nombreux décès et dommages socio-économiques. L’émergence de ce nouveau problème montre une nouvelle facette de la sensibilité de cette région aux changements hydro-climatiques, appelant à une meilleure caractérisation de l’aléa inondation, des processus qui le génèrent, ainsi que la mise en place de méthodes permettant de projeter les évolutions futures de cet aléa pour mieux s’en prémunir.Dans ce contexte, la thèse cherche à répondre à trois questions principales :1) L’augmentation des dommages liés aux inondations s’est-elle accompagnée d’une intensification des crues extrêmes en Afrique de l’Ouest?2) Comment modéliser les orages de mousson, premier facteur de génération du ruissellement, afin d’explorer l’impact de leurs caractéristiques sur les crues?3) Compte tenu des changements climatiques à l’œuvre dans la région, à quelles tendances hydro-climatiques peut-on s’attendre dans le futur ?Dans un premier temps, on évalue l’évolution des crues en Afrique de l’Ouest au cours des soixante dernières années en utilisant de méthodes basées sur la théorie de valeurs extrêmes. Les résultats montrent une augmentation forte des événements hydrologiques extrêmes depuis les années 1970s dans les sous-bassins Sahéliens du fleuve Niger et depuis les années 1980s dans les sous-bassins soudano-guinéens du fleuve Sénégal. Les niveaux de retour calculés à partir des modèles non-stationnaires dépassent ceux qui ont été calculés avec un modèle stationnaire avec plus de 95% de certitude pour les périodes de retour les plus courtes (<10 ans).On présente ensuite des développements récents apportés à un simulateur stochastique d’orages de mousson à meso-échelle (StochaStorm). Ils incluent: une modélisation de l’occurrence de ces orages, la représentation explicite des valeurs de pluie extrêmes et une amélioration du schéma temporel d’intensité infra-événementielle. Implémenté et évalué à partir des donnés haute-résolution de l’observatoire AMMA-CATCH, le générateur montrent de très bonnes capacités à reproduire les propriétés des orages, confirmant son potentiel pour des études d’impact hydrologique.Enfin, une chaîne de modélisation est élaborée afin de proposer des projections hydrologiques pour le futur sur un bassin sahélien de meso-échelle (Dargol, 7000 km²). L’originalité de cette chaîne provient de la prise en compte du continuum d’échelles entre climat global et impact local à travers la représentation du régime des pluies à l’échelle des orages de mousson, dont les propriétés d’occurrence et d’intensité ont des impacts majeurs sur la réponse hydrologique. La chaîne de modélisation inclut le modèle climatique CP4-Africa, unique modèle à convection explicite fournissant des simulations de long terme en Afrique ; une méthode de débiaisage statistique; le simulateur Stochastorm ; et un modèle pluie-débit spécifiquement adapté aux processus hydrologique sahéliens. La chaine est évaluée sur une période de contrôle 1997-2006 puis utilisée pour des projections futures montrant une hausse par un facteur 1,5 des débits maximum annuels et un doublement des volumes moyens annuels à l’horizon 2100.Les résultats ont des implications majeures notamment pour l’ingénierie hydrologique. Les méthodes actuellement utilisées pour appréhender les risques hydrologiques dans la région ne prennent pas en compte la non-stationnarité hydro-climatique risquant de sous-évaluer l’aléa hydrologique et sous-dimensionner les ouvrages hydrauliques utilisés pour s’en protéger. La thèse suggère aussi quelques pistes afin mieux définir les trajectoires hydrologiques passées et futures en incluant, au-delà des précipitations, les changements sociétaux et environnementaux, leurs interactions et rétroactions dans les approches de modélisation. / The semi-arid regions of West Africa are known for their dry conditions which have predominated since the 1970s. In recent years, however, West Africa has witnessed a series of severe flooding events which caused widespread fatalities and socioeconomic damages. The emergence of this new problem demonstrates the sensitivity of the region to changes in the hydroclimatic system and calls for an improved characterization of flood hazard and the mechanisms that generate it. It also signals the need to develop projections for how flood hazard may evolve in the future in order to inform appropriate adaptation measures.In this context, the following PhD thesis seeks to answer three main questions:1) Is there a significant trend in extreme streamflow in West Africa, or are the documented flooding events isolated incidences?2) How can one model mesoscale convective systems, the primary driver of runoff in the region, in order to explore the properties of precipitation that drive streamflow?3) Based on potential climate change in the region, what trends might be observed in streamflow in the future?First, changes in extreme hydrological events West Africa over the past 60 years are evaluated by applying non-stationary methods based on extreme value theory. Results show a strong increasing trend in extreme hydrological events since the 1970s in the Sahelian Niger River basin and since the 1980s in the Sudano-Guinean catchments in the Senegal River basin. Return levels calculated from non-stationary models are determined to exceed those calculated from a stationary model with over 95% certainty for shorter return periods (<10 years).Next, recent developments are presented for a stochastic precipitation simulator (Stochastorm) designed for modeling mesoscale convective storms, the main rainfall source in the Sahel. Developments include a model for storm occurrence, the explicit representation of extreme rainfall values, and an improvement in the modeling of sub-event intensities. Using high-resolution data from the AMMA-CATCH observatory, simulation outputs were confirmed to realistically represent key characteristics of MCSs, showing the simulator’s potential for use in impact studies.Finally, a modeling chain for producing future hydrological projections is developed and implemented in a Sahelian river basin (Dargol, 7000km2). The chain is original as it is the first attempt in West Africa to encompass the continuum of scales from global climate to convective storms, whose properties have major impacts on hydrological response and as a result local flood risk. The modeling chain components include the convection-permitting regional climate model (RCM) CP4-Africa, the only RCM (to date) explicitly resolving convection and providing long-term simulations in Africa; a bias correction approach; the stochastic precipitation generator Stochastorm; and a rainfall-runoff model specifically developed for Sahelian hydrological processes. The modeling chain is evaluated for a control period (1997-2006) then for future projections (ten years at the end of the 21st century). Hydrological projections show that peak annual flow may become 1.5-2 times greater and streamflow volumes may double or triple on average near the end of the 21st century compared to 1997-2006 in response to projected changes in precipitation.The results raise critical issues notably for hydrological engineering. Current methods used to evaluate flood risk in the region do not take non-stationarity into account, leading to a major risk of underestimating potential floods and undersizing the hydraulic infrastructure designed for protecting against them. It is also suggested to not only consider rainfall changes but also societal and environmental changes, interactions, and feedbacks in order to better attribute past hydrological hazards and their future trajectories to related causes.

Le modèle de neige est souvent dépendant du modèle hydrologique avec lequel il est couplé, ce qui peut favoriser la représentation du débit au détriment de celle de la neige. L'objectif est de rendre le calage du modèle de neige plus indépendant de celui du modèle hydrologique en restant facilement utilisable en opérationnel. Dans cette optique, un modèle contraint sur des données d'observations de la neige permettrait d'améliorer d'une part la robustesse des paramètres du modèle de neige et d'autre part la simulation de l'état du manteau neigeux. Dans la première partie de cette thèse, nous avons étudié et modifié le modèle degrés-jour semi-distribué CemaNeige afin qu'il puisse simuler de manière plus réaliste la variable de surface d'enneigement du bassin versant. Cette modification, couplée au calage du modèle sur des données de surface enneigée et sur le débit, a permis d'améliorer la simulation de l'enneigement par le modèle sans détériorer significativement les performances en débits. Nous alors ensuite débuté le développement d'un nouveau modèle de neige à l'échelle ponctuelle. Celui-ci se compose d'un modèle de rayonnements, simulant les rayonnements incidents à partir de données d'amplitude de températures journalières, et d'un modèle de manteau neigeux. Le modèle de manteau neigeux résout les équations de la chaleur au sein du manteau neigeux à l'aide d'une représentation spectrale du profil de température. Cette représentation permet de simuler les profils et gradients de températures en utilisant moins de variables d'état qu'une discrétisation verticale par couches. Pour mieux prendre en compte les mesures ponctuelles de neige, ce modèle devra être distribué. / Snow models are often dependent on the hydrological model they are coupled with, which can promote higher performance on runoff simulation at the expense of snow state simulations performances. The objective of this thesis is to make the calibration of the snow model more independent from the calibration of the hydrological model, while remaining easily usable for runoff forecasting. Calibrating snow model on observed snow data would on one hand improve the robustness of the snow model parameters and on the other hand improve the snowpack modelling. In the first part of this manuscript, we modified the semi-distributed CemaNeige degree-day model so that it can explicitly simulate the watershed snow cover area. This modification coupled with the calibration of the model on snow cover area data and on river runoff data significantly improved the simulation of the snow cover area by the model without significantly deteriorating the runoff performances. Then we started the development of a new point scale snow model. It is based on a radiation model, which simulates incoming radiations from daily temperature range data, and a snowpack model. The snowpack model solves the heat equations within the snowpack by using a spectral representation of the temperature profile. This representation simulates the temperature profile and gradients using fewer state variables than a vertical discretization of the snowpack. In order to be able to use point scale snow observations in the model, it should be distributed on the watershed.