<p>Severe floods caused by heavy autumn rains in year 2000 raised the question whether measures to reduce the damage from high water levels, in the area surrounding lake Glafsfjorden and along the river Byälven down to lake Vänern, are possible. One option is to reduce flow resistance along the river and thereby lower the maximum water level a given inflow would cause. Good knowledge of hydraulic and hydrological conditions is necessary in order to estimate the effect of such flow-reducing measures. In order to quantify such effect a 1-dimensional hydraulic flow model has been set up for the river Byälven using the software package MIKE 11. The model is more detailed, especially concerning topography and bathymetry, than earlier models used for studies of the river. Boundary conditions consist of measured inflows, the level of the lake Vänern and runoff calculated using the HBV-model. The model was calibrated for two different floods and a good fit to measured water levels was obtained for both these periods. Using the calibrated model critical sections, causing much flow resistance during high floods, were identified. With that knowledge different measures to reduce high water levels was adopted to the model both individually and combined with each other and the model was run with boundary conditions mainly from the flood in year 2000. The most radical measures simulated resulted in a lowering of the maximum water in the two largest reservoirs Glafsfjorden and Harefjorden with 78 and 97 cm respectively. A more modest combination of measures gave water levels 48 and 84 cm lower than a model run without changes. Some combinations of relatively small measures lowered the maximum water level by a few decimeters. The simulation results give good guidance to further investigations and decisions of actual changes. The model constitutes a useful tool when making flood maps of the area and if water level forecasts would be needed during future floods.</p> / <p>Allvarliga översvämningar i samband med höstregn år 2000 väckte frågan om det går att vidta åtgärder för att minska skadorna vid höga flöden i området runt Glafsfjorden och längs Byälvens sträckning ner till Vänern. Ett alternativ är att med åtgärder längs älven underlätta vattnets utflöde och på så sätt minska den högsta vattennivå ett givet flöde orsakar. God kunskap om hydrauliska och hydrologiska förhållanden behövs för att bedöma nyttan av olika åtgärdsalternativ. För att kunna avgöra effekterna av olika åtgärdsalternativ har en 1-dimensionell strömningsmodell satts upp för Byälven i programverktyget MIKE 11. Modellen är mer detaljerad, framförallt beträffande höjdinformationen, än tidigare modeller som använts för studier av Byälven varit. Randvillkor till modellen utgörs av registrerade inflöden, Vänerns vattenstånd och avrinning modellerad med HBV-modellen. Modellen har kalibrerats för två översvämningsperioder och god anpassning uppnåddes för de vattenstånd som dessa situationer representerar och med dess hjälp har sedan älven studerats och områden som bromsar flödet har kunnat identifieras. Med kunskap om vilka områden som begränsar flödet mest har ett antal olika åtgärder simulerats i modellen, både var för sig och kombinerade med varandra. Randvillkoren för översvämningen år 2000 behölls och förändringarna lades in i modellen. De extremaste åtgärderna som simulerats resulterade i minskningar av de högsta vattennivåerna i de två största vattenmagasinen Glafsfjorden och Harefjorden med 78 respektive 97 cm. Mer realistiska åtgärdspaket gav minskningar med i storleksordningen 48 respektive 84 cm och även relativt små ingrepp gav minskningar på några decimeter. Simuleringsresultaten ger god vägledning för vidare undersökningar av och beslut om konkreta åtgärder i Byälven. Dessutom utgör modellen ett bra verktyg för att ta fram översvämningskartor och för att prognostisera vattennivåer vid nya översvämningssituationer.</p>

Les développements d'algues benthiques dans les canaux de transport d'eau induisent d'importantes contraintes pour la gestion des canaux de distri bution d'eau. Les nuisances physiques et chimiques associées à ces développements nécessitent des stratégies de gestion alternatives. La thèse étudie des méthodes pour la gestion de ces populations algale basées sur le contrôle hydraulique du système: les chasses hydrauliques. Ces opérations consistent à détacher une partie de la biomasse algale fixée en augmentant les contraintes de cisaillement exercées par le courant sur ces algues fixées au substrat. Leur remise en suspension, entraînant un pic de turbidité, doit également être maîtrisée. L'approche proposée vise à caractériser et modéliser les processus de développement, de détachement et de transport des algues lors de ces chasses hydrauliques. Des suivis expérimentaux de la croissance sont réalisés en mésocosme (à l'échelle de canaux réduits). Les suivis de biomasse permettent de caler un modèle de croissance de la couverture algale intégrant l'effet de l'hydrodynamique et de la s ensibilité des algues aux perturbations hydrodynamiques. Des stratégies de chasses sont ensuite expérimentées sur deux canaux de distribution d'eau en zone méditérannéenne. Un modèle de la dynamique des algues fixées et en dérive en réponse à une chasse hydraulique est ensuite élaboré sur la base de ces expérimentations, et calé sur les nuages de turbidité observés. Finalement, un cadre méthodologique basé sur un modèle linéaire est proposé pour des applications à la gestion en temps réel d'une variable de qualité : la turbidité. Deux approches de contrôle sont présentées : la commande en boucle ouverte et la commande adaptative qui permet de recaler les paramètres inconnus comme la biomasse initiale. / Algae developments in open-channel networks induce strong constraints for the network management. The physical and chemical nuisances linked to these developments require alternative management strategies. The thesis proposes an original method for these algae management based on the hydraulic control of the system using flushing-flows. These flushes consist in detaching a part of the fixed algae by increasing the hydraulic shear stress exerted on the biomass fixed on the substratum. The re-suspension of algae in the water column induces a turbidity peak which also has to be controlled. The proposed approach aims at characterizing and modelling the processes of algae development, detachment and transport during the flushes. Experimental monitoring of the growth phase is conducted in experimental flumes. The biomass samples are used to calibrate a model of algal growth which integrates the hydrodynamic effect and the algae sensitivity in the Med iterranean region. A model of the fixed and drift algae dynamics in response to a flush is then developed and calibrated on the observerd turbidity plumes. Finally, a control framework based on a linear model is proposed for the turbidity control during a flush. An open-loop control is first developed, then an adaptative feedback controller is tested to estimate unknown parameters such as initial biomass.

A drenagem ácida de mina (DAM) gerada no processo de mineração de carvão, na presença de minerais sulfetados, tem provocado danos ambientais significativos no ecossistema de sua abrangência. Tecnologia de tratamento ativo baseada em processos de Neutralização, Precipitação e Sedimentação tem sido empregada para atenuar a carga de poluentes no efluente, antes do seu descarte em corpos receptores. A mesma, apesar da sua eficiência vem se mostrando bastante onerosa quando aplicada durante um longo período, devido aos custos com insumos, manutenção, potencial humano e energia. Nos últimos anos, vem sendo desenvolvidos sistemas que socorrem-se da ocorrência natural de processos químicos, biológicos e físicos para purificar água de mina contaminada. Estes são designados sistemas passivos, cuja implantação e funcionamento tem se mostrado menos onerosa em relação ao sistema ativo. Capão da Roça, situado no município de Charqueadas é uma das regiões do Brasil onde ocorre contaminação de solos e rios pela DAM gerada a partir de um depósito de rejeitos. Aplicando o fluxograma recomendado por diversos autores para a seleção do sistema passivo, tomando em conta as características do efluente achou-se viável instalar um canal aberto de calcário para o tratamento da DAM do Capão da Roça em virtude de a mesma apresentar acidez maior que a alcalinidade, oxigênio dissolvido maior que 5mg/l, Fe+3 maior que 25% em relação ao Fe2+. A quantidade de efluente e a declividade do terreno da área estudada permite que se opere com vazão maior que 12m3/h no sistema passivo. De acordo com a acidez do efluente foi determinado o tempo de detenção de 1hora para o tratamento da DAM no sistema. A partir de estudos similares sobre o uso de calcário em sistemas passivos, encontrou-se a massa de 338,6 toneladas para o empreendimento funcionar em 10 anos, considerando uma dissolução de calcário de 100%, num canal com 10% de declividade, 1m de profundidade e 2, 5 metros de largura para tamponar uma solução de DAM com vazão de 1000 L.min-1 num canal de 47metros de cumprimento. De acordo com cálculos baseados num modelo empírico, ficou demonstrado que o diâmetro e área de superfície do calcário poderão diminuir ao longo do tempo, considerado a sua dissolução. / Acid mine drainage (AMD) generated in the coal mining process in the presence of sulfide minerals, have been causing significant environmental damages to the ecosystem of its coverage. Active treatment technology based on neutralization, precipitation and sedimentation processes, has been used to alleviate the load of pollutants in the effluent prior to discharges into receiving bodies. Despite their efficiency has proved quite costly when applied over a long period due to input costs, maintenance, manpower and energy. In recent years project defined 'passive treatment' has been developed as the improvement of water quality using only naturally occurring chemical, biological and physical processes, hence, the deployment and operation have been less costly compared to the active systems. Capão da Roça, located in the municipality of Charqueadas is one of the regions of Brazil where occurs contamination of soils and rivers by AMD generated from a waste dump. Using the flowchart recommended by several authors for selecting the passive system, taking into account the wastewater characteristics, was found to be feasible to install an open limestone channel for the treatment of AMD because it has higher acidity than alkalinity, dissolved oxygen greater than 5mg / l, Fe3+ greater than 25 % in relation to Fe2+. The amount of effluent and the slope of the study area terrain allows to operate with a flow rate greater than 12m3/ h in the passive system. According to the acidity of the effluent was determined retention time of 1 hour for the treatment of the AMD system. From similar studies on the use of limestone in passive systems, was found the mass of 338.6 tons for the enterprise operating over 10 years, assuming a 100% limestone dissolution channel with a 10% slope, 1 meter deep and 2,5 meters wide to buffer an AMD solution with a flow rate of 1000 L.min-1 in channel with 47 meters of length. According to the calculations based on empirical model, it was shown that the diameter and the surface area of limestone may decline over time, considering its dissolution.

Severe floods caused by heavy autumn rains in year 2000 raised the question whether measures to reduce the damage from high water levels, in the area surrounding lake Glafsfjorden and along the river Byälven down to lake Vänern, are possible. One option is to reduce flow resistance along the river and thereby lower the maximum water level a given inflow would cause. Good knowledge of hydraulic and hydrological conditions is necessary in order to estimate the effect of such flow-reducing measures. In order to quantify such effect a 1-dimensional hydraulic flow model has been set up for the river Byälven using the software package MIKE 11. The model is more detailed, especially concerning topography and bathymetry, than earlier models used for studies of the river. Boundary conditions consist of measured inflows, the level of the lake Vänern and runoff calculated using the HBV-model. The model was calibrated for two different floods and a good fit to measured water levels was obtained for both these periods. Using the calibrated model critical sections, causing much flow resistance during high floods, were identified. With that knowledge different measures to reduce high water levels was adopted to the model both individually and combined with each other and the model was run with boundary conditions mainly from the flood in year 2000. The most radical measures simulated resulted in a lowering of the maximum water in the two largest reservoirs Glafsfjorden and Harefjorden with 78 and 97 cm respectively. A more modest combination of measures gave water levels 48 and 84 cm lower than a model run without changes. Some combinations of relatively small measures lowered the maximum water level by a few decimeters. The simulation results give good guidance to further investigations and decisions of actual changes. The model constitutes a useful tool when making flood maps of the area and if water level forecasts would be needed during future floods. / Allvarliga översvämningar i samband med höstregn år 2000 väckte frågan om det går att vidta åtgärder för att minska skadorna vid höga flöden i området runt Glafsfjorden och längs Byälvens sträckning ner till Vänern. Ett alternativ är att med åtgärder längs älven underlätta vattnets utflöde och på så sätt minska den högsta vattennivå ett givet flöde orsakar. God kunskap om hydrauliska och hydrologiska förhållanden behövs för att bedöma nyttan av olika åtgärdsalternativ. För att kunna avgöra effekterna av olika åtgärdsalternativ har en 1-dimensionell strömningsmodell satts upp för Byälven i programverktyget MIKE 11. Modellen är mer detaljerad, framförallt beträffande höjdinformationen, än tidigare modeller som använts för studier av Byälven varit. Randvillkor till modellen utgörs av registrerade inflöden, Vänerns vattenstånd och avrinning modellerad med HBV-modellen. Modellen har kalibrerats för två översvämningsperioder och god anpassning uppnåddes för de vattenstånd som dessa situationer representerar och med dess hjälp har sedan älven studerats och områden som bromsar flödet har kunnat identifieras. Med kunskap om vilka områden som begränsar flödet mest har ett antal olika åtgärder simulerats i modellen, både var för sig och kombinerade med varandra. Randvillkoren för översvämningen år 2000 behölls och förändringarna lades in i modellen. De extremaste åtgärderna som simulerats resulterade i minskningar av de högsta vattennivåerna i de två största vattenmagasinen Glafsfjorden och Harefjorden med 78 respektive 97 cm. Mer realistiska åtgärdspaket gav minskningar med i storleksordningen 48 respektive 84 cm och även relativt små ingrepp gav minskningar på några decimeter. Simuleringsresultaten ger god vägledning för vidare undersökningar av och beslut om konkreta åtgärder i Byälven. Dessutom utgör modellen ett bra verktyg för att ta fram översvämningskartor och för att prognostisera vattennivåer vid nya översvämningssituationer.

Tyrolean type water-intake structures are widely used on mountain rivers to provide water to hydropower stations. The main concern encountered in these kinds of structures is the amount of water diverted from the main channel and sediment carried by this flow. The diverted flow should not be less than the design discharge of the hydropower station and the amount of the sediment entering the hydraulic system should be minimum. In this study a physical model of a Tyrolean weir was constructed at the Hydromechanics Laboratory and by varying the dimensions of the various components of this system / the length, the inclination angle of the rack and the distance between the rack bars, the amount of water and sediment entering the system were measured for a wide range of discharges. The experiments were conducted in two stages. In the first stage the tests were made with only water, and in the second stage, water and sediment having different gradation were used. Applying dimensional analysis to the related parameters of the system dimensionless terms were defined for water capture efficiency and discharge coefficient of the system, and their variations with the relevant parameters were plotted. Using these diagrams one can determine the amount of water to be diverted by a Tyrolean weir of known geometry and main channel flow.

Tyrolean type water-intake structures are commonly used on mountain rivers to supply water to hydropower stations. The amount of water to be diverted from the main channel is the major concern in these kind of structures and should not be less than the design discharge. In this study a physical model of a Tyrolean type water-intake structure was built at the laboratory and the diverted flow from the main channel through the intake structure having steel racks and perforated plates of different types were measured. The experiments were conducted in two stages. In the first stage the tests were carried out with only steel racks having three different bar openings and slopes, and in the second stage, perforated screens of three different circular openings and screen slopes were used. Applying dimensional analysis to the related parameters of the system the dimensionless terms were defined for the water capture efficiency and discharge coefficient of the system, and their variations with the relevant parameters were plotted. Using these diagrams one can determine the amount of water to be diverted by a Tyrolean weir of known geometry and main channel discharge.

This study is an experimental research to formulate the discharge over sharp-crested rectangular weirs. Firstly, a series of measurements on different weir heights were conducted to find the minimum weir height for which channel bed friction has no effect on discharge capacity. After determining the appropriate weir height, weir width was reduced to collect data on discharge-water head over weir relationship for a variety of different weir openings. Then, the data was analyzed through regression analysis along with utilization of global optimization technique to reach the desired formulation for the discharge. By taking advantage of a newly-introduced &ldquo / weir velocity&rdquo / concept, a simple function was eventually detected for the discharge where no discharge coefficient was involved. The behavior of the weir velocity function obtained in the present study illustrates the transition between the fully contracted and partially contracted weirs. In addition, the proposed weir velocity formulation is simple and robust to calculate the discharge for full range of weir widths.

A generalized non-dimensional mathematical expression has been developed to describe the rating relation of depth and discharge for intermediate and high streamflow of natural and controlled streams. The expressions have been tested against observations from forty-three stations in West-Central Florida. The intermediate-flow region model has also been validated using data from thirty additional stations in the study area. The proposed model for the intermediate flow is a log-linear equation with zero intercept and the proposed model for the high-flow region is a log-linear equation with a variable intercept. The models are normalized by the depth and discharge values at 10 percent exceedance using data published by the U.S. Geological Survey. For un-gauged applications, Q10 and d10 were derived from a relationship shown to be reasonably well correlated to the watershed drainage area with a correlation coefficient of 0.94 for Q10 and 0.86 for d10. The average relative error for this parameter set shows that, for the intermediate-flow range, better than 50% agreement with the USGS rating data can be expected for about 86% of the stations and for the high-flow range, better than 50% for 44% of the stations. Testing the model outside West Central Florida, in some stations at North Florida, and South Alabama and Georgia, show some reasonable relative errors but not as good as the results obtained for West Central Florida. Using a model with a different slope, developed specific for those particular stations improved the results significantly.

A drenagem ácida de mina (DAM) gerada no processo de mineração de carvão, na presença de minerais sulfetados, tem provocado danos ambientais significativos no ecossistema de sua abrangência. Tecnologia de tratamento ativo baseada em processos de Neutralização, Precipitação e Sedimentação tem sido empregada para atenuar a carga de poluentes no efluente, antes do seu descarte em corpos receptores. A mesma, apesar da sua eficiência vem se mostrando bastante onerosa quando aplicada durante um longo período, devido aos custos com insumos, manutenção, potencial humano e energia. Nos últimos anos, vem sendo desenvolvidos sistemas que socorrem-se da ocorrência natural de processos químicos, biológicos e físicos para purificar água de mina contaminada. Estes são designados sistemas passivos, cuja implantação e funcionamento tem se mostrado menos onerosa em relação ao sistema ativo. Capão da Roça, situado no município de Charqueadas é uma das regiões do Brasil onde ocorre contaminação de solos e rios pela DAM gerada a partir de um depósito de rejeitos. Aplicando o fluxograma recomendado por diversos autores para a seleção do sistema passivo, tomando em conta as características do efluente achou-se viável instalar um canal aberto de calcário para o tratamento da DAM do Capão da Roça em virtude de a mesma apresentar acidez maior que a alcalinidade, oxigênio dissolvido maior que 5mg/l, Fe+3 maior que 25% em relação ao Fe2+. A quantidade de efluente e a declividade do terreno da área estudada permite que se opere com vazão maior que 12m3/h no sistema passivo. De acordo com a acidez do efluente foi determinado o tempo de detenção de 1hora para o tratamento da DAM no sistema. A partir de estudos similares sobre o uso de calcário em sistemas passivos, encontrou-se a massa de 338,6 toneladas para o empreendimento funcionar em 10 anos, considerando uma dissolução de calcário de 100%, num canal com 10% de declividade, 1m de profundidade e 2, 5 metros de largura para tamponar uma solução de DAM com vazão de 1000 L.min-1 num canal de 47metros de cumprimento. De acordo com cálculos baseados num modelo empírico, ficou demonstrado que o diâmetro e área de superfície do calcário poderão diminuir ao longo do tempo, considerado a sua dissolução. / Acid mine drainage (AMD) generated in the coal mining process in the presence of sulfide minerals, have been causing significant environmental damages to the ecosystem of its coverage. Active treatment technology based on neutralization, precipitation and sedimentation processes, has been used to alleviate the load of pollutants in the effluent prior to discharges into receiving bodies. Despite their efficiency has proved quite costly when applied over a long period due to input costs, maintenance, manpower and energy. In recent years project defined 'passive treatment' has been developed as the improvement of water quality using only naturally occurring chemical, biological and physical processes, hence, the deployment and operation have been less costly compared to the active systems. Capão da Roça, located in the municipality of Charqueadas is one of the regions of Brazil where occurs contamination of soils and rivers by AMD generated from a waste dump. Using the flowchart recommended by several authors for selecting the passive system, taking into account the wastewater characteristics, was found to be feasible to install an open limestone channel for the treatment of AMD because it has higher acidity than alkalinity, dissolved oxygen greater than 5mg / l, Fe3+ greater than 25 % in relation to Fe2+. The amount of effluent and the slope of the study area terrain allows to operate with a flow rate greater than 12m3/ h in the passive system. According to the acidity of the effluent was determined retention time of 1 hour for the treatment of the AMD system. From similar studies on the use of limestone in passive systems, was found the mass of 338.6 tons for the enterprise operating over 10 years, assuming a 100% limestone dissolution channel with a 10% slope, 1 meter deep and 2,5 meters wide to buffer an AMD solution with a flow rate of 1000 L.min-1 in channel with 47 meters of length. According to the calculations based on empirical model, it was shown that the diameter and the surface area of limestone may decline over time, considering its dissolution.

Submitted by GUILHERME HENRIQUE FIOROT null (ghfiorot@aluno.feis.unesp.br) on 2016-08-31T16:48:18Z No. of bitstreams: 1 GHFiorot-tese-unesp.pdf: 21279930 bytes, checksum: f08d052fded3d144bcad4b9a9f1c007f (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-09-01T17:08:21Z (GMT) No. of bitstreams: 1 fiorot_gh_dr_ilha.pdf: 21279930 bytes, checksum: f08d052fded3d144bcad4b9a9f1c007f (MD5) / Made available in DSpace on 2016-09-01T17:08:21Z (GMT). No. of bitstreams: 1 fiorot_gh_dr_ilha.pdf: 21279930 bytes, checksum: f08d052fded3d144bcad4b9a9f1c007f (MD5) Previous issue date: 2016-07-01 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Dentro da temática de riscos naturais, mais precisamente no contexto das corridas de lama, esta tese surge da necessidade que existe na literatura em melhor se conhecer as características temporais destes eventos. A chuva, fonte da vazão liquida, conduz aos escoamentos superficiais, responsáveis pela redução da coesão do material sedimentar do solo (areia e argila) e seu consequente transporte. Em locais de topografia íngreme, de montante a jusante, a vazão sólida do escoamento principal pode, eventualmente, evoluir devido às contribuições laterais de pequenos escoamentos, alterando não só as propriedades reológicas do fluido e dinâmicas do escoamento, como se manter até que o transporte sólido atinja elevada concentração na composição do fluido. Na primeira parte desta tese, um experimento de superfície livre foi projetado para reproduzir escoamentos superficiais sobre um fundo móvel, com o objetivo de estudar propriedades não-permanentes do transporte de sedimentos. Um sistema de medição foi projetado e construído com o intuito de medir quase instantaneamente a vazão sólida e suas correlações com as propriedades hidráulicas do escoamento. Este aparato é também utilizado para observar a influência de instabilidades de superfície livre sobre o transporte. Um conjunto de resultados é apresentado e analisado e mostra que a presença de ondas pode, em média, reduzir a quantidade total de sedimentos transportada. Na segunda parte desta tese, a dinâmica de escoamentos com elevada concentração de sedimentos é estudada. Neste trabalho, executa-se a aplicação de um modelo de primeira ordem de roll waves para fluidos de reologia Herschel-Bulkley para simular um evento natural registrado na literatura. Os resultados apresentados mostram que roll waves poderiam, de fato, ser identificadas no evento e que a amplitude média observada poderia ter sido estimada com 8% de incerteza. Assim, um modelo mais complexo para a solução do perfil de velocidade é proposto, adicionando a porosidade do solo ao problema. Resultados do modelo são comparados com simulações numéricas. Uma análise paramétrica é efetuada e o caso de estudo é novamente avaliado. Como conclusão geral do trabalho, a presença de fenômenos não-estacionários durante a evolução escoamento superficial - corrida de lama afeta a dinâmica global do sistema acoplado hidráulica-transporte de sedimentos, quando comparado ao caso permanente e uniforme. Assim, a verificação de que tais fenômenos podem aparecer deve constituir parte de projetos engenharia, especialmente quando estes, em situações de catástrofes, envolvem danos a infraestruturas civis e quase sempre perdas de vidas, como é o caso das corridas de lama. / This thesis was motivated by the need to better understand time-dependent features related to mudflow evolution on natural sloped channels. Basically, the research is focused on events that are confined in channels formed due to the topography. The rain, source of the liquid discharge, generates the runoff flow which is responsible for wetting the soil surface, promoting reduction of soil cohesiveness and erosion of small particles such as clay and sand. From this point, the sediment transport can increase as small water flows merge and form greater streams. The scenario keeps its evolution until it reaches high concentration of particles in the fluid mixture. In the first part, to study the non-permanent feature of sediment transport, an open-channel experiment was designed for simulating runoff flow over a mobile bed. A measurement system was designed and constructed to instantaneously inspect the solid discharge of particles and the flow friction at the bed. This apparatus is further used to explore the influence of free-surface waves on the sediment transport. Hydraulic properties of flows are qualitatively and quantitatively studied and data are used to correlate characteristics of flow and sediment transport. A set of experimental runs is presented and explored. Analysis of results shows that for fixed flow conditions, waves induce an overall smaller quantity of transported sediment. In a second part, the dynamics of high concentrated flows is addressed and this thesis attempts to apply a first-order roll-wave model for Herschel-Bulkley laminar fluid flow to a registered natural event. Results presented point out that roll waves could have occurred during this already published case-study event. Simulations could predict wave heights within 8% on uncertainty with respect to the mean amplitude of measured waves. Finally a new theoretical solution for the velocity profile is proposed taking into account the porosity of the bed. Results are then compared with numerical simulation performed in FLUENT. A parametric analysis is employed and the case-study is once again evaluated. As general conclusion, the non-permanent phenomena that can appear during the evolution of a mudflow event affect the overall dynamics of the coupled system (hydraulic-sediment transport) in comparison to the steady and uniform case. Verifying that such phenomena could appear should indeed be an important part in hydraulic engineering projects, especially when dealing with lives, which is the case of mudflows. / CNPq: 201557/2012-6