La compréhension et la prévision des phénomènes d'éboulements rocheux sont des éléments déterminants pour la gestion des risques dans l'aménagement des zones et des infrastructures de montagnes, qui nécessitent, entre autre, la mise au point d'outils numériques opérationnels permettant d'anticiper la trajectoire des épisodes rocheux et les zones susceptibles d'être impactées. L'approche numérique proposée dans le cadre de la thèse, est basée sur une modélisation numérique discrète qui permet de simuler le comportement collectif de blocs rocheux lors d'un éboulement, en considérant des blocs de géométrie réaliste et une topographie tridimensionnelle du versant de propagation. Pour faciliter son utilisation en bureau d'études, le modèle numérique de contact, qui gère les interaction entre les blocs et entre les blocs et le versant de propagation, fait appel à un nombre restreint de paramètres, pouvant être estimés par des mesures in situ ou par des rétro-analyses de cas existants. Les paramètres les plus influant sur les mécanismes de propagation sont : la géométrie des blocs et la topographie de surface, les paramètres dissipatifs de contact tels que le coefficient de restitution normale qui agit dans la direction normale au contact, le coefficient de frottement qui agit dans la direction tangentielle au plan de contact, et la résistance au roulement entre la pente et les blocs rocheux dans l'hypothèse d'un impact rocheux sur un sol meuble.La thèse présente des nombreuses données de terrain qui ont servies de base à l'analyse des mécanismes de propagation sur d'anciens cas d'éboulements et sur des falaises potentiellement instables. Des méthodes permettant la reconstruction d'un volume instable pour la modélisation de la propagation ont été développées sur la base des modèles tridimensionnels de terrain. Après des tests de validation et de compréhension du modèle numérique, ce dernier a été appliqué à des cas réels. Trois sites, très différents en termes de géométrie, ont été retenus pour tester le modèle numérique. Les paramètres d'études sont suivant les cas, les mécanismes de propagation, les mécanismes de dissipation d'énergie, les zones de dépôt, les forces d'interactions et les énergies d'impact sur des structures de protection.Ce travail a permis d'établir une méthodologie de modélisation des éboulements rocheux adaptée à l'ingénierie. Un protocole spécifique permettant de déterminer ou d'estimer les paramètres a été proposé et des logiciels de pré et post traitements permettant à la fois une analyse pertinente et rapide des résultats ont été développés. La corrélation entre les résultats numériques et les observations de terrain sont satisfaisantes et les résultats en termes de prévision encourageants. / Understanding and predicting rock avalanches are key elements in risk management when developing mountainous areas. Due to the complexity of the mechanisms involved, developments of numerical and operational tools are useful and necessary to properly estimate block trajectories and define riskiest areas. The numerical approach proposed in this thesis is based in the discrete element method which allows simulating the collective behavior of a group of rocks by using realistic block geometries and three-dimensional slope topographies. The numerical contact model handles interaction between the blocks and between the blocks and the slope by using a limited number of parameters that can be estimated by in situ measurements or feed-back analysis of ancient rockfalls events. The most influential parameters in the propagation phenomena are: the geometry and shape of blocks and topography, the contact parameters such as the normal restitution coefficient which acts in the normal direction to the contact, the friction coefficient acting in the tangential direction to the contact plane and the rolling resistance coefficient of blocks with the slope that somehow accounts of the impact mechanisms in case of soft soil.Various field results of past rockfall events or instable rocky cliffs are presented in the thesis. In addition, different procedures allowing the modeling of the whole unstable volume involved in the propagation motion are presented through real applications by using three-dimensional terrain models as input data. The numerical model was applied to three real rockfalls events, very different in terms of geometry. The parameters analyzed concerned mainly the propagation distances and energy dissipation mechanisms, deposit zones, interaction forces and impact energies on protective structures.A specific protocol for determining and estimating the contact parameters was proposed and some pre and post processing software enabling both relevant and rapid analysis of the results have been developed. The correlation between the numerical results and field observations are satisfactory with very encouraging results in terms of forecasting.

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

abstract: This doctoral thesis investigates the predictability characteristics of floods and flash floods by coupling high resolution precipitation products to a distributed hydrologic model. The research hypotheses are tested at multiple watersheds in the Colorado Front Range (CFR) undergoing warm-season precipitation. Rainfall error structures are expected to propagate into hydrologic simulations with added uncertainties by model parameters and initial conditions. Specifically, the following science questions are addressed: (1) What is the utility of Quantitative Precipitation Estimates (QPE) for high resolution hydrologic forecasts in mountain watersheds of the CFR?, (2) How does the rainfall-reflectivity relation determine the magnitude of errors when radar observations are used for flood forecasts?, and (3) What are the spatiotemporal limits of flood forecasting in mountain basins when radar nowcasts are used into a distributed hydrological model?. The methodology consists of QPE evaluations at the site (i.e., rain gauge location), basin-average and regional scales, and Quantitative Precipitation Forecasts (QPF) assessment through regional grid-to-grid verification techniques and ensemble basin-averaged time series. The corresponding hydrologic responses that include outlet discharges, distributed runoff maps, and streamflow time series at internal channel locations, are used in light of observed and/or reference data to diagnose the suitability of fusing precipitation forecasts into a distributed model operating at multiple catchments. Results reveal that radar and multisensor QPEs lead to an improved hydrologic performance compared to simulations driven with rain gauge data only. In addition, hydrologic performances attained by satellite products preserve the fundamental properties of basin responses, including a simple scaling relation between the relative spatial variability of runoff and its magnitude. Overall, the spatial variations contained in gridded QPEs add value for warm-season flood forecasting in mountain basins, with sparse data even if those products contain some biases. These results are encouraging and open new avenues for forecasting in regions with limited access and sparse observations. Regional comparisons of different reflectivity -rainfall (Z-R) relations during three summer seasons, illustrated significant rainfall variability across the region. Consistently, hydrologic errors introduced by the distinct Z-R relations, are significant and proportional (in the log-log space) to errors in precipitation estimations and stream flow magnitude. The use of operational Z-R relations without prior calibration may lead to wrong estimation of precipitation, runoff magnitude and increased flood forecasting errors. This suggests that site-specific Z-R relations, prior to forecasting procedures, are desirable in complex terrain regions. Nowcasting experiments show the limits of flood forecasting and its dependence functions of lead time and basin scale. Across the majority of the basins, flood forecasting skill decays with lead time, but the functional relation depends on the interactions between watershed properties and rainfall characteristics. Both precipitation and flood forecasting skills are noticeably reduced for lead times greater than 30 minutes. Scale dependence of hydrologic forecasting errors demonstrates reduced predictability at intermediate-size basins, the typical scale of convective storm systems. Overall, the fusion of high resolution radar nowcasts and the convenient parallel capabilities of the distributed hydrologic model provide an efficient framework for generating accurate real-time flood forecasts suitable for operational environments. / Dissertation/Thesis / Ph.D. Civil and Environmental Engineering 2012

Accurate forecasting and up-to-date warning is very important for the coastal people to protect them from the devastation of cyclone. Bangladesh Meteorological Department (BMD) and their concern organizations have important role to provide proper and accurate cyclone forecasting and warning message to the people. The coastal zone of the country is the most precarious place to natural disaster due to its geographical location, frequent formation of cyclone in the Bay, poor infrastructure and insecure socio-economic conditions of the people.  Accurate and timely warning, good infrastructure such as roads, transportations, cyclone shelters, cyclone preparedness training centers can reduce  human vulnerability to cyclone in the coastal area of the country. Due to very high population growth rate in the coastal zone, new settlements are being built in the areas which were under agricultural land, forest or bare before. To study the people’s perceptions on cyclone forecasting, warning and management system in Bangladesh, two questionnaire surveys have been done, one with meteorologists of BMD and the other with the people living in the coastal zone. As land use change has great impact on human vulnerability to disaster so, a brief study on land-use change has also been done under the current research.   Keywords: Cyclone, forecasting technique, questionnaire survey, Natural hazards and Land- use change.

Les risques naturels majeurs constituent une menace plus ou moins récurrente pour la plupart des populations de la planète. Les catastrophes naturelles sont à la fois sources et révélatrices d’inégalités sociales et environnementales, dans le monde, mais aussi sur le territoire de la République française. Les Antilles françaises sont très fréquemment, et très lourdement frappées par les aléas naturels. La réponse en matière de gestion des crises, et, en amont, en matière de prévention, ne nous semble pas à la hauteur des défis, et des besoins des populations. C’est la raison pour laquelle nous nous interrogeons, à travers la présente thèse, sur la place de la solidarité et de l’égalité, dans le régime juridique des risques naturels majeurs. C’est une préoccupation doctrinale majeure, inscrite dans la constitution. La recherche du lien entre droit des risques naturels majeurs et justice sociale et environnementale est l’objet de la présente étude, s’agissant de la réponse juridique à la préoccupation des populations et catégories défavorisées, qui s’avèrent a priori les plus atteintes par les catastrophes naturelles. Les limites des textes, l’insuffisance des moyens, ainsi que les pratiques locales, facteurs d’aggravation des vulnérabilités, le laxisme des pouvoirs publics nationaux et territoriaux, l’absence de culture de risque et l’esprit « kokagneur » des populations (avec des différences de comportement entre la Guadeloupe et la Martinique), toutes ces considérations rendent illusoire la détermination proclamée des pouvoirs publics de résoudre les problèmes de risques naturels majeurs. Des voies d’un renforcement de la solidarité sont proposées. Cette contribution à la recherche sur les risques ambitionne d’apporter aux acteurs, une vision transversale de la problématique des risques naturels, par l’analyse du régime juridique confronté à une exigence de justice sociale et environnementale. Les Antilles françaises servent de support à cette étude. / Major natural hazards are more or less recurring threat for most people in the world. Natural disasters are both sources and revealing social and environmental inequalities in the world, but also in the French Republic. The French West Indies are very frequently and strongly hit by natural hazards. The answer in terms of crisis management, and beforehand, in terms of prevention, doesn’t seem to be up to the population’s challenges and needs. This is why we wonder, in this thesis, about the place of solidarity and equality in the legal system of major natural hazards. This is a major doctrinal concern in the constitution. The research of the relationship between major natural hazards law and environmental and social justice is the subject of this study, concerning the legal answer to the concerns of the underprivileged people and categories, which prove to be a priori the most struck by natural disasters. The limits of the legislation, inadequate resources and local practices, vulnerabilities worsening factor, the laxity of the national and territorial public authorities, the lack of risk culture and the "kokagneur" spirit of the populations (with behavior differences between Guadeloupe and Martinique), all these considerations make unreal the government’s proclaimed determination to solve the major natural hazards issues. Ways to strengthen solidarity are proposed. This contribution to risks research aims to bring to the players an interdisciplinary view of natural hazards issues, through the analysis of the legal system confronted with the requirement of social and environmental justice. The French West Indies are used as research support.

Orientador: Geraldo de Freitas Maciel / Abstract: 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 the... (Complete abstract click electronic access below) / Resumo: 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 eleva... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

<p>Predmet ovog istraživanja su direktne materijalne posledice realizacije prirodnih nepogoda (direktna materijalna šteta) i procena štete na teritoriji AP Vojvodine. U prvom delu istraživanja analizirana je prostorna distribucija prirodnih nepogoda karakterističnih za područje AP Vojvodine sa ciljem utvrđivanja izloženosti populacije rizicima od prirodnih nepogoda. U drugom delu istraživanja, primenom kvantitativnih metoda koje uključuju parametarske i neparametarske statističke metode i regresiono modeliranje utvrđen je optimalni analitički izraz procene štete nastale usled realizacije rizika od oluje kao prirodne nepogode za koju je ustanovljena povećana izloženost populacije AP Vojvodine.</p> / <p>The subject of this research is the direct material consequences of the realization of natural disasters (direct material damage) and the assessment of damage in the territory of Vojvodina. In the first part of the research, the spatial distribution of natural disasters characteristic for the region of Vojvodina was analyzed in order to determine the population&#39;s exposure to natural hazards. In the second part of the research, the optimal analytical expression of damage estimation was determined by applying quantitative methods including parametric and non-parametric statistical methods and regression modeling. The optimal analytical expression of damage estimation has been identified for the risk of a storm as a natural disaster which has created increased exposure of the population of Vojvodina.</p>

Modern engineering structures should ensure an economic design, construction and operation of structures in compliance with the required safety for persons and the environment. In order to achieve this aim, all contingencies and associated consequences that may possibly occur throughout the life cycle of the considered structure have to be taken into account. Today, the development is often based on decision theory, methods of structural reliability and the modeling of consequences. Failure consequences are one of the significant issues that determine optimal structural reliability. In particular, consequences associated with the failure of structures are of interest, as they may lead to significant indirect consequences, also called follow-up consequences. However, apart from determining safety levels based on failure consequences, it is also crucially important to have effective models for stress forces and maintenance planning ... (aus dem Vorwort)

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Vid inträffandet av naturolyckor och katastrofer påverkas människor i olika omfattning, inte bara beroende på deras bostads läge utan även utifrån deras sociala förhållanden och förutsättningar. I denna studie genomförs en riskanalys samt utvecklas en metod för beräkning av ett områdes sociala sårbarhet genom ett index. Studiens geografiska avgränsning är en sträcka av Klarälven i Värmland och baseras på data framställt av Skogsstyrelsen, Myndigheten för samhällsskydd och beredskap (MSB), Lantmäteriet och Statistiska centralbyrån (SCB).   I studien beräknades ett socialt sårbarhetsindex genom att kombinera flera lager av SCB:s statistiska data i ett geodatalager med kvadratiska polygoner. Det sociala sårbarhetsindexet kombinerades sedan med resultatet från en flerfaroanalys (multi-hazard analysis) med flera översvämningsscenarion samt områden känsliga för jordskred och ras. Flerfaroanalysen utfördes genom en sammanställning av MSB:s kartering av potentiella översvämningsscenarion och Skogsstyrelsens kartering av områden som kan drabbas av ras eller jordskred. Det sociala sårbarhetsindexet och flerfaroanalysen karterades och överlagrades för att identifiera särskilt sårbara områden.   Med hjälp av det sociala sårbarhetsindexet identifieras en högre social sårbarhet i mer tätbebyggda områden. Indexet påvisar även en högre social sårbarhet i den södra halvan av studieområdet. I flerfaroanalysen ses naturolyckorna variera i omfattning över studieområdet. I den norra delen är risken för jordskred och ras större än i den södra delen som nästan enbart drabbas av översvämningar. Resultaten från riskanalysen visar en “medel-risk” längs en längre sträcka av Klarälven och ökad risk i tätbebyggda områden. För förbättring av det sociala sårbarhetsindexet behövs mer detaljerade data över mindre områden för att öka indexets tillförlitlighet och användningsområden. / When natural phenomena and disasters occur, people are affected to varying degrees, not only depending on the location of their homes, but also on the basis of their social background. In this study, a multi-hazard risk analysis and a method for estimating an area’s social vulnerability through an index were developed. The study was carried out along River Klarälven in Värmland and was based on data produced by the Swedish forest agency, The Swedish Civil Contingencies Agency (MSB), The Swedish Mapping, Cadastral and Land Registration Authority and Statistics Sweden (SCB).   The study presents a social vulnerability index by combining several layers of SCB's statistical data, in a geodata layer with square polygons. The social vulnerability index was combined with a multi-hazard analysis considering several flood scenarios and landslide susceptibility. The multi-hazard analysis was performed through a compilation of MSB's mapping of potential flood scenarios and the Swedish forest agency’s mapping of areas that may be affected by landslides. The social vulnerability index and the results from the multi-hazard analysis were mapped and combined in order to identify areas with substantial risk.    The social vulnerability index indicates a higher social vulnerability in more densely populated areas. The index also shows a slightly higher social vulnerability in the southern half of the study area. The results from the multi-hazard analysis, the spatial distribution of natural hazards varied. The northern part of the study area has a greater susceptibility to landslides than the southern part, which is almost exclusively are induced by floods and extreme flows. The result of the risk analysis shows a “medium risk” along the largest studied part of the River Klarälven and a slightly increased risk in densely populated areas. For future improvements in the development of the social vulnerability index, more data is needed with a higher spatial resolution to increase the index's reliability and areas of use.