Societal awareness and general understanding of the diversity of geosciences environments and phenomena across regions is vital. The primary method to obtain information about geosciences is through mass media. However, there is little coverage of geosciences information and the public may not trust it because of low geosciences awareness. Geosciences are rarely included as part of K-12 curricula and are optional at the collegiate level, contributing to the public deficiency regarding awareness and understanding of the geosciences. This research study investigated methods utilizing outdoor resources in an effort to increase region-specific understanding and awareness of geosciences among diverse groups. A Mississippi K-12 educator professional development session and two middle-high schools were assessed for impact on understanding and interest related to geosciences. All participants utilized outdoor resources to model erosional processes and potential natural hazard events. Both participating schools have high underrepresented minority populations. Pre assessment evaluated participant awareness of Mississippi natural hazards. Teachers and student participants all demonstrated a low awareness of erosion processes specific to the region. Teachers completed erosion models indoors or outdoors, with indoor participants having a significant increase in earth science interest. All student participants completed the erosion model outside, with pre-post erosion comprehension resulting in significant increases for both the middle and high schools. The middle school had significant gains in earth science interest while the high school had a significant decrease regarding careers in geosciences. Virtual field guides developed by online graduate students demonstrating personal understanding of broad geosciences concepts in their local region were evaluated pre-post for impact on geosciences awareness, understanding, and confidence. Awareness factors included geographical community size and locations included in the field guide to demonstrate participant understanding. Significant increases in awareness regarding geoscience resources, including those outdoors, occurred. Significant increases also occurred in confidence utilizing geosciences resources and communicating about geosciences. The majority agreed that the experience of creating the field guide enhanced understanding of geosciences and interest in outdoor activities. Geographical size of participants’ residential communities was significantly related to awareness of regional locations, with urban residents including fewer outdoor locations in the field guide.

Since ancient times, mankind has faced a constant battle against natural hazards. From the earlieststages of human communication, when human beings communicate by some sort of harsh gruntsand unintelligible words, people were struck by the awe-inspiring power of nature as floods, storms,earthquakes, and other events which reshaped their environment and way of living. However,among these events, droughts have been particularly devastating, and have left a profound mark onhuman history. Throughout centuries, droughts have forced communities to adapt and evolve in response tochanging environmental conditions. In California, the frequency and severity of droughts haveincreased in recent decades, leading to significant changes in land use patterns. These changes haveimpacted the economy, social structure, and ecology of the region, making the study of land usechanges after drought periods a crucial area of research. In this master thesis, the effects of droughts on land use in California will be deeply explored,analysing the outcome and impacts resulting from extreme dry events in the state, and identifyingpotential climate adaptation actions that can be implemented based on an enhanced understandingof the consequences of droughts on land use. By understanding the complex relationship betweendroughts and land use, mankind may better prepare and adapt to the challenges posed by futureclimate change and other environmental stressors. / Sedan urminnes tider har mänskligheten stått inför en ständig kamp mot naturliga faror. Ända frånde tidigaste stadierna av mänsklig kommunikation, när människor kommunicerade genom någonform av hårda grymtningar och obegripliga ord, har människor imponerats av naturens mäktigakraft i form av översvämningar, stormar, jordbävningar och andra händelser som omformat derasmiljö och levnadssätt. Bland dessa händelser har torka varit särskilt förödande och har satt djupaspår i mänsklighetens historia. Under århundraden har torkor tvingat samhällen att anpassa sig och utvecklas som svar påförändrade miljöförhållanden. I Kalifornien har frekvensen och allvaret av torkor ökat under desenaste decennierna, vilket har lett till betydande förändringar i markanvändningsmönster. Dessaförändringar har påverkat ekonomin, den sociala strukturen och ekologin i regionen, vilket görstudiet av markanvändningsförändringar efter torkperioder till ett avgörande forskningsområde. I denna masteruppsats kommer effekterna av torkor på markanvändningen i Kalifornien attutforskas ingående. Resultat och påverkan av extrema torkhändelser i delstaten kommer attanalyseras, och potentiella åtgärder för klimatanpassning kommer att identifieras baserat på en ökadförståelse för konsekvenserna av torkor för markanvändningen. Genom att förstå det komplexaförhållandet mellan torkor och markanvändning kan mänskligheten bättre förbereda sig ochanpassa sig till utmaningarna som framtidens klimatförändringar och andra miljömässigapåfrestningar medför.

Tesis por compendio / Flood risk reduction is a global challenge. Society demands higher safety and security levels, including those actions related to flood defence infrastructure protection against natural hazards and manmade threats. Dams and levees, among other flood defence infrastructures, are critical hydraulic infrastructures, aiming at reducing the likelihood that people and property will get flooded, but whose failure would result in consequences for the community downstream, including not only economic damages but also loss of life. There is always a probability associated with infrastructure failure, although in general it might be very low. The purpose of the PhD research, with title "Integrated flood risk management: towards a risk-informed decision making incorporating natural and human-induced hazards", here presented is to propose a framework to enhance integrative flood risk management from a multi-hazard perspective (pluvial flooding, river flooding, dam and levee failure, including man-made threats), addressing current needs for decision making on flood risk reduction and analyzing the complexity of multiple hazards and systems which include multiple components. The thesis is structured in three main parts, including: (i) Part I, a methodology aiming at providing a common framework for identifying and characterizing flood risk due to pluvial flooding, river flooding and dam failure, and incorporate information on loads, system response and consequences into risk models to analyse societal and economic flood risk, (ii) Part II, an approach for quantifying and analyzing risk for complex dam-levee systems, to incorporate information from levee failure into risk models based on the aforementioned methodology, and to analyse societal and economic flood risk, including the potential failure of these infrastructures, and (iii) Part III, a screening tool to characterize the impact of human induced threats on risk due to dam failure or mission disruption. Results from this research have proven that the use of risk models provides a logic and mathematically rigorous framework for compiling information for flood risk characterization and analysis from different natural hazards and flood defence performance. The proposed framework in this thesis and applications aimed at encouraging key actors on flood risk management (infrastructure managers, authorities, emergency action planners, etc.) on the use of QRA, and at demonstrating to what extent QRA can usefully contribute to better understanding risk drivers and inform decisions on how to act to efficiently reduce flood risk. / La reducción del riesgo de inundación es un reto global. La sociedad actual demanda cada vez mayores niveles de seguridad, incluyendo la consecución de acciones vinculadas a la protección de las infraestructuras de defensa frente a inundaciones ante amenazas naturales y antrópicas. Presas y diques, entre otras obras de defensa, son infraestructuras críticas cuyo objetivo es reducir la probabilidad de inundación. Sin embargo, su fallo puede resultar en consecuencias para la comunidad situada aguas abajo, incluyendo no sólo daños económicos sino también pérdida potencial de vidas. Siempre existe una cierta probabilidad asociada al fallo de estas infraestructuras, aunque en general muy baja. El objetivo de la investigación llevada a cabo en la presente tesis doctoral, con título "Integrated flood risk management: towards a risk-informed decision making incorporating natural and human-induced hazards", es proporcionar un marco que fomente la gestión integral del riesgo de inundación desde una perspectiva multi-amenaza, considerando las necesidades actuales en la toma de decisiones para la gestión del riesgo de inundación y analizando la complejidad de sistemas con múltiples componentes, afectados por diferentes amenazas. La tesis se estructura en tres partes principales, incluyendo: (a) Parte I, una metodología para proporcionar un marco común para la identificación y caracterización del riesgo de inundación por inundación pluvial, fluvial y fallo de presas, incorporando información sobre solicitaciones, respuesta del sistema y consecuencias en modelos de riesgo que permiten analizar y evaluar el riesgo social y económico por inundación, (b) Parte II, un método para la cuantificación y análisis del riesgo en sistemas complejos presa-dique, con el objetivo de incorporar información referente al fallo de diques en la metodología propuesta en la Parte I, y analizar el riesgo social y económico por inundación incluyendo el fallo de varias infraestructuras de defensa, y (c) Parte III, una herramienta de cribado que permite caracterizar el impacto de amenazas de origen antrópico en el riesgo asociado al fallo de presas. Los resultados de esta investigación demuestran que el uso de modelos de riesgo proporciona un marco lógico y matemáticamente riguroso para la consideración de toda la información necesaria para la adecuada caracterización y análisis del riesgo de inundación por amenazas naturales y por fallo o mal funcionamiento de obras de defensa. El marco metodológico propuesto y las aplicaciones descritas en esta tesis tienen como objetivo impulsar la aplicación del análisis de riesgo por parte de los actores clave en la gestión del riesgo de inundación (gestores de infraestructuras, autoridades locales, gestores de emergencias, etc.) y demostrar en qué medida estos análisis pueden contribuir a alcanzar un mejor conocimiento de los factores clave que componen el riesgo e informar en la toma de decisiones hacia una reducción del riesgo más eficiente. / La reducció del risc d'inundació és un repte global. La societat actual demana majors nivells de seguretat, incloent-hi la realització d'accions vinculades a la protecció de les infraestructures de defensa enfront del risc d'inundacions afectades per amenaces naturals i antròpiques. Preses i dics fluvials, entre altres obres de defensa, són infraestructures crítiques i tenen l'objectiu de reduir la probabilitat d'inundació però el seu trencament pot resultar en conseqüències en, danys econòmics i també pèrdua potencial de vides. Sempre hi ha una certa probabilitat vinculada al trencament d'aquestes infraestructures, encara que en general molt baixa. L'objectiu de la investigació duta a terme en aquesta tesi doctoral, amb títol "Integrated flood risk management: towards a risk-informed decision making incorporating natural and human-induced hazards", és proporcionar un marc per a fomentar la gestió integral del risc d'inundació des d'una perspectiva multi-amenaça, tenint en compte les necessitats actuals per prendre decisions per a la gestió del risc d'inundació i analitzant sistemes complexes amb múltiples components i afectats per diferents amenaces. La tesi s'estructura en tres parts principals: (a) Part I, una metodologia proposada per a proporcionar un marc comú per a la identificació i caracterització del risc d'inundació per inundació pluvial, fluvial i trencament de preses, incorporant informació de sol¿licitacions, resposta del sistema i conseqüències en models de risc que permeten analitzar el risc social i econòmic per inundació, (b) Part II, un mètode per a la quantificació i anàlisi del risc en sistemes complexes, amb l'objectiu d'incorporar informació referent al trencament de dics fluvials en la metodologia descrita en la Part I, i analitzar el risc social i econòmic pel trencament de diverses infraestructures de defensa, i (c) Part III, una ferramenta de pre-anàlisi per a caracteritzar l'impacte d'amenaces de origen antròpic en el risc associat al trencament de preses. Els resultats de la investigació demostren l'utilitat de l'aplicació de models de risc, proporcionant un marc lògic i matemàticament rigorós per a la consideració de tota la informació necessària per a l'adequada caracterització i anàlisi del risc d'inundació per amenaces naturals i per trencament d'obres de defensa. El marc metodològic i les aplicacions derivades d'aquesta tesi tenen com a objectiu impulsar l'aplicació d'anàlisi de risc quantitatius per part dels actors vinculats a la gestió del risc d'inundació (gestors d'infraestructures, autoritats locals, gestors d'emergències, etc.) i demostrar que poden contribuir a disposar d'un millor coneixement dels factors clau que componen el risc, i per a informar les decisions necessàries per a una reducció del risc més eficient. / Castillo Rodríguez, JT. (2017). Integrated Flood Risk Management: Towards a Risk-Informed Decision Making Incorporating Natural and Human-Induced Hazards [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/82305 / Compendio

Ethiopia like other developing countries depends on domestic agricultural production, struggling with infrastructure and healthcare is also at a low level. Among these factors there is also added impact of catastrophic natural processes. Landslides in this area have caused enormous material damage and also human deaths. Effects of those losses are huge and locals are dealing with them difficuly. Therefore, prevention should be a priority concern. In theoretical part the basic facts about modeling and simulation of landslides susceptibility is presented. Those facts are complemented with specific researches from Ethiopian highlands. Furthermore, it describes the methodology that was used. It compares the real distribution of slope movements against the expected occurrence across the classes of input layers. An essential part of the model is mapping work, supported with terrain work, during which 242 landslides was mapped. Model parameters are: slope, altitude, lithology, land cover, distance from geological boundary and distance to river. Slope was determined as most significant factor. Used methodology is universally applicable and the results it generates match reality well. Key words: slope movements, natural hazards, susceptibility analysis, geomorphology, Ethiopian Highland

En cas d’alerte aux inondations, l'information en temps réel et sa diffusion à un large public sont des éléments cruciaux pour limiter les comportements à risque, détecter les premiers dégâts ou préparer les acteurs locaux à gérer la crise. Face à ces enjeux, les technologies smartphones apparaissent, deplus en plus, comme des solutions logicielles et matérielles qui pourraient compléter de façon positiveles dispositifs d’alerte institutionnels, notamment grâce à la dynamique des contenus partagés et auxnombreuses interactions dont ils sont le support. Alors que plusieurs pays (États-Unis, Norvège, Pays-Bas, Suède, Philippines) utilisent déjà de tels outils, et même si le Ministère de l'Intérieur a lancé uneapplication urgentiste (SAIP) le 8 juin 2016, la population et les services de l’État semblent beaucoupplus réticents en France. La défense de la propriété individuelle, le manque de crédit attribué auxmessages postés et les verrous technologiques sont les principaux facteurs de blocage avancés. Aprèsavoir mené une enquête dans plusieurs communes rurales des départements du Var et du Vaucluse(qui confirme la méconnaissance des applications déjà existantes alors que les besoins sont bien réelsface aux crues rapides), une nouvelle application a été développée (Al’in). Le prototype créé vise àréduire les écarts entre une approche étatique descendante (top-down), qui positionne et impose l’Étatcomme le seul lanceur d’alerte, et une initiative citoyenne (approche « Bottom-Up »), qui érigel’individu au rang de « citoyen capteur », à la fois capable de remonter ou de diffuser une alerte àtravers l’usage de son smartphone. Répondre à ce défi ne s’avère toutefois pas si simple au regard descontraintes juridiques et techniques préexistantes en France. / The information given on flash floods in real time should undoubtedly answers to the citizens needs aswell as to the politic and the safety services. Face to such objective, Smartphone could positivelycomplete the official institutional systems, especially thanks to the dynamic and nature of postedmessages, and to the social interactions they support. This study questions the opportunity ofdeveloping a proactive and innovative alert system using the Smartphone technologies to face therisks due to flash flood hazards. A first study focuses on several alert systems existing actually inFrance but we quickly aim at identifying limits (legal rules, technologies and scientific problems) andchallenges usefulness and opportunities in the numeric sphere) of our objective in general manner.Finally, a local study in Var and Vaucluse permits us to see if population and local stakeholdersshould be interested (or not) by a smartphone application. The proposed solution tries to achieve amajor challenge: reducing the gap between a state approach (top-down), which positions and imposedthe state as the main official alert source, and the citizen action (bottom-up) which establishes theindividual as “Citizen sensor” (both in go up or disseminate information) through the use of issmartphone. Meeting this challenge is indispensable if we hope effectively minimizing material andhuman damages especially when high temporal acuity phenomena such as flash floods happen.

This research integrates the theoretical implications of risk perception, the social amplification of risk, and the role of place-specific contexts, in order to explore the various perceptions surrounding Florida red tides. Florida red tides are a naturally-occurring event, yet most scientists agree that they are increasing in frequency, duration, and severity. This has profound implication for public health, the local economy, and the biological community. While many of the negative impacts are not easily controllable at this time, some of the secondary impacts can be mitigated through individuals' responses. Unfortunately, public perceptions and consequent reactions to red tides have not been investigated. This research uses questionnaire surveys, semi-structured interviews, and newspaper content analysis to explore the various perceptions of risk surrounding red tides. Surveys and interviews were conducted along two Florida west coast beaches, Fort De Soto Park and Siesta Key. Results indicate that the underlying foundations of the social amplification of risk framework are applicable to understanding how individuals form perceptions of risk relative to red tide events. There are key differences between the spatial locations of individuals and corresponding perceptions, indicating that place-specific contexts are essential to understanding how individuals receive and interpret risk information. The results also suggest that individuals may be lacking efficient and up-to-date information about red tides and their impacts due to inconsistent public outreach. Overall, particular social and spatial factors appear to be more influential as to whether individuals amplify or attenuate the risks associated with red tides.

Even though quite different in occurrence and consequences, from a modeling perspective many natural hazards share similar properties and challenges. Their complex nature as well as lacking knowledge about their driving forces and potential effects make their analysis demanding: uncertainty about the modeling framework, inaccurate or incomplete event observations and the intrinsic randomness of the natural phenomenon add up to different interacting layers of uncertainty, which require a careful handling. Nevertheless deterministic approaches are still widely used in natural hazard assessments, holding the risk of underestimating the hazard with disastrous effects. The all-round probabilistic framework of Bayesian networks constitutes an attractive alternative. In contrast to deterministic proceedings, it treats response variables as well as explanatory variables as random variables making no difference between input and output variables. Using a graphical representation Bayesian networks encode the dependency relations between the variables in a directed acyclic graph: variables are represented as nodes and (in-)dependencies between variables as (missing) edges between the nodes. The joint distribution of all variables can thus be described by decomposing it, according to the depicted independences, into a product of local conditional probability distributions, which are defined by the parameters of the Bayesian network. In the framework of this thesis the Bayesian network approach is applied to different natural hazard domains (i.e. seismic hazard, flood damage and landslide assessments). Learning the network structure and parameters from data, Bayesian networks reveal relevant dependency relations between the included variables and help to gain knowledge about the underlying processes. The problem of Bayesian network learning is cast in a Bayesian framework, considering the network structure and parameters as random variables itself and searching for the most likely combination of both, which corresponds to the maximum a posteriori (MAP score) of their joint distribution given the observed data. Although well studied in theory the learning of Bayesian networks based on real-world data is usually not straight forward and requires an adoption of existing algorithms. Typically arising problems are the handling of continuous variables, incomplete observations and the interaction of both. Working with continuous distributions requires assumptions about the allowed families of distributions. To "let the data speak" and avoid wrong assumptions, continuous variables are instead discretized here, thus allowing for a completely data-driven and distribution-free learning. An extension of the MAP score, considering the discretization as random variable as well, is developed for an automatic multivariate discretization, that takes interactions between the variables into account. The discretization process is nested into the network learning and requires several iterations. Having to face incomplete observations on top, this may pose a computational burden. Iterative proceedings for missing value estimation become quickly infeasible. A more efficient albeit approximate method is used instead, estimating the missing values based only on the observations of variables directly interacting with the missing variable. Moreover natural hazard assessments often have a primary interest in a certain target variable. The discretization learned for this variable does not always have the required resolution for a good prediction performance. Finer resolutions for (conditional) continuous distributions are achieved with continuous approximations subsequent to the Bayesian network learning, using kernel density estimations or mixtures of truncated exponential functions. All our proceedings are completely data-driven. We thus avoid assumptions that require expert knowledge and instead provide domain independent solutions, that are applicable not only in other natural hazard assessments, but in a variety of domains struggling with uncertainties. / Obwohl Naturgefahren in ihren Ursachen, Erscheinungen und Auswirkungen grundlegend verschieden sind, teilen sie doch viele Gemeinsamkeiten und Herausforderungen, wenn es um ihre Modellierung geht. Fehlendes Wissen über die zugrunde liegenden Kräfte und deren komplexes Zusammenwirken erschweren die Wahl einer geeigneten Modellstruktur. Hinzu kommen ungenaue und unvollständige Beobachtungsdaten sowie dem Naturereignis innewohnende Zufallsprozesse. All diese verschiedenen, miteinander interagierende Aspekte von Unsicherheit erfordern eine sorgfältige Betrachtung, um fehlerhafte und verharmlosende Einschätzungen von Naturgefahren zu vermeiden. Dennoch sind deterministische Vorgehensweisen in Gefährdungsanalysen weit verbreitet. Bayessche Netze betrachten die Probleme aus wahrscheinlichkeitstheoretischer Sicht und bieten somit eine sinnvolle Alternative zu deterministischen Verfahren. Alle vom Zufall beeinflussten Größen werden hierbei als Zufallsvariablen angesehen. Die gemeinsame Wahrscheinlichkeitsverteilung aller Variablen beschreibt das Zusammenwirken der verschiedenen Einflussgrößen und die zugehörige Unsicherheit/Zufälligkeit. Die Abhängigkeitsstrukturen der Variablen können durch eine grafische Darstellung abgebildet werden. Die Variablen werden dabei als Knoten in einem Graphen/Netzwerk dargestellt und die (Un-)Abhängigkeiten zwischen den Variablen als (fehlende) Verbindungen zwischen diesen Knoten. Die dargestellten Unabhängigkeiten veranschaulichen, wie sich die gemeinsame Wahrscheinlichkeitsverteilung in ein Produkt lokaler, bedingter Wahrscheinlichkeitsverteilungen zerlegen lässt. Im Verlauf dieser Arbeit werden verschiedene Naturgefahren (Erdbeben, Hochwasser und Bergstürze) betrachtet und mit Bayesschen Netzen modelliert. Dazu wird jeweils nach der Netzwerkstruktur gesucht, welche die Abhängigkeiten der Variablen am besten beschreibt. Außerdem werden die Parameter der lokalen, bedingten Wahrscheinlichkeitsverteilungen geschätzt, um das Bayessche Netz und dessen zugehörige gemeinsame Wahrscheinlichkeitsverteilung vollständig zu bestimmen. Die Definition des Bayesschen Netzes kann auf Grundlage von Expertenwissen erfolgen oder - so wie in dieser Arbeit - anhand von Beobachtungsdaten des zu untersuchenden Naturereignisses. Die hier verwendeten Methoden wählen Netzwerkstruktur und Parameter so, dass die daraus resultierende Wahrscheinlichkeitsverteilung den beobachteten Daten eine möglichst große Wahrscheinlichkeit zuspricht. Da dieses Vorgehen keine Expertenwissen voraussetzt, ist es universell in verschiedenen Gebieten der Gefährdungsanalyse einsetzbar. Trotz umfangreicher Forschung zu diesem Thema ist das Bestimmen von Bayesschen Netzen basierend auf Beobachtungsdaten nicht ohne Schwierigkeiten. Typische Herausforderungen stellen die Handhabung stetiger Variablen und unvollständiger Datensätze dar. Beide Probleme werden in dieser Arbeit behandelt. Es werden Lösungsansätze entwickelt und in den Anwendungsbeispielen eingesetzt. Eine Kernfrage ist hierbei die Komplexität des Algorithmus. Besonders wenn sowohl stetige Variablen als auch unvollständige Datensätze in Kombination auftreten, sind effizient arbeitende Verfahren gefragt. Die hierzu in dieser Arbeit entwickelten Methoden ermöglichen die Verarbeitung von großen Datensätze mit stetigen Variablen und unvollständigen Beobachtungen und leisten damit einen wichtigen Beitrag für die wahrscheinlichkeitstheoretische Gefährdungsanalyse.

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