Use of large-scale hydrological models to predict dam break-related impacts

In this research study, the MGB-IPH (acronym for Large Scale Model in Portuguese - Modelo de Grandes Bacias) was used to simulate the propagation of a dam breach hydrograph estimated from predictor equations for the Três Marias Hydropower Dam, considered one of the largest in South America. The results of the peak flow, peak time and flood spot were compared with results of the Hec-Ras 5.06 model, typically used for local-scale dam break studies. As for the extent of the flood, a hit rate of 84% and a median error of 2.1 meters deep, along 4,055 km2 of the flooded area downstream was obtained. Maximum errors of 13% were observed in the prediction of the peak flow and of 20% for the peak time in distant locations up to 526 km downstream from the dam, thus establishing itself within the limits of the typical uncertainties associated with dam break studies. Thus, the potential of using this type of approach in previous studies of large dam failures is explored, configuring this method as an alternative to the use of robust or simplified models for determining downstream areas potentially affected by these disasters.Neste trabalho, foi utilizado o Modelo de Grandes Bacias (MGB-IPH) para simular a propagação de um hidrograma de ruptura estimado a partir de equações preditoras para a barragem da UHE Três Marias, considerada uma das maiores da América do Sul. Os resultados, quanto à vazão de pico, tempo de pico e mancha de inundação foram comparados com os resultados advindos do modelo Hec-Ras 5.06, tipicamente utilizado para estudos de rompimento de barragens em escala local. Quanto à extensão da mancha de inundação, obteve-se um índice de acerto de 84% e um erro mediano de 2,1 metros de profundidade, ao longo de 4.055 km2 de área inundada a jusante. Observaram-se erros máximos de 13% na predição da vazão de pico e de 20% para o tempo de pico em locais distantes até 526 km a jusante da barragem, estabelecendo-se, portanto dentre os limites das incertezas típicas associadas a estudos de rompimento de barragens. Desta forma, o uso potencial deste tipo de abordagem em estudos prévios de rompimento de barragens é explorado, configurando-se este método como uma alternativa ao uso de modelos robustos ou simplificados para determinação de áreas de jusante potencialmente afetadas por estes desastres

Abordagem de grande escala para simulações de cheias geradas por rompimentos de barragens de armazenamento de água

Barragens são estruturas que fizeram, fazem e farão parte da sociedade. Se por um lado elas são capazes de trazer inúmeros benefícios, por outro, podem ser também responsáveis por grandes impactos, dos quais se destacam os rompimentos. O grande número de rupturas de barragens observados no passado trazem à tona uma discussão acerca da necessidade de identificação dos possíveis impactos associados a rupturas de barragens estabelecidas em vastos territórios, como o Brasil. Considerando o elevado número de barragens em território nacional (que ultrapassava 22.000 no ano de 2020), torna-se um grande desafio a identificação desses possíveis impactos, inicialmente definidos a partir da classificação de barragens quanto ao chamado Dano Potencial Associado (DPA). Dessa forma, essa Tese de Doutorado procura explorar técnicas de mapeamento sistemático e preliminar de áreas possivelmente impactadas por ruptura de diversas barragens de armazenamento de água sob uma abordagem hidrodinâmica de grande escala, que é discutida sob a óptica recentemente adotada em Modelos Hidrológicos de Grande Escala (MHGEs). Esses modelos utilizam o esquema de propagação inercial, que despreza apenas o termo de inércia advectiva das equações de Saint-Venant, associado a uma abordagem de descrição topológica de terreno (que utiliza curvas Cota-Área-Volume definidas ao longo do trecho de interesse) para simular e representar cheias naturais. Geralmente associado a uma majoração da vazão de pico, subestimativas nas profundidades calculadas, atrasos no tempo de chegada de cheia e adiantamentos no tempo de chegada de vazão de pico, o modelo inercial foi utilizado na constituição de um novo modelo matemático hidrodinâmico unidimensional de planície ativa retangular com largura variável e que conta com troca de fluxo entre canal e planície, chamado de DB-HiFlow (acrônimo de Dam Break Hydrodynamic Inertial Flow Model). Esse modelo (em sua segunda versão) foi capaz de reproduzir manchas de inundação de ruptura de barragens geradas a partir do modelo HEC-RAS 6.1 com acurácia que variou entre 79,5% e 84%, associadas a diferenças típicas da ordem de +-15% para o tempo de chegada de pico e de -16% a +9% para a vazão de pico calculada em diferentes seções das barragens analisadas. Tendo sido concebido para aplicações de grande escala, esse modelo foi capaz de gerar informações como mapas de inundação e mapa de tempo de chegada de vazão de pico para 26 pequenas barragens localizadas em diferentes pontos na bacia do Lago Guaíba em apenas 6 horas de simulação, com pouca intervenção humana, se demonstrando útil no âmbito de classificação rápida de diversas barragens quanto ao DPA por parte de organismos de controle, entre outras aplicações. Dessa forma, as técnicas aqui apresentadas podem ser vistas como uma alternativa hidrodinâmica complementar aos comumente adotados métodos simplificados de rompimento de barragens (que em geral são restritivos na representação dos impactos de ondas de ruptura em locais com determinadas características), trazendo aos órgãos regulamentadores uma opção adicional de análise rápida e simplificada de potenciais danos sociais econômicos e ambientais associados a ruptura de barragens.Dams are structures that were, are and will be part of society. If, on the one hand, they are capable of bringing numerous benefits, on the other hand, they can also be responsible for major impacts, of which ruptures can be highlighted. The large number of dam failures observed in the past brings up a discussion about the need to identify the possible impacts associated with dam failures established in vast territories, such as Brazil. Considering the high number of dams in the national territory (which exceeded 22,000 in 2020), it is a great challenge to identify these possible impacts, initially defined from the classification of dams in terms of the so-called Associated Potential Damage (APD). Thus, this PhD Thesis seeks to explore systematic and preliminary mapping techniques of areas possibly impacted by the failure of several water dams under a large-scale hydrodynamic approach, which is discussed from the perspective recently adopted in Large-Scale Hydrological Models (LSHMs). These models use the inertial propagation scheme, which ignores only the advective inertia term of the Saint-Venant equations, associated with a topological terrain description approach (which uses Elevation-Area-Volume curves defined along the stretch of interest) to simulate and represent natural floods. Generally associated with a higher peak flow, underestimations in the calculated depths, delays in the time of arrival of the flood and small time of arrival of the peak flow, the inertial model was used in the constitution of a new one-dimensional hydrodynamic mathematical model of active rectangular floodplain with variable width and that has flow exchange between channel and floodplain, called DB-HiFlow (acronym for Dam Break Hydrodynamic Inertial Flow Model). This model (in its second version) was able to reproduce dam failure flood patches generated from the HEC-RAS 6.1 model with an accuracy that varied between 79.5% and 84%, associated with differences of the order of +- 15% for the peak arrival time and from -16% to +9% for the peak flow calculated for different sections of the analyzed dams. Having been designed for large scale applications, this model was able to generate information such as flood maps and peak flow arrival time map for 26 small dams located at different points in the Guaíba Lake watershed in just 6 hours of simulation, with little human intervention, proving to be useful in the scope of rapid classification of several dams in terms of APD by regulatory agencies. In this way, the techniques presented here can be seen as a hydrodynamic alternative complementary to the commonly adopted Dam-Break simplified methods (which in general are restrictive in the representation of the impacts of rupture hydrograms in downstream valleys with certain characteristics), providing regulatory agencies with an additional option for a quick and simplified analysis of potential social, economic and environmental damages associated with dam failure

Management System for Dam-Break Hazard Mapping in a Complex Basin Environment

Flood disasters from dam breaks cause serious loss of human life and immense damage to infrastructure and economic stability. The application of Geographic Information System technology integrated with hydrological modeling for mapping flood-inundated areas and depth can play a momentous role in further minimizing the risk and possible damage. In the present study, base terrain data, hydrological data, and dam engineering data were integrated using the MIKE-21 dam-break model to analyze flood routing under the most serious scenarios. A deterministic approach was used to calculate the hydraulic elements of dam breakage during a flood. Additionally, the hydraulic elements generated by the MIKE-21 dam-break model (a modelling system for estuaries, coastal waters, and seas)—including flood depth, submersion time, and flow direction—were integrated with a digital elevation model of the site downstream of the dam in order to map the possible affected areas. Using an empirical model in addition to using the superimposition of dam flood calculation results and the social and economic survey data, dam damage assessment was implemented. In accordance with a relevant standard, the flood risk mapping guidelines and a set of client/server structures were developed for a management system for dam-break hazard mapping of the Foziling reservoir. The simulation data and the study results can provide a scientific basis for emergency management of the reservoir and provide a socio-economic framework for downstream areas

Mapeamento de perigo potencial associado a rompimentos de barragens sob efeito cascata

Barragens são estruturas que, mediante o contexto histórico dos recursos hídricos, possuem um papel extremamente relevante para a sociedade. Se, por um lado, as construções desses reservatórios trazem benefícios, por outro lado, possíveis rompimentos dessas estruturas resultam em potenciais danos que podem se intensificar em rios que possuem reservatórios em cascata. Os grandes desastres ocorridos no passado levantaram a discussão sobre a importância da criação de mapas de perigo em grande escala para auxiliar na gestão e prevenção desses eventos. Considerando o crescente aumento no número de barragens no Brasil, torna-se um grande desafio elaborar mapas com índices simples, intuitivos e que também apresentem embasamento físico para identificar possíveis impactos ocasionados por acidentes dessa natureza. Em vista disso, este estudo apresenta uma alternativa para mapear o perigo de inundações de rompimentos de barragens sob efeito cascata, através do desenvolvimento e aplicação de um modelo físico que prevê a atenuação da vazão de pico da onda de cheia à medida que ela se propaga para jusante. O modelo pode ser facilmente aplicado com parâmetros comumente disponíveis relacionados às características do rio e do hidrograma afluente. A proposta de elaboração dos mapas de perigo apresenta etapas para estimar as vazões de pico, aplicar o modelo de atenuação de forma recursiva ao longo dos segmentos de comprimento do rio, determinar o tempo de propagação da onda de cheia e propor a obtenção dos períodos de retorno das vazões de pico. A validade e precisão do modelo foram demonstradas através de três análises diferentes. Quando testado, ele replicou soluções numéricas das equações de Saint-Venant, mostrou precisão na reprodução das observações históricas de vazão de pico e foi consideravelmente mais preciso que um modelo empírico simplificado. Além disso, forneceu previsões de atenuação equivalentes às fornecidas por um modelo hidrodinâmico detalhado e observações in situ para uma cheia real. Os produtos da aplicação da metodologia foram distribuídos espacialmente em formato de mapas de perigo, com informações atraentes e também embasadas fisicamente por meio de índices de vazão máxima, tempo de propagação e período de retorno da onda de cheia. O mapa de vazões máximas de ruptura apresentou as vazões de pico diminuindo à medida que se propagam para jusante, conforme o comportamento proposto no modelo de atenuação. O produto do tempo de propagação da onda de cheia apresentou informações que podem ser necessárias para a elaboração de planos de evacuação mediante a ocorrência de acidentes, e o mapa de período de retorno das cheias expôs alto grau de perigo para a maioria dos cursos d’água, com cheias que podem comprometer a segurança das estruturas construídas. O principal propósito desta dissertação foi a elaboração de mapas de perigo em grande escala, com o intuito de fomentar a comunicação sobre os riscos de inundações decorrentes de possíveis rupturas de barragens sob efeito cascata e auxiliar na tomada de decisões.Dams are structures that, within the historical context of water resources, play an extremely relevant role for society. While the construction of these reservoirs provides benefits, potential failures of these structures can result in significant damage, particularly in rivers with cascading reservoirs. The occurrence of major disasters in the past has sparked a discussion about the importance of creating large-scale hazard maps to assist in the management and prevention of such events. As the number of dams in Brazil continues to rise, developing maps with simple, intuitive indices that have a solid physical basis to identify potential impacts resulting from accidents of this nature presents a significant challenge. Therefore, this study presents an alternative approach to mapping the hazard of flooding resulting from cascading dam breaks by developing and applying a physical model that predicts the attenuation of the peak flow of the flood wave as it propagates downstream. The model can be easily applied with commonly available parameters related to the characteristics of the river and the inflow hydrograph. The proposed methodology for developing hazard maps includes steps such as estimating peak flows, recursively applying the attenuation model along the river's length segments, determining the propagation time of the flood wave, and obtaining the return periods of peak flows. The validity and accuracy of the model were demonstrated through three different analyses. When tested, it replicated numerical solutions of the Saint-Venant equations, showed accuracy in reproducing historical observations of peak flow, and was considerably more accurate than a simplified empirical model. Furthermore, it provided attenuation predictions equivalent to those provided by a detailed hydrodynamic model and in-situ observations for a real flood event. The methodology outputs were spatially distributed as hazard maps with appealing information and also physically supported by maximum flow indices, wave travel time and flood wave return period. The maximum flows map showed peak flows decreasing as they propagate downstream, according to the proposed behavior of the attenuation model. The flood wave travel time product provided information that may be necessary for the development of evacuation plans in case of accidents, and the flood return period map showed a high degree of hazard for most watercourses, with floods that can compromise the safety of built structures. The main purpose of this work was to develop largescale hazard maps in order to promote communication about the risks of floods resulting from possible dam breaks under cascading effect and assist in decision-making

INVESTIGATION INTO GAME-BASED CRISIS SCENARIO MODELLING AND SIMULATION SYSTEM

A crisis is an infrequent and unpredictable event. Training and preparation process requires tools for representation of crisis context. Particularly, crisis events consist of different situations, which can occur at the same time combining into complex situation and becoming a challenge in coordinating several crisis management departments. In this regards, disaster prevention, preparedness and relief can be conceptualized into a design of hypothetical crisis game. Many complex tasks during development of emergency circumstance provide an opportunity for practitioners to train their skills, which are situation analysis, decision-making, and coordination procedures. While the training in physical workouts give crisis personal a hand-on experience in the given situation, it often requires a long time to prepare with a considerable budget. Alternatively, computational framework which allows simulation of crisis models tailoring into crisis scenario can become a cost-effective substitution to this study and training. Although, there are several existing computational toolsets to simulate crisis, there is no system providing a generic functionality to define crisis scenario, simulation model, agent development, and artificial intelligence problem planning in the single unified framework. In addition, a development of genetic framework can become too complex due to a multi-disciplinary knowledge required in each component. Besides, they have not fully incorporated a game technology toolset to fasten the system development process and provide a rich set of features and functionalities to these mentioned components. To develop such crisis simulation system, there are several technologies that must be studied to derive a requirement for software engineering approach in system’s specification designs. With a current modern game technology available in the market, it enables fast prototyping of the framework integrating with cutting-edge graphic render engine, asset management, networking, and scripting library. Therefore, a serious game application for education in crisis management can be fundamentally developed early. Still, many features must be developed exclusively for the novel simulation framework on top of the selected game engine. In this thesis, we classified for essential core components to design a software specification of a serious game framework that eased crisis scenario generation, terrain design, and agent simulation in UML formats. From these diagrams, the framework was prototyped to demonstrate our proposed concepts. From the beginning, the crisis models for different disasters had been analysed for their design and environment representation techniques, thus provided a choice of based simulation technique of a cellular automata in our framework. Importantly, a study for suitability in selection of a game engine product was conducted since the state of the art game engines often ease integration with upcoming technologies. Moreover, the literatures for a procedural generation of crisis scenario context were studied for it provided a structure to the crisis parameters. Next, real-time map visualization in dynamic of resource representation in the area was developed. Then the simulation systems for a large-scale emergency response was discussed for their choice of framework design with their examples of test-case study. An agent-based modelling tool was also not provided from the game engine technology so its design and decision-making procedure had been developed. In addition, a procedural content generation (PCG) was integrated for automated map generation process, and it allowed configuration of scenario control parameters over terrain design during run-time. Likewise, the artificial planning architecture (AI planning) to solve a sequence of suitable action toward a specific goal was considered to be useful to investigate an emergency plan. However, AI planning most often requires an offline computation with a specific planning language. So the comparison study to select a fast and reliable planner was conducted. Then an integration pipeline between the planner and agent was developed over web-service architecture to separate a large computation from the client while provided ease of AI planning configuration using an editor interface from the web application. Finally, the final framework called CGSA-SIM (Crisis Game for Scenario design and Agent modelling simulation) was evaluated for run-time performance and scalability analysis. It shown an acceptable performance framerate for a real-time application in the worst 15 frame-per-seconds (FPS) with maximum visual objects. The normal gameplay performed capped 60 FPS. At same time, the simulation scenario for a wildfire situation had been tested with an agent intervention which generated a simulation data for personal or case evaluation. As a result, we have developed the CGSA-SIM framework to address the implementation challenge of incorporating an emergency simulation system with a modern game technology. The framework aims to be a generic application providing main functionality of crisis simulation game for a visualization, crisis model development and simulation, real-time interaction, and agent-based modelling with AI planning pipeline