Uncertainty assessment in hydrodynamic modeling of floods generated by dam break

Abstract

The objective of the present work was to evaluate sources of uncertainty in dam break simulations for areas with contrasting characteristics: one in a narrow valley with high slopes, and another an open valley with low slopes. A sensitivity analysis of the hydrodynamic model Hec-Ras 5.03 was performed, varying the input data of the model (Manning coefficient, breach configurations, reservoir volume, type of valley topography and equation considered). These variations cause different changes in peak flow, peak time, maximum depth and a maximum speed for different sections of the downstream watercourse. It was concluded that there are uncertainties in determining the input data that impacts in many ways at the generated flood wave, considering both a hydraulic variable of interest, the distance of the section from the dam and the mean geomorphological characteristic of the downstream valley. Topography is not always the most important input data, which allows the possibility of use of low resolution topographies to estimate the peak time in some sections, depending on the valley. Finally, safety coefficients for dam break studies are suggested, aiming to represent uncertainties of the input data in the generated results.Keywords: Geoprocessing; Hec-Ras 5.03; 2D Hydrodynamic modeling; Dam break; Safety coefficients. RESUMOO presente trabalho teve como objetivo realizar uma avaliação de fontes de incerteza em simulações de onda de cheia de rompimentos de barragens para áreas de características contrastantes: uma em vale encaixado e altas declividades e outro com vale aberto e baixas declividades. Uma análise da sensibilidade do modelo hidrodinâmico Hec-Ras 5.03 foi realizada, perturbando-se os dados de entrada do modelo (coeficiente de Manning, configurações da brecha, volume do reservatório, topografia do vale de jusante e tipo de equacionamento considerado). Após observou-se como essa variação alterava a vazão de pico, tempo de pico, profundidade máxima e a velocidade máxima para diferentes seções localizadas ao longo dos cursos hídricos. Concluiu-se que as incertezas existentes na determinação dos dados de entrada impactam de forma variada na onda de cheia gerada, considerando tanto a variável hidráulica de interesse como o distanciamento da seção em relação ao barramento e a característica geomorfológica média do vale de jusante. A topografia nem sempre é o dado de entrada de maior importância, o que permite, até certo ponto, a utilização de topografias de baixa resolução para estimar tempo de pico em algumas seções, dependendo do vale. Por fim, sugerem-se coeficientes de segurança para estudos de rompimento de barragens, que visam representar as incertezas dos dados de entrada nos resultados gerados. Palavras-chave:Geoprocessamento; Hec-Ras 5.03; Modelagem hidrodinâmica 2D; Rompimento de barragens; Coeficientes de segurança.RBRH, Porto Alegre, v. 23, e30, 2018Uncertainty assessment in hydrodynamic modeling of floods generated by dam break 2/17

A Fuzzy Clustering Logic Life Loss Risk Evaluation Model for Dam-Break Floods

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Dam-Break analysis: proposal of a simplified approach

“…Currently, due to modern computer processing capabilities, dam-break hydraulic and hydrodynamic software that have been developed, tested and improved over the years can easily be accessed, such as HEC-RAS (U.S. Army Corps of Engineers, 1995), DAMBRK (Fread, 1991), FLDWAV (Fread & Lewis, 1998) and LISFLOOD (Bates & De Roo, 2000). In general, most of these software require the following input data: downstream valley Manning coefficient; breach configuration; reservoir volume; downstream valley topography and; set of equations and simplifications considered for flood wave propagation (Tschiedel & Paiva, 2018).…”

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