Avaliação dos fatores influentes no estudo hipotético de rompimento e propagação da onda de inundação em uma barragem de água

Abstract

This study evaluates the factors that most strongly influence the outcomes of a hypothetical dam-break and the propagation of the flood wave at the Chapéu d’Úvas Dam, located approximately 36 km east of Juiz de Fora, Minas Gerais. It constitutes an applied study with numerical analysis and coupled hydrologic–hydrodynamic simulation. The structure under analysis comprises the main dam, a tulip spillway, and a bottom outlet with two conduits. The study considers two failure mechanisms, overtopping and piping. HEC-HMS is employed to generate both the operational outflow hydrographs and the breach hydrographs, which serve as boundary conditions for a two-dimensional model in HEC-RAS to simulate inundation patterns over the terrain. The analysis investigates which 2D mesh configuration offers the best balance of numerical stability and physical representativeness and how terrain resolution affects hydraulic parameters and the resulting inundation envelope. The results indicate that overly fine or overly coarse meshes degrade model performance, while an intermediate configuration with 50×50 m cells outside the channel and 20×20 m cells within a 100 m buffer along the channel provides the most favorable trade-off between stability and fidelity. Terrain resolution proves decisive, since coarser digital elevation models tend to underestimate local depths and velocities and overestimate lateral spreading in low-relief areas. Differences between inundation patterns for piping and overtopping are secondary when compared with the influence of topography and its cartographic resolution.