Aplicação de métodos estatísticos e empíricos para estimativa do nível máximo do rio Ibirapuitã devido a eventos hidrológicos extremos

Abstract

The occurrence of extreme hydrological events in large basins is linked to long-term precipitation, while for small basins it is short-term precipitation that causes problems of greater magnitude. Consequently, for both cases, the water level of the rivers rises and reaches the floodplains, this being responsible for causing damage and ruin in structures. Bridges are generally very affected by these events, because with the increase in the river level, they may end up suffering unforeseen stresses in the design of the structure as a whole. Therefore, it is necessary to estimate what level will be reached so that hydraulic structures can be built safely. This work analyzes six statistical distributions to determine the maximum flows obtained from the historical series of fluviometric data, while using empirical methods based on the historical series of pluviometric data, to then compare the values obtained by the different methodologies. Finally, the rating curve equation was used to estimate the maximum level reached. The methodology was applied to the section of the bridge over the Ibirapuitã river in the urban area of the city of Alegrete/RS. The maximum flow observed was 1401.48 m3/s with an observed level of 14.22 m, and the maximum flow calculated by the GEV distribution was 1440.54 m3/s with an estimated level of 15.53 m, both for the time of return of 81 years. As the bridge is closed when the level reaches about 13 m, it is possible to affirm that the structure, in this case study, is not safe in the face of an extreme hydrological event of this proportion. Keywords: Maximum flow rate. Maximum level. Statistical. Empirical. Modeling.