Análise hidrometeorológica e modelagem hidráulica e hidrológica para simulação da mancha de inundação: estudo de caso na bacia do rio Quitandinha - Petrópolis-RJ

Abstract

The floods problem in urban areas has been growing in large proportions and significantly affects cities, especially where urban development has not taken place in a planned or controlled manner. In the Serrana region of Rio de Janeiro, especially in Petrópolis, floods have extremelly affected the city, with the overflow of the Quitandinha river. Hydraulic-hydrological modeling is a very important tool, since it can provide forecasts of flood patches in a hydrographic basin, allowing the public manager to establish a physical limit, where they can focus on contingency plans or even mitigation actions in the sensitive or vulnerable regions identified by the modelling. Therefore, the objective of this study was to carry out a pluviometric and fluviometric study of the hydrographic basin of the Quitandinha river, from the historical series of hydrometeorological monitoring of this basin, as well as to simulate flooding spots a meteorological event with overflow of the river channel using the hydraulic-hydrological modeling softwares HEC-HMS and HEC-RAS. To this end, cartographic databases of the region were adopted, at a scale of 1:20,000, to prepare the digital terrain model (DTM), which estimate the basin geometric data, such as the Quitandinha river basin delimitation, the thalweg length and average slope. These cartographic bases and the MDT were also used to determine other modeling input data, through the use of the ArcGis cartographic software. In addition, precipitation data from seven pluviometric stations located in the Quitandinha river basin and fluviometric data from two monitoring points in the Quitandinha river were also adopted, both provided by the State Environmental Institute, in order to calibrate and validate the HEC-HMS and HEC-RAS modeling results. The results of the simulations for the Quitandinha river overflow event that occurred in the summer of 2019 were satisfactory (accuracy of 95%), which shows the efficiency of the tool in predicting flood scenarios in hydrographic basins with recurrence of this phenomenon. It is concluded that the use of the hydraulic-hydrological model (HEC-HMS and HEC-RAS) associated with a geographic information system (GIS) can be a very important tool to assist in the decision-making process of public management regarding flood risks. It is expected that these results support actions to mitigate and contain floods in the Petrópolis city.