Mapeamento do perigo de inundações na porção urbana da bacia do Rio Botas em Nova Iguaçu, RJ, por meio de modelagem matemática

Abstract

The urbanization process in Brazil occurs in a disorganized way with the waterproofing of the soil, deforestation of the riparian forest and management of rivers without previous study. Brazilian urban areas have high values of population density where one of the consequences is the unrestrained occupation of inappropriate regions such as the banks of rivers and the floodplain, thus flooding in urban areas causes great material and human losses (TUCCI, 1995). The municipality of Nova Iguaçu, RJ has recurrent floods and according to Civil Defense data, the flooding of the Botas River causes great losses since it intercepts densely populated neighborhoods, so a study of its floods becomes essential as a support for Civil Defense measures and as basis for municipal planning. In this way, hydrological and hydrodynamic modeling are useful tools for creating scenarios and simulating hydrometeorological events. In this context, the present work aims to analyze, through hydrological and hydraulic simulations, the floods of the Botas River in function of five rain scenarios, three from the protocol used by the Civil Defense of Nova Iguaçu and two from the study carried out in this dissertation, in the rain records of the Ecology Agricultural meteorological station located in Seropédica. For this, with the aid of the ArcGIS 10,5 program, a digital elevation model with a resolution of 1m was created, a map of land use and cover, in addition to the delimitation of the Botas river basin. Through the use of the HEC- HMS and HEC-RAS programs, hydrological and hydraulic modeling were carried out, but before that, tests were made with different rain distributions in addition to different Manning values for the channel and for the floodplain. With the results obtained (flood hydrographs and flood spots referring to each scenario), it was observed that all the neighborhoods along the Botas River are flooded with different extensions and depths of water depth. After analyzing the scenarios, four degrees of danger were formulated due to material losses and inconvenience caused to residents. All of these criteria were selected in a way that supports the actions of the Civil Defense. Elements exposed to floods were also identified, such as homes, residents and public buildings, such as schools and hospitals. The results prove that the protocol used by the Civil Defense, in relation to floods, is efficient, as it is compatible with the extreme values of rain for the summer found in this work.