Mapeamento das áreas em risco de alagamentos no município da Passo Fundo com base em diferentes projeções climáticas

Abstract

The urbanization process has negative effects on the hydrological cycle, reducing soil infiltration, causing surface runoff to occur more quickly and intensely, leading to flooding. In addition, the Brazilian Panel on Climate Change (PBMC) estimates that rainfall will increase by 5% to 10% for temperature increases of 0.5ºC to 1ºC and by 25% to 30% for temperature increases of between 2.5ºC and 3ºC. The combination of increased rainfall, highly impermeable environments and inadequate infrastructure projects will make cities more vulnerable to flooding. To combat these negative impacts, it is necessary to use drainage structures and map areas at risk of flooding. The municipality of Passo Fundo, when designing its drainage system, used the intensity-duration-frequency equation proposed by Denardin and Freitas in 1982. The use of this equation has become obsolete, since the precipitation regime is not stationary and its use may favor the undersizing of new drainage structures. Therefore, the objective of this study was to map the areas susceptible to flooding in the municipality of Passo Fundo based on different climate projections. This study proposed a new IDF equation for the municipality, and proposed equations based on different climate projections. The municipality of Passo Fundo was then divided into smaller sub-basins to enable modeling of the network and analysis of its behavior, demonstrating which points suffer from flooding and how these floods will behave with rising temperatures. After modeling and obtaining the points suffering from the aforementioned hydrological disaster, four maps were created, showing the flooded volumes. And, based on the analysis of the points suffering from flooding, structural and non-structural measures were proposed to support the municipality's decision-making regarding the occurrence of these floods. Modeling using the SWMM software demonstrated that the Denardin and Freitas Equation has already become obsolete, since for the Current Projection Equation the rainfall intensities are greater and the points suffering from flooding increase. Mapping was carried out, demonstrating at which points there are floods, and their concentration areas, enabling the government to analyze which areas require more severe interventions. In addition, the design of a detention basin was proposed, which reduced the peak flow of an analyzed section by 64%, demonstrating that this could be a good complement to the existing structure.