Aplicação do modelo SWMM para análise de inundações na área urbana de Itajubá - MG

Abstract

Floods and inundations are a reality in many cities in Brazil due to intense urban expansion and disorderly land occupation. To quantify surface runoff in urban basins, understand its hydrological behavior and assess the causes of flooding, hydrological models can be used. These models help in the planning of urban space, in the evaluation of drainage control measures to be implemented and subsidize decision-making. In this context, the present work aimed to evaluate the applicability of the SWMM hydrological model (Storm Water Management Model) for the analysis of flooding in urban neighborhoods in the neighborhood in relation to the minimum data necessary for this type of study. For this, a case study of the Vila Rubens neighborhood, in Itajubá/MG, will be carried out to analyze the main causes of flooding and the effects of adopting some sustainable measures to control urban drainage. First, the delimitation and diagnosis of the study area were carried out. The defined hydrographic basin was characterized in relation to its physical and hydrological aspects. The study of intense rains was elaborated through analysis of the frequency of maximum precipitations, the rain disaggregation in sub-daily quantiles was carried out by the Torrico method and the temporal discretization by the Huff method to obtain the design rain for return period of 2, 5 and 10 years. Surface runoff was estimated using the CN-SCS infiltration method and the Dynamic Wave model for hydraulic transport. The current scenario of the basin was simulated and then some scenarios were defined with LID (Low Impact Development) control measures. For the three return times, the critical rainfall duration obtained in the current scenario was 30 min and the sub-basin corresponding to the Morro Chic neighborhood was the main contributor to the runoff portion. The adoption of LID measures, mainly at the source of the problem, contributed to the minimization of flooding. Despite the results of the measurements, the location of the basin, which is located in a floodplain, on very flat terrain, must be considered. The large amount of necessary input data and the uncertainties in the determination of some of them were difficulties encountered. Faced with these uncertainties, it can be said that the validation with the residents was fundamental in the application of the SWMM model to areas with little data that feed the model and without measured flow data for calibration and verification. The SWMM model proved to be suitable for this study and can be used as an urban planning tool.