Identificação de áreas vulneráveis as enchentes e inundações em áreas urbanas através de modelos topográficos e hidráulicos

Abstract

The development of most Brazilian cities occurred along rivers, on the need to use water in different activities. The occupations have been causing several problems that directly affect society, including urban flooding. One reason for these events is that the expansion of urban centers are not always follow by the implementation of an appropriate infrastructure which is aggravated by the inobservance of the natural characteristics of occupied environments. In Brazil, the urban occupations should follow a Master Plan defined by municipalities and it establishes guidelines for territorial occupation. In this concerned legislation is suggested the use of geotechnologies as tools for analysis and simulation, especially the Geographic Information Systems (GIS). This research presents the hydraulic modeling associated with GIS, by comparing two models with extensive use, the HEC-RAS and algorithms inserted put into GRASS. These simulations of flooding risk areas require knowledge of several common to GIS data, such as terrain models, dimensions and contours, but also historical precipitation data, water flows, and other hydraulic parameters. Due to the difficulty on obtaining such data in small municipalities in considerable time scale to form the historical series, this research proposes the evaluation of indicated models that use topographic parameters, hydraulic modeling and use of GIS in an attempt to delimitating flooding risk areas on a micro scale, from the Córrego Rangel watershed in the city of Patrocínio, MG. Comparing the product of both models it can be noted that each model provides a particular result. The model generated by GRASS QGIS, for evaluating the topographical characteristics across the watershed, the integrated data of precipitation and soil infiltration holds information flow and accumulation of all basin, it being possible to evaluate the effects of urbanization across the study area. The HEC-RAS model analyzes the system defined by the cross sections, and the simulation restricted area demarcated by sections and constructive parameters. With the study it was possible the creation of risk maps floods and floods in the Ribeirão Rangel basin, composed of different ways the location and depth of the occupying spots of water in intense rainfall events, highlighting the integrated unification and use the integrated of two models presented in decision making.