DEFINITION OF FLOOD-PRONE AREAS IN ESTRELA AND LAJEADO/RS USING IBER 2D MODEL.

Abstract

In Rio Grande do Sul/Brazil, many cities are frequently affected by floods, such as Estrela and Lajeado. The use of 2D hydrological models helps to identify flood-prone areas and flood levels. In this context, the objectives of this article are: to define the flood areas and water height in the urban areas of Estrela and Lajeado based on a 2D hydraulic model, to identify the number of buildings and their types of use and coverage that are exposed, and to validate the results with fieldwork and past flood history. The hydrological data were based on the work of Oliveira et al. (2018), and the hydraulic model was processed using IBER 2.5.1. The model was validated by comparing the results with another hydrological model and field data. The data showed satisfactory similarity between the 2D hydraulic model obtained with IBER and the data published by IPH/UFRGS, with a spatial overlap of 92.6% and 95.9% in Estrela and Lajeado, respectively. The results made it possible to efficiently quantify the exposed buildings, where it was found that Lajeado has 1,958 and Estrela 3,385 exposed buildings. Additionally, the study identified the types of land use and coverage located in flooded portions of the Taquari-Antas river in the urban areas of the two municipalities. This work contributes to emergency management and response to flood events. The 2D model generated in IBER proved to be a suitable option for strategic planning and is presented as a tool for reducing flood risk.