Estudo do perigo à inundação da área edificada do município de Barra do Quaraí/RS utilizando aerofotogrametria com aeronaves remotamente pilotadas

Abstract

The need for housing in recent years has compelled the most economically vulnerable class to reside in unsuitable locations, such as riverside areas and regions with steep slopes, lacking infrastructure and progressively farther away from major urban centers. In an effort to mitigate losses resulting from climate events, civil society endeavors to establish specific organizations, associations, or departments to promote territorial planning and public policies. However, in most cases, the high cost of conducting mapping and comprehensive studies often becomes a hindrance, with substantial funds allocated only in the event of major disasters. The municipality of Barra do Quaraí-RS serves as an example of the reality in small municipalities within the state of Rio Grande do Sul, where response measures and investments translate into palliative actions after extreme events. Given the presented circumstances and the necessity for studies on natural disasters and urban planning, this work aims to analyze the dynamics of flood risk in the urban area of the municipality of Barra do Quaraí/RS. Furthermore, it explores and suggests a discussion on the utilization of new technologies for detailed mapping using RPA (Remotely Piloted Aircraft). The research was constructed based on the deductive method, relying on the consulted bibliography and renowned works on the proposed subject. Data from the municipal government, the National Water Agency (ANA), Civil Defense, and the press served as the foundation of information. To create the Digital Terrain Model, an RPA, specifically the Phantom 4 Pro model from the DJI brand, was employed for executing a planned flight. The calculation of Return Times (TR) for intervals of 2/5/10/25/100 years was utilized as the methodology to assess the danger and exposure to the flooding threat. The mapping revealed a good state of preservation in the riverside area, with no houses in the TR 2 category, only two houses within the TR 5 years category (Very High Hazard), 37 houses within the TR 10 category (High Hazard), 139 houses in the TR 25 category (Medium Hazard), and 340 houses within the TR 100 years area (Low Hazard). There are 518 housing units located in an area at risk of flooding from the Quaraí River. The maps produced can be utilized beyond the civil defense sector, encompassing other sectors as well, with a focus on projects aimed at updating the municipal register and property tax assessments (IPTU), inspection efforts along the riverbanks, monitoring urban expansion, and city master plan development. In the short term, education initiatives should be implemented, including campaigns in schools highlighting the significance of the riverside area (TR 2 years). Moreover, public authorities should take steps to manage and regulate spaces in close proximity to the Quaraí River (TR 5 years), as these urban voids, if left unused, can potentially transform into areas with irregular housing, consequently posing a risk of flooding.