AVALIAÇÃO DO RISCO DE INUNDAÇÃO DO LAGO GUAÍBA E DELTA DO JACUÍ, RIO GRANDE DO SUL/BRASIL

Resumen

For the delimitation of flood risk areas around Lago Guaíba and Delta of Jacuí, hazard and vulnerability information were correlated. For the hazard assessment flood return period and protection systems in areas with susceptibility were integrated. The characterization of vulnerable areas was carried out based on the assessment of exposure of the dwellings and  also socioeconomic characteristics of the population. Flood hazard areas around Lago Guaíba and Delta Jacuí are total 230 km2; from which 95 km2 are in high hazard. High hazard areas do not have flood protection systems and the return period of floods is less than 10 years, with small magnitude floods predominating. In the period of 1950-2015, urban expansion in the hazard areas amounts to 18 km2. Areas with high vulnerability amount to 7 km2. In these places the houses have low constructive standard, precarious state of conservation and limited access to basic services. In general, the income of households is less than 937 reais monthly and the number of children or elder people is high. Flood risk areas are located near the islands, central and southern portion of the city of Porto Alegre, in Itapuã ((located in the municipality of Viamão), in some portions of the urban area of Eldorado do Sul, Guaíba and Barra do Ribeiro. High-risk areas are marked by high flood hazard and high vulnerability, with limited physical and social conditions of response and mitigation in the face of flood events, totaling 7 km2. The assessment of risk is important to direct prevention and response actions during the occurrence of floods.