Abstract
Abstract. Porto Alegre is the capital and largest city in the Brazilian state of Rio Grande do Sul in Southern Brazil with approximately 1.5 million inhabitants. The city lies on the eastern bank of the Guaiba Lake, formed by the convergence of five rivers and leading to the Lagoa dos Patos, a giant freshwater lagoon navigable by even the largest of ships. This river junction has become an important alluvial port as well as a chief industrial and commercial centre. However, this strategic location resulted in severe damage because of its exposure to flooding from the river system, affecting the city in the years 1873, 1928, 1936, 1941 and 1967. In order to reduce flood risk, a complex system of levees and pump stations was implemented during 1960s and 1970s. Since its construction, not a single large flood event occurred. However, in recent years, the levees in the downtown region of Porto Alegre were severally criticized by city planners and population. Several projects have been proposed to demolish the Mauá Wall due to the false perception of lack of flood risk. Similar opinions and reactions against flood infrastructure have been observed in other cities in Brazil, such as Itajaí and Blumenau, with disastrous consequences. This paper illustrates how the perception of flood risk in Porto Alegre has changed over recent years as a result of flood infrastructure, and how such changes in perceptions can influence water management decisions.
Highlights
Human society has positioned itself in areas with locally sustainable water supplies, in the form of runoff, and/or river and stream flows (Vörösmarty et al, 2005)
Allasia et al.: Decreasing flood risk perception in Porto Alegre – Brazil caused by severe flooding that affected the city in the years 1873, 1928, 1936, 1941 and 1967 (Fig. 1)
Participation on TV and radio debate shows happened. The results of such efforts have limited reach in audience and, more important, in time, as people quickly forget the lessons from these debates. Another example is the National Architectural Competition, organized by DEP/PMPA (Department of Rainwater Sewers/Municipality of Porto Alegre) and IAB/RS (Institute of Architects of Brazil – Section Rio Grande do Sul) in 1994 in order to award architectural interventions that maintaining the Mauá Wall improve the integration between the city and Guaiba Lake
Summary
Human society has positioned itself in areas with locally sustainable water supplies, in the form of runoff, and/or river and stream flows (Vörösmarty et al, 2005). The administrative and commercial heart of the city grew in a complex area that includes 27 streams that flows in-between hills as well as lower flatlands, which were mostly marshes This region is located at an average altitude of 3 meter above sea level and only slightly higher than the streams mean water level, and represents 35 % of the urbanized area. The flooding in the city’s central area is caused by interrelated factors such as Guaiba Lake basin floods, inner city heavy rainfall, and Southern wind-induced surge This combination of factors led to the worst and best known of these events, in May/June 1941 when the flooding reached the most populated and wealthier areas of the city, leaving more than 70 000 homeless Since the construction of this protection system, not a single large flood event has occurred
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
