Urban Floods in Brazil

STEVAUX, J.C., LATRUBESSE, E., HERMANN, M.P., AQUINO, S.

Geomorphology of Natural Hazards and Human Exacerbated Disasters in Latin America

Elsevier

Año: 2008; p. 245 - 266

Floods in three very different urban areas of Brazil are presented in this chapter: Sa˜o Paulo, the largest city of South America; the mountain basins of Santa Catarina State, southeastern Brazil; and the city of Rio Branco (Acre State), a typical medium-sized city of the southwestern Brazilian Amazonia. Sa˜o Paulo represents a case of uncontrolled and disorganized urban growth, typical of many cities of southeastern Brazil where the infrastructure and production systems (railroads, roads, and industries) have been settled on the alluvial plains. Santa Catarina disasters are produced because of a combination of tropical storms in a region of mountain fluvial basins that are characterized by flash floods, slope instability (landslides), and urban occupation of the valleys. The Amazonian city of Rio Branco suffered similar fast population growth and because of the cultural Amazonian tradition of ‘‘living near the river’’ suffered many consequences from flooding. The intensive urbanization in both Sa˜o Paulo and Rio Branco around and within the floodplains has introduced many problems involving rain-water drainage. Urban interference in the drainage system is strong in Sao Paulo. The city’s flat topography, associated with channel rectification and the pluvial drainage system, improves surface runoff and consequently water concentration in the lowest areas. On the other hand, obstructed and underfitted sweepers are responsible for many of the small but frequent localized floods. In both cities, floods are more a planning than a natural problem, and the number of deaths and affected people related directly to floods is very small when compared with countries like Bangladesh, India, or China. Nonetheless, the number of persons affected is high, and the diseases and urban problems brought by floods are significant