Sustainable Flood Controls and Pollution Mitigation

Curitiba embarked on a large restoration project in 2004, which led to a sustainable flood plain and a village for their lowest income and homeless residents.

Background: The Curitiba Metropolitan Area (RMC) is on the Upper Iguacu River Basin and had a population of 2.5 million in 2004. The river has a low capacity, resulting in a large natural flood plain. The following factors related to urban growth exacerbated the natural flood risks of the downtown core. First, in the 1980s, growth from di
splaced migrant workers resulted in unauthorized residential squatters or slum developments on the flood plain and adjacent to the city boundaries.  These individuals were looking for work in any realm possible. They also were not educated on the importance of proper waste disposal and recycling. Secondly, the growth of impermeable surfaces (representing up to 40% of the surface area of some basin tributaries) increased flooding in the basin six-fold flooding the downtown core almost annually. Finally, poor urban drainage works and infrastructure such as bridges obstructed river flow.

A 100-year precipitation and flood event in January 1995, however, caused more than USD $40 million in damages and caused the city to rethink its flood management strategy.

Program: In 1996 as part of a sanitation program developed by the World Bank, the RMC adopted an alternative strategy for flood management. Following a series of studies, the creation of a large public park around the river path and flood plain became the clear choice. The state bought the land along the river and resettled the population to other areas, creating self-sustainable suburbs within a short bus ride to the downtown. In these new state owned suburbs unemployed residents are given training, collect trash, maintain homes, parks and streets for food credits.  Meanwhile an artificial channel was dug to give distinct borders to the park and help increase the river capacity. Areas were reserved for structured sports, several miles of walking trails, educational centers and constructed wetlands to improve water quality.

Following creation of the park, an Integrated Urban Drainage Master Plan was developed that called for a strategic system of a flood warning system, and more urban parks were redeveloped on the tributaries to help absorb precipitation runoff. Regulatory measures including new river construction standards, tax incentives for maintaining conservation areas, and integration with the urban master plan were used to conserve the parks for water storage and source control.

Furthermore, the lack of waste in an around the city and parks is due to the robust recycling program and education efforts of all citizens.  Those without regular employment become state daily labors and can turn in bags of trash each day to earn food credits.