São Paulo, Brazil

Photo by Luciana Minami/City of São Paulo

The power of plants and natural ecosystems to deliver benefits

How is the initiative shaped by scientific evidence of the potential for plants and natural ecosystems to deliver benefits?

When it rains, water can run off impermeable surfaces such as roofs or pavements, collecting pollutants such as waste particles, fertilizers, chemicals, oil, rubbish, and bacteria along the way. The sediment pollution enters untreated sewage and flows directly into nearby streams and ponds.

The Rain Garden collect rainwater runoff, allowing the water to be filtered by vegetation and infiltrate the soil, recharging underground aquifers. These processes filter out pollutants.

The landscape redesign of the intervention points ensures ideal accessibility conditions, as well as the creation of urban micro-environments in roadbeds, either with a modular size and dimension (2×5 m in the case of green spaces) or tailor-made for specific situations. By replacing sites such as concrete and asphalt pavement to leisure spaces linked to the Rain Gardens, the City of São Paulo aims at complementing the urban surface drainage system using micro-environments and water collectors, as well as enabling unrestricted tree-planting.

The purpose is to ensure that the population reproduces the Municipal Administration’s initiatives in their homes. The proportion of land in residential areas corresponds to 70% of the city’s total, which, together with 30% of public properties (including roads), can make the city more environmentally responsible. In general terms, the programme will reduce the effects of flooding in São Paulo since drainage systems will be able to work in an integrated manner.

How has the city exploited the potential of plants and associated ecosystems to deliver more than one benefit?

The potential of plants was explored when choosing the species, seeking the use of hardy plants, preferably native ones that respond better to climate change, parasites, and weeds, thus reducing the need for maintenance and keeping the conservation of the fauna and flora habitat.

Another key factor that was taken into account was the specific characteristics of each species chosen and how they are used in the project, providing a better performance of the drainage system, better uptake of nutrients, control of erosion, silting, flooding and improved water quality, reducing diffuse pollution of micro basins.