Urban Drainage Master Plan in a Megacity: The City of São Paulo Case

This paper aims to present the framework of the Urban Drainage Master Plan of the City of São Paulo, the largest city in Brazil and South America. The São Paulo population is around 13 million people with a density of 7.400 people per sq. km.

The fast development of São Paulo throughout the 20th century caused a set of environment problems, being the most important the occupation of the flood plain for poor housing and for São Paulo transport infrastructure. The land use and its occupation modified the hydrology of São Paulo basins. Due to this the city has today a high index of in impermeable areas, which is the main source of floods that occur in the rainy season. Many flood control projects have been implemented to reduce the impacts of this complex situation but until now the city does not have a drainage master plan to evaluate water works and other measures for a long-term horizon. A new methodology to deal with the master plan was adopted which analyse the flood problem by small catchments. In this way the master plan can considerate the specificities of each region and its hydrological features. At the moment ten small basins were studied which correspond to 22% of the municipality area. This small catchment plan is published by the São Paulo municipality and it’s called notebook basin. Basically, it aims to diagnose and analyse the current drainage system and then to propose a set of structural and non-structural measures to reduce floods. The goal in a long-term horizon is to get hydrological protection for 100 years but the notebook presents an expansion capacity proposal for short and medium actions. In addition, the notebook provides subsidies for the integration of urban drainage planning with land use planning, and also encourages the adequate coexistence of the population with urban waters increasing the urban resilience. The main products of the notebooks are: characterization of the hydrography and the land use and its occupation, population distribution, hydrological studies, computational model for hydraulic simulation, characterization of land use and occupation, distribution of flood zone areas to a set hydrological risks, set of structural and non-structural measures and preliminary costs for the proposed actions. At the moment ten notebooks were published and distributed to the different agencies which deal with the City of São Paulo urban water problems.