City growth and urban drainage alternatives : sustainability challenge/ created by Marcelo Gomes Miguez, Osvaldo Moura Rezende and Aline Pires Veról

Since the 1970s, growing concerns about urban development’s effects on the natural environment have been prompting efforts to find more sustainable solutions for the problems arising from the built environment. In this context, this work discusses the need to integrate innovative stormwater drainage practices with the urban planning process, especially regarding the limitation associated with the increase of impervious surfaces, while trying to handle the runoff generated by the urban sprawl. The interaction between urban growth and stormwater management is investigated, using a case study in the metropolitan region of Rio de Janeiro to illustrate the main findings. To fulfill this objective, the present flooding scenario for this area is modified under two premises: considering a traditional drainage system approach, focusing on channelization measures, and a distributed stormwater management approach, based on the sustainable urban drainage system (SUDS) concepts. Then, these two solutions are tested for their effectiveness under three different scenarios of future urban growth and land-use changes, ranging from uncontrolled urbanization to planned urban growth with land-use control. The capacity of these two approaches to maintain their design functions is verified for the proposed future urban patterns. The quantitative evaluation of urban flooding prospective scenarios is supported by mathematical modeling. From the results of the conducted simulations, one can confirm the crucial importance of land-use planning in the urban flood control process. Decentralized stormwater controls, although more resilient than traditional channelization measures, tend to fail in the long term if land-use planning is not properly addressed. A key element for flood control is the integration of drainage solutions with urban development, in a systemic way and considering the basin scale as the planning and design reference.