Flooding and overflow are recurring problems in several Brazilian cities, which usually face disorderly development. The causes vary, and include increased impervious surface areas, deficiency/inefficiency of drainage structures and lack of maintenance, siltation of rivers, channel obstructions, and climatic factors. In this paper, we present an analysis of mitigation measures to minimize flooding in a watershed located in the core of the city of São Paulo, the biggest city with the highest gross domestic product (GDP) in Brazil. Observed rainfall records and existing intensity duration frequency (IDF) curves for the region are used to obtain design storms. To account for climate change, the equidistance quantile matching method for updating IDF curves under climate change, a well-known procedure, was applied to the existing historical data. Several different global climate models (GCMs) and one regional model were applied to obtain and update rainfall design storms. The GCMs and future scenarios used were from Intergovernmental Panel on Climate Change-IPCC Assessment Report 5 (AR5) and two future projections-representative concentration pathway (RCP) 4.5 and 8.5. Spatially distributed reservoirs combined with low-impact development (LID) measures were used to evaluate different design storm scenarios combined with return periods of 25 and 100 years as well as the updated IDF under climate change for RCP 4.5 and RCP 8.5. Results show that the proposed changes to the drainage system can help reduce the risk and damage of flooding. The climate change scenarios, however, impose a significant threat and need immediate attention from city planners and stakeholders.

This paper aims to present a methodology to conduct a water stress assessment of water resources systems through indices. The proposed methodology was applied to Cantareira System, which is one of the most important water supply systems of São Paulo Metropolitan Region (SPMR). The authors used two indices to support this evaluation: Normalized Deficit Index (NDI) and Normalized Deficit Cumulated (NDC). Both of them consider only the natural flow as the renewable source of water (supply), and account for natural and anthropic uses of this water (demand) as a way to determine the dependence level that the area relies on endogenous and/or exogenous sources of water to meet its needs. To support this assessment, two meteorological drought indices were used as well: the Standardized Precipitation Index (SPI) and Drought Magnitude (DM). The diagnosis of a water supply system, a country, region or even district, based on indices that represent the local water risk, is extremely important not only to bring a better understanding of extreme events, such as droughts and floods, but also to support strategic decision-making process regarding water resources management. This sort of assessment is a useful tool, for instance, in indicating eventual necessity of water storage, such as large reservoirs, or interbasin water transfers, which could improve the water security levels of the study unit.

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Para cada um destes modelos é realizada uma análise de sensibilidades dos seus parâmetros. Baseado nos avanços tecnológicos mais recentes na ciência da computação foi desenvolvido, em paralelo a esta pesquisa, uma ferramenta computacional que compila todos os conceitos aqui apresentados e tem distribuição acadêmica livre. Palavras-chave: Ciclo hidrológico. Hidrologia sintética. Simulação (modelos).