Located in the southeast region of Brazil, the Cantareira System consists of six interconnected reservoirs and supplies around 14 million people in the state of São Paulo. Built in the 1970s, when extensive fluviometric series were not available in the region, the system underwent several operating rules that culminated in the water crisis caused by the 2014/2015 drought. This article makes a brief critical account of what has been experienced in these almost 50 years of operating the system, the factors that influenced the water crisis, and what has been learned.

The Soil Conservation Service Curve Number (SCS-CN) model is widely used to estimate the watershed runoff. However, the model may result in inaccurate estimations when assuming a tabulated CN value and an initial abstraction (λ) of 0.20. Therefore, in this paper, we evaluated the suitability of four CN estimation methods for an urban watershed: Tabulated CN, National Engineering Handbook 4, Least Squares and Asymptotic Fitting. Also, the effect of ordering the data and different λ values (0.20 or 0.05) were analyzed. Our findings suggest that the transient approach of Asymptotic Fitting method, a variance from the original Asymptotic Fitting method, provides the best runoff estimations using rank ordered data and λ equal to 0.05 (R2 = 0.79, PBIAS = 0.01% and NSE = 0.78). It is to be noted that similar results were also obtained through a simple linear model.

Resumo O Nordeste Brasileiro (NEB) apresenta, como característica marcante, a irregularidade em acumulados de precipitações, o que é decorrência de vários fatores, tais como as características ambientais e de sistemas atmosféricos. Análises estatísticas adequadas são necessárias para ter conhecimento dos níveis de retorno da precipitação em uma região e são muito importantes para auxiliar ações para prevenção de desastres naturais causados por chuvas máximas. O objetivo dessa pesquisa consistiu em apresentar os níveis de retorno da precipitação máxima diária (PMD) em todo o estado da Paraíba, o qual está localizado na NEB. O conjunto de dados foi composto por 238 estações pluviométricas, abrangendo o período de 1994 a 2020. Para a modelagem estatística foi ajustada a distribuição Gumbel, por meio do método da máxima verossimilhança. Os resultados indicaram que o Sertão Paraibano apresentou as maiores estimadas da PMD nos meses de janeiro a março, com volumes superiores a 75 mm. A Mata Paraibana apresentou as maiores estimativas da PMD nos meses de abril a junho, com valores superiores a 125 mm no mês de junho em regiões litorâneas. As informações obtidas sobre os níveis de retorno da PMD são relevantes e podem ser de grande auxílio na implementação de políticas públicas, visando a diminuição dos impactos causados pelas chuvas intensas.

From 2013 to 2015, the Brazilian southeast region experienced the most severe and intense drought recorded, the Water Crisis. This outstanding drought led the government to make efforts toward an adequate water resources management. In Campinas, the third most populous city of the State of São Paulo, the government proposed the Campinas Water Resources Master Plan (CWRMP), the main objective of which was to ensure the quantity and quality of water, reducing water vulnerability in the municipality. In this study, we evaluated the effectiveness of this plan through the major guidelines into four actions: (1) increase the permeability rate and the soil infiltration capacity, (2) increase the vegetation cover, (3) improve the sanitation services, and (4) minimize the number of contaminated areas. For Actions 1 and 2, we inferred that the aforementioned parameters have increased after the CWRMP enactment. About the Action 3, we found that Campinas has historically provided good sanitation services to the population, regardless of the CWRMP promulgation. However, more improvements should be given to waste collection and recycling services. The underground water consumption also has to be regulated, as significant exploitation has no legal permit. Finally, considering Action 4, the number of contaminated areas was reduced in the available data period. Therefore, the CWRMP was considered a valuable initiative to support an integrated and sustainable use of water, improving the water resources management in Campinas.

The hypothesis of stationarity is a fundamental condition for the application of the statistical theory of extreme values, especially for climate variables. Decadal-scale fluctuations commonly affect maximum and minimum river discharges. Thus, the probability estimates of extreme events need to be considered to enable the selection of most appropriate time series. The current study proposed a methodology to detect the fluctuation of long wet and dry periods. The study was carried out at the gauging station 4C-001 in Pardo River, State of São Paulo, Brazil. The Spearman, Mann–Kendall and Pettitt’s non-parametric tests were also performed to verify the existence of a temporal trend in the maximum annual daily flows. The graph achieved from the Pettitt’s statistical variable allowed for the identification and separation of the longest dry period (1941 to 1975) and the longest wet period (1976 to 2011), decreasing again in 2012. Analysing the series separately, it was observed that both mean and standard deviation were higher than those corresponding to the dry period. The probable maximum flows for the corrected series showed estimates 10% higher than those estimated for the uncorrected historical series. The proposed methodology provided more realistic estimates for the extreme maximum flows.

A design storm can be defined as a precipitation pattern used to determine indirectly the design flood, which is an important data in many hydrologic design projects. Due to difficult to obtain historical data on precipitation, it has become common to construct design storms using general characteristics of precipitation in the surrounding region, represented by intensity-duration-frequency (IDF) relationships. In addition, it’s also necessary specify design return period, storm duration and the temporal distribution. For this purpose, is used the Alternating Block Method. In the view of software development applied to hydrology and to make more practical using this Alternating Block Method, this article intended to develop the AltBlock, a software able to calculate design storms automatically. Using Visual Studio .NET and the programming language Visual Studio .NET it was sought to build a graphical user-friendly interface. The AltBlock is applicable to any location and it’s useful for educational uses, engineering projects and hydrological studies.