STATIONARITY OF ANNUAL MAXIMUM DAILY STREAMFLOW TIME SERIES IN SOUTH-EAST BRAZILIAN RIVERS

Jorge Machado Damázio, Fernanda da Serra Costa

Resumo


DOI: 10.12957/cadest.2014.18302

The paper presents a statistical analysis of annual maxima daily streamflow between 1931 and 2013 in South-East Brazil focused in detecting and modelling non-stationarity aspects. Flood protection for the large valleys in South-East Brazil is provided by multiple purpose reservoir systems built during 20th century, which design and operation plans has been done assuming stationarity of historical flood time series. Land cover changes and rapidly-increasing level of atmosphere greenhouse gases of the last century may be affecting flood regimes in these valleys so that it can be that nonstationary modelling should be applied to re-asses dam safety and flood control operation rules at the existent reservoir system. Six annual maximum daily streamflow time series are analysed. The time series were plotted together with fitted smooth loess functions and non-parametric statistical tests are performed to check the significance of apparent trends shown by the plots. Non-stationarity is modelled by fitting univariate extreme value distribution functions which location varies linearly with time. Stationarity and non-stationarity modelling are compared with the likelihood ratio statistic. In four of the six analyzed time series non-stationarity modelling outperformed stationarity modelling.

Keywords: Stationarity; Extreme Value Distributions; Flood Frequency Analysis; Maximum Likelihood Method.


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Referências


GILLELAND E; KATZ R. W (2011). New software to analyze how extremes change over time. Eos,11January, 92, (2), pp. 13-14

COSTA, F. S.; RAUPP, I. P.; DAMAZIO, J. M.; OLIVEIRA, P.D;.GUILHON, L.G (2014). The Methodologies for the Planning of the Flood Control using Hydropower Reservoirs in Brazil, In. 6th International Conference on Flood Management (ICFM6), 16-18 September 2014, São Paulo – Brazil

ONS (2015); http://www.ons.org.br/operacao/vazoes_naturais.aspx; visited in 10/10/2014.




DOI: https://doi.org/10.12957/cadest.2014.18302

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ISSN impresso: 1413-9022 / ISSN on-line: 2317-4536

DOI do periódico: dx.doi.org/10.12957/cadest


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