Multivariate statistical analysis to support the minimum streamflow regionalization

Abstract

This study aimed to develop a methodology based on multivariate statistical analysis of principal components and cluster analysis, in order to identify the most representative variables in studies of minimum streamflow regionalization, and to optimize the identification of the hydrologically homogeneous regions for the Doce river basin. Ten variables were used, referring to the river basin climatic and morphometric characteristics. These variables were individualized for each of the 61 gauging stations. Three dependent variables that are indicative of minimum streamflow (Q 7,10 , Q 90 and Q 95 ). And seven independent variables that concern to climatic and morphometric characteristics of the basin (total annual rainfall -P a ; total semiannual rainfall of the dry and of the rainy season -P ss and P sc ; watershed drainage area -A d ; length of the main river -L p ; total length of the rivers -L t ; and average watershed slope -S L ). The results of the principal component analysis pointed out that the variable S L was the least representative for the study, and so it was discarded. The most representative independent variables were A d and P sc . The best divisions of hydrologically homogeneous regions for the three studied flow characteristics were obtained using the Mahalanobis similarity matrix and the complete linkage clustering method. The cluster analysis enabled the identification of four hydrologically homogeneous regions in the Doce river basin. KEYWORDS: principal component analysis, cluster analysis, homogeneous regions. ESTATÍSTICAS MULTIVARIADAS COMO SUPORTE À REGIONALIZAÇÃO DE VAZÕES MÍNIMAS1 RESUMO: Este trabalho teve por objetivo propor uma metodologia baseada em análises estatísticas multivariadas de componentes principais e de agrupamento, com o intuito de identificar as variáveis mais representativas em estudos de regionalização de vazões mínimas e otimizar a obtenção das regiões hidrologicamente homogêneas para a bacia hidrográfica do Rio Doce. Foram utilizadas 10 variáveis referentes às características climáticas e morfométricas da bacia. Essas variáveis foram individualizadas para as 61 estações fluviométricas adotadas, sendo três variáveis dependentes e indicativas das vazões mínimas (Q 7,10 , Q 90 e Q 95 ) e sete independentes (precipitação total anual -P a ; precipitação total do semestre seco -P ss e chuvoso -P sc ; área de drenagem da bacia -A d ; comprimento do rio principal -L p ; comprimento total dos cursos d'água da bacia -L t ; e declividade média da bacia -S L ). O resultado da análise de componentes principais apontou a variável independente S L como a menos representativa e foi excluída do estudo. As variáveis independentes mais representativas foram A d e P sc . As melhores divisões de regiões hidrologicamente homogêneas para as três vazões características estudadas foram obtidas utilizando-se conjuntamente da matriz de similaridade de Mahalanobis e do método de agrupamento do vizinho mais distante. A análise de agrupamento possibilitou a identificação de quatro re...

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“…The results found in this study differ from those found by Minuzzi and Caramori (2011), who verified a trend of precipitation increase in the state of Paraná when they analyzed data from 21 hydrological stations. However, more recent research by Silva et al (2015) corroborate the results identified in this study, since these authors verified trends of reduction in the annual rainfall in Paraná, mainly in the central and northern regions of the Paraná state, with increasing rainfall behavior only in the coast and southwest of the state.…”

“…On the other hand, studies on spatial and temporal variability of precipitation are more frequent (Silva and Guetter, 2003;Minuzzi and Caramori, 2011;Silva et al, 2015), thus, an analysis at the state level, encompassing a consistent historical database of ET can help to identify possible changes in the ET, improving activities that are directly affected by it, such as the irrigated agriculture. This understanding was also supported by Xu et al (2006), who stated that ET data when regionalized become valuable information in the planning of the use of water resources, considering the importance of this variable as the driving force of the hydrological cycle.…”

Streamflow Regionalization in Piquiri River Basin

“…Streamflow data accuracy is of great importance for water resources planning and monitoring (Nruthya & Srinivas, 2015). Elesbon et al (2015) described the need for good quality information, both in time and in space, for a proper and integrated management of water resources.…”

“…In Brazil, Eletrobrás published a methodological guide, in 1985, presenting streamflow regionalization procedures, thus standardizing the technique, which became recognized as Traditional method or Eletrobrás method, used by several authors (Reis et al, 2013, Virões, 2013, Elesbon et al, 2015, Moreira & Silva, 2014.…”

Avaliação da distribuição de Gumbel na determinação de vazões mínimas da sub-bacia do Rio Negro

“…Sendo assim, é importante a realização de uma gestão considerada eficiente na utilização dos recursos hídricos, em que o uso de distribuições estatísticas para mensuração de eventos extremos de vazão, se tornam ferramentas imprescindíveis para esta gestão (SOUZA et al, 2012;ELESBON et al, 2015). Com isso, o objetivo do presente trabalho é a verificação da adequabilidade da distribuição de probabilidade de Gumbel para ajuste de séries históricas de vazões mínimas, para a sub-bacia hidrográfica do Rio Negro no Paraná.…”