Cluster analysis and hydrological regionalization for Brazilian states /Analise de cluster e regionalizacao hidrologica para Estados brasileiros

Streamflow data from gauging stations are essential for effective water resources management. However, some regions in Brazil lack the necessary data. Hydrological regionalization is an alternative technique for obtaining data such regions. However, not all regions in Brazil have defined hydrological regionalization models, including the state of Goias and the Brazilian Federal District. The objective of this study was to develop a hydrological regionalization methodology based on the separation of hydrologically homogeneous regions and multiple linear regression, using a Geographic Information System (GIS) program. Historical series data were used to calculate reference flows with 90 or 95% duration over time in the watercourse (Q90 and Q95) and the mean flow ([bar.Q]). Rain gauge station data were used to calculate the mean annual rainfall in each watershed through spatial interpolation by ordinary kriging. Subsequently, the physiographic characteristics of each watershed were calculated. The hydrologically homogeneous regions were delimited based on these data using cluster analysis, which identified seven hydrologically homogeneous regions in Goias, two of them belonging to the Federal District. Multiple regression allowed the development of seven regionalization models. Models for regions 1, 3, 4, 5, and 7 showed better performance. Key words: homogeneous hydrological regions, hydrological modeling, multiple regression Para gerenciar os recursos hidricos de forma eficaz, os dados de vazao das estacoes hidrometricas sao cruciais. No entanto, no Brasil, algumas regioes nao dispoem dos dados necessarios. A regionalizacao hidrologica e uma tecnica alternativa para obter dados para essas regioes. Infelizmente, nem todas as regioes do Brasil tem modelos de regionalizacao hidrologica definidos, incluindo Goias e o Distrito Federal. O objetivo deste estudo foi desenvolver uma metodologia de regionalizacao hidrologica, baseada na separacao de regioes hidrologicamente homogeneas e na regressao multivariada, utilizando o programa Sistema de Informacoes Geograficas (SIG). Com base na serie historica, foram calculadas as vazoes de referencia com 90 ou 95% de permanencia ao longo do tempo no curso d'agua (Q90 e Q95) e a vazao media ([bar.Q]). Com os dados das estacoes pluviometricas, foi calculada a precipitacao media anual de cada uma das bacias hidrograficas fluviometricas, por meio de interpolacao espacial por krigagem ordinaria. Posteriormente, foram calculadas