Cluster analysis and hydrological regionalization for Brazilian states¹

Análise de cluster e regionalização hidrológica para Estados brasileiros

ABSTRACT

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 Goiás 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 (Ǭ). 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 Goiás, 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

HIGHLIGHTS:

Seven homogeneous hydrological regions were obtained using cluster analysis.

Five models showed excellent performance, while two showed satisfactory to good performance based on classification indices.

GIS models are useful for water agencies in Goiás state and the Brazilian Federal District to grant water use rights.