Identification of homogeneous rainfall regions in the Eastern watersheds of the state of Paraná, Brazil

Abstract

The objectives of this study are to use a clustering technique to identify homogeneous rainfall regions in the watersheds of the eastern region of the state of Paraná and to associate the spatial and temporal distribution of rainfall with the influences of orography, the ocean and regional atmospheric dynamics. Rainfall data were obtained from 54 pluviometric stations and from eight meteorological stations, which comprise the historical series from 1976 to 2015. A cluster analysis technique was used with the Euclidean distance for measuring proximity and Ward's method for hierarchical grouping. The Litorânea watershed exhibited the highest rainfall totals in the study area, and the annual average was 2551 mm for the homogeneous group with the highest rainfall. The Ribeira river watershed exhibited the lowest total rainfall (1488 mm); therefore, it was considered a rain shadow region with a more tropical climate due to the concentration of rainfall in the period from September to March. The Alto Iguaçu watershed was characterized by the smallest spatiotemporal variation in rainfall due to its flatter relief and the influence of the subtropical climate.