Identification of Homogeneous Rainfall Regions in the Eastern Watersheds of the State of Paraná, Brazil

Paulo Terassi,Emerson Galvani

doi:10.3390/cli5030053

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.

Highlights

Rainfall is the main input in analyses of the hydrological balance of a watershed, and it is the climatic attribute that provides the greatest interaction between the climatic elements and the physical aspects of this study, according to Clarke and Silva [1], especially in regions with tropical climates due to an abundance of annual rainfall [2,3,4]
The cluster analysis resulted in nine homogeneous groups and three anomalous pluviometric stations, which demonstrated the structure of rainfall in the study area
This paper allowed a satisfactory application of cluster analysis for understanding the interaction between the geographic factors of climate, highlighting the role played by the oceanic influence for the highest rainfall totals in the coastal watershed, the orographic effect for the rainfall reduction in the Alto Iguaçu and Ribeira watersheds, and the interference of regional atmospheric dynamics in the monthly rainfall distribution

Summary

Introduction

Rainfall is the main input in analyses of the hydrological balance of a watershed, and it is the climatic attribute that provides the greatest interaction between the climatic elements and the physical aspects of this study, according to Clarke and Silva [1], especially in regions with tropical climates due to an abundance of annual rainfall [2,3,4]. Wrege et al [8] highlighted the relevance of the grouping technique to identifying homogeneous zones with respect to the water regime and its contribution in land use planning studies, such as the reduction of climatic risk in agriculture, livestock and forestry production. They stressed that a lower water balance compromises agricultural yield, whereas a water surplus can increase the majority of crop yields and favours the appearance of pests and diseases, hampering the quality of the crops

Objectives

Results

Discussion

Conclusion