MULTIVARIATE ANALYSIS AND TREND OF PLUVIOMETRIC PRECIPITATION IN THE HYDROGRAPHIC REGION OF THE RECONCAVO SOUTH (BA)

Multiariate analysis and trend of pluviometric precipitation in the hydrographic region of the Reconcavo South (BA)

Abstract

The objective of this research was to analyze the spatial and temporal variability of rain, in the ambit of the hydrographic region of the Recôncavo South, from of trend techniques and multivariate analysis. This region is located in the eastern part of the state of Bahia, with an area of approximately 16.990 km². In possession of the historical series of rainfall data between 1985 and 2010, the complete annual data were organized and analyzed temporally through the basic descriptive statistics. After that, the possibility of existence of trends in the historical serie was identified, applying the Mann-Kendall and Linear Regression tests, both for the significance level of 5%. Finally, for those years, a multivariate analysis was carried out, where, through cluster analysis, using the Cluster Technique, similar pluviometric groups were formed, which configure the homogeneous zones, as a function of the monthly precipitation. The municipality with the highest average rainfall was Valença and the year was 1985, while the lowest precipitated averages were observed in the municipality of Milagres and the year was the of 1993. In both methods of trend analysis, the result was the same: only the municipality of Nilo Peçanha has a significant tendency of precipitation decrease. The analysis of clusters resulted in the division of the area of the Recôncavo South into three homogeneous groups and an anomalous group, formed by two municipalities.