Analysis of the standardized precipitation index for the Paraíba state, Brazil

Abstract

Drought is a complex natural phenomenon that affects various parts of the world and causes social, economic and environmental impacts. The study of droughts in Paraíba state is very important because approximately 80% of its area is in the semiarid Northeast region of Brazil. The aim of this study was to subdivide the Paraíba state in three rainfall homogeneous sub-regions using cluster analysis and afterwards to calculate the Standardized Precipitation Index (SPI) on time scales of 12 and 24 months to monitor severe extreme droughts in these sub-regions. The rainy season of each 49 rainfall sites was obtained by standardizing the rainfall data. The results showed the occurrence of severe drought for all three sub-regions. IPP-12 months revealed the occurrence of longer duration droughts in the period 1990 to 1994 in Araruna and Coremas cities. IPP-12 months also identified extreme longer duration droughts in Monteiro city, Cariri sub-region, possibly due to local geography features. On another hand, the IPP-24 months identified a severe drought with longer duration in Coremas from 1991 to 1995. In these periods, the droughts have been intensified, possibly due to El Niño effects. In short, the IPP-12 months and IPP-24 months proved to be effective for drought monitoring in the Paraíba state.

Keywords

• Cluster analysis
• droughts
• standardized precipitation index