Caracterização de seca em bacias de climas semiárido e subtropical.

Abstract

Drought is a natural phenomenon that generates social, environmental, and economic impacts, which requires a greater understanding. Among the indexes to assess drought is the Standardized Precipitation Index, SPI, which is based on rainfall and provides values in the form of a normal distribution. It is applied in the drought characterization studies in different time scales. This work aimed to evaluate the characteristics of meteorological drought (intensity, duration, and severity) in the historical period (since 1980) and in the future (until 2090) in two Brazilian hydrographic basins of different climates: the Piancó-Piranhas-Açú basin, from semiarid region in the Northeast of Brazil, and the Piracicaba basin in the Southeast, with a predominantly subtropical climate. SPI was calculated using spatially interpolated data in the historical period and the MIROC5 model was used to analyze climate projections of two greenhouse gas emissions scenarios: RCP8.5 (pessimistic ) and RCP4.5 (intermediate). As a result, it was noted that despite presenting higher levels of rainfall, the subtropical climate basin presented greater severity in relation to the basin of semiarid climate. In the future, projections showed an increase in dry and extremely dry events in the Piancó-Piranhas-Açú basin notably greater in the pessimistic scenario.