Standardized precipitation index applied to drought conditions of the State of Espirito Santo, Brazil

The Standardized Precipitation Index (SPI) is one of the most widely used methods for quantification of drought conditions. In order to apply the SPI model to the climate conditions of the State of Espirito Santo, Brazil, the study evaluated the adjustment of the monthly rainfall time series to the gamma distribution in five regions of this State. Using the Kolmogorov-Smirnov test and the Chi-Square test, it was possible to verify that the monthly rainfall time series, used in this study, can be fitted to the gamma distribution. On this sense, the SPI model can be applied for monitoring the meteorological drought conditions in the State of Espirito Santo. Using the autocorrelation function and the cross-correlation function, it was possible to verify that the main characteristic of the monthly SPI series is high temporal variability of its values. This indicates that, within a same region, extreme dry months may be preceded and/or followed by normal or wet months, and different drought condition can be observed, at the same period, among the five analyzed regions.