Monitoring of droughts in municipalities of the Sertão Paraibano

Drought is a natural phenomenon that affects all regions. There is great difficulty in getting a consensus to define the real meaning of the theme, this happens mainly be differences in hydrometeorological variables and socioeconomic factors as well as the stochastic nature of the demand for water. Despite the large number of researchers working with dried in the world, there is an information gap, especially in duration, water deficit, intensity and return period of droughts in Northeast Brazil. The research objective is to analyze the duration, water deficit, intensity and return period of droughts in the municipalities of Sertão Paraibano. They were used data of precipitates monthly totals for the period of 1994-2014  the municipalities of Cajazeiras, Catolé do Rocha, Patos, Pombal, São Bento and Sousa. The execution method was used in order to identify periods of droughts and assess their statistical properties. The municipality of Sousa had the highest number of droughts, eight in total, followed by Cajazeiras, Catolé do Rocha, São Bento (seven droughts), Patos and Pombal (six droughts). The longest occurred in Patos, starting in 1997 and ending in 2001, lasting five years. The more severe droughts in the municipalities occurred during 1997-1999, 2001-2003 and 2012-2014, that is, those who had longer duration, water deficit and intensity. The analysis of period of return of droughts most severe in the municipalities show very different values, with the longest occurring in Patos, during the drought of 1997-2001, where the likelihood of ocurred another drought of the same duration is every 89 years. Droughts with durations equal or superior this may occur in 67 years. Already the water deficit can be overcome in 33 years.