Avaliação das secas nas bacias do Rio Taperoá e Alto Paraíba

Abstract

The droughts are natural events that affect different regions of the globe and are related to the water shortage. There are innumerous historic stories that narrate the impacts of the drought event, especially at the Brazilian Northeast, a zone of semiarid climate and constantly affected by this phenomenon. The population living in this area – around 26,62 million of habitants – suffer from the negative consequences of prolonged periods of drought. Understand the phenomenon, its severity and predict the proportions possibly achieved by it is essential for management entities to take actions that mitigate the effects of the drought. The “Cariri paraibano” is the Brazilian region with the lowest average rainfall index in the country, and on this region the hydrological basins of “Taperoá River” (Rio Taperoá in Portuguese) and High Course of Paraíba River (Alto Curso do Rio Paraíba in Portuguese) are contained, major affluent of the Epitácio Pessoa weir, prevailing water supplier of Campina Grande city and surrounding region. That way, are used meteorological indicators of drought (SPI) and hydrological (SRI) to the categorization and evaluation of the drought at this region, as well as its correlation with the volume variation of the reservoir in the study. Was observed during the historical series the droughts’ occurrence and frequency, as well as its severity and capacity variation of the Epitácio Pessoa reservoir. It was verified the presence of drought periods in both basins, with its category varying between weak to exceptional, so as to constitute intervals of up to 85 consecutive months of drought, of moderate average, as an answer to the SPI analysis, 36 consecutive months through SRI results, 18 of them being of exceptional drought. The observed periods affected by the phenomenon had reflexes in the volume of the reservoir, which reached about 70% of its capacity in the studied period. It was observed that in the case of such basins, the greater the time scale, both for SPI and SRI, the longer the periods of drought, although less severe, the opposite being also true.