ANÁLISE DAS SECAS NA SUB-BACIA HIDROGRÁFICA DO RIO PIRACURUCA, FRONTEIRA DOS ESTADOS DO CEARÁ E DO PIAUÍ, BRASIL

Abstract

The study aimed to identify and analyze the most critical dry areas in the Hydrographic Sub-basin of the Piracuruca River, on the border of the states of Ceará and Piauí, Brazil. The research classified as descriptive as to its objective, required bibliographic and cartographic survey, having been necessary to obtain the following information: monthly data (August and September) of precipitation of twelve pluviometric stations and vector files of the drought monitor, from the Agência Nacional de Águas, for the years 2014 to 2019; alphanumeric files of the Emergency Situation Recognition Ordinances, acquired from the database of the Secretaria Nacional de Defesa Civil, for the municipalities with headquarters located within the surveyed Sub-basin, considering the years 2014 to 2019. The rainfall data indicated that the months of August and September have low rainfall, for the years 2014 to 2019. It is noteworthy that in the month of August 2018 and 2019 there were episodes of exceptional droughts, respectively, by 38.2% and 100% of the Piracuruca River Sub-basin. While for the month of September, the years 2015 and 2016 stand out, in which episodes of severe drought occurred, respectively, in 79.7% and 62.8% of the Sub-basin area. Droughts, therefore, can be associated with the manifestation of El niño and positive dipole, as in the case of the years 2015 and 2016 where El niño weak and strong, respectively, associated with the positive dipole. Such situations demanded the issuance of emergency decrees, especially in 2014, with sixteen decrees issued.