COMPARATIVE STUDY AND DELINEATION OF ARIDITY INDICES IN

Given the relevance of understanding the acidity index (AI) since it is related to the susceptibility to desertification, the objective of this work was to map and compare the acidity indices in the hydrographic basin of the Paraíba River, specifically, the AI in the sub-basin of Alto Paraíba-PB. To determine the Aridity Index in the Upper Paraíba-PB sub-basin, the total annual precipitation and estimated potential evapotranspiration were obtained, in this work calculated by the method of Thornthwaite & Mather (1955). From the calculation of the dryness index, the risks of desertification were determined, as well as the climatic classification that delimits the climatic zones established by UNEP (1991). Thus, the indices varied, as to the climatic classes for aridity, as follows: less than 0.03 (< 0.03) Hyperarid; 0.03 to 0.20 Arid; 0.21 to 0.50 Semi-arid; 0.51 to 0.61 Subhumid and Dry; and greater than 0.65 (> 0.65) Subhumid and Humid. The production of the maps used census data from the Brazilian Institute of Geography and Statistics (IBGE), which helped both in the elaboration of the maps and in the interpretation of the data.