Variabilidad espacial y temporal de la concentración de precipitación en el noreste de Brasil

Resumen

Drought is a recurring natural phenomenon. It is considered a natural disaster whenever it occurs intensively in highly populated regions, resulting in significant damage (material and human) and losses (socioeconomic). In the semi-arid region of Brazil, there are frequent occurrences of drought during the rainy season, which, depending on intensity and duration, can cause significant damage to family crops, with production system characterized by low productivity indexes. Rainfed agriculture has great economic expression and high social importance, since the region is densely occupied and contributes to the establishment of countryside communities. Spatial and temporal changes in precipitation concentration have been analyzed using Precipitation Concentration Index (CI) and Concentrated Precipitation Index (PCI). The nonparametric Mann-Kendall (1975) test was used to detect monotonic trends in annual total, CI and PCI time series. The study area is the Northeastern region of Brazil, represented by 82 pluviometric stations with daily rainfall data. The results revealed that, based on CI values, precipitation occurred in much of northeastern Brazil, covering the Drought Polygon and the coastal part of this study area. Of the 82 series analyzed, 26 showed positive or negative trends, corresponding to 32% of series used. Of this total, 14% showed negative trend, i.e., a decrease in rainfall in the study area. These percentages indicate that one cannot generalize trends (positive or negative) in northeastern Brazil.