SPATIAL AND TEMPORAL ANALYSIS OF DROUGHT EVENTS IN UPPER PARANÁ RIVER HYDROGRAPHIC REGION (BRAZIL) FROM 1990 TO 2020

The Paraná River Hydrographic Region is of great socioeconomic relevance for Brazil. Therefore, due to the history of droughts in the region, the aims of the current study were to assess rainfall spatial and temporal variability, as well as to analyze drought features based on using the Normalized Percentage Index (NPI) to contribute to water management processes in Upper Paraná River (UPR). The study area encompasses 14 Planning and Management Units, distributed in Goiás, Mato Grosso do Sul, Minas Gerais and São Paulo states. Climate data were obtained from the National Hydrometeorological Network database. A geostatistical analysis of rainfall was carried out, based on the annual series of 408 stations, and subsequently the calculation of NPI for classifying the droughts severity. All periods analyzed (1990-2020) showed spatial dependence (moderate to high), allowing the elaboration of droughts maps. The dry and rainy periods and areas did not indicate direct influence of El Niño-Southern Oscillation (ENSO). Mato Grosso do Sul and São Paulo units were the main contributors to the identified droughts. The data showed that 2010-2020 was the driest decade of the period, with a greater contribution from the 2019/2020 period, where droughts exceeded 60% of the area for two consecutive years, an event never identified in the last 3 decades. The NPI curves referring to “initial drought” and “mild” allowed verifying years of water crisis when their summed percentages reached at least 50% of the region. The methodology used is versatile, allowing its use in any watershed. Keywords: Rains. Water management. NPI. Kriging.