Occurrence of drought in the State of Parana

The influence of global climate change on agriculture and its consequential impact on the loss of productive potential in various Brazilian regions are widely recognized. This study aims to assess the prevalence of drought by examining the relationship between actual evapotranspiration and potential evapotranspiration (ETa/PET) in the state of Parana. Daily meteorological data on precipitation and air temperature were sourced from the meteorological stations of the Parana Rural Development Institute IAPAR-EMATER (IDR-Parana) over the period from 1976 to 2020. This data collection covered six distinct regions within the state: central, south, north, coast, northwest, and southwest. Potential evapotranspiration data were estimated using the method Thornthwaite (1948), while ETa data were derived from the Climatological Water Balance model proposed by Thornthwaite and Mather (1955). Drought conditions were defined as instances when ETa/PET < 0.6, evaluated on annual, quarterly, monthly, and decade (10-day) scales. The month of August and the last decade of this month were found to be the period with the highest frequency of drought occurrences across the state. The northwest region demonstrated the highest susceptibility to drought, followed by the north, south, southwest, and coastal regions.