Analysis of Spatio-Temporal Characteristics of Drought in Serbia From 1961 to 2020 Using SPI and SPEI

The main objective of this study was to analyse the spatial and temporal characteristics of drought in Serbia using the standardised precipitation index (SPI) and the standardised precipitation and evapotranspiration index (SPEI). The duration and severity of drought were determined, and the trend of the indices for different accumulation periods, for 3 months (SPI3 and SPEI3), 6 months (SPI6 and SPEI6) and 12 months (SPI12 and SPEI12) were analysed for 10 meteorological stations in Serbia in the period 1961–2020. There was a high correlation between the SPI and SPEI on all time scales. Droughts were observed in Serbia in the following periods: 1961–1963, 1971–1972, 1987–1993, 2000–2003 and after 2011. The drought observed in 2000–2001 was recorded with both indices for all time scales at all stations. The longest drought was measured from June 2011 to February 2013, with a duration of 21 months and a severity of −37.5 with the SPEI12 in Loznica. The 1972 drought is observed in almost all of Serbia, although it was more pronounced in northern Serbia. A statistically significant negative trend is observed for SPEI12 at 6 stations. The SPEI tends to show longer and more severe dry periods than the SPI for the later part of the period under consideration, especially after 2000. As there is a significant increase in temperature in Serbia, the SPEI is better suited than the SPI for analysing drought characteristics under warming conditions.