ASSESSMENT OF DROUGHT IN BULGARIA IN RECENT YEARS THROUGH THE STANDARDIZED PRECIPITATION INDEX

Abstract

Drought is a complex weather and climate-related phenomenon with significant ecological and socioeconomic consequences. In light of the increasing severity and frequency of droughts in Europe in recent years, this study focuses on assessing the spatiotemporal evolution of drought in Bulgaria during the period 2014-2022. To achieve this, the Standardized Precipitation Index (SPI) is calculated at different time scales (1, 3, and 6 months) for both the country's territory and individual municipalities using software recommended by the World Meteorological Organization. The spatiotemporal analysis is performed in the QGIS environment, utilizing the Ordinary Kriging method for spatial interpolation and the Zonal Statistics tool to calculate selected statistical features at the municipality level. Additionally, area-averaged values are extracted from all raster layers, forming time series spanning the period 2014-2022, which are used for further statistical analysis. The study reveals several drought events, with the most significant occurrence in 2019-2020, affecting 60-80% of the country's territory during certain months. However, the considered period is characterized by normal and wet conditions. The results also show that several municipalities in the western and southeastern regions of the country are particularly vulnerable to severe and extreme droughts. Overall, the study emphasizes the importance of integrating different spatial and time scales in drought monitoring and analysis.