UTILIZATION OF STANDARDISED PRECIPITATION INDEX, PALMER DROUGHT SEVERITY INDEX AND RECONNAISSANCE DROUGHT INDEX AS DROUGHT INDICATORS IN SOUTH BULGARIA

During the last decades an increase of the number of extreme natural events has been observed all over the world. Drought in Southeastern Europe is among the extreme events, which might have significant negative impacts on the socio-economic sectors. Drought in Bulgaria has been in details studied by many researchers, but being a problem of vital importance, is continuously considered with enhanced attention. 50-years time series of precipitation, collected from 20 weather stations located at the Maritsa and Tundja river basins (South Bulgaria) are used for SPI, PDSI and RDI calculation with the purpose to detect drought periods and intensity. Some trends in drought frequency are analysed. A comparison between SPI, PDSI and RDI is also done in order to assess applicability of these indices for the regional climatic conditions. This study is implemented under the activities dedicated to the Drought Management Centre for Southeastern Europe.