Evaluation of drought characterization using SPI and SC-PDSI drought indices in baseline and upcoming periods in Birjand region

The aftermaths of climate change, particularly as result of increasing greenhouse gas emissions have posed numerous problems in recent years. Theses aftermaths have directly or indirectly affected different regions of the world of which floods and droughts are the most prevalent disasters. Drought as one of the most widespread and devastating natural disasters has been considered more complicated owing to climate change. Various indices widely used to monitor drought conditions. In the present study, the outputs of GCM models with RCP4.5 and RCP8.5 emission scenarios applied and also the LARS-WG statistical model used for their downscaling. Then precipitation and temperature data generated for the upcoming period (2025–2055). Finally, the drought status of Birjand considered, as study area evaluated not only using these data but also drought indices (SPI and SC-PDSI) during the studied period. In addition, baseline droughts (1975–2005) evaluated using these indices and the frequency and severity of droughts compared with the upcoming period. The results indicated that the drought conditions would have a relative increase in the upcoming years compared to the baseline period demonstrating the occurrence of climate change in the region. Moreover, the statistical years (2026–2028) were the only common SPI drought periods in all five models applying both emission scenarios. Furthermore, the statistical years (2026–2035) in the upcoming periods were an agricultural drought period based on the predictions of the models with both emission scenarios in the SC-PDSI drought index evaluation. The results by MK test showed that there are significant negative trends at Birjand Station at the %95 confidence level.