This study examines the impact of climate change on drought features in the Dez Basin of Iran. The Hydro-Meteorological Drought Index (HMDI) is a newly developed index that combines the Standardized Precipitation Evapotranspiration Index (SPEI) and the Standardized Runoff Index (SRI). Monthly data from CRU TS was acquired for the baseline period 1980 to 2012, and forecasted climatic data was down scaled based on three CMIP6 models under two SSP1-2.6 and SSP5-8.5 during the period of 2020-2052. The rainfall-runoff HBV-Light model was used to compute streamflow for future period. The characteristics of the drought were computed using the run theory. Results showed the CanEsm5 climate model significant increases in monthly temperature and runoff in the basin under two scenarios: SSP5-8.5, with the Bakhtiari and Borujerd sub-basins experiencing the largest increases (63% and 56%). Droughts are expected to become more severe in the future, particularly under the SSP5-8.5 scenario. The most severe drought generated by the SSP5-8.5 scenario for HMDI 12 was increased from -43.44 to -44.05 in Borujerd station. So the SSP5-8.5 scenario is more probable to cause a severe and prolonged HMDI-derived drought than SSP1-2.6 and the historical period. The drought characterize analysis indicates that the percentage of normal levels will remain mostly unchanged, while it will increase for mild and severe drought levels in the future.
