Impact of climate change on droughts: a case study of the Zard River Basin in Iran

In this research a SWAT model was assembled and used to evaluate the effects of climate change on runoff and drought in a semi-arid basin in Iran. The SWAT model showed good performance in the simulation of runoff. Eleven General Circulation Models (GCMs) under Representative Concentration Pathway 4.5 and Representative concentration Pathway 8.5 (RCP45 and RCP85) scenarios, and the period 2022-2041 was selected to investigate future projections. It was predicted that under all of the scenarios, runoff will decrease significantly. Annual rates showed that runoff will fall to 7.73 m3/s (11.6% decreased) and 6.78 m3/s (22.5% decreased) under RCP45 and RCP85 from 8.75 m3/s during next 20 years in this basin, respectively. In this research, the meteorological and hydrological droughts were estimated using SPI and SDI indices, respectively. By coupling of climate change scenarios and SWAT models it was found that the severity of droughts in the future will be far greater than has ever happened before. Key words: climate change, hydrological drought, SDI, semi-arid basin, SPI, SWAT. HIGHLIGHTS Evaluation of SDI and SPI for the 2022–2041 period.; Using compatible models to simulate future climate scenarios.; Description of Iran's macro-level drought management strategies.;