CLIMATE CHANGE IMPACTS UNDER CMIP5 RCP SCENARIOS ON AGRICULTURAL DROUGHT AND CROP VIRTUAL WATER CONTENT

The aim of this study is to investigate climate change impact on agricultural drought and its combined effect on crop virtual water content (VWC) in future periods. CanESM2 climate data under two representative concentration pathways (RCP) scenarios were used in Khouzestan province located in southwestern of Iran. Through CanESM2 data, rainfall and maximum and minimum temperature of the selected meteorological stations for three periods 2020-2040, 2070-2050, and 2080-2100 predicted and compared with the base period (1990-2011). Statistical downscaling method was used to downscale CanESM2 data by SDSM. Agricultural Drought Index (RDI) in Khouzestan province was calculated using six weather stations data. Crop Virtual Water Content (VWC) was calculated according to the information available for selected crops including wheat, barley, rice, maize and sugar cane. Model calibration and validation was performed. Agricultural drought indices, crop potential evapotranspiration, and average VWC were obtained with the data generated in future periods. The results showed that the average temperature in all selected stations and in two RCP scenarios increases and this increase is higher in RCP8.5 than RCP4.5 scenario. The average rainfall in 2060s and 2090s reduces. The highest temperature rise in Khouzestan is 4.6°C on average in 2090s under RCP8.5 scenario, and the lowest decrease in temperature is in 2030s approximately 1°C under RCP4.5 scenario. The VWC obtained for all crops has increasing trend, but this increase shows more increase for rice and corn on average during 2060s and 2090s.