Future meteorological drought conditions in southwestern Iran based on the NEX-GDDP climate dataset

Investigation of the climate change effects on drought is required to develop management strategies for minimizing adverse social and economic impacts. Therefore, studying the future meteorological drought conditions at a local scale is vital. In this study, we assessed the efficiency of seven downscaled Global Climate Models(GCMs) provided by the NASA Earth Exchange Global Daily Downscaled Projections(NEX-GDDP), and investigated the impacts of climate change on future meteorological drought using Standard Precipitation Index(SPI) in the Karoun River Basin(KRB) of southwestern Iran under two Representative Concentration Pathway(RCP) emission scenarios, i.e.,RCP4.5 and RCP8.5. The results demonstrated that SPI estimated based on the Meteorological Research Institute Coupled Global Climate Model version 3(MRI-CGCM3) is consistent with the one estimated by synoptic stations during the historical period(1990–2005). The root mean square error(RMSE) value is less than 0.75 in 77% of the synoptic stations. GCMs have high uncertainty in most synoptic stations except those located in the plain. Using the average of a few GCMs to improve performance and reduce uncertainty is suggested by the results. The results revealed that with the areas affected by wetness decreasing in the KRB, drought frequency in the North KRB is likely to increase at the end of the 21st century under RCP4.5 and RCP8.5 scenarios. At the seasonal scale, the decreasing trend for SPI in spring,summer, and winter shows a drought tendency in this region. The climate-induced drought hazard can have vast consequences, especially in agriculture and rural livelihoods. Accordingly, an increasing trend in drought during the growing seasons under RCP scenarios is vital for water managers and farmers to adopt strategies to reduce the damages. The results of this study are of great value for formulating sustainable water resources management plans affected by climate change.