The Effects of Climate Change on Drought Conditions Using Fuzzy Logic Under SSP3 and SSP5 Scenarios

Investigation of future drought trends and variations under climate change scenarios plays a key role in developing management strategies for minimizing drought's negative societal and economic impacts. Therefore, this study aimed to assess changes in drought characteristics such as the frequency of dry and wet periods, and the trend of drought index based on fuzzy drought index (at time scales of 3, 6, and 12 months) under SSP3 and SSP5 scenarios of CMIP6 during the 21st century. The data of 6 synoptic stations in Karoon River Basin during 1991-2014 have been used in this study. Assessing the reliability of climate models for drought monitoring with fuzzy drought index in the base period showed that the highest correlation coefficient (CC>0.90) and the lowest root mean square error (RMSE<0.14) are found at 3 and 6 month time-scales. In addition, monitoring the drought conditions of the basin under climatic scenarios in future periods revealed an increasing trend (at the 95% confidence level) and the wetness frequency in the northern, northwestern, and western of the basin is more likely to decrease. Over the periods 2046–2072 and 2073-2099 the result of the non-parametric Mann-Kendall test for the scenarios of SSP3_7.0 and SSP5_8.5 was 1.64. Therefore, due to the increasing trend of fuzzy drought index changes to dry conditions in Boroujerd, Safiabad, and Kuhrang stations, the risk of drought during the periods 2073-2099 and 2046-2072 are higher. Accordingly, water managers and farmers should adopt strategies in order to reduce the damages. The results of this research can be valuable in adopting policies and planning for sustainable management of water resources affected by climate change.