Evalution of drought under increasing of temperature due to climate change in rainfed wheat-growing areas of Fars province using Aridity Index

Background and objectives: Making a reliable prediction of drought index status for the future is one of the major elements in a successful water resources management particularly under climate change processes, including increase in atmospheric carbon dioxide concentration, temperature and fluctuations in rainfall. The present study aims at assessing drought trend under changing climate conditions in some locations of Fars province.
Materials and methods: This study was conducted in six locations of Fars province (Shiraz, Lar, Abadeh, Darab, Eghlid, Fasa). In the current study, two general circulation models (IPCM4 and HadCM3) under three emission scenarios (A1B, B1 and A2) were applied during three time periods of 2011-2030, 2046- 2065 and 2080-2099. LARS-WG program was employed to assess rainfall, maximum and minimum temperatures during the mentioned periods and in different emission scenarios. AI (Aridity Index) was used to study drought pattern in study locations.
Results: Results showed that the impact of climate change on AI was a result of increasing temperature and evapotranspiration (ET) as well as decreasing cumulative rainfall which consequently reduced AI in all locations, scenarios and time periods compared to the baseline (i.e. locations would be drier in the future). There was no difference between climate models, scenarios and time periods in terms of ET. Generally, there will be a substantial increase in ET in Fars province in the future as a result of rising temperature which is highly correlated with ET. Results also revealed that the highest variability in AI was observed in Lar under three scenarios. In B1, fluctuation in AI was lowest amongst study locations and ranged from -55 to +55 percent while it was -100 to +150 in the other two scenarios compared to the baseline.
Conclusion: Results of the current study indicated that a reduction in AI in Fars province would be observed under future climate change. There will be a substantial increase in AI in Fars province in the future as a result of rising temperature which is highly correlated with ET. Drought spatial map also portrayed that drought would be intensified as the time period became closer to 2090 in all locations. According to the interpolations map, almost the entire province will be included in dry class category in 2090 under A2. Overall, it is concluded that under all emission scenarios and time periods, the drought will be intensified in the entire region of Fars province due to an increase in ET and a decrease in rainfall.