Abstract

In this paper, one of the probabilistic characterizations of drought events (i. e. intensity values) was simulated by a global climate model (GCMs) under enhanced greenhouse gases conditions for near future (2011-2030). Output of the Hadley Centre Global Climate Model (HadCM3) was used to provide a future climate scenario for precipitation in selected western stations of Iran, including Ilam, Hamedan, Kermanshah, KhoramAbad, Sanandaj, Zanjan. Because of the coarse resolution of GCM output model, a statistical downscaling method, LARS_WG, was applied in order to obtain site specific daily weather Series. The downscaling model was evaluated against available observational reference data (1961-1990). The performance of LARS-WG during the validation period was suitable to reproduce daily precipitation series, therefore this model was used to provide future scenario of daily precipitation for 2011-2030 period. The simulation was forced by the A1B, B2 and A2 emission scenario for HadCM3. SPI was calculated using the downscaled precipitation time series for baseline and near future period. The model also captures the properties of drought for baseline acceptably. The results show that the future amounts of precipitation do not differ significantly in comparison with baseline. The most percentage change is obtained by 28% in the Kermanshah station Under B1 emission scenario during near future, but the increase is not significant. SPI was calculated for long-time drought (12 months) and then 2, 5, 10, 20, 25, 50, 100 return periods were estimated for all stations. Based on the results, the severity of drought will increase with longer return period i. e. 100 years in Kermanshah, Zanjan and Khoram Abad Stations. This information was achieved by this research can be considered indicative in long-term planning focusing on sustainability.

Keywords: Drought; Standard precipitation index; Return period