Drought Forecasting for Future Periods Using LARS-WG Model (Case Study: Shiraz Station)

In this study, in order to simulate the current climate (1970-2016) for calculating the drought index in Fars Province, the data used include daily rainfall, minimum temperature, maximum temperature, and sunny hours at Shiraz station in a period of 46 years (1970-2016) as the entry for the LARS-WG statistical model. To simulate the climatic parameters at the Shiraz station basin, the data of HADCM3 model were downscaled using WG-LARS model under two scenarios A2 and A1B. The results showed that the average annual rainfall will increase under A2 scenario by about 1.5% and under A1B scenario by about 5.5% during 2020-2066 periods. Moreover, sunshine hours in the study period will be reduced under both scenarios. With high precision, the model could simulate maximum temperature, minimum temperature, and radiation parameters, but more error in simulating was presented in the precipitation parameter than other parameters. The highest increase, with about 80%, was due in September under scenario A2, which occurred in the upcoming period of the study period. Based on the SPI drought index, the most severe droughts occurred in 2008 in Shiraz station showing an index value of -2.89. Moreover, SPI shows that the most precipitation was recorded in 1995 with an index value of 1.91.