Investigation of Climate Change Effect on Drought Characteristics in the Future Period using the HadCM3 model (Case Study: Northwest of Iran)

Investigation of drought event has a great importance in the natural resources management and planning water resources management. In this research، the effect of the climate change on drought characteristics in northwest of Iran was investigated using the HadCM3 model under A2 scenario. The statistical downscaling was executed using SDSM 4. 2. 9 and observed daily precipitation، observed predictors and large-scale predictors derived from the HadCM3 model. Afterwards the SPI was calculated for different time scales of 3، 12، 24 and 48 months in the observed period of 1977-2006 and three periods of 2007-2036، 2037-2066 and 2067-2096. Obtained results show that the mean annual precipitation at the stations of Ardebil، Khoy and Oroomieh was decreased in the future periods and it was also increased at the station of Tabriz in the future period. The Ardebil station with the depletion of 97 mm (32 %) in the fourth period than the observed period has maximum rate of the depletion. The results also show that the drought occurrence with more intensity، duration and frequency can occur in the future periods. The comparison of the results between different stations shows that the Ardebil station has the most intensity of dry period in time scales of 3، 12 and 24 months based on the maximum cumulative intensity of dry periods among the stations. On the time scale of 48 months، the Oroomieh station with the cumulative intensity of -92. 78، has the most intensity of dry period between the different stations.