the perusal of climate change impact on drought intensity and duration

abstract this research evaluates climate change effects on drought severity in the region of gharesou, iran. the standardized precipitation index (spi) has been used for estimation of drought severity. a geographical information system is applied for calculating the mean areal precipitation time series from 11 meteorological stations, in and out of the area for the hydrological period jan 1971-dec 2000 using inverse distance weighting method. this precipitation time series have been used for the estimation of standardized precipitation index (spi) for three timescales, 6, 12 and 24 months, for the region. the outputs of hadcm3-a2 were applied for the assessment of climate change impact on droughts. the hadcm3 outputs were downscaled statistically to the region of gharesou using sdsm software to estimate precipitation time series for a future period 2040-2069. a method has been used for the estimation of annual cumulative drought severity-time scale-frequency curves. these curves integrate the drought severity and frequency for various types of drought. the spi time series were estimated and compared with the respective time series of the historical period 1971-2000. the comparison indicated that the annual drought intensity decreases for the three examined spi time series. furthermore, analysis of drought period has shown that value and frequency of drought would be declined in future in the region.