Temporal and Spatial analysis of the drought in Khorasan region using SPI during 1966 - 2005

Drought is one of the atmospheric events that causes great losses and is inevitable in most areas if the world Since soil moisture, stream fiow, and reservoir storge reflect precipitation anamolies, This study aims at a spatial analysis of drought in three Iranian provinces namely North khorasan, Razavi khorasan and South khorasan to quantify precipitation anamolies by means of SPI in 3, 6, 12, and 24 month scale. Monthly precipitation data of 12 long period stations during 1966-2005 were used which was taken from Iranian Meteorological Organization. Geostatistical methods were also applied to prepare spatial distribution maps. The results of the study showed that in 3 and 6 – month- scale period most – severe droughts are are frequent in the Razavi khorasan and North khorasan is affected by severe droughts in the same period. However, in 12 and 24 – month– scale period most serious droughts are frequent in South Khorasan and Western Razavi Khorasan experiences severe droughts. SPI values showed that most droughts happened in the first decade (1966- 1975) and the fourth decade (1996- 2005) as well and 1973 and 2001 have experienced the most serious drought.