Comparison of Monitoring of Drought Using SPI, DI and PNI and Zoning Them (Case study: Northern Khorasan Province)

The necessity of drought preparedness can be verified by assembling drought mitigation scheme. In this study, the severity, duration and extent of drought during 1986 to 2005 have been studied using monthly precipitation data of all IRIMO stations over Northern Khorasan province. For all stations, meteorological drought indices including Standard Precipitation Index (SPI), Deciles Index (DI), Percent of Normal Index (PNI) have been used in order to assess and compare their capability for drought severity and duration in annual scale. Finally, for the purpose of study on the drought extent, the zoning maps have been prepared by IDW method. The consequences resulting from the zoning of drought severity, have illustrated that the most extensive drought occurred in 1990 and 2001 respectively. The most durable drought, Based on SPI capability has occurred during 1994-1997.