Drought is a creeping natural hazard, which is caused by short raining and humidity deficit. When a drought occurs dramatic social, economic and environmental effects are inevitable. Because of the vast impact of drought, it is essential to be monitored timely and spatially. Specifically, SPI was used as drought monitoring Index, and for zoning proposes four models (namely: Regression, Kriging, Splin and IDW) were employed. We studied drought periods in Khorasan using 33 years climatic data (1968- 2000). The study showed that during last years of the 33 years period recurring drought has been more frequent and also it lasted longer than the early years. However, the severity of drought has been reduced. It can be seen that the duration and severity of drought is more in the sought area than in the central and northern parts of the province. We used different methods to interpolate drought data for spatial analysis using Geographic Information Systems (GIS). We then concluded that Kriging method is suitable for this analysis this method was used for zoning drought over Khorasan province and produced zoning map of drought severity for different time scales. As a conclusion, Kriging was approved as the best zoning model among the four Models, due to its performance (Regression coefficient= 0.71, MDE=-1.1 and MAE= 0.95).
Keywords: Drought, Drought Duration, Drought Frequency, Spatial interpolation, SPI.
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