Analysis of relationship between hydrogeological and climatological droughts using SWI and SPI indices in Sabzevar Plain

In arid and semi-arid areas, drought damages are more than other regions due to the fragility of environment. Parts of central, eastern and southern Iran with arid and semi- arid climate are include these regions. The object of this study was to investigate the relationship between hydrological and climatological drought in Sabzevar Plain. In this study, SPI and SWI indices were used for the zonation of hydrological and climatological droughts in Sabzevar plain. Precipitation and groundwater data were collected from 1999 to 2007 and from 2001 to 2007, respectively and then were analyzed by the mentioned indices. After calculating SPI and SWI, drought zonation was performed for each year using Kriging method in ArcGIS. Results showed that climatological and hydrological droughts did not follow a certain order and the highest intensity and frequency of droughts were west Sabzevar plain. In other hand, the east region has enjoyed normal and wet condition. According to the results, a significant relationship was found between climatological and hydrological drought in the study area as hydrological drought occurred one year later compared to climatological drought.