Zoning Drought with Standardized Precipitation Index and ‎Reconnaissance Drought Index in Sistan and Baluchestan ‎Province, Southeastern Iran

Aims: Drought has become a main concern in Iran. The drought is posing a serious threat to life in Sistan and Baluchestan Province. This study aimed to evaluate the severity and extent of drought in Sistan and Baluchestan Province, Southeastern Iran.
Standardized precipitation index (SPI) and reconnaissance drought index (RDI) were used to determine the severity, duration, and extent of drought in Sistan and Baluchestan Province. Seven synoptic stations located across the province with data period of 2001–2012 were used in monthly timescale. DrinC software was used to calculate SPI and RDI indices. Drought zoning maps were generated using ArcGIS software.
Findings: Iranshahr and Saravan stations showed the most severe drought in 2003–2004 water year and Nikshahr station had the lowest drought severity in the same water year. The drought zoning maps indicated that the lowland areas and plains, especially in the southwestern part of the province and Iranshahr and Nikshahr stations, were vulnerable at the time of drought occurrence.
Both drought indices behaved similarly, but the RDI index was more sensitive in a specific climate condition due to using potential evapotranspiration of reference crop. It can be recommended that the RDI index can be used as an appropriate indicator for drought monitoring in Sistan and Baluchestan Province.