Monitoring Drought Using SPI, DI, and PNI Indices in Semi-Arid Regions of Northwestern Iran

Drought is one of the natural hazards that is sometimes considered a natural and dangerous disaster that occurs as a result of less than normal or expected precipitation. One of the ways to evaluate and monitor drought is based on indices that can determine the severity and duration of drought in a region. The drought index calculated from known quantities of selected parameters provides the possibility of describing and expressing drought quantitatively. The drought index is actually a function of various environmental factors that affect the phenomenon of drought. In this study, the semi-arid regions of western and northwestern Iran were selected as study areas and monthly precipitation data from all weather stations belonging to the meteorological organization in these areas, which includes ۸ selected stations, were used from ۱۹۸۶ to ۲۰۰۵ to investigate the severity, duration, and extent of drought. Also, in order to examine and compare the capabilities of standardized precipitation index (SPI), deciles (DI), and percentage of normal (PNI) drought indices based on their ability to determine the severity and duration of drought, each of these indices was calculated annually for each of the stations.

کلیدواژه ها:

Drought ، Standard Precipitation Index (SPI) ، Deciles Index (DI) ، Percent of Normal Index (PNI) ، Semi-Arid Areas of North West of Iran