A Review of Drought Indices and their Performance

Drought is an inevitable natural phenomenon and a disaster that should be considered without the possibility of prevention, but this phenomenon can be managed and organised. In general, from a climate perspective, drought represents a type of deviation from the average condition. Drought types include agricultural, hydrological, and meteorological, where meteorological drought occurs more than the agricultural and hydrological drought types. To assess quantitatively and qualitatively of the drought phenomenon, some indicators called drought indices are commonly used in the world. In this study, considering the importance of drought, eight rainfall indices namely Deciles Precipitation Index )DPI(, Palmer Drought Severity Index )PDSI(, Percent of Normal Precipitation Index )PNPI(, Surface Water Storage Index )SWSI(, Standardised Precipitation Index )SPI(, Crop Moisture Index )CMI(, Reconnaissance Drought Index )RDI(, and Rainfall Anomaly Index )RAI( were evaluated. The results of this study indicate that the SPI index has a high comparative advantage for drought monitoring. Based on rainfall and potential evapotranspiration, the RDI index is more sensitive to climate change variables than the rainfall-driven SPI index. Also, the PNPI indicator is a dysfunctional method for estimating drought, and drought prediction will have many errors due to this index. The CMI index is also limited to use only in the growing season. Also, it cannot determine the long duration of drought.