Determining the most suitable index for droughts rainfall region in Iran

Droughts are the most important natural disasters. Droughts exist in 3 forms Climate, Hydrology and Agriculture. Due to the location of Iran in the realm of global dry climates and high sensitivity to this issue in country, it is necessary to study and investigate about the problems related to droughts. For this purpose, this presented research is considered the climate drought and evaluated the valid indicators of drought on the various regions of country. In this order, the whole area of Iran considered as six regions of rainfall and among all existing stations, the stations which have the more perfect and valid statistics of aerology rather than others were selected. Then among the climate drought indicators, six indicators Z, DI, PNPI, SIAP, RAI and SPI were selected and the drought of each various regions of rainfall were defined through these indicators and results was compared using Spearman's correlation coefficient between rainfall and indicators ranking and it was found that the best indicator for each region of rainfall; Finally it was found that the DI indicator has the highest Spearman's correlation coefficient and it will be the most appropriate indicator for whole area of Iran.