A Review of Drought Indices

Shortage of food and water resources resulted from climatic crises has alarmed people around the world, in particular that the rain-watered agriculture and vegetation of natural resources suffer from the irregular rainfall in most of the water years.Drought and wetness year causes significant impacts on water resources, crops, commerce, trade and in general, economy and political crises.Give the fact that some countries like Iran are located in the dry belt of the world their rainfall pattern possess unique features: low intensity and high fluctuation.The persistent negative fluctuations of precipitation lead to drought characterized by different severity which imposes extensive damage on ecological and economic condition of the affected areas.Therefore, in this paper the comprehensive review of drought indices is presented and the advantages and disadvantages related to each index is discussed enabling policy makers to manage drought effectively.