The Study of Drought and Wet Year Assessment models for Stations in Mazandaran province

Annual rainfall data related to a 26 year period from a number of Mazandaran climatologicalstations were employed to analyze and model the precipitation toward a determination ofdrought as well as wet years. Results indicate the occurrence of different intensity drought phenomenon in all stations. As regards the classification of the annual wet and dry years, normal precipitation among various alternate dry and wet years can be observed with the normal years having more stability and continuity as compared to wet and dry years. The Standardized precipitation Index (SPI) was recognized better and more accurate model compared to the other models because of more potential such as high sensitivity to precipitation variation and more punctual separating of drought and wet year classes in every events.