Drought Modeling and Management Using SPIand RDI Indexes (Case study: Markazi provin

Drought is defined as the continuous and abnormal moisture deficiency and phenomenon is unavoidable that most parts of the world are facing. Drought is a natural hazard that creates a lot of damages to human health and natural ecosystems.In every drought study four main characteristics are considered: severity, duration, frequency or return period and areal extent. The objective of this study was to analyze these characteristics of drought and to use them in plotting drought maps over the Markazi province. To study the drought andmodeling, deferent indexes has been invented, an index is the Standardized Precipitation Index and one index is Reconnaissance Drought Index. To review the 10 synoptic stations with the same period of 13 years (1379-1392) at the monthly time scale was used.Theindexs is calculated by the software drinc, zoning maps of drought in a separate area is provided by the Arc GIS.The most severe drought in Ashtian station in year of blue of 87-86 and lowest drought in Station Komijan in year of blue 87-86 be seen.Drought map of the Markazi province using the Standardized Precipitation Index and Reconnaissance Drought Indexof lowland areas during the drought shows. These areas are located in the central and western plains, among which in Arak, Komijan and Shazand are whittherisk of drought.