Mapping Drought Hazard Using SPI index And GIS (A Case study: Fars province, Iran)

Abstract

Drought is defined as the continuous and abnormal moisture deficit. The term of continues means continuation of deficit and the term abnormal means deviation of favorite index of natural condition from the mean. 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 droughts and to use them in plotting drought maps over Fars province. To study drought and mapping, different indexes have been invented, one of these index is the Standardized Precipitation Index (SPI) .It is practical and simple method. The base of this index is precipitation. To study the drought, Records from10 stations within the same period of 13 years (1994-2006) and 17 stations within the same period of (2007-2011) in scale of annual. For better results kriging, natural neighbor interpolation and IDW are compared and Inverse Distance Weighted (IDW) interpolation is more practical for this study area. The result of analysis, is showed that the least SPI and drought magnitude has happened in Sadedorodzan station, in the north of Fars province for 17 stations between 1994-2011 and 10 stations between 2007-2011. For 10 stations during 1994-2006, the least SPI is related to the Lamerd station in the south of the province. Figures that produced by interpolation method between 1994-2011 illustrated that drought was generated in the south and it was rapidly extended to north and northeast and northwest. This prediction is used in Fars province to manage the drought.