Error Analysis of SPI Drought Index Assessment using by Geostatistics, Case Study: Boushehr

Spatial distribution of drought indices and most importantly, its modeling accuracy, are considered an important topic to obtain reliable results in the spatial analysis of these indicators. Management’s approaches against drought are not only requires quantity information about drought but also knowing the likelihood and risk of occurrence of this phenomenon can help in managing the appropriate measures. In this study, the rainfall data of 27 climatic stations in Boushehr province for period of 19 years (1995-2013) were used for calculation the SPI index. According to the initial assessment, the 1999-2000 was known as the most arid year and the spatially variability of SPI index was evaluated only in this year. In this research, several geostatistical methods including Ordinary kriging, Inverse Distance Weighted and PSS were assessed for the derivation of maps of drought indices at 27 climatic stations in the Boushehr province of Iran. The results indicated that IDW method with the power of two is more appropriate for spatial analysis of SPI index and Ordinary Kriging method is more appropriate for spatial analysis of EDI index. Several geostatistical methods including Ordinary kriging, Inverse Distance Weighted (IDW) and TPSS were used to assess the spatial analysis of SPI index, mapping the seasonal and annual drought index. The results indicated that IDW method with the power of two is more appropriate for spatial analysis of SPI index.