Assessment of Spatial Analysis of SPI and EDI Drought Indices in Tehran Province

Drought monitoring is quite important in planning for drought mitigation schemes. Drought indices are normally used for monitoring purposes. However, the indices are calculated at sites and it is required to estimate the spatial distribution of drought in the forms of maps. Geostatistical methods are among such tools that may be applied for preparing spatial distribution maps. In this research, several geostatistical methods including Kriging, Cokriging, TPSS with and without secondary variables as well as weighted moving average (WMA) were assessed with respect to derivation of drought index maps. Drought monitoring and mapping was conducted based on SPI and EDI indices using data of 43 rain gauge stations within Tehran province. The results indicated that although Kriging was the most accurate method, WMA provided reasonable accuracy blended with more efficient computer time, a major consideration in monitoring systems.