Evaluation of geostatistical methods in mapping the severity of the drought in West Azerbaijan province

Drought as a complex event that caused by the occurrence of one or more of the dry period¡ has the adverse effects of economic¡ social and environmental in a short period of time. Investigation of the drought spatial variability using appropriate indicators can help to the correct management of drought. In this study¡ using data obtained from the drought indicators of short-term (3-months) SPI¡ ZSI and PNI¡ drought severity zoning map was obtained using the geostatistical methods in GIS software for West Azerbaijan Province. The results showed that among the geostatistical interpolation and definitive methods¡ the method of inverse distance weighting (IDW) with 2 power for ZSI and SPI index has the lowest error of RMSE¡ MAPE and MBE compared to other interpolation methods. The least estimated amount of RMSE for each indicator was calculated respectively 0.22¡ 0.3 and 0.36. The zoning maps showed that the south and southwest of West Azerbaijan Province have less drought due to the focus of forests and the good rainfall in these areas whereas was observed more drought in the north and northeast of province than other regions in West Azerbaijan Province. According to SPI index¡ 48.12 % of the province consist of the severe drought and 32.25 % has normal drought conditions.