| Abstract:
Drought is an inseparable part of climatic fluctuations which caused to lot of damages to different sections annually. Therefore, drought prediction can effectively reduce its damages. Markov Chain method is one of the drought prediction methods. In this study, the effect of Markov Chain order (orders 1, 2 and 3) were evaluated in drought forecasting accuracy (based on SPEI index), using Markov Chain method on climatological data of five synoptic stations of Iran with different climatic conditions during 1967 to 2014. Based on the results, transition probability from all drought classes to class 4 (normal) had the most frequency and to class 1 (extreme wet) had the lowest frequency. Results demonstrated that when observed and predicted drought classes have no difference, Markov order 3 has the best results. When observed and predicted drought classes have one class of difference, in 60% of cases Markov order 3 and in 40% of cases Markov order 2 has the best results. When observed and predicted drought classes have difference of two or three classes, Markov order 3 has the best results. Therefore, it is recommended to use Markov order 3 and Markov order 2, respectively with SPEI index and Markov Chain method, for drought forecasting.
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