Drought is a creeping phenomenon which occurs because of insufficient environmental moisture as a consequence of precipitation shortage. To analyze Tehran’s Droughts, we used monthly precipitation data of 14 stations for the period of 1976 – 2007 and Standardized Precipitation Index (SPI) in 1, 6 and 12 month time scales. Severity and duration of dry periods were estimated for each of these three scales. Result of this research shows that when duration increases, the number of drought occurrences and the highest frequency of drought events happen in 1 till 6 month durations. In addition to it, it was found that the severest drought of Tehran province has been in 1995 with SPI coefficient of more than -3 and the greatest precipitation in 1982 with SPI coefficient above +2. Markov chain model was used to calculate the balance of probabilities of wet, dry and normal courses in annual SPI. The results showed that the equilibrium probability of dry, wet and normal periods in the stations of this province is 29, 30 and 41 percent respectively. This means that the climate conditions in the region often are normal. Furthermore the probabilities of dry and wet conditions are very close to each other.
Hanafi, A., Khoshakhlagh, F., & Soltani, M. (2012). Analyzing the Droughts of Tehran Province Using SPI Index and Forecasting it by the Markov Chain Model. Geography and Environmental Sustainability, 2(2), 87-100.
MLA
Ali Hanafi; Faramarz Khoshakhlagh; Mohsen Soltani. "Analyzing the Droughts of Tehran Province Using SPI Index and Forecasting it by the Markov Chain Model". Geography and Environmental Sustainability, 2, 2, 2012, 87-100.
HARVARD
Hanafi, A., Khoshakhlagh, F., Soltani, M. (2012). 'Analyzing the Droughts of Tehran Province Using SPI Index and Forecasting it by the Markov Chain Model', Geography and Environmental Sustainability, 2(2), pp. 87-100.
VANCOUVER
Hanafi, A., Khoshakhlagh, F., Soltani, M. Analyzing the Droughts of Tehran Province Using SPI Index and Forecasting it by the Markov Chain Model. Geography and Environmental Sustainability, 2012; 2(2): 87-100.
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