Spatial Analysis and regionalization of Climatic Dry Periods in Iran Based on DDSLR Indice
2017
حسن ذوالفقاری | مجتبی میرزایی
In terms of climate, Iran is an arid and semi-arid country, where vital water resources in this country are highly dependent on atmospheric precipitation. Understanding the characteristics of climatic dry periods such as frequency, severity, and duration of periods is important in environmental planning. In this regard, characteristics of the country's dry climatic periods based on "dry days after the last day of the rainfall" (DDSLR) using statistical data of 48 synoptic stations in Iran over a 30-year period from 1979 to 2008 were studied. DDSLR index trend changes with a probability of 25, 50, 75 and 90 percent (optimistic, average, pessimistic and very pessimistic) as an indicator of the severity of the drought periods of low, medium, high and very high determined for each of the stations and dry period features including start, stop, frequency, and duration of driest days was determined for each station. Finally, based on the length of dry period and through interpolation method Kriging zoning maps for the entire country was drawn. The results showed that climatic dry periods in stations of southeast of the country, especially port stations such as the Oman Sea (Chabahar and Bandar Abbas), before other stations begin. Also dry period ends earlier in the Caspian Sea coast stations. The shortest period of drought on the northern coast of the country and the longest period of drought occurs in the southeast of the country. The driest days at most stations will happen in October. It also turned out that with an increased probability of 25% (probably optimistic) to 90 percent (likely very pessimistic) the area has a very long period of drought in parts of the south; southeast and northwest of the country will increase.
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