The effect of climate change on the distribution pattern of droughts in time and space using the index reference crop evapotranspiration (ETo)

Several factors in the development of effective drought , which change and intervene in order to keep them from victory and their occurrence , and it is impossible to be foreign humanOn the same principle, the possibility that lives up to these requirements in any region of the Earth's surface country rich and poor, wet and dry, developed and developing, etc. occur.In this study, meteorological data gathered from 19 weather stations in Iran during 2003-1961 using a composite index (CI) of meteorological drought analysis of spatial and temporal characteristics of drought in Iran. The frequency, scope and severity of drought calculated to reveal the spatial and temporal patterns in different sectors were examinedAnd then the system dynamics approach was to simulate the effects of different aspects. . ETo values in all stations in July reached its highest value. In all stations, ETo values from January to July increased and is then reduced until December. ETo Iran in the period 1961 to 2003 the average annual total is about 1154 mm. The annual average of 9.2 millimeters per year upward trend in Iran ETo (mm / yr) during the period indicated. Most of ETo in the year 1970 (mm / yr 1309) and then in 1999 and 2001 (mm / yr 1308) happened and minimum on the years 1979 (mm / yr 893) and 1990 (mm / yr 974) Find respectively.