University of Tehran Desert 2008-0875 18 1 2013 01 01 Spatial Analysis of Meteorological Drought in Iran from 1965 to2003 63 71 36276 10.22059/jdesert.2013.36276 EN J. Bazrafshan Irrigation and Reclamation Engineering Department, University of Tehran, Iran A. Khalili Irrigation and Reclamation Engineering Department, University of Tehran, Iran Journal Article 2013 02 23 The present study examined year-to-year variations in areas affected by drought during a period of 39 water years<br />in Iran. Ninety-five meteorological stations were chosen to provide near-continuous long-term records, although<br />some data was missing (less than 10%). The missing data points were estimated using a linear correlation method<br />between the reference station with the missing data points and a neighboring station that had a complete record. At all<br />stations, the standard index of annual precipitation (SIAP) was calculated for water year (sum of precipitation from<br />October 1 to September 31). The geo-statistical method of weighting moving average (WMA) was applied to a 2×2<br />km grid network map of Iran and the geographical distribution of SIAP was calculated and displayed. From this, the<br />percentage of area affected by severe, moderate, and mild drought was computed for each year; the frequency of<br />drought was analyzed by severity and the behaviors of the most extensive historical droughts were determined. The<br />results showed that: a) the maximum frequency of severe drought was 5.1 times and moderate drought was 23.1 times<br />per 100 years; b) the most extensive droughts (more than 80% of the country) occurred during 1970-1971 (82.21%),<br />1988-1989 (92.05%), and 1999-2000 (96.27%); and c) drought spread in Iran beginning from the northwestern and<br />southeastern regions, gradually extending to the central regions. https://jdesert.ut.ac.ir/article_36276_b25d8a53280855e5a10ceedcdda64ed2.pdf