Analyzing and Monitoring the Meteorological Droughts in the Region of Sistan and Balouchestan

In this research, analyzing the meteorological drought is performed by using of five commonly used indices including: Rainfall Standard Index (ZI), Deviation from Mean Index (SDI), Percent of Normal Precipitation Index (PNPI), Rainfall Anomaly Index (RAI) and Precipitation Classification range (PC) on seasonal and yearly precipitation data in the four synoptic stations of Zahedan, Zabol, Chabahar and Iranshahr, using the same period starting from 1964 and ending to 2005. The result showed that SDI method performs more reliable estimation compared with PNPI, ZI, RAI methods in the annual and seasonal time scales. Based on SDI method, Sistan and Balouchestan Province has experienced frequent meteorological drought in both seasonal and annual time scales. In annual time scale, the frequency (percent) of intense and severe droughts was smaller than frequency of mild and medium droughts. In the seasonal time scale, on average, based on SDI method, most (42%) of severe and intense droughts occurred in summer, but in winter, the risk of severe and intense droughts was smaller (12%), We also used 3-year and 5-year moving averages method for evaluation of trends anddrought duration in the annually time scale in the mentioned sites. The results showed that the rainfall standard index (RAI) performs different results from other indices. Other results also indicate that the intensity and frequency of meteorological drought are increasing in this province.