Droughts Analysis in Northeast of Iran Using Joint Deficit Index (JDI)

Monitoring and prediction of droughts, especially accurate determination of its emersion time and duration, is very important in water resources management and planning drought mitigation strategies. In this study drought conditions in Northeast of Iran was evaluated by means of Joint Deficit Index (JDI). Monthly precipitation data from 6 synoptic stations including Torbat Heydariyeh, Sabzevar, Semnan, Shahroud, Gorgan and Mashhad during the period of 1971 to 2011 were used for calculating the JDI index. Results showed that in recent years the number of dry months across study area (especially at wet regions) increased, significantly. As in all of considered stations (except Semnan station) the percentage of dry months increased to over (more than) 50% during recent 10 years (2002-2011). Results showed that the JDI provides a comprehensive assessment of droughts and that it is capable of reflecting both emerging and prolonged droughts in an accurate manner and allows for a month-by-month drought assessment.