Investigating the Trends of Drought Severity Changes in Iran

Nowadays, competing for having access to water resources has become a worldwide problem. This problem would impose new challengeable dimensions to the most of the world regions especially Middle East countries in the near future. In recent years, mostly due to world climatic changes, precipitation anomalies have been increased in various areas of Iran. Additionally, extreme spatial and temporal drought fluctuations have imposed enormous expenses on this country s economy, especially during recent decades. This study aimed at investigating the trends of drought severity changes in Iran through two seasonal and annual temporal scales. To this end, monthly precipitation data of 63 synoptic stations during 30 years of statistical period (1986-2016) were obtained from Iranian meteorological organization. Using monthly precipitation data, stations seasonal and annual precipitation were assumed. To recognize the various drought degrees frequency, Standard Precipitation Index (SPI) was utilized. Moreover, to detect the trends of drought severity changes, Sen s Slope Estimator Non-Parametric Method was used. The results of the current study indicated that the trends of drought severity changes in Iran had excessively varied across one season to the other, and from one temporal scale to the other. In autumn, the trend of drought severity changes in Iran had increased except for south and southern-east parts of Caspian Sea and it decreased during winter and spring. In other words, the drought severity of Iran had increased in autumn and it had decreased in winter and spring. Regarding annual scale, the trends of drought severity changes signified a reducing process for the most of Iranian areas.

کلیدواژه ها:

Drought ، Standardized Precipitation Index (SPI) ، Sen’s Slope Estimator ، Trend ، Iran