Investigation of PCI Drought Index and Its Trend Over Iran in The Recent Half Century

Khalili, Keyvan; Nazeri Tahrodi, Mohammad; Moghadam Nia, ALi Reza; Moravej, Mojtaba; Abbas Zadeh Afshar, Marziye

doi:10.22055/jise.2016.12356

Investigation of PCI Drought Index and Its Trend Over Iran in The Recent Half Century

Document Type : Research Paper

Authors

Keyvan Khalili

Mohammad Nazeri Tahrodi

ALi Reza Moghadam nia

Mojtaba Moravej

Marziye Abbas zadeh Afshar

10.22055/jise.2016.12356

Abstract

Precipitation is one of most the important parameters of climate that affects water resources directly. In this research changes of precipitation pattern in Iran investigated by means of PCI index. In this order 25 synoptic stations of Iran during two periods of 1961-1986 and 1986-2010 used to calculate PCI index and then significance of this index evaluated by t-test method. Results of mapping this index over Iran showed that precipitation changes had the same pattern in the two studied periods of time. Also results indicated that PCI index was high in the central part of Iran and in the low-precipitation provinces such as Kerman, Hormozgan, Yazd, Zahedan, Shahrekord, Birjand, Booshehr, Ahwaz and Isfahan. These stations according to the Oliver (1980) classification showed high irregular precipitation pattern. According to the results most parts of northwest followed irregular precipitation pattern. Two stations of Rasht and Gorgan had intermediate PCI index values and Zanjan and Tabriz stations had almost intermediate PCI index values. In none of stations uniform precipitation pattern (PCI<10) found. Finally trend of PCI index analyzed in the regional and stational scales and non-significant upward trend detected at 5% level at clusters 2 and 5 while in other clusters non-significant downward trend observed.

Keywords

Precipitation pattern

Fuzzy classification

PCI index

Regional Kendall