Monitoring of drought large Caron basin by using SPI index (1978-2014)

One of the features of Iran's climate chief is little rainfall and sharp fluctuations in the time -scale daily, seasonal and annually.Each drought has 4 key characteristics which include continuation of that period, the intensity, frequency and scope. The main objective of this study, the evaluation and the zoningof the characteristics of drought in the basin Caron.In this study, the index of SPI used , for investigate the characteristics of the drought in 42 station located inside and outside the basin with joint 28 -year -old statistical during the period in three time scale 6, 3 and 12 -month.characteristics of drought, includingcontinuing,intensityin each scale was determinedand maps of the extent of the severe drought was drawing in GIS environments.The lowest SPI observed in basin belonging to Yasouj (-3.29) in scale 12 months, and the longest continuity observed in Bostan with 61 months.also the longest of continuity and scope of drought per each yearwas determined.