Calibration and Zonation of Palmer Index Climatic Coefficients for Drought Risk Management in Natural Ecosystems (Wetlands) of Iran

According to the importance of obtaining accurate informations on drought conditions and it risk management for water right of major wetlands in Iran, in this study climatic coefficients of Palmer Index for 17 watersheds in country was calibrated and zonation and their range in basins containing international wetlands were investigated. Results showed that in wet conditions, in basins such as Caspian, Karoon, Gavkhooni, Bakhtegan this coefficient in cold months was obtained less than 10 and in Bandarabbas, Oroumiye and Hamoon basins was between 20 to 30 and in warm months was between 20 to 30 and the maximum value (30 to 40) was obtained in Hamoon basin. In dry conditions this coefficient in cold months, almost in most basins was less than 5 and in Bandarabbas, Oroumiye and Hamoon basins was between 5 to 10. Also, coefficient value in warm months was obtained 5 to 10 in Gavkhooni, Karoon, Bakhtegan basins, and in Bandarabbas and Balouchestan basins, compared to other areas the maximum value (15 to 20) was obtained. Generally, in dry and wet conditions, the coefficient value on the Caspian coastal regiones was less than and in Hamoon was higher than of other areas, and incresaed in humid toward dry climates. This coefficient in wet conditions was higher than dry conditions and in cold months was higher than warm months. According to agreement of this results with the Iran climate conditions, this index can be used to estimate of the minimum water necessary for wetlands life in drought risk management.