Merge L-Moment Method, Regional Frequency Analysis and SDI for Monitoring and Zoning Map of Short-Term and Long-Term Hydrologic Droughts in the Khuzestan Province of Iran

In recent years, the climatic change and global warming have affected on meteorological and hydrologic conditions in dry and warm regions. The severity of occurred droughts has increased in these regions. This research monitors 3- , 6- , 9- and 12-month hydrologic drought severity in the Khuzestan Province, with 51 hydrometric stations, based on drought return periods and streamflow drought index (SDI). The length of the statistical period is 62 years (1954-2016). Application of homogeneity statistic shows that the Khuzestan Province has 3 homogeneous regions for three-month time scale and 2 homogeneous regions for other time scales. The applied method for regional frequency analysis is linear moment method. By increasing of linear moment parameters, intensity of droughts will increase and drought return periods will reduce. Results of research show that severe and extreme hydrologic droughts can observe at the whole of this province in near future. Return period of these droughts is larger than 5 years. Also, intensity of hydrologic drought is milder in north and east of this province.