Comparison of meteorological drought analysis methods: The case of Asi basin

In this study, drought was evaluated in the basin using the Standardized Precipitation Index (SPI), Decile Drought Index (DDI) and Percentage of Normal Index (PNI) methods on a monthly, seasonal and annual basis, using the long-term rainfall series of 11 meteorological observation stations in the Asi basin in the south of Turkey. According to the mentioned methods; the longest lasting dry period, the distribution of drought frequencies according to months, seasons, months and duration, the number of drought occurrences in the same duration and the rate of dry years were compared. Additionally, the driest years were mapped in the ARCGIS program. Monthly, seasonal and annual results are graphed. The correlation coefficients were examined between the monthly, seasonal and annual results of the method. The biggest correlation values between spring, summer, winter and annual results were obtained between DDI-PNI methods. It has been observed that the methods are similar in detecting droughts occurring in months other than July and August, and give closer results in detecting seasonal droughts than annual droughts.