Analysying drought events over Turkey by standardized precipitation index

In this study, the standardized precipitation index (SPI) is proposed for determining and monitoring drought events over Turkey. According to the preliminary application in the thesis, the proposed SPI approach offers more precise results with respect to the meteorological and climatologic sensibility according to the studies of drought events had been occurred during 1970s, 1974s, 1983s, 1984-1989s and 2001s. The SPI is locally defined; eg., for monthly- or running means-scale, because the SPI computation does not account the adjacent months or the running-means of precipitation totals, a drought event would begin when the standardized precipitation is below zero. That is, based on the end users; the SPI values are obtained by running means of 1, 3, 6, 12, and 48-months precipitation totals over the interesting place. In the study, it has been taken into the impacts of climatic and meteorological features of the precipitation and physical geographic controls, the SPI approach is very likely more capable of estimating the probabilities for various time-slices of the precipitation series. As it can be understood from the primarily application, the SPI approach could not fully capture extreme drought events truly (particularly for wet and dry extremes), but it clearly represents many drought events seen over Turkey. Thus, 1,3, 6, 12 and 48-months SPI values were also calculated, and the results were interpreted by mapping the results in accordance with climatic variability and physical geographic controls of the climate. Consequently, yet this study is applied to the drought events in Turkey, the method presents significant results to the policy-makers for determining and/or monitoring drought conditions.