Spatial analysis of major droughts in Seyhan River Basin, Turkey

A particular location in a region may suffer from drought conditions while another may experience normal or even wet conditions. This study, therefore, performs spatial analysis using station-based monthly precipitation data for 19 meteorological stations over the Seyhan River basin in Turkey. Six major droughts each 2-year long at minimum were identified from the basin-average annual precipitation deficit. The Standardized Precipitation Index (SPI) was calculated for the meteorological stations at different time scales to characterize the severity and spatial extent of the major droughts. For the most severe month of each major drought, severities were interpolated over the river basin to form drought severity maps by using the Inverse Distance Weighted (IDW) technique. The study illustrates that the river basin experienced drought at least once every decade, which can be as severe as to impact the region and the whole country. Drought severity does not vary greatly over the river basin and it decreases with increasing accumulation time scales. The distribution of the most severe droughts changes depending on the characteristics of the major drought. We observed that the major drought in 1989-1990 was the most severe event in the time period. This is a significant statement for water resources planning with reference to the Seyhan River basin. Focusing only on the major droughts observed in the past when characterizing the severity of current drought events may improve our understanding of extreme meteorological drought events causing severe and long-lasting impacts.