Hydrological drought analysis of Mediterranean basins, Turkey

Drought is one of the most common natural disasters that have devastating effects on the economy and ecology. In terms of water resources engineering, it is very important to know the temporal and spatial change of hydrological drought in the design, planning, and operation of hydraulic structures on rivers. Accordingly, in today’s world where the scarcity of water resources is of a vital importance, it is necessary to carry out temporal and spatial hydrological drought analysis for critical regions. This is expected to yield the provision of effective precautions to protect the existing water resources. In this study, hydrological drought analyses of 3-, 6-, and 12-month periods were performed by Streamflow Drought Index (SDI) method using the streamflow data of 29 streamflow-gauging stations (SGS) in the Mediterranean Basin which is located in the southern region of Turkey. Monotonic trends of the calculated drought indices are obtained by the nonparametric Mann–Kendall method, and the slope values were obtained by Sen’s slope method. The temporal change of the drought index was handled for three different periods as 1960–1979 (first period), 1980–1999 (second period), and 2000–2015 (third period), and the severity of the drought has increased in the third period covering the years 2000–2015. It was determined that the occurrence percentages of extreme drought generally in the middle part of the basin are higher than the other parts of the basin. As a result of the trend analysis, a significant downward trend was determined between 13 and 35% of the stations for different timescales. It was observed that the stations with significant trends are in the western part of the basin. © 2021, Saudi Society for Geosciences.