Evaluation of meteorological drought and its trend: The case of Aras and Çoruh basins

In this thesis, meteorological drought analysis of Aras and Çoruh Basins was made. In determining meteorological drought, 52 years of precipitation and temperature data measured between 1969 and 2020 at meteorological observation stations located within the borders of the basin were used. In the drought analysis, Standardized Precipitation Index (SPI) based on precipitation data and Reconnaissance Drought Index (RDI) methods, which use potential evapotranspiration data as well as precipitation data, were used. With two different drought methods, the percentages of occurrence of dry-rainy periods were calculated, and the percentages of occurrence of different drought classes were evaluated. In addition, the duration, intensity, and magnitude parameters of the driest period, which are the characteristic features of drought, were calculated. In addition, the trend of drought index values obtained in 3-, 6-, 9- and 12-month periods with two different meteorological drought methods was determined by the Innovative Trend Analysis (ITA), a graphical method.