Yeşilırmak, Kızılırmak ve Konya kapalı havzalarında kurak ve ıslak dönem karakteristiklerinin farklı kuraklık indisleri ile incelenmesi

Within the scope of this thesis, drought analyses were conducted using the SPI, RDI, SPEI, and SRI methods based on a total of 38 meteorological stations in the Yeşilırmak, Kızılırmak, and Konya closed basins. The SPI method was employed for drought analysis at 1, 3, 6, 9, 12, and 24-month accumulations. The Weibull and Generalized Extreme Value (GEV) distributions were determined as the most suitable distributions for the SPI index. In the analyses conducted using the RDI method, low correlations were observed, leading to the conclusion that the RDI index is not entirely reliable. For the analyses conducted using the SPEI method, critical situations were initially not detected, and D values were used to determine the most appropriate distribution methods. It was observed that the Generalized Extreme Value (GEV) distribution was generally suitable for SPEI 3 and 12-month accumulations. The SRI method was applied to a limited number of streamflow stations, and significant results could not be obtained due to data insufficiency. After the completion of drought analyses, correlation calculations were performed to understand the relationships between the meteorological stations. Histograms were obtained for the 3-month and 12-month drought indices based on the classifications. Additionally, distribution maps of drought indices throughout the basin were created using the Inverse Distance Weighting (IDW) method. Trend analyses were conducted on precipitation data for meteorological stations using the SPI, RDI, and SPEI drought analysis results. Trend results were obtained using the Mann-Kendall (MK) and Innovative Şen Trend Analysis (ITA) methods and presented with maps. Magnitude-Duration-Frequency (MDF) analyses were performed to characterize drought and estimate the duration of drought magnitudes. MDF graphs revealed comparisons between stations for each method. Basin-specific MDF comparison maps were obtained, indicating higher drought magnitudes in the northern regions.