Determination of kizilirmak and yeşilirmak basin characteristics and evaluation of water quality

The objective of this research is to assess the impact of natural and artificial factors on water quality in the Kızılırmak and Yeşilırmak Basins, two significant river basins in Turkey. The study aims to provide a comprehensive characterization of the basins and evaluate the water quality by analyzing the measurement data of 26 water quality parameters from 8 monitoring stations in Kızılırmak and 36 monitoring stations in Yeşilırmak. The first phase of the study focuses on basin characterization, which involves identifying the pressure factors and load amounts in the basins. The Total Maximum Daily Load (TMDL) approach was used to analyze total nitrogen (TN) and total phosphorus (TP) parameters. The second phase involves determining the overall water quality status and calculating water quality index values. Finally, Principal Component Analysis (PCA) was conducted to identify the key factors influencing the water quality. The study also produced spatial distribution maps for each water quality parameter. Based on the findings of the study, it was observed that out of 462 surface water bodies in Kızılırmak Basin, 147 were affected by point sources of pressure, and 421 were affected by diffuse sources of pressure. In the case of Yeşilırmak Basin, out of 116 surface water bodies, 63 were impacted by point sources of pressure, and 96 were impacted by diffuse sources of pressure. According to the GMTY analysis, if the same discharge standard is applied throughout the Kızılırmak Basin, TN and TP levels should be reduced by 49.06% and 94.9%, respectively. Similarly, in the Yeşilırmak Basin, TN and TP levels should be reduced by 42.8% and 83.3%, respectively. The study also concluded that the water quality of both basins is in the "Medium" level, based on the National Sanitation Foundation Water Quality Index, the Canadian Ministry of Environment Water Quality Index, and the Fuzzy Water Quality Index. The PCA analysis revealed that the first 3 axes accounted for 78.92% of the total variance in water quality in Kızılırmak Basin, and the first 5 axes accounted for 95.78%. In the case of Yeşilırmak Basin, the first 3 axes accounted for 62.60% of the total variance, and the first 5 axes accounted for 84.45%. Furthermore, based on the characteristic values, it was determined. This study came to the conclusion that it would be beneficial to determine monitoring parameters that would reflect the temporal and spatial changes in the basin and to evaluate water quality using an index.