Assessment of Lake Water Quality Using Trophic State Index and Multivariable Statistical Analysis: A Case Study of Karagöl, Şavşat, Turkey

The study area is the lake located within the Karagöl-Sahara National Park, which is one of the important tourism regions of Turkey. This area, with its rich biodiversity and natural selection forests, is located in the Caucasus hotspot, which is defined as one of the 35 biodiversity hotspots in the world by the Conservation International. The aim of the study was to evaluate the water quality of Karagöl using the trophic state index (TSI) and multivariate statistical analysis. For this purpose, water samples were taken from six points on the lake surface from July to August in 2021. Water samples were taken from points where polluting factors are concentrated. Parameters measured to assess water quality are total nitrogen (TN), total phosphorus (TP), secchi disc (SD), chlorophyll (Chla), pH, electrical conductivity (EC), dissolved oxygen (DO), suspended solids, and turbidity. The index proposed by Carslon was used for the trophic classification of the lake ecosystem. This index is evaluated by considering the relationships between chlorophyll (Chla), total phosphorus (TP), and secchi disc depth (SD) for lakes. Relationships between data were evaluated using multivariate statistical analysis. Statistical methods used in the evaluation of data are principal component analysis (PCA). With the trophic status index, the water quality of the lake was found to be close to the mesotrophic level. As a result of the PCA analysis, it was calculated that two important factors are important in the lake water quality.