Index based on determination of seasonal changes in water quality of Upper Sakarya River and evaluation based upon pollution sources

The concept of water quality that is defined as availability criteria of diminishing water resources year after year is stated by using many different parameters. By the reason of various difficulties and differences in interpretation in the evaluation of these parameters, water quality indices were established. Within this study, seasonal monitoring studies depending various water quality indexes have been done at twelve stations which are identified in Upper Sakarya River. By the help of the obtained data, the river's quality situation has been determined via three widely used Water Quality Indexes (NSF-WQI, CWQI and OWQI). In calculating CWQI, intended use based and reference point based limit values were put together and water quality indexes were calculated for three different scenarios. While the most compatible results in between seasons were obtained by NSF-WQI, the most similar results of current quality situations of the river were obtained by CWQI calculation, which took account of the intended use limits of 2nd class water. It was detected that Intended Use Based Water Quality Index is an effective index that can be used for representing existing water quality of streams. When the results received were evaluated according to pollutive sources, Ankara Creek was detected as major source of pollution.