Occurrences of water quality assessment using improvised water quality index at the Danube River, Serbia

The water quality index is very often used to classify the water quality of a river. The paper aims to develop a new improvised water quality indicator using statistical methods. To reduce the number of analysed chemical parameters and simplify the tests, WQI min was used. The results of the research conducted in Serbia in 2019 were subjected to correlation and principal component analysis (PCA). This reduced the number of parameters from 29 to 8, significantly reducing the time and cost of laboratory analyses. The temporal and spatial variability evaluation can be performed using WQI min , which consists of dissolved oxygen, total phosphorus, orthophosphate, total dissolved solids, suspended solids, chlorides, ammonium, and nitrite nitrogen. The main sources of river contamination were untreated industrial sewage, fish farming wastewater, and soil erosion. The highest level of pollution was observed in winter. Good water quality was found in the river’s upper course and very good in the lower course. Water quality values obtained based on a complete and simplified set of parameters were strongly correlated with each other.