Water quality investigation of the main river in Daegu, South Korea

Abstract

Abstract River water quality of Daegu city has been fluctuating for the last several years. This condition requires attention to avoid the possibility of severe water quality degradation. This study aims to identify temporal and spatial distribution, sources of pollutants, and the dominance of specific pollutants on the Nakdong River. River water quality data with a duration of 5 years has been collected and analyzed statistically and combined with Geographic Information System (GIS). The data included BOD, COD, SS, TN, TP, Chl-a, and TOC. The results showed a repetition of a period of decline in river water quality due to the algal bloom phenomenon. This phenomenon closely related to the BOD concentration in the river. Also, the emergence of TOC in high concentrations requires special attention so that it does not become an ongoing problem. COD has the most positive correlation with TOC. This problem becomes serious because it was located at the inlet of water treatment plant in this river. Controlling BOD and COD concentration, especially from effluent of wastewater treatment plant, might become one of the relevant solutions to restrain river water quality degradation. The results of further identification indicate the possibility of nonpoint sources influence, which resulting the river water quality decrease.