Water quality trend and pollutant load and source analysis of Tamjin River water system.

To systematically manage water quality based on watersheds, it is necessary to understand the characteristics of changes in river water quality. This study used observational data of the Tamjin River water system to analyze changes in water quality due to farming activities during the farming period. Water quality trends were analyzed through a long-term trend analysis. Furthermore, the loads and sources of substances regulated under the total maximum daily load system were evaluated. Biochemical oxygen demand and total phosphorous, water quality factors of the target basin, showed recent increasing trends. Loads increased from April, which corresponded to the non-farming period before farming activities began, and characteristics of pollutant discharged in the basin from farming activities were observed. Pollutant sources were different from those observed in water systems with a high proportion of farming activities, and water quality management measures considering the target basin's characteristics were proposed. The results of this study will serve as logical baseline data for establishing water quality management plans.