Study on the Estimating the Contribution Rate of Livestock-Induced Pollution in River Basins using Correlation Coefficients by Branch

The recent expansion of livestock farming has significantly increased livestock wastewater discharge, which contains a higher pollutant load compared to other wastewater sources and poses a serious threat to river water quality. This study quantitatively evaluates the impact of livestock wastewater on river water quality and proposes optimal management measures. The Hwanggujicheon watershed in Gyeonggi Province was selected as the study area, with the main river stretch defined from the upstream micro-watershed endpoint (Q0) to the downstream micro-watershed endpoint (Q1). Additionally, four sub-watersheds—BJ (Q2), SM (Q3), G (Q4), and HG (Q5)—were analyzed. To evaluate pollution contributions, statistical methods were employed to assess the influence of upstream pollutant loads on Q1. Livestock non-point source pollution contributions were estimated based on livestock status survey data and national pollution source survey data, following the guidelines for total water pollution load management. The results revealed that the Galcheon (Q4) sub-watershed had the most significant impact on river water quality, with livestock pollution contributing 1.851%, 11.85%, and 7.20% to total nitrogen (T-N), total phosphorus (T-P), and biological oxygen demand (BOD), respectively. These findings confirm that statistical contribution analysis is an effective tool for quantitatively evaluate the impact of livestock-related pollution on river water quality. Furthermore, the alignment of the statistical analysis with field survey data validates this approach as a reliable scientific analysis method. Effective management of major pollution sources, such as the Galcheon (Q4) sub-watershed, is crucial in improving downstream water quality. This study provides a scientific foundation in developing livestock-related pollution management and non-point source pollution control policies. By quantitatively identifying the contribution of livestock-related pollution sources to river water quality through advanced statistical methods, the findings emphasize the importance of systematic management in preserving river ecosystems and promoting sustainable watershed management. Moreover, the study offers practical insights in formulating effective water quality improvement strategies.