Journal of Korean Society of Agricultural Engineers ISSN:1738-3692(Print) 2093-7709(Online) 한국농공학회논문집

This study investigates the relationship between Chl-a concentration and various water quality factors, including temperature, nutrients (TN, TP), TOC, COD, and BOD, in the Namgang Dam region from 2007 to 2023. The correlation analysis between Chl-a and water quality parameters was conducted using the Pearson method, and the cluster analysis of Chl-a was performed using the average linkage method. At Namgang Dam Site 1, Chl-a concentration shows positive correlations with TOC (0.300), TP (0.302), BOD (0.272), and water temperature (0.309). At Site 2, Chl-a shows positive correlations with water temperature (0.273), COD (0.229), TP (0.379), and TOC (0.295). At Site 3, Chl-a concentration has significant positive correlations with COD (0.265), TOC (0.304), TP (0.277), and water temperature (0.302), indicating that these factors play important roles in the growth of phytoplankton. A strong correlation between Chl-a and both TOC and TP, with TP being a major contributor to algal growth, suggesting that phosphorus is a key limiting factor. Conversely, dissolved oxygen (DO) showed a negative correlation, indicating that as algal growth progresses, DO levels decrease, potentially impacting aquatic health negatively. Spatial distribution analysis showed that Chl-a levels were lower upstream and increased significantly downstream, influenced by reduced flow, higher temperatures, and nutrient inflow from agricultural and industrial activities. Dendrogram analysis indicated that certain sites along the Deokcheon and Namgang rivers exhibited similar Chl-a patterns, forming clusters, while the Geungho River site was distinct, suggesting unique water quality characteristics. These findings provide critical insights for predicting and managing algal blooms in the Namgang Dam area, emphasizing the importance of tailored regional water quality management strategies.