| Title |
Prediction of Water Quality and Trophic State Index Changes in the Gangjeong-Goryeong Weir under SSP Scenarios: A Comparison of COD- and TOC-Based Indicators |
| Authors |
정다현(Chung DaHyun) ; 정찬영(Jeong ChanYoung) ; 장유진(Jang Yujin) ; 임나연(Lim NaYeon) ; 이윤경(Lee YunKyung) |
| DOI |
https://doi.org/10.15681/KSWE.2025.41.6.495 |
| Keywords |
Eutrophication prediction; Multiple regression Analysis; SSP scenarios; Trophic state index; Water quality |
| Abstract |
Climate change is accelerating eutrophication, which significantly contributes to water quality deterioration and ecosystem imbalance in lentic and regulated river systems. This study quantifies the impact of climate variability on water quality indicators related to eutrophication and projects their long-term trends under future climate scenarios. Focusing on the Gangjeong?Goryeong Weir section of the Nakdong River, we analyzed 14 years (2012?2025) of monthly water quality data, including chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), and chlorophyll-a (Chl-a), alongside climate variables such as precipitation, water temperature, and solar radiation. Using multiple linear regression (MLR), we identified key climatic drivers, revealing moderate explanatory power for COD, TN, TP, and TOC (R² = 0.33?0.40), but low for Chl-a (R² = 0.03), indicating that algal biomass is heavily influenced by non-climatic factors. We employed downscaled SSP1-2.6 and SSP5-8.5 projections for the years 2025?2100 to estimate future trophic states using COD-based (TSIKO) and TOC-based (TSIKO_TOC) indices. Both indices suggested sustained eutrophic to hypereutrophic conditions, with TSIKO_TOC consistently showing higher values, indicating a greater sensitivity of TOC to climate changes. The minimal differences between the scenarios highlight the limitations of linear models for long-term predictions. These findings emphasize the importance of incorporating climate-responsive indicators, such as TOC-based indices, into the assessment and management of eutrophication, providing a basis for adaptive policies in regulated river-reservoir systems. |