• Journal of Environmental Impact Assessment
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• v.33 no.5
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• pp.228-251
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• 2024

It is clear that the implementation of Total Pollution Load Management (TPLM) has contributed to the improvement of river water quality in Korea. However, it is also true that the TPLM has focused on point source pollution management, with limitations in addressing non-point source pollution. This study examined the issues of the current TPLM from the perspective of non-point source pollution, which is closely related to high-flow conditions, by analyzing Load Duration Curves (LDC) using water quality and flow data collected over the past four years from 21 sub-watersheds in the Geum River Basin. Since the current TPLM is based on water quality predictions using a static water body model that applies the average flow of the dry season, we found that the reduction in loads required under actual flow conditions could be up to 140 times greater than under the reference flow condition, indicating that load amounts under high-flow conditions are not reflected. Additionally, there were abnormal correlations between discharge loads and water quality in several sub-watersheds, and illogical situations arose where compliance with allocated loads did not align with achieving the target water quality. While the causes of such abnormal and illogical situations are diverse and complex, this study highlights the need for rational reflection of non-point source loads under high-flow conditions in water quality modeling. As a solution, we propose the application of watershed models and dynamic water body models.