Sediment plays an important role in the water quality of a lake by acting as both a nutrient source and sink. The amount of phosphorus and nitrogen in the water depends on the internal load from the sediment as well as the external load. To estimate the effects of sediment load on the water quality of a reservoir, we applied a three-dimensional hydrodynamic and transport model based on the benthic chamber experimental results at Euiam Lake, South Korea. As shown in the sensitivity analysis results, the eutrophication period could be significantly extended by a change of phosphorus flux rates from the sediments. The increased phosphorus flux from the sediments intensifies the algal growth of Euiam Lake, which could cause serious algal bloom during spring and fall. This study provides information on nutrient concentrations in the sediment of Euiam Lake, verifies the role of the sediment as a source or sink of nutrients, and evaluates the effect of sediment release of nutrients and contaminants on water quality. This research is a useful tool in determining the effects of internal load in lakes and establishing the operation guideline for sediment management in order to maintain feasible water quality for beneficial use.

Water resource disputes for Transboundary Rivers are frequent and critical issues among countries. The Kumgangsan Dam was constructed (in North Korea) in the Transboundary River (North Han river) that affects the water resources downstream (in South Korea) of the dam. The amount of water resource (e.g., streamflow, discharge) downstream of the Kumgangsan dam has decreased after the dam construction which might cause decreased hydroelectric power and water pollution in the downstream dams, especially during the dry season. Thus, this study analyzed the changes in the inflow into the Euiam Lake (North Han River) by the construction of the Kumgangsan Dam through hydrological modeling and examined the discharge of Chuncheon Dam (inflow into Euiam Lake) considering the flow control in the Kumgangsan Dam under the dry condition scenario. In addition, the changes of base flow during different seasons were analyzed because the majority of streamflow is contributed by the base flow during dry and drought seasons. As shown in the results, it was found that the discharge from the Kumgangsan Dam has a wide effect on the downstream dams located in South Korea. The inflow of downstream dams was significantly influenced by the discharge of the upstream dam, and the base flow was also affected by the decreased discharge of dams. Based on these findings, upstream dam managements should be carefully considered to maintain the water resource and aquatic ecosystem for the downstream dam watershed. Furthermore, the results of this study can be used as the preliminary information when discussing the problems of water allocation and flood prevention with North Korea.

In this study, we investigated the feasibility of using constructed wetlands for non-point source pollution reduction. The effect of constructed wetlands in reducing suspended solids (SS) was analyzed using an integrated modeling system of watershed model (HSPF), reservoir model (CE-QUAL-W2), and stream model (EFDC) to investigate the behavior and accumulation of the pollution sources based on 2017 water quality data. The constructed wetlands significantly reduced the SS concentration by approximately 30%, and the other in-lake management practices (e.g., artificial floating islands and sedimentation basins) contributed an additional decrease of approximately 7%. Selective withdrawal decreased in the average SS concentration in the influents by ~10%; however, the effluents passing through the constructed wetlands showed only a slight difference of 1.9% in the average SS concentration. In order to meet the water quality standards, it was necessary to combine the constructed wetlands, in-lake water quality management, and selective withdrawal practices. Hence, it was determined that the model proposed herein is useful for estimating the quantitative effects of water quality management practices such as constructed wetlands, which provided practical guidelines for the application of further water quality management policies.

River Water Quality (RWQ) is significantly influenced by natural and anthropogenic activities such as land use and land cover changes. Urbanization has led to an increase in impervious surfaces, which alters hydrological flow pattern and delivers non-point pollutants to the stream more efficiently. In addition, intensification of agricultural activities can result in the increased nutrient loads due to alternations in surface soil properties. Hence, it is necessary to understand the impact of surrounding environment with specific emphasis on geographical factors (e.g. climate change, land use patterns and landscape metrics) on the RWQ in order to develop sustainable water quality management strategies effectively. We collected pollutant concentration Biochemical Oxygen Demand (BOD), Total Phosphorus (T-P), and Total Organic Carbon(TOC) from monitoring stations in the Nakdong River watershed. To utilize field monitoring data, we developed a Machine Learning (ML) models (DNN, XGBoost and Random Forest) to predict RWQ in accordance with different environmental factors. SHapley Additive exPlanations (SHAP) was used to illustrate the significance of land uses and landscape patterns on RWQ in Nakdong River. The results of this study can (1) demonstrate the relationship of water quality variables with land uses and landscape patterns, (2) identify pollution sources and factors that affect Nakdong River, and (3) support catchment managers and stakeholders in evaluating the benefits and risks of water management strategies in priority areas.

The Integrated Environmental Management System is a system that moves away from the traditional single-medium approach and adopts a medium-integrated approach to achieve a higher level of environmental protection. Korea has been implementing the Integrated Environmental Management System since 2017, and as of 2024, total of 19 industries have received integrated permits. In 2023, the cement manufacturing industry was added to the list of industries subject to the Integrated Environmental Management System. As a critical industry with significant emission of air pollutants and particulate matter, it requires systematic environmental management that prioritizes public health and sustainability. This study aims to compare and analyze the Best Available Technique Reference Documents (BREFs) for the cement manufacturing industry in Korea and the European Union (EU) to explore environmental management improvement strategies for Korea’s cement industry. The analysis revealed that the K-BREF provides strong practical guidelines and is more focused on industrial sites, while the EU-BREF is characterized by an integrated environmental management approach reflecting carbon neutrality strategies and resource circulation policies. Particularly in terms of waste fuel management, the EU-BREF provided specific details on waste handling and preparation processes, suitability assessment of waste fuels, lists of maximum allowable substance values, and actual application cases. Additionally, the BAT-AEL (Best Available Techniques Associate Emission Level) and monitoring intervals were also further specified. In contrast, the K-BREF reflects the early stage of implementing an integrated environmental management system, resulting in a lack of technical examples related to waste fuels and BAT-AEL standards being limited to a single criterion per pollutant. The Korean cement industry must expand its use of waste fuels to meet greenhouse gas reduction targets of 12% by 2030 and 53% by 2050. Accordingly, specific multi-media integrated control standards should be established. To effectively respond to increasingly stringent emission regulations and ensure sustainable environmental management, a multi-faceted approach including regulatory improvements, technological development, and policy support is essential.

The Integrated Environmental Management System (IEMS) was introduced in Korea in 2017 to shift from a single-media regulatory framework to an integrated, facility-based environmental management approach. As part of this system, Best Available Techniques–Associated Emission Levels (BAT-AELs) provide reference ranges for achievable emission levels and serve as a basis for establishing sector-specific emission limits and facility-level permitted emission standards. However, in practice, permitted emission standards are finalized through emission impact assessments that consider local environmental quality. Nevertheless, it remains to be further empirically examined whether the stringency of BAT-AEL compared to permitted emission standards has been reflected in actual emission reduction outcomes. Accordingly, this study empirically evaluates the relationship between the stringency of permitted emission standards and environmental performance following the implementation of the IEMS, providing insights for future policy discussions. Municipal waste incineration facilities were selected as the study subject because relatively long-term operational data are available for this sector. Publicly available data from the CleanSYS and Integrated Environmental Permit System (IEPS) were utilized. Environmental performance was assessed using emission intensity (kg/ton-waste), defined as pollutant emissions per ton of waste incinerated. For five air pollutants (dust, sulfur oxides, nitrogen oxides, carbon monoxide, and hydrogen chloride), the stringency of permitted emission standards was quantified as a normalized value within the BAT-AEL range, and the reduction performance was evaluated based on its relationship with changes in emission intensity. Statistically significant association was not observed between stringency and changes in emission intensities across the examined pollutants. However, emission intensities for nitrogen oxides, dust, hydrogen chloride, and sulfur oxides showed significant reductions after the IEMS implementation, indicating overall emission reduction performance under the IEMS. These results suggest that although emissions improved after IEMS implementation, the magnitude of improvement was not directly associated with differences in the stringency of permitted emission standards. Thus, differences in environmental performance among facilities cannot be sufficiently explained by the numerical stringency of permitted emission standards based on BAT-AEL alone. It suggests that the actual level of BAT implementation, and the facility operating conditions should be considered together when interpreting the environmental improvement outcomes. The findings also provide practical implications into developing a management framework where BAT-AEL and monitoring data can be more effectively linked to the establishment and improvement of permitted emission standards.