• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.174-174
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• 2022

수질지수는 여러 수질 데이터 값을 수학적으로 결합하고 다 변수 특성을 줄여 수치 및 등급으로 나타낸 지표이다. 수질지수를 통해 수질을 평가하고 서로 다른 위치와 시간의 수역을 종합적으로 비교할 수 있으며 수자원관리에 있어 정책입안자, 의사결정자, 국민이 수질에 대해 일반적이고 쉽게 이해할 수 있다. 현재 환경부에서는 국내수질자동측정망 최근 12시간 데이터 값을 근거로 실시간수질지수 RTWQI(Real-Time Water Quality)값을 제공한다. 국내 호소에 설치된 수질 자동측정망은 총 8개소이며 매 시간 공통 항목인 수온, pH, DO, 전기전도도, TOC 5개, 선택항목인 탁도, Chl-a, TN, TP, 중금속, 생물감시항목 등 27개를 측정한다. RTWQI는 캐나다에서 2001년에 개발된 CCME WQI(Canadian Council of Ministers of the Environment Water Quality Index) 산출식을 기초하였으며 F1(기준치를 위반하는 수질항목의 개수/ 총 수질항목 개수), F2(기준치를 위반한 샘플들의 총 횟수/총 샘플횟수) F3(기준치를 위반한 정도) 3가지의 요소로 계산된다. 그러나RTWQI 산출식의 기초인 CCME WQI는 개발 이후 여러 문제점들은 개선되었으나 F1이 다른 F2, F3 보다 CCME WQI 점수의 기여도가 2배 이상 높은 문제점은 개선하지 못하였다. 본 연구에서는 수질자동측정망이 설치된 2012년 7월부터 2021년 12월 동안 매 시간 별 수질 데이터를 이용하였다. 또한 CCME WQI 문제점을 개선한 MWQI(Modification of Canadian water qaulity index)를 기초하여 실시간 수질지수를 재 산정하였다. 추가적으로 Pearson 상관관계 분석 및 추가 통계분석을 통해 환경부에서 제공하는 기존의 RTWQI, 개선된 실시간수질지수, 한국형 호소수질평가지수 LQI(Lake Water Quality Index)를 비교 및 평가하였다. 이러한 연구를 통해 정확성 높은 수질지수를 찾고 수자원 관리 정책 수립에 적극 활용 될 수 있을 것으로 사료된다.

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.46-56
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• 2017

The Youngsan River estuary was physically changed by the construction of a sea embankment at near the mouth of estuary. Weirs were also constructed recently in the freshwater zone and it was reported that algal blooms occur more frequently. The freshwater introduced into saltwater zone from sluice gates of the embankment affects water quality but it has not been addressed that how the freshwater inputs influence the health of marine ecosystem. In this study, we used the data of water properties and phytoplankton communities collected at three stations for 4 days including before the freshwater discharge, during the discharge and after 1 and 2 days of discharge events. WQI(water quality index), TRIX (trophic status index) and P-IBI(phytoplankton index of biotic integrity) were used to evaluate the ecosystem health and long-term data were also utilized to determine the criteria for P-IBI. The results showed that grades of the ecosystem health assessed by the indices were low at the station near the gates and increased as downstream. However, the temporal pattern of grades was different depending on methods. Grades of WQI and TRIX decreased during the discharge and restored after the discharge whereas the grades of P-IBI decreased slightly even after the discharge. This suggests that P-IBI is more applicable to estuarine systems where experience extreme change of water properties than WQI and TRIX since P-IBI includes phytoplankton that can respond quickly to the change.

• Journal of Environmental Impact Assessment
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• v.30 no.2
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• pp.61-74
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• 2021

In this study, we used marine environment assessment indices to evaluate impacts of various development projects on the marine environment. TheWaterQuality Index (WQI) was applied in the field of marine water quality and the Cleanup Index of Harmful Chemicals (CIHC), the Cleanup Index of Eutrophication (CIET), the Enrichment Factor(EF) were used in the field of marine sediment. In the field of marine benthic organisms, the Benthic Health Index (BHI) and the Benthic Pollution Index (BPI) were utilized. Each assessment index was calculated using the data observed in the development project, and its characteristics and usefulness were evaluated. The assessment method and criteria were clearly defined for WQI, CIHC, and BHI. Furthermore, through these indices, an integrated environment impact analysis was possible. Apart from the indices presented in this study, there are various indices that can be used for evaluating the marine environment. Therefore, it is important to utilize appropriate indices according to the characteristics of each project.

• Journal of Korean Society on Water Environment
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• v.37 no.4
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• pp.249-262
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• 2021

This study investigated the pollution characteristics of the main pollution zone in the Hwangguji watershed and the influence of the tributary on the main stream. The characteristics of the main pollution zone, including, the water quality index (WQI), stream rating, load duration curve (LDC), delivery load density (DLD), and contribution of the tributary to the mainstream, were evaluated by time-series visual heatmap. The WQI of the mainstream of Hwangguji was lowered to the poor (IV) level from the inflow point of Suwon stream (SW) and the LDC excess rate in the T-P was higher than that of BOD₅, especially for the wet season, suggesting that management of non-point source with T-P is preferred. The contribution (%) of the tributaries in the upstream section of Hwangguji watershed were BOD₅ 14.54%, TOC 15.67%, T-N 5.43%, and T-P 6.97%. In particular, the Suwon sewage treatment plant located in the mainstream showed a high contribution of BOD₅ (64.40%) and T-P (53.54%), respectively, due to the high discharge rate (6.019 m³/sec). Meanwhile, Sammi and Gal stream have a large impact on the mainstream with high DLD and poor WQI. Thus, both streams were considered as pollution hot spots. These results provide useful basic data for preparing more effective water quality improvement and management plans in the watershed.

• Journal of the Korean Geographical Society
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• v.38 no.1
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• pp.16-31
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• 2003

The water quality environment in Youngsan and Seumjin river basins was investigated based on the concept of the comprehensive Water Quality Index (WQI) and a spacial pollution source. Artificial factors influencing to river water quality have been analyzed. The specific delivery load of Youngsan river basin was found to be 8.34~97.25 kg/day/$\textrm{km}^2$, Gomagwon stream and Gwangju stream showed the relatively high rates as 97.25 kg/day/$\textrm{km}^2$ and 86.06 kg/day/$\textrm{km}^2$, respectively. The specific delivery load in Seumjin river basin was estimated to be 10.98∼19.51 kg/day/$\textrm{km}^2$, Suggesting no Significant Contribution of pollution. WQI of Youngsan watershed revealed 1.36~3.45, whereas Seumjin watershed showed a relatively low value of 0.5~1.47 And it is concluded that the specific delivery load suggested in this study provides the essential core data of the upper limit of pollutants receptor in the watershed area studied. From this study, it is suggested that the integrated environmental management of river basin requires the analysis of pollutants generation rate of the basin and the receptor capability for the self-purification.

• Journal of Korea Water Resources Association
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• v.55 no.5
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• pp.371-381
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• 2022

Since tributaries have greater water quality variability than main streams, a comprehensive evaluation method that considers the effects of various parameters rather than one water quality parameter has been introduced for effective water quality management of tributaries, but the characteristic of the watershed is not considered. In this study, the urbanization rate, livestock excreta generation, and industrial wastewater discharge in the Hantan River middle-watershed classify urban and non-urban watersheds, and evaluate the suitability of water quality indexes by watershed characteristics by analyzing water quality characteristics and calculating CCME WQI, RTWQI, and NSFWQI. Factor analysis was used to understand the effect of water quality parameters used to calculate the water quality index on the water quality index results. As a result of the factor analysis, the relationship between CCME WQI, TC, and FC was derived, and the relationship between RTWQI and DO, SS in urban watersheds and NSFWQI and FC in non-urban watersheds was revealed. As a result of evaluating suitability through comparison with BOD and T-P grades, it was interpreted that the suitability of the water quality index was low in urban watersheds and that comprehensive water quality evaluation using RTWQI was possible in non-urban watersheds.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2017.10a
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• pp.109-109
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• 2017

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.189-189
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• 2023

최근 이상 기후변화로 인해 환경과 생태계 등 다양한 분야에서 문제들이 발생하고 있다. 특히 하천에서는 유량 부족, 부영양화, 탁수 등 수질 악화 현상이 대두되고 있어 체계적인 하천 수질관리의 필요성이 높아지고 있다. 국내에서는 수질오염총량제도를 통해 BOD, T-P 항목을 대상물질로 수계의 수질을 관리하고 있지만, 오염원이 다양해짐에 따라 다항목의 수질인자를 활용한 평가방안이 필요한 실정이다. 최근 효율적인 하천의 수질관리를 위해 다양한 항목을 고려한 종합적인 수질 평가 방법이 도입되고 있다. 국내외에서는 하천의 종합적인 수질을 평가하고자 CCME WQI, RTWQI, NSFWQI 등의 수질지수(Water Quality Index, WQI)를 개발하여 하천의 복잡한 수질 정보를 점수 및 등급으로 산정하여 하천의 수질을 평가하고 있으나 하천 유역 특성에 따라 주요 영향 인자가 상이하므로 유역 특성에 따른 맞춤형 수질관리가 필요하다. 본 연구에서는 유역 특성별 수질을 평가하기 위해 의사결정나무 기법을 적용한 수질지수를 산정하고자 한다. 군집분석을 통해 비슷한 특징을 가지는 유역을 분류하고, 군집별 특성 및 관계 분석을 통해 유역별 주요 수질인자 도출 및 가중치를 산정하여 군집별 적합한 수질지수를 산정하고자 한다. 이러한 연구를 통해 유역 특성별 수질 관리를 위한 기초 자료로 활용될 수 있을 것으로 사료된다.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.2
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• pp.102-114
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• 2013

The basin of Lake Shihwa is one of highly industrialized region of Korea and a current environmental issue of study area is the operation of tidal power plant (TPP) to improve water quality. The application of water quality index (WQI) which integrates five physiochemical parameters (transparency, DO, DIN, DIP and chlorophyll-a) of water quality in Lake Shihwa and outer sea during 2011~2012 were performed not only to evaluate the spatial and temporal distribution of the water quality but also to assess the effect of water quality improvement by the operation of tidal power plant. The higher WQI values were observed in monitored sites near the industrial complexes in Lake Shihwa and the outfall of wastewater treatment plants (WWTPs) in outer sea. This indicates that the quality of seawater is influenced by diffuse non-point sources from industrial, municipal and agricultural areas in Lake Shihwa and by point sources from the effluence of municipal and industrial wastewater throughout WWTPs in outer sea. Mean WQI value decreased from 53.0 in 2011 to 42.8 in 2012 of Lake Shihwa. Water quality has improved significantly after TPP operation because enhancement of seawater exchange between Lake Shihwa and outer sea leads to improve a hypoxic condition which is primarily a problem in Lake Shihwa. Mean WQI of outer sea showed similar values between 2011 and 2012. However, the results of hierarchical cluster analysis and the deterioration of water quality in summer season indicate that the operation of tidal power plant was not improved the water quality in the upper most area of Lake Shihwa. To successfully improve overall water quality of Lake Shihwa, it is urgently necessary to manage and reduce of non-point pollution sources of the basin of Lake Shihwa.

• Journal of Environmental Science International
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• v.29 no.6
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• pp.659-672
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• 2020

Water and sediment qualities were investigated in the Oncheon Stream and at the Wondong bridge of the Suyoung River, during the summer rainy season, 2019. Dissolved oxygen (DO) showed the lowest levels at 4.7 and 5.0 m/L, and biogeochemical oxygen demand (BOD) showed the highest at 5.3 mg/L downstream where the tributary flows into the main river. Chemical oxygen demand (COD) increased from 2.0 to 5.9 mg/L on average as it flowed downstream, The COD/BOD ratio decreased gradually as it flowed downstream, reaching 1.0. However, COD/BOD ratio at the Wondong bridge was 5.8-22.2, indicating that easily biodegradable and non-biodegradable organic matter flows into the Oncheon Stream and Suyoung River, respectively. Total nitrogen (T-N) / total phosphorus (T-P) ratio tended to decrease from 72 to 21 as it flowed downstream, measuring 71 to 86 at the Wondong bridge. The water quality index (WQI) generally improved better than grade IV after heavy rainfalls. However, DO and T-P were the parameters that deteriorated the WQI. Ignition loss (IL), COD, T-N, and T-P of sediments had distribution of 1.44 ± 1.01%, 0.35 ± 0.16%, 43 ± 63 mg/kg, and 10.9 ± 21.9 mg/kg, respectively. These were several times lower than the annual averages of IL, T-N, and T-P in 2017 before the dredging project was conducted in the first half of 2018.