• Journal of Wetlands Research
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• v.16 no.3
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• pp.441-450
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• 2014

In this study, we consider ability of self-purification for a rational water quality management. And we assess the risk of Alkyl Benzene Sulfonic acid sodium salt(ABS) of harmful ingredients in Anseong Cheon watershed using QUAL2E model. The observations and simulated results were fitted well for BOD and ABS, but even though the trend of DO concentration change was well represented, the error between observation and simulation values was existed. We assessed the Risk assessment by calculating Risk quotient(RQ) by Predicted Exposure Concentration(PEC) and Predicted No-Effect Concentration(PNEC). Results of the impact of ABS on the self-purification of the river were Anseongcheon[0.0003(Bressan), 0.06(Criteria of Ministry of environment)], Jinwicheon[0.0002(Bressan), 0.04(Criteria of Ministry of environment). And result of the impact of ABS on the Aquatic ecosystem of the river were Anseongcheon[0.0667(Bressan), 0.005(Criteria of Ministry of environment)], Jinwicheon[0.1(Bressan), 0.0075(Criteria of Ministry of environment). All of these results were smaller than the 1.0 which is the reference value suggested by Norification No.30 of the National Institute of Environment Research. So, ABS did not affect a self-purification and aquatic ecosystem of the river. The method suggested in the study is a simple one and can provide more information for harmful ingredients than criteria of Ministry of environment.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.119-119
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• 2022

인위적, 자연적 요인에 의한 물순환 왜곡과 물순환 건전성 저하는 이수, 치수, 환경 등 다양한 물 관리 분야의 문제를 일으키고 있다. 이에 건전한 유역 물순환 관리에 관한 사회적 요구가 증대되고 있다. 유역의 물순환 관리를 위해서는 유역 전반의 물 이동과 물 이용에 관한 정량적인 평가가 선행되어야 하고, 유역의 물순환 건전성을 평가할 수 있는 체계가 필요하다. 이 연구에서 물순환 정량화를 위해 자연계 및 인공계 물순환 요소를 반영한 유역 유출 모형을 구축하였고, 관측 자료와 모형을 통해 분석된 결과를 이용하여 물순환을 정량화하였다. 한편, 물순환 건전성 평가를 위해 물환경, 물이용, 물안전의 3가지 범주 내에 수질 관리, 비점오염 관리, 수생태 관리, 하천유지기능, 지하수 보전, 치수 관리, 이수 관리의 7가지 항목에 대한 건전성을 평가할 수 있는 평가지표와 기준을 제시하였다. 그리고 계층 분석적 의사결정 기법에 따른 가중치를 이용하여 7개의 평가항목을 종합한 물순환 건전성 지수(hydrologic soundness index; HSI)를 도입하였다. 구성된 물순환 정량화 및 건전성 평가체계를 경안천과 남강, 미호천, 황룡강 중권역에 적용하여 중권역별로 필요한 물순환 개선 사업과 투자 우선순위가 높은 표준유역을 식별하였다. 이 연구에서 제시한 물순환 정량화 및 건전성 평가체계는 유역의 다양한 물 문제를 객관적으로 진단하는 한 가지 방편으로서, 유역의 물 문제 해결을 위한 기술적 정보 제공에 이바지할 수 있다.

• Korean Journal of Environment and Ecology
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• v.33 no.2
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• pp.187-201
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• 2019

This study examined the physicochemical water quality and evaluated the ecological health in 14 sites of Geum River (upstream, mid-stream, and downstream) using the fish community distribution and guilds and eight multi-variable matrices of FAI (Fish Assessment Index) during June 2008-May 2009. The analysis of the water quality variables showed no significant variation in the upstream and mid-stream but a sharp variation due to the accumulation of organic matter from the point where the treated water of Gap and Miho streams flew. The analysis of physicochemical water properties showed that BOD, COD, TN, TP, Cond, and Chl-a tended to increase while DO decreased to cause eutrophication and algae development from the downstream where Miho and Gap stream merged. The analysis of fish community showed that the species richness index and species diversity index increased in the mid-stream area but decreased in the downstream area, indicating the stable ecosystem in the upper stream and the relatively unstable ecosystem in the downstream. The analysis of the species distribution showed that the dominant species were Zacco platypus that accounted for 20.9% of all fish species and Zacco koreanus that accounted for 13.1%. The analysis of the fish tolerance and feeding guild characteristics showed that the sensitive species, the insectivore species, and the aquatic species were dominant in the mid-stream point. On the other hand, contaminants from the sewage water treatment plant of Miho stream had a profound effect in the downstream to show the dominance of tolerant species, omnivorous species, and lentic species. Therefore, it is necessary to improve water quality by reducing the load of urban pollutants and to pay attention to the conservation and restoration of aquatic ecosystems.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.4
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• pp.258-271
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• 2010

In order to figure out hydrodynamic and water quality changes after completion of dike construction of the Saemangeum, which behaves as a semi-enclosed estuarine lake, numerical simulations based on fine grid structure by using EFDC were intensively carried out. In this study some limitations of precedent study has been improved and gate operation were considered. Also 3 phases such as air-water-sediment interaction modeling was considered. It is clear that inner mixing of the Saemangeum is dominated by Mankyeong and Dongjin riverine discharges rather than the gate opening influence through the Lagrangian particle tracking simulations. Vertical DO structure after the dike completion shows steep gradient especially at Dongjin river estuary due to lessen of outer sea water exchange. Increasing SOD at stagnantly changed man-made reservoir might cause oxygen deficiency and accelerating degradation of water quality. According to TSI evaluation test representing eutrophication status, it shows high possibility of eutrophication along Mankyeong waterway in spite of dike completion, while the index is getting high after final closing along Dongjin waterway. Numerical tests with gate operations show significant differences in water quality. Thus it should be noted that proper gate operation plays a major role in preserving target water quality and management for inner development plan.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.3
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• pp.417-428
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• 2018

The purpose of this study is to raise the necessity of ensuring sustainability of water infrastructures in economic, social and environmental sectors by using index that evaluates the sustainability centering on water supply and wastewater utilities. This study identified sub-indexes that should be stressed among different indexes in economic, social and environmental aspects and those indexes were compared by each clusters of cities. The principal component analysis was used to calculate the weights of the sub-indexes, and the k-mean cluster analysis was conducted to classify the clusters. As a result of the weighting analysis, financial independence, service revenue ratio, subsidy ratio, population coverage ratio, deterioration, stream/river ecosystem health and river water quality were found to be the major variables in assessing sustainability. Cities were then classified into two groups using the k-mean cluster analysis. The overall sustainability scored high in the economic sector was relatively satisfactory, but it was necessary to improve the environmental sustainability. The group with relatively good environmental sustainability showed low score in the overall sustainability and required improvements in the economic sector.

• Korean Journal of Ecology and Environment
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• v.39 no.2 s.116
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• pp.198-208
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• 2006

This research was to apply a multi-metric approach, so called the Index of Biological Integrity (IBI) as a tool for biological evaluations of water environments, to a wadable stream. For the study, we surveyed 5 sampling locations in Kap Stream during August 2004 ${\sim}$ September 2005. We also compared the biological data with long-term water quality data, obtained from the Ministry of Environment, Korea and physical habitat conditions based on the Quantitative Habitat Evaluation Index (QHEI). We used ten metric systems for the IBI model to evaluate biological stream health. Overall IBI values in Kap Stream averaged 24 (range: 20${\sim}$30, n=5), indicating a "fair ${\sim}$ poor" conditions according to the modified criteria of Karr (1981) and US EPA(1993). Exclusive of 4th survey, average IBI values at the upstream reach (S1 ${\sim}$ S3)and downstream reach (S4 ${\sim}$ S5) were 20 and 24, respectively. However, in 4th survey the averages were 21 and 20 in the upstream and downstream reaches, respectively. This difference was larger in the upstream than in the downstream because of physical condition disturbed during summer monsoon. Values of the QHEI varied from 75(fair condition) to 148 (good condition) and values of QHEI in the S3 were significantly (P=0.001, n=5) lower than other sites. Biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) were greater by 3 ${\sim}$ 8 fold in the downstream than in the upstream reach. We believe that present IBI approach applied in this study may be used as a key tool to set up specific goals for restoration of Kap Stream.

• Korean Journal of Environment and Ecology
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• v.31 no.6
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• pp.508-519
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• 2017

There have been many studies on monitoring of biodiversity changes and preservation of Gwangneung Forest Biosphere Reserve (GFBR) in South Korea in recognition of the rare ecosystem that has been preserved for a long period. However, there are few studies on diversity and community characteristics of benthic macroinvertebrates as an indicator of stream health of GFBR. The purpose of this study was to assess the water quality of Bongseonsa Stream that penetrated through Gwangneung Forest and the nearby torrents by analyzing the benthic macroinvertebrates community during April to September 2016. The investigation collected a total of 114 species of benthic macroinvertebrates belonging to 56 families, 17 orders, 8 classes, and 5 phyla from the Bongseonsa Stream and Kwangneung Stream. Ephemeroptera and Trichoptera were the largest groups in species diversity with 30 species (32.3%) and 16 species (17.2%), respectively, and Tubificidae sp., Baetis fuscatus, Antocha KUa, and Cheumatopsyche brevilineata, which usually habit in contaminated streams, appeared frequently. Among the feeding function groups, the gatherers and hunters appeared relatively frequently, and the shredders and scrapers appeared frequently in the torrents. Among the habitat oriented groups, the clingers and burrower appeared more frequently and represented the microhabitats in the shallow areas. The result of the analysis of benthic macroinvertebrates community showed that the dominant index was $0.48{\pm}0.10$ in average while it was lowest with 0.33 in GS 8 of the Gwangneung Forest torrent and highest in BS 1 of Bongseonsa Stream. The diversity and richness indices were inversely proportional to the dominant index and were 2.53 and 4.22, respectively, in GS 8 where the dominant index was low. The result of the analysis of community stability showed that area I, which had high resistance and restoration, was high in Bongseonsa Stream while the area III, which had low resistance and restoration, was high in Gwangneung Forest, indicating that the water system in Gwangneung Forest had a wider distribution of specifies sensitive to agitation. The biological water quality assessment showed ESB of $50.88{\pm}17.69$, KSI of $1.11{\pm}0.57$, and BMI of $78.55{\pm}11.05$. GS 8 of Gwangneung Forest torrent was judged to be the highest priority protective water area with the best water environment and I class water quality with ESB of 63, KSI of 0.55, and BMI of 89.9. On the contrary, BS 1 of Bongseonsa Stream was judged to be the high priority improvement area that had the lowest water quality rating of III with ESB of 25, KSI of 2.13, and BMI of 62.7. Although the diversity of water beetle was higher in the water system of nearby Bongseonsa Stream than the water system inside the Gwangneung Forest, the annual community structure appeared to have distinct differences.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.2
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• pp.47-55
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• 2016

In this study, WUA (Weighted Usable Area) based on the Instream Flow Incremental Methodology (IFIM) was calculated to determine ecological flow at JeonJu-Cheon by using River2D model. To calibrate River2D, simulation results for low flow conditions of River2D were compared with calibrated HEC-RAS simulation results and the optimum parameters were determined. The results were RMSE (0.18), NSE (0.71) and coefficient of determination (0.78) for velocity and RMSE (0.02), NSE (0.71), coefficient of determination (0.73) for water depth. The result shows that the model successfully simulates the water flows. A selected target fish species to build the habitat suitability index were composed of Zaccoplatypus and Coreoleuciscus splendidus. These species showed the highest occurrences over the past decade in f ish monitoring. Also, The WUA-Discharge curve was calculated with the suitability index in a medium flow conditions. From the result, WUA is changed according to flowrate. In the flowrate-WUA/A graph, ecological flow can be determined at $1.8{\sim}2.0m^3/s$ for Zaccoplatypus $2.0m^3/s$ and Coreoleuciscus splendidus $1.8m^3/s$ at JeonJu-Cheon upstream. When compared with flow-duration analysis, it is demonstrative that simulation results fitted ecological flow considering quantity of available habitat for each fish species.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.110-110
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• 2020

최근 낙동강유역에서는 여름철 폭염 및 가뭄의 영향으로 조류대경보가 발령되고 있으며, 급격한 수질환경적 변화가 이루어지고 있다. 본 연구대상유역인 낙동강에서도 가뭄으로 인해 녹조가 발생하여 조류경보가 발령되었다. 남조류의 대발생은 대량 번성 및 사멸에 따라 수체 내 산소 고갈 및 유기물 증가와 같은 문제를 야기하고 있다. 또한 남조류가 분비하는 독성물질 또한 수생태계와 인체에 유해하다. 그리고 인체에는 무해하다고 밝혀졌지만 수돗물 등에서 흙냄새와 같은 좋지 않은 냄새를 유발하는 냄새물인 지오스민, 2-MIB을 분비하여 정수공급체계의 악영향을 미친다. 본 연구대상 지점인 낙동강은 다기능 보 건설로 인해 하천 수심이 증가하고 유속이 느려지면서 정체성 수역 특성을 나타내고 있다. 이는 호소성 수역 특성을 나타내고 있음과 동시에 녹조발생과 같은 수질환경적 변화가 이루어지고 있다는 것을 의미한다. 본 연구에서 시각화 분석을 통해 낙동강 하류 남조류 발생현황을 분석하였으며, 랜덤포레스트를 이용하여 지점별 남조류 발생 주요 영향인자를 도출하였다. 조류경보제 발생 등급은 발령기준으로 관심, 위험, 대발생으로 구분된다. 학습데이터로 관심단계 기준인 남조류세포수 1,000 cell/mL 보다 작게 측정된 데이터들은 관심미만의 데이터로 Normal 등급으로 구분하였다. 구분된 발생등급을 범주형 변수로 설정하여 학습 데이터를 통해 모형을 구축하고 검증 데이터를 이용하여 모형 정확성을 평가하였다. 본 연구를 통해 조류발생 주요 영향인자를 도출하고 변수별 중요도를 평가를 통해 지점별 녹조 발생특성을 비교 분석하였다.

• 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.