• 한국환경과학회지
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• 제27권10호
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• pp.883-899
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• 2018

In this study, water quality data of eight main sites in the Geumho River watershed were collected and analyzed for long-term changes in water quality over the period from 2005 to 2015. The results showed that BOD concentration was gradually improved by the Total Maximum Daily Load (TMDL), stages 1 and 2. Recently, a tendency of increasing BOD concentration was observed in the downstream section of the river. The concentration of COD was analyzed to be contaminated throughout the water system regardless of the water quality improvement project, and the TN concentration tended to increase in the midstream of the river from 2013. The TP concentration has clearly decreased from 2012 after the second stage of TMDL. For the statistical analysis of PCA ordination, monthly water qualities (pH, DO, Electrical Conductivity (EC), Water Temperature (WT), BOD, COD, TN, TP, TOC, and SS) and flow rate data for 5 years from 2012 to 2016 were used. Seasonally the Geumho River showed an increase in the TN concentration at point sources during the dry season (December to February). TP showed the effect of non-point sources in the summer, because rainfall has caused a rise in flow rate in the upstream. Besides, the origin of pollution source was changed from non-point sources with BOD, COD, and TOC.

• 한국물환경학회지
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• 제20권6호
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• pp.615-624
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• 2004

The distribution pattern of water quality parameters and phytoplankton biomass in upper inflow rivers of lake Paldang had surveyed. In North-Han river system, nutrient concentrations and algal biomass was below the standard of mesoand oligotrophy from lake Soyang to lake Paldang, maintaining good water quality, except the N5 site located near the Chuncheon-Si, showing high nutrients concentrations and algal biomass. The algal biomass of the South-Han river system showed oligotrophic level in the upstream near the lake Chungju, and increased along the flow direction showing eutrophic level in the downstream within the lake Paldang area. On the other hand, the highest concentrations of nutrients were detected in the middle stream near the Yeoju-Si and Yangpyung-Gun rather than in the downstream suggesting algal biomass in lake Paldang would not come from the upper river area but come from the growth within the lake area using nutrients from the upper inflow river.

• 한국물환경학회지
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• 제27권5호
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• pp.710-718
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• 2011

An integrated water quality management of reservoir and river would be required when the quality of downstream river water is affected by the discharge of upstream dam. In particular, for the control of downstream turbidity during flood events, the integrated modeling of reservoir and river is effective approach. This work was aimed to develop a laterally-averaged two-dimensional hydrodynamic and water quality model (CE-QUAL-W2), by which water quality can be predicted in the downstream of Yongdam dam in conjunction with the reservoir model, and to validate the model under two different hydrological conditions; wet year (2005) and drought year (2010). The model results clearly showed that the simulated data regarding water elevation and suspended solid (SS) concentration are well corresponded with the measured data. In addition, the variation of SS concentration as a function of time was effectively simulated along the river stations with the developed model. Consequently, the developed model can be effectively applied for the integrated water quality management of Yongdam dam and downstream river.

• 한국물환경학회지
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• 제27권6호
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• pp.813-821
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• 2011

While various aspects affect river water quality, reduction of water flow rate during dry seasons is one of the most significant factors causing severe water pollution in river water environment. The aim of this study is to investigate the feasibility of applying a physicochemical method (sand filtration + ozonation) for improving river water quality within a short period. The parameters analyzed and assessed were $COD_{cr}$, BOD, SS and color. The source river water had a severe pollution level showing COD 8.8~17.2 mg/L (ave. 11.9 mg/L), BOD 4.8~13.3 mg/L (ave. 8.3 mg/L), SS 9.0~22.1 mg/L (ave. 12.8 mg/L) and color 34.4~77.1 degree (ave. 56.5 degree) during the experimental periods. The variation trends showed a relatively low correlation between BOD and COD and between color and COD, while SS showed very low correlation with other parameters. The combined process of sand filtration and ozonation showed averaged removal efficiency of COD 37.2%, BOD 48.4%, SS 60.1% and colority 45.1%, respectively. The marked change of BOD level from 8.3 mg/L to 4.3 mg/L under the experimental conditions in this study implied the improvement of class V to class III set by the river water quality standard in Korea.

• 한국환경생물학회:학술대회논문집
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• 한국환경생물학회 2004년도 학술대회
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• pp.27-27
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• 2004

We studied algal growth-related water quality of the Sangsa lake which is the drinking water reservoir for the south-eastern region of Jeonnam province. Peridinium cinctum and several diatomic algal species frequently caused water bloom throughout the lake from early spring to late autumn. With the heaviest predominance of Peridinium cintum in May 2003, COD was 22.7 mg/l in the surface layer. Highly turbid surface water of 15 NTU was also caused by Perdinium bloom. Cyanobacterial growth was effectively prohibited by dominant growth of Peridinium in the Sangsa lake, otherwise confronted with cyanobacterial bloom. Dense algal layer was confined in the upper several meters of the water column above the thermocline, which gives relatively algae-free water in deeper layer suitable for drinking source water supply. Upon collapse of thermocline, water quality of the surface layer was improved while deeper layer was deteriorated. This paper deals with some details of water quality changes with algal growth in the Sangsa lake past two years.

• 한국물환경학회지
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• 제26권6호
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• pp.895-902
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• 2010

The effect of seasonality on water quality variation is very significant. Generally, it reduce the power of the trend extraction. A parametric time-series model was used for detecting trends in historic constituent concentration data. The effect of seasonality is able to remove from time series decomposition technique. According to such statistic methode, long-term water quality trend analysis system (NTrend 1.0) was developed by Nakdong River Water Environmental Research Center. The trend analysis of BOD variation was conducted with NTrend 1.0 at Goreong and Moolkum site in Nakdong river to show the effect of water quality management action plan. Power test of trend extraction was tried each case of 'deseasonalized and deannulized' data and 'deseasonalized' data. Analysis period was from 1989 to 2006, and it's period was divided again three times, 1989~1993, 1994~1999 and 2000~2006 according to action plan period. The BOD trend was downward in Goreong site during three times and it's trend slope was very steep, and upward in Moolkum during 1989~1993, but it was turned downward during 1994~1999 and 2000~2006. It was revealed that it's very effective to reduce the concentration of BOD by water quality management action plan in that watershed. The result of power test was shown that it is high for trend extraction power in case of 'deseasonalized' data.

• 한국방재학회 논문집
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• 제2권4호
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• pp.69-75
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• 2002

본 연구에서는 하천수질자료를 현장계측하고 무선으로 실시간 전송하여, GIS 상에서 자료를 분석하여 하천수질의 이상을 신속, 정확하게 파악하여 하천의 수질관리를 효율적으로 관리할 수 있는 GIS에 기반한 하천수질 관리시스템을 개발하였다. 시스템을 성능을 테스트할 목적으로 한강의 제1지류인 탄천을 시범유역으로 선정하여 개발된 시스템을 테스트하였다. 하천관리시스템은 크게 GPS 수신기가 탑재된 무선 실시간 계측시스템, 서버컴퓨터, GIS 시스템의 세 부분으로 나뉘어지며 각각의 시스템을 통합, 연계하여 최종 시스템을 개발하였다. 개발된 하천관리시스템을 시험유역에 적용한 결과 탄천 수질자료의 측정이 실시간으로 이루어짐과 동시에 서버컴퓨터에 저장되는 자료를 GIS 시스템 상에서 즉시 표출하고 가공할 있게 됨으로서 하천 수질을 실시간으로 관리할 수 있는 가능성을 제고하였으며 수질오염확산예측 및 수질방재등의 목적으로 활용할 수 있는 가능성을 확인하였다.

• Water Engineering Research
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• 제3권4호
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• pp.259-267
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• 2002

South Africa has developed a policy and law that calls and provides for the equitable and sustainable use of water resources. Sustainable resource use is dependent on effective resource protection. Rivers are the most important freshwater resources in the country, and there is a focus on developing and applying methods to quantify what rivers need in terms of flow and water quality. These quantified and descriptive objectives are then related to specified levels of ecological health in a classification system. This paper provides an overview of an integrated and systematic methodology, where, fer each river, and each river reach, the natural condition and the present ecological condition are described, and a level/class of ecosystem health is selected. The class will define long term management goals. This procedure requires each ecosystem component to be quantified, starting with the abiotic template. A modified flow regime is modelled for each ecosystem health class, and the resultant fluvial geomorphology and hydraulic habitats are described. Then the water chemistry is described, and the water quality changes that are likely to occur as a consequence of altered flows are predicted. Finally, the responses to the stress imposed on the biota (fish, invertebrates and vegetation) by modified flow and water quality are predicted. All of the predicted responses are translated into descriptive and/or quantitative management objectives. The paper concludes with the recognition of active method development, and the enormous challenge of applying the methods, implementing the law, and achieving river protection and sustainable resource-use.

• 한국물환경학회지
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• 제36권6호
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• pp.521-534
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• 2020

In this study, the variation of water quality was analyzed for six sites in major tributaries of the Nakdong River Basin. Standard-FDC (Flow Duration Curve) was developed using PM (Percentile Method), one of the statistical FDC estimation methods. The LDC (Load Duration Curve) was obtained using the developed FDC. The current method and the LDC evaluation method were compared and analyzed to evaluate the achievement of TWQ (Target Water Quality). Regarding the monthly flow rate variation, the five sites showed the distribution of the lowest flow rate between May and June, indicating a high probability of dry weathering of the streams. The variation of water quality confirmed the vulnerable timing of flow rate in each site, and it is therefore deemed necessary to plan to reduce T-P and TOC. A comparison and evaluation of TWQ showed that there was a difference between the TWQ values achieved by the two techniques. In addition, the margin ratio to the 50% excess ratio can be found in the LDC evaluation. The results of the LDC evaluation by section and by month showed whether or not the water quality was exceeded by flow conditions, along with the vulnerable sections and timing. Accordingly, it is judged that this method can be used for water quality management in TMDLs (Total Maximum Daily Loads).

• 한국물환경학회지
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• 제23권6호
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• pp.863-871
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• 2007

Spectroscopic characteristics of river water from four major watersheds in the Ulsan area were measured to examine their potential for estimating water quality parameters. The total 176 river samples were collected from 44 sites of small streams within the watersheds during the year 2006. Spectroscopic characteristics investigated included protein-like fluorescence (FLF) intensity, fulvic-like fluorescence (FLF) intensity, terrestrial humic-like fluorescence (TLF) intensity, UV absorbance at 254 nm, and UV absorbance difference at 220 nm and 254 nm. Protein-like fluorescence intensity showed linear relationships with biochemical oxygen demand (BOD), chemical oxygen demand (COD), total phosphorous (TP) concentrations of the samples with the correlation of 0.784, 0.779, and 0.733, respectively. Due to the UV absorption characteristics of nitrate at 220 nm, UV absorbance difference at 220 nm and 254 nm was selected to represent total nitrogen (TN) concentration. Exclusion of some samples with PLF intensity higher than 5.0 improved the correlation between the UV absorbance difference and TN as demonstrated by the increase of the correlation coefficient from 0.392 to 0.784. Instead, for the samples with PLF intensity lower than 5.0, the highest correlation of TN was achieved with UV absorbance at 254 nm. The results suggest that PLF intensity could be used as the estimation index for BOD, COD, and TP concentration of river water, and as the primary screening index for the prediction of TN using UV absorbance difference. Some BOD-based water quality levels among the river water were statistically discriminated by the PLF intensity. Low p-values were obtained from the t-tests on the samples with the first level and the second level (p=0.0003) and the samples with the second and the third levels (p=0.0413). Our combined results demonstrated that the selected spectroscopic characteristics of river water could be utilized as a tool for on-site real-time monitoring and/or the primary estimation of water quality.