• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.743-753
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• 2011

One of the most important water management issues of Soyang Reservoir, located in North Han River in Korea, is a long term discharge of turbid water to downstream during flood season. Installation of a selective withdrawal structure (SWS) is planned by the reservoir management institute as a control measure of outflow water quality and associated negative impacts on downstream water use and ecosystem. The objective of the study was to explore the effectiveness of the SWS on the control of outflow turbidity under two different hydrological years; one for normal flood year and another for extreme flood year. A two-dimensional (2D), laterally averaged hydrodynamic and water quality model (CE-QUAL-W2) was set up and calibrated for the reservoir and used to evaluate the performance of the proposed SWS. The results revealed that the SWS can be an effective method when the ${\Theta}$ value, the ratio between the amount of turbid water that containing suspended sediment (SS) greater than 25 mg/L and the total storage of the reservoir, is 0.59 during the normal flood year. However, the effectiveness of the SWS could be marginal or negative in the extreme flood year when ${\Theta}$ was 0.83. The results imply that the SWS is an effective alternative for the control of turbid water for moderate flood events, but not a sufficient measure for large flood events that are expected to happen more often in the future because of climate change.

• Journal of the Korean Association of Geographic Information Studies
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• v.8 no.2
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• pp.157-165
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• 2005

The purpose of this study is to examine the relationship between land use patterns of riparian zones and water quality in the Geumho River watershed. A GIS database included digital land use maps (1:25,000), stream network extracted from digital topographic maps (1:5,000) and riparian zones maps by multi-buffering method. Pearson's correlation analysis was used to explain the relationship between the environmental conditions of a 30 meter buffer strip on each side and water quality. According to the result of investigation of riparian-level land use patterns, sub-watersheds on the lower Geumho River including Daegu metropolitan city were mainly developed as urban area such as residential, commercial and industrial ones, while sub-watersheds on the middle Geumho River and the main course of Nakdong River, agricultural ones such as a paddy, a dry field and an orchard. Meanwhile, the area-rate of riparian forests which play an important role in filtering nitrogen, phosphorus and sediment was estimated below the average 16%. The proportion of urban area in a 30 meter riparian bufferstrip had a negative correlation with water quality in each sub-watershed. But the proportion of forest area had a positive correlation with water quality. Henceforth, it is necessary to establish landscape planning for preparing and restoring the riparian buffer zones, concerning land form, soil type, the present land use pattern and economic aspects.

• Journal of Environmental Impact Assessment
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• v.16 no.2
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• pp.143-156
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• 2007

This study has researched the management status and the pollution level of water, soil, stream sediments of 11 abandoned coal mines out of a total of 12 within Obong-Dam area except Bukyung mine, which was submerged when constructing Obong-Dam, and selected areas which are in needs to have pollution control facilities in the first place. From the results of examination on the runoff at the waste rock pile and mineheads, the runoff from Sueun mine (pH, Fe, Al), Samwon mine (pH, Al), Wangdo mine (pH, Al), Mose mine (pH, Fe, Al) and Daeryeong mine (pH) exceeded the permissible discharge standards of the water quality, but the water at merging point with Obong-Dam after joined with Doma branch satisfied both Water Quality Standards and Drinking Water Quality Standards. In regard to groundwater contamination, it is found that areas where exceeded the Drinking Water Quality Standards are Wangdo mine (pH), Jangjae mine (pH, Zn), Daeryeong mine (pH) whereas all areas satisfied Soil Contamination Warning Standards of Soil Environmental Conservation Law. When comparing a research result on underwater sediments of branches of abandoned mines to the EPA Guidelines for classification of great lakes harbor sediments, Dongguk Gaerim (Fe), Jungwon mine (Fe), Daebo mine (Mn), Samwon mine (Mn) and Daeryeong mine (Mn) showed mid-level of contamination, whereas Sueun (Fe, Mn), Daebo mine (Fe), Woosung mine (Fe, Mn), Wangdo mine (Fe, Mn), Mose mine (Fe) and Daeryeong mine (Fe) showed high-level of contamination. In addition, contamination levels of underwater sediments in Wangsan and Doma branch where abandoned mine's branches merge together, Wangsan branch showed no contamination at all whereas Doma branch shows mid-level of contamination which reflect the Doma branch is affected by waste rock pile and minehead runoff of the abandoned mines in the Doma branch area. It is concluded that Mose mine and Sueun mine required treatment of acid mine drainage. and Wangdo, Jungwon, and Samwon mines were in need of mine tailing and erosion control work. The Samwon mine additionally required a control system for closed minehead runoff. Although the Samwon mine reached a high concentration of Al, Mn $Ca^{2+}$, $SO{_4}^{2-}$ in the runoff, the levels decreased after it was combined with a tributary. It has been concluded that after further monitoring of the cause of pollution, a preventive measure system may be needed to be built.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.4
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• pp.279-287
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• 2010

To identify characteristics of the water quality at Goseong bay, we analyzed long term monitoring data collected at surface and bottom water which was accumulated during the period of 1987~2009. The result showed that the waters of Goseong bay represented mesotrophic level that is based on chlorophyll-a, DIP and DIN and seasonal average of COD that indicates level by the COD criteria. This analysis can be translated that the waters is comparatively clean even though the waters is in the closed bay that slowly diffuses influx mass. We also did the time series analysis, correlation analysis and regression analysis on the moving average of the water parameter at Goseong bay. According to the results, DIP showed a increasing trend as time passed while DIN was on a decreasing trend under the same condition. In the waters of Goseong bay, the phyto-plankton growth was shown to be limited by DIN concentration. The chlrophyll-a was at the peak in August, at $4.60{\mu}g/L$. As the seasonal average and index were the highest in November, it was understood that the balance of nutrient at Goseong bay was dependent more on inner factors, ie, mass farming of aquatic species and release of bottom sediment rather than on inflow of fresh water. Accordingly, it is needed to consider the balance of nutrient like DIP and DIN to manage the water quality or estuaries at Goseong bay.

• Korean Journal of Ecology and Environment
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• v.36 no.3 s.104
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• pp.344-355
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• 2003

Water quality model applicable paddy field was developed using field experiment during 1999 ${\sim}$ 2002. This model involves inputs from fertilization and sediment release as dirac delta function and continuous source function, respectively, and can simulate various processes such as ponded depth, surface drainage, total nitrogen concentration and total phosphorus concentration in a daily basis. The model was calibrated using data collected from field experiments which was irrigated with ground water and validated from field experiments which was irrigated with surface water. The nutrient concentration of surface water depended on the fertilization and dirac delta function can efficiently explain the valiance of nutrient concentration of surface water by fertilizer. As a result of calibration and validation, this model demonstrates good agreement. The model fit efficiencies ($R^2$) of ponded depth, surface concentration of TN and TP were 0.93,0.98 and 0.95, respectively for calibration, and those of TN and TP were 0.99 and 0.70, respectively for validation. We can apply lake and reservoir model to analysis paddy field considered with shallow ponded system, but it will need so many parameters and have much uncertainty. Fortunately, paddy field have a series of cultural practices yearly basis, such as irrigation-fertilization-forced drain-harvest with a similar time , so simple model may explain the mechanism for paddy field. Water quality model for paddy field developed in this study is simply, needs little parameters, but appeared high applicability to evaluate paddy filed drainage. We recommend this model to estimate nutrient loading from paddy field and establish best management practice.

• Journal of Korea Water Resources Association
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• v.37 no.11
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• pp.897-913
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• 2004

There has been continuous efforts to manage the water resources for the required water quality criterion at river channel in Korea. However, we could not obtain the partial improvement only for the point source pollutant such as, wastewater from urban and industrial site through the water quality management. Therefore, it is strongly needed that the Best Management Practice(BMP) throughout the river basin for water quality management including non-point source pollutant loads. This problem should be resolved by recognizing the non-point source pollutant loads from upstream river basin to the outlet depends on the land use and soil type characteristic of the river basin using the computer simulation by distributed parameter model based on the detailed investigation and the application of Geographic Information System(GIS). Used in this study, Annualized Agricultural Non-Point Source Pollution (AnnAGNPS) model is a tool suitable for long term evaluation of the effects of BMPs and can be used for un gauged watershed simulation of runoff and sediment yield. Now applications of model are in progress. So we just describe the limited result. However If well have done modeling and have investigated of propriety of model, well achieve our final goal of this study.

• Korean Journal of Environmental Agriculture
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• v.20 no.3
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• pp.143-149
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• 2001

A contact oxidation canal system with sedimentation basin was installed to study the efficiency of water quality purification. The primary sedimentation basin with 60 min of HRT (Hydraulic Retention Time) included in the system was aimed to sediment pollutants in the water and the deposit being released by the drainage culvert located at the bottom of the system. The oxidation canal aerated by nozzle was to contact the pollutants and oxygen in the surface of plastic filter to purify the water. Discharge, HRT, length of the oxidation canal were $200\;m^3/day$, 90 min, 20 m, respectively. The treatment efficiency of total nitrogen was lower compared with other water quality items such as SS, BOD, TP because the anoxic condition for denitrification was not ensured after the oxidation canal. However, $25%{\sim}89.6%$ of SS, $75.0%{\sim}91.5%$ of BOD, $44.3%{\sim}95.3%$ of TP were removed in this system. Overall, the results indicates that this system appears to have a potential capability for water quality improvement of the reservoirs or the canals in the agricultural watershed.

• Journal of Environmental Impact Assessment
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• v.30 no.4
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• pp.203-214
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• 2021

Assessment of benthic quality status was implemented along the subtidal areas of Jindo and Jejudo to understand faunal structure of polychaete assemblages and ecological quality of the benthic environment. Sediment analysis was characterized by well sorted of both mud and sand in Jindo, and a little higher sand in Jejudo instead. A total of 68 polychaete species were found at 14 sampling stations with a mean density of 231 inds./m², and 61 species, 167 inds./m² and 62 species, 295 inds./m² in Jindo areas and Jejudo areas. Dominant species found in Jindo areas were Heteromastus filiformis, Ampharete arctica, Prionospio sp., Sigambra tentaculata, Thelepus sp. and Amphicteis gunneri, Ampharete arctica, Prionospio sp., Spiochaetopterus costarum, Heteromastus filiformis in Jejudo. With a help of cluster analysis, it was found that the sampling stations showed distinctive pattern of the distribution pattern and benthic quality status in Jindo and Jejudo except sampling station numbers 5 and 6, respectively. AMBI analysis the results were 1.2-3.4, grade V benthic polychaetes did not appear. It was evident that both Jindo and Jejudo had different sedimentary characteristics as well as distribution pattern of polychaete assemblages.

• Korean Journal of Environmental Agriculture
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• v.42 no.4
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• pp.408-417
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• 2023

This study aimed to investigate the effects of an aquaponics system utilizing catfish recirculating water on the growth and water quality in lettuce and chicory cultivation. After 60 d of catfish cultivation in the BFT-AP, the survival rate was 96.0% and average weight gain was 178.5 g. The WGR grew by 241.4% and the SGR was 3.0%. A comparison between lettuce and chicory cultivation using BFT-AP and hydroponics revealed significant increases in shoot height, leaf count per week, and biomass of the cultivated lettuce and chicory. The SPAD values also increased significantly by 15.4-43.3%. Water quality analysis of the BFT-AP systems and crop cultivation beds showed significant differences, except for K and Na. The average NO₃^- concentration in the sediment pond was significantly higher at 45.3±1.0. Comparison of water temperature, pH, EC, DO, and ORP in the BFT-AP system and crop cultivation beds revealed similar monthly water temperatures from July to September. The pH in the catfish culture pond was 0.3-1.2 lower than that in the crop cultivation beds, and the EC was approximately 0.01- 0.03 dS/m lower in the catfish culture pond than the crop cultivation beds. The monthly average ORP in the catfish culture bed steadily increased to 479.9 mV in October. Bacillus velezensis (AFB2-2) and Chlorella fusca (CF) were applied to the biological activation bed; the population density of CF showed a continuous increase, whereas that of AFB2-2 decreased after 15 d and gradually increased thereafter. Thus, the application of the recirculating aquaponics cultivation technology with catfish (BFT) enhances catfish cultivation and promotes the growth of lettuce and chicory. Therefore, it is considered suitable for the environment-friendly cultivation of lettuce and chicory.

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.1
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• pp.25-36
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• 2016

Heavy metals in the stream sediments around Shihwa Lake were studied not only to investigate the characteristics of spacio-temporal distribution but also to assess the pollution degree and ecological risk using various pollution indices. Among metals, Zn had the highest values (1,311 mg/kg) and Hg showed the lowest value (0.261 mg/kg). The order of mean concentrations (mg/kg) of metals was Zn>Cu>Pb>Cr>Ni>Co>As>Cd>Hg in stream sediments around Shihwa Lake. Metal concentrations showed different pollution pattern with industrial region, indicating that these metals originated from different sources and industrial region had higher metal concentration than rural/urban regions. The results of geoaccumulation index (Igeo) showed that the stream sediments were significantly polluted with Cd, Cu, Zn and Pb, indicating moderately to highly polluted by these metals. According to PLI consideration, industrial region was more seriously polluted by metals whereas an rural/urban region was not polluted. About 85% of sampling site for Cr, Ni, Cu, Zn and Pb from industrial regions were exceeded the PEL values. The mPELQ and SQI values derived from PEL of industrial region were classified as 'highly toxic' and 'very poor' and metal pollution level tend to be worse in wet season. This indicates that the industrial activities and stromwater runoff represents an important sources of heavy metals around Shihwa Lake.