• Journal of Wetlands Research
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• v.23 no.3
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• pp.252-259
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• 2021

Numerous valley waters originating from Mt. Mudeung and flowing into Gwangju Cheon flowed into the confluence-type sewage conduit, the Gwangju Cheon became dry and water quality deteriorated. In this study, a method to create a stream was studied by using the valley water of Mt. Mudeung in the Gwangju cheon that flows into the sewage treatment plant as a water source. Flow and water quality surveys were investigated at four points with meaningful flow quantity. As a result, it showed a flow quantity was 105~2,721 m³/day at each point. And the average water quality was BOD₅ 0.3~1.6 mg/L. If a stream with a flow quantity of 1,500 m³/day is created during the dry season and then flows into the Namgwang bridge of Gwangju cheon, it is predicted that there will be improvements in BOD 7.3%, COD 6.5%, T-P 5.8%, and T-N 5.2%. In addition, it was determined that the load on the flow quantity of the sewage treatment plant due to the inflow of valley water would be reduced, the cost of sewage treatment would be reduced, and it would be the basis for BGN construction by creating waterside amenity in the city.

• Journal of Environmental Impact Assessment
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• v.32 no.6
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• pp.473-487
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• 2023

Korea's multi-purpose dams, which were constructed in the 1970s and 1980s, have a single outlet located near the bottom for hydropower generation. Problems such as freezing damage to crops due to cold water discharge and an increase the foggy days have been raised downstream of some dams. In this study, we analyzed the effect of water intake depth on the reservoir's water temperature stratification structure and outflow temperature targeting Hapcheon Reservoir, where hypolimnetic withdrawal is drawn via a fixed depth outlet. Using AEM3D, a three-dimensional hydrodynamic water quality model, the vertical water temperature distribution of Hapcheon Reservoir was reproduced and the seasonal water temperature stratification structure was analyzed. Simulation periods were wet and dry year to compare and analyze changes in water temperature stratification according to hydrological conditions. In addition, by applying the intake depth change scenario, the effect of water intake depth on the thermal structure was analyzed. As a result of the simulation, it was analyzed that if the hypolimnetic withdrawal is changed to epilimnetic withdrawal, the formation location of the thermocline will decrease by 6.5 m in the wet year and 6.8 m in the dry year, resulting in a shallower water depth. Additionally, the water stability indices, Schmidt Stability Index (SSI) and Buoyancy frequency (N²), were found to increase, resulting in an increase in thermal stratification strength. Changing higher withdrawal elevations, the annual average discharge water temperature increases by 3.5℃ in the wet year and by 5.0℃ in the dry year, which reduces the influence of the downstream river. However, the volume of the low-water temperature layer and the strength of the water temperature stratification within the lake increase, so the water intake depth is a major factor in dam operation for future water quality management.

• Journal of Korea Water Resources Association
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• v.45 no.3
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• pp.301-316
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• 2012

Two models, TANK and SWAT (Soil and Water Assessment Tool) were compared for simulating natural flows in the Paldang Dam upstream areas of the Han River basin in order to understand the limitations of TANK and to review the applicability and capability of SWAT. For comparison, simulation results from the previous research work were used. In the results for the calibrated watersheds (Chungju Dam and Soyanggang Dam), two models provided promising results for forecasting of daily flows with the Nash-Sutcliffe model efficiency of around 0.8. TANK simulated observations during some peak flood seasons better than SWAT, while it showed poor results during dry seasons, especially its simulations did not fall down under a certain value. It can be explained that TANK was calibrated for relatively larger flows than smaller ones. SWAT results showed a relatively good agreement with observed flows except some flood flows, and simulated inflows at the Paldang Dam considering discharges from upper dams coincided with observations with the model efficiency of around 0.9. This accounts for SWAT applicability with higher accuracy in predicting natural flows without dam operation or artificial water uses, and in assessing flow variations before and after dam development. Also, two model results were compared for other watersheds such as Pyeongchang-A, Dalcheon-B, Seomgang-B, Inbuk-A, Hangang-D, and Hongcheon-A to which calibrated TANK parameters were applied. The results were similar to the case of calibrated watersheds, that TANK simulated poor smaller flows except some flood flows and had same problem of keeping on over a certain value in dry seasons. This indicates that TANK application may have fatal uncertainties in estimating low flows used as an important index in water resources planning and management. Therefore, in order to reflect actually complex and complicated physical characteristics of Korean watersheds, and to manage efficiently water resources according to the land use and water use changes with urbanization or climate change in the future, it is necessary to utilize a physically based watershed model like SWAT rather than an existing conceptual lumped model like TANK.

• Economic and Environmental Geology
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• v.38 no.6 s.175
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• pp.607-622
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• 2005

This study was carried out in order to evaluate where the soil loss was mainly occurred, .and to verify how riverbed sediments in the tributaries of the Seomjin River were related to their source rocks distributed in Sunchang area. The study area including the Seomjin River with 4 tributaries of Kyeongcheon, Okgwacheon, Changjeong-cheon and Ipcheon was divided into 10 watershed. The RUSLE (Revised Universal Soil Loss Equation) was estimated for all the grids (10 m cells) in the corresponding watershed. The amount of soil loss per unit area was calculated as follows: dry fold (53,140.94 tons/ha/year), orchard (25,063.38 tons/ha/year), paddy field (6,506.7 tons/ha/year) and Idlest (6,074.36 tons/ha/year). The differences of soil loss per unit area appear to be depends on areas described earlier. Soil erosion hazard zones were generally distributed within dry fields. Several thematic maps such as land use maps, topographical maps and soil maps were used as a data to generate the RUSLE factors. The amount of soil loss, computed by using the RUSLE, showed that soil loss mainly occurred at the regions where possible source rocks were distributed along the stream. Based on the this study on soil loss and soil erosion hazard zone together with chondrite-normalized REE patterns that were previously analyzed in same study area, a closed relationship between riverbed sediments and possible source rocks is formed. Especially in the Okgwacheon that are widely distributed by various rocks, chondrite-normalized REE pattern derived from the riverbed sediments, source rock and soil is expected to have a closed relationship with the distribution of soil loss.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.2
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• pp.83-99
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• 2005

To evaluate environmental charateristics of the South Sea and East China Sea on summer, water and sediment quality were measured in June 2001-2003. Surface layer was affceted by Warm water originated from the high temperature and salinity-Tsushima Warm Current, on the other hand, Yellow Sea Cold Water was spread to the bottom layer in the south-western part of the Jeju island, and salinity at stations near the Yangtze River was decreased below 29psu because of a enormous freshwater discharges. Thermocline-depth was formed at about 10m, and chlorophyll maximum layer was existed in and below the thermocline. COD(Chemical Oxygen Demand), TN(Total Nitrogen), and TP(Total Phosphorus) concentrations showed seawater quality grade II in surface layer of the most area, but concentrations of such as COD, Chl. a, TSS(Total Suspended Solid), and nutrients were greatly increased in the effect area of Yangtze River discharges. Correlations between dissolved inorganic nitrogen, Chl. a and salinity were negative patterns strongly, in contrast, those of inorganic phosphorus, COD and Chl. a were positive, which indicates that phytoplankton biomass and phosphorus are considered as important factors of organic matter distribution and algal growth, respectively. in the study area. The distribution of ignition loss, COD, and $H_2S$ of surface sediment were in the ranges of 2.61-8.81%, $0.64-11.86mgO_2/g-dry$, and ND-0.25 mgS/g-dry, respectively, with relatively high concentration in the eastern part of the study area. Therefore, to effective and sustainable use and management of this area, continuous monitoring and countermeasures about major input sources to the water and sediment, and prediction according to the environmental variation, are necessary.

• Korean Journal of Environment and Ecology
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• v.25 no.1
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• pp.17-30
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• 2011

This study has analyzed the vegetation composition in the areas using different slope revetment techniques of riverbanks, in a way to improve the vegetation induction in the future considering the ecological aspects of the induction in Garaeyoul Village, Gangdong-gu, Seoul. The result of the vegetation distribution in each different slope revetment technique was analyzed, that the naturalized herb was dominant in the pole block accounting for 70.7%, while native herb was dominant in the lawn block occupying 48.5% and in the crib block occupying 55.7%. The vegetation coverage measured by different slope revetment techniques was highest in the crib block(average 97.5%), followed by the lawn block(average 95.3%) and pole block(average 27.9%). The vegetation base area was the most wide in the crib block and the most narrowest in the pole block. The result of community analysis in areas using different slope revetment techniques, dry herbs and vine herbs were dominated and the coverage was very poor in the pole block. In the lawn block, the barb was fragmented into narrow areas due to the blocks, which prevented the creation of large-scale plant communities. In the crib block, Miscanthus sacchariflorus, Fescue arundinacea and Aster pilosus, which also consisted of large-scale communities. Average dry weight was also measured by each slope revetment technique. The weight was heaviest in the crib block with $187.63g/m^2$, followed by the lawn block($137.65g/m^2$) and pole block($6.75g/m^2$). The soil moisture contents in the crib block and lawn block was 16.3% and 15.2%, respectively, while that of the pole block was 4.7%, which revealed the highly dry condition of the pole block soil. The analysis result of soil chemical property showed that there was little difference in soil texture, soile acidity(pH), and exchangeable ion content, however, the soil organic matter(OM) content and available $P_2O_5$ were highest in the pole block. In the future, in order to induce more vegetation into river banks and walls, a proper construction method should be applied so that the vegetation area can be expanded as much as possible, considering the safety of the banks.

• Korean Journal of Environmental Agriculture
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• v.24 no.2
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• pp.91-97
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• 2005

This study was conducted to evaluate the influence of pollutant loads on the water quality in the Dongjin River area from January 2003 to December 2004. The average value of BOD and T-N showed the highest peak in Yongho, Dukcheon watershed among Dongjin River. Concentrations of BOD, T-N and T-P in Jeongeup watershed were 2.29 mg $L^{-1}$, 4.40 mg $L^{-1}$ and 0.27 mg $L^{-1}$, respectively. Concentration of BOD in Chilbo was 1.19 mg $L^{-1}$ which would be in the grade I according to water quality criteria by Ministry of Environment. The BOD level in Wonpeung and Sinpeung watershed ranged from 4.06 to 7.35 mg $L^{-1}$. The T-N effluent loads of non-point pollutants were high in Wonpeung, Gobu, Yongho Dukcheon, Jeongeup and Sinpeung watershed in order. The major sources of BOD, T-N and T-P effluent loads were Livestock. The T-P effluent load of non-point pollutant was 68 kg $day^{-1}$ in Wonpeung, 58 kg $day^{-1}$ in Yongho Dukcheon and 45 kg $day^{-1}$ Jeongeup watershed. The delivered loads of BOD was high in Gobucheon, while both T-N and T-P were high in Yongho Dukcheon. The delivery ratio of BOD and T-N at dry season was below 100% in all watershed of Dongjin River. The delivery ratio of T-N at raining season was high in Yongho Dukcheon and Chilbo watershed

• Journal of Bio-Environment Control
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• v.16 no.4
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• pp.322-327
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• 2007

This study was conducted to analysis the chemical properties of Peunggang river and investigate the effect of irrigation sources on the growth of tomato and cucumber. The salt concentration in Peunggang river was high by $3.22{\sim}3.62dS{\cdot}m^{-1}s$ from March to May and lower gradually from April to February of next year, which was also lower in upper stream than in middle or low stream of Peunggang river. The growth such as plant height, fresh weight and dry weight in tomato and cucumber was better in drain water and tap water irrigation than in PR water (Peunggang river) irrigation. Mean fruit weight was highest in the tap water, and that of cucumber was no significance in the treatments. The number of setting fruit was lower in the PR water than in the treatments, and which was no significance between rain water and tap water. The yield of tomato and cucumber was found to be highest by 10,594 and 11,826 kg/10a in tap water, respectively and also lowest in the PR water among the three treatments. The fruit quality, soluble solids of tomato shows a tendency to increase in the PR water as compared with the other treatment, and the rate of blossom-end rote was higher by 13.6% in the PR water. T-N and P content of tomato and cucumber were no significance in the treatments. Ca content was lowest, but Na content highest in the PR water. It was thought that a rain water and tap water as alternative irrigation source of a PR water were proper.

• Korean Journal of Environmental Agriculture
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• v.25 no.2
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• pp.147-156
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• 2006

This study was conducted to investigate natural distribution of aquatic plane and to find out natural aquatic plants which highly absorb nutrient N and P. We surveyed vegetation within ${\pm}2m$ from streamside in 12 tributaries of the West Nakdong river watershed during May to October in 2003. Hydrophytes surveyed in tributaries of the West Nakdong river watershed were 27 families, 61 genera, 76 species, 3 varieties. Major dominance species of aquatic plants were Z. latifolia, P. communis, P. thunbergii, P. arundinacea, P. japonica, and P. distichum var. indutum. Aquatic plants having high production ability of biomass were Z. latifolia, P. communis, P. arundinacea, P. japonica, and E. crus-galli var. echinata. In the vertical distribution of hydrophytes within streams, dominant species were P. thunbergii and P. japonica in the upper stream, but dominant species in the downstream were P. communis and Z. latifolia. Species diversity or aquatic, plants was reduced, but their biomass and nutrient (T-N and T-P) content per the natural area unit $(m^2)$ were increased in the downsteaam. Nutrient N and P content of aquatic plants per the natural area unit were high at Joman river, Pyeonggangcheon, Bulam drainage canal, and Hogyecheon. Fifty-seven species of aquatic plants having high biomass were grounped into 4 categories $(I{\sim}IV)$ according to their nutrient content per dry weight unit. I group $(T-N,\;\geqq20gkg^{-1}\;&\;P_2O_5,\;\geqq7gkg^{-1})$ was comprised of 3 submerged plants (H. verticillata, P. crispus, and C. demersum), e emergent plants (O. javanica, P. distichum var. indutum, and R. sceleratus), 1 suspended plant (T. japonica), and 1 riparian plant (A. lobatum). Otherwise, in classification of natural hydrophytes according to their nutrient content per natural area unit, Z. latifolia, P. communis, P. longiseta, P. arundinacea, and P. distichum var. indutum possessing great biomass productivity as emergent plants were included in I group $(T-N,\;\geqq1gm^{-2}\;&\;P_2O_5,\;\geqq0.7gm^{-2})$.

• Journal of the Korean Institute of Landscape Architecture
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• v.52 no.2
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• pp.79-95
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• 2024

The purpose of this study was to find the changes in the habitat of wild birds caused by climate change in urban rivers and protected areas that greatly require ecological functions. In the future, this study can be used as a management index to protect the urban river ecosystem and maintain the health of sustainable urban rivers, thereby ensuring biodiversity. The Tancheon Ecological and Landscape Conservation Area, selected as a target site, has been affected by climate change. The four seasons of Korea have a distinct temperate climate, but the average annual temperature in Seoul has risen by 2.4-2.8℃ over the last 40 years. Winter temperatures tended to gradually increase. Precipitation, which was concentrated from June to August, is now changing into localized torrential rain and a uniform precipitation pattern of several months. Climate change causes irregular and unforeseen features. Climate change has been shown to have various effects on urban river ecosystems. The decrease in the area of water surface and sedimentary land impacted river shape change and has led to large-scale terrestrialization. Plants showed disturbance, and the vegetation was simplified. The emergence of national climate change indicator species, the development of foreign herbaceous plants, the change of dry land native herbaceous species, and wet intelligence vegetation were developed. Wild birds appeared in the territory of winter-summer migratory. In addition, species change and the populations of migratory birds also occurred. It was judged that fluctuations in temperature and precipitation and non-predictive characteristics affect the hydrological environment, plant ecology, and wild birds connecting with the river ecosystem. The results of this study were to analyze how climate change affects the habitat of wild birds and to develop a management index for river ecological and landscape conservation areas where environmental and ecological functions in cities operate. This study can serve as a basic study at the level of ecosystem services to improve the health of urban rivers and create a foundation for biodiversity.