• Journal of Korean Society on Water Environment
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• v.37 no.4
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• pp.296-305
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• 2021

This work investigated heavy metal pollution in surface sediments of rivers in Busan, Korea. Surface sediments were analyzed in order to conduct contamination assessment of organic matter, nutrients, and heavy metal concentrations. Contamination assessment of heavy metals was conducted using geoaccumulation index (I_geo), pollution load index (PLI), and potential ecological risk index (RI). Accumulation of organic matter and nutrients were affected by water discharged from sewage treatment plant. The concentrations of organic matter and nutrients were found to be greater in points which were close to the sewage treatment plant more than points furthest. The concentrations of Pb, Zn, Cu, Cd, Hg, As, Cr, and Ni were found to be greater in surface sediment more than in the background. The mean concentrations of heavy metals were in the order of Zn (323.5 mg/kg) > Cu (70.5 mg/kg) > Pb (39.8 mg/kg) > Cr (33.4 mg/kg) > Ni (13.5 mg/kg) > As (9.4 mg/kg) > Cd (0.84 mg/kg) > Hg (0.092 mg/kg). The result of geoaccumulation indices indicated that Hg > Cr > Cu > Ni > Zn > As > Pb > Cd were found in order of severe contamination by heavy metals. From PLI and RI analysis, it was evident that the Suyeonggang 2 was the most contaminated river.

• Korean Journal of Environmental Agriculture
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• v.41 no.3
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• pp.177-184
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• 2022

BACKGROUND: Recently, the inflow of nonpoint pollutants into rivers caused by rapid urban and industrialization promotes the proliferation of algae, which causes eutrophication of rivers. This study was conducted to evaluate the seasonal variation of water quality characteristics and cryptomonads growth in the Oncheon River. METHODS AND RESULTS: The water quality and distribution characteristics of cryptomonads in the Oncheon River were investigated monthly for 12 months from January 2021. The cell number of cryptomonads was intensively developed in January-April, and it decreased sharply in the summer with heavy rainfall. In particular, cryptomonads moved to the downstream side of the river depending on the time, and as a result, significant differences were shown for each investigation point. The Korean trophic state index (Tsi_KO) in Oncheon River was classified as eutrophy all year round, indicating that cryptomonads can grow year-round. Distribution characteristics of cryptomonads in Oncheon River showed high correlations with DO (r=0.678), BOD (r=0.826) and chlorophyll-a (r=0.613) in water. CONCLUSION(S): In order to reduce cryptomonads in the Oncheon River, it is judged that a complex countermeasure considering the residence time, insolation and precipitation along with water quality factors is required.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.4
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• pp.275-282
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• 2009

PAHs(Polycyclic Aromatic Hydrocarbons) compounds may enter into the marine environment in a number of ways, and PAHs in coastal area and estuary adjacent to urban area and industrial activities region are mainly introduced into marine environment via atmosphere or river. The field surveys to evaluate the pollution of PAHs in rivers of Jinhae bay were carried out in August, 2008. The water samples collected from seven main rivers and Deokdong WWTP(Waste water Treatment Plant) which lead to Jinhae bay. 16 PAHs which had been selected as priority pollutants by EPA were analyzed. The range and mean of dissolved Total PAHs concentrations in the rivers and Duckdong WWTP that lead to Jinhae bay were shown to be 9.79~128.25(mean 36.94)ng/L, while the range and mean of Total PAHs concentrations in SPM(Suspended Particulate Matter) were shown to be 1,81434~8,893.37(mean 4,657.73)${\mu}g$/kg dry wt. The dissolved Total PAHs and Total PAHs in SPM were shown to be high concentrations in the Semhocheon which leads to Masan bay that is the most polluted area of Jinhae bay, while those were shown to be low concentrations at rivers which lead to the west area of the bay. The ranges and means of the loading fluxes from rivers and Duckdong WWTP were calculated at 0.06~12.05(mean 1.86)g/day for dissolved Total PAHs and at 0.12~16.00(mean 2.41)g/day tor Total PAH in SPM. The loading flux of Total PAHs from Duckdong WWTP was shown to be the greatest, occupying more than 80% of Total loading flux from all rivers and WWTP to Jinhae bay. The composition patterns of PAHs compound by the number of benzene ring between dissolved PAHs and PAHs of SPM were different each other. Low molecuar weight PAHs of dissoloved compounds were in high concentration, while high molecular weight PAHs of SPM were in high concentration. These results were due to physical and chemical characteristics of PAHs and were similar to those of other studies. The total PAHs concentrations of dissolved and SPM in this study are lower than those of other studies. The extent of PAHs pollution appeared to be not serious in reverine waters of Jinhae bay.

• Korean Journal of Ecology and Environment
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• v.43 no.1
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• pp.44-54
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• 2010

In this study, a comprehensive exploration and evaluation of washland candidate locations by means of field monitoring as well as spatial analysis in six major river system (Han, Nakdong, Nam, Geum, Youngsan, and Seomjin Rivers). Washland(in other words, river detention basin) is an artificial wetland system which is connected to streams or rivers likely to riverine wetlands. Major purpose of washland creation is to control floodings, water supply and purification, providence of eco-cultural space to human and natural populations. Characteristics and functions of riverine wetlands can be expected as well, thus it is believed to be an efficient multi-purpose water body that is artificially created, in terms of hydrology and ecology. Geographical information and field monitoring results for the washland candidate locations were evaluated in 2009, with respect to optimal location exploration, ecosystem connectivity and educational-cultural circumstances. A total of $269\;km^2$ washland candidate locations were found from spatial analysis (main channel of Rivers South Han, 71.5; Nakdong 54.1; Nam, 2.3; Geum, 79.0; Youngsan 46.4; Seomjin 15.7), and they tended to be distributed in mid- to lower part of the rivers to which tributaries are confluent. Field monitoring at 106 sites revealed that some sites located in the Rivers Nam and Geum is appropriate for restoration or artificial creation as riverine wetlands. Several sites in the Nakdong and Seomjin Rivers were close to riverine wetlands (e.g., Upo), habitats of endangered species (e.g., otters), or adjacent to educational facility (e.g., museums) or cultural heritages (e.g., temples). Those sites can be utilized in hydrological, ecological, educational, and cultural ways when evidence of detailed hydrological evaluation is provided. In conclusion, determination of washland locations in the major river basins has to consider habitat expansion as well as hydrological function (i.e. flood control) basically, and further utility (e.g. educational function) will increase the values of washland establishment.

• Journal of Environmental Impact Assessment
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• v.30 no.4
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• pp.225-236
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• 2021

The master plan for the Four Rivers Restoration Project (June 2009) was devised, the procedure of pre-environmental review (June 2009) and environmental impact assessment (Nov. 2009), and post-environmental impact survey were implemented, and 4 times audits also inspected. and finally the Ministry of Environment's Four Rivers Investigation and Evaluation Planning Committee proposed the dismantling or partial dismantling of the five weirs of the Geum River and Yeongsan River. But controversies and conflicts are still ongoing. Therefore, this study intend to reestablish the management plan for the four major rivers by reviewing and analyzing the process so far. The results are as follows. First, a cost-benefit analysis should be performed by comparing the water quality impact of weir operation and weir opening. Therefore, it is inevitably difficult to conduct cost-benefit analysis. Second, according to the results of cost-benefit analysis on the dismantling of the Geum River and the Yeongsan River, the dismantling of the weir and the regular sluice gate opening was decided. However, there is a problem in the validity of the decision to dismantle the weir because the cost-benefit analysis for maintaining the weir is not carried out. Third, looking at the change in water quality of 16 weirs before and after the Four Major Rivers Restoration Project, COD and Chl-a were generally deteriorated, and BOD, SS, T-N, and T-P improved. However, in the cost-benefit analysis related to water quality at the time of weir dismantling, only COD items were targeted. Therefore, the cost of BOD, SS, T-N, and T-P items improved after the project were not reflected in the cost-benefit analysis of dismantling weirs, so the water quality benefits were exaggerated. Fourth, in the case of Gongju weir and Juksan weir, most of them are movable weirs, so opening the weir alone can have the same effect as dismantling when the water quality deteriorates. Since the same effect can be expected, there is little need to dismantle the weirs. Fifth, in order to respond to frequent droughts and floods, it is desirable to secure the agricultural water supply capacity to the drought areas upstream of the four majorrivers by constructing a waterway connected to the weir. At present it is necessary to keep weirs rather than dismantling them.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.1
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• pp.58-66
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• 2014

Water pollution problems of urban rivers due to the urbanization and industrialization have been the subject of public attention. In particular, considering the fact that the characteristics of water cycle of each basin change dramatically through the development of new towns, a large number of concerns about future water quality have been raised. However, reasonable measures to predict future water quality quantitatively have not been presented by this moment. In this study, by the linkage of annual unit load generation based on long-term monitoring results of the ministry of environment (MOE) to a semi-distributed rainfall runoff model, SWMM (Storm Water Management Model), we proposed a new methodology to estimate future water quality macroscopically and testified it to verify its applicability for the estimation of future water quality of a small watershed at G new town. As a result of the estimation using Y-EMC (Yearly based Event Mean Concentration), future water quality were simulated as BOD 18.7, T-N 16.1 and T-P 0.85 mg/L respectively which could not achieve the grade III of domestic river life guidance and these criteria could be satisfied by the reduction of domestic wastewater discharge load by over 80%. The results of this study are shown to be utilized for one of basic tools to estimate and manage water quality of urban rivers in the course of new town developments.

• Analytical Science and Technology
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• v.15 no.2
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• pp.149-156
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• 2002

In this study, the levels of DEHA, carbaryl, and amitrole contained in the fresh water fishes and amphibians were determined. The 31 sampling sites were selected including 29 sites along the several rivers and 2 sites from the well-known wet lands. The rivers consists of the Han, Nakdong, Kum, Youngsan, and other small scaled rivers. DEHA was detected from 10 sites, but carbaryl and amitrole were not detected at any sites. The highest average concentration of DEHA was determined from the Kum River by $52.7{\mu}g/kg$. In the detected 10 sites, the average concentration of DEHA from fishes was $40.0{\mu}g/kg$, and that from amphibians was $8.90{\mu}g/kg$ which indicates that 5 times more DEHA was observed from fishes than amphibians. The detection frequency from fishes was 10/62 while that from amphibians was 2/62, and the highest concentration from fishes was $95.5{\mu}g/kg$ (crucians from Kongjoo) and that from amphibians was $12.1{\mu}g/kg$ (bullfrog from Najoo). Among the 10 detected sites, 6 sites were agricultural area and the other 4 sites were semi-urban area.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.4
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• pp.36-51
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• 2016

This study assessed urban flood risk using a Bayesian probability statistical method and GIS incorporating a climate change scenario. Risk is assessed based on a combination of hazard probability and its consequences, the degree of impact. Flood probability was calculated on the basis of a Bayesian model and future flood occurrence likelihoods were estimated using climate change scenario data. The flood impacts include human and property damage. Focusing on Seocho-gu, Seoul, the findings are as follows. Current flood probability is high in areas near rivers, as well as low lying and impervious areas, such as Seocho-dong and Banpo-dong. Flood risk areas are predicted to increase by a multiple of 1.3 from 2030 to 2050. Risk assessment results generally show that human risk is relatively high in high-rise residential zones, whereas property risk is high in commercial zones. The magnitude of property damage risk for 2050 increased by 6.6% compared to 2030. The proposed flood risk assessment method provides detailed spatial results that will contribute to decision making for disaster mitigation.

• Journal of the Korean Institute of Landscape Architecture
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• v.39 no.5
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• pp.101-110
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• 2011

The objective of this study is to classify the characteristics of green landscapes in suburban cities and identify methods for managing them. The study site is Matsudo city in the outskirts of Tokyo, Japan. All the greenery in Matsudo was categorized into different landscape patterns using spatial analysis and field surveys. Afterwards, assessments of green landscapes were conducted using questionnaire surveys and factor analyses. There are a variety of green landscapes in Matsudo, formed by a number of different reasons such as urban planning, topographical characters and socio-cultural environments. Twenty different green landscape patterns were identified in Matsudo. The survey concluded that green landscape patterns of parks and rivers in Urbanization Control Areas are more attractive than patterns of farmland or forest in residential areas. Three major factors influenced perceptions: legibility, intimacy and the locality on the landscape assessment. Urban farmland and urban forest are two characteristics of suburban cities, and these green landscapes relate to intimacy or localities in a regional image. Finally, based on the results of this study, some implications were discussed for a green master plan and green landscape management.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.481-489
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• 2017

The study area,Cheonan Stream, is an urban river that flows through urban areas in close proximity to densely populated areas and multi-use facilities. The natural river improvement project from 2006 to 2015 improved the quality of life of local residents with the improvement of river function, the restoration of the natural ecosystem and the securement of hydrophilic space. A bike way in the constructed waterside space was built focusing on trails. This study suggests improvements appropriate for insufficient bike way function-related regulations. The problems of ramps, river crossing facilities, stairway facilities, safety facilities, signs, road markings, and parking facilities, etc.have arisen in the utilization situation and citizen consciousness survey. As an improvement, it was suggested that 12% or fewer ramps should be improved, a submerged bridge should be installed at 7 places separated by stepping bridges, and signs and road markings according to bike way-related regulations should be installed and bike parking facilities at Cheonan station and Cheonan bus terminal should be expanded. The bike way in the waterfront of ChoenanCheon(river) will increase the accessibility and utilization rate of short-distance transportation with the institutional expansion of bike use facilities and work organizations and the improvement of facilities in accordance with urban rivers and bike-related regulations. Therefore, it is expected that the development of the living space will be beneficial for the citizens due to the elimination of traffic in the city and the activation of bike traffic.