• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.102-108
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• 2012

This study has performed comparative analysis on characteristics of reservoirs in their use through correlation analysis on seasonal variation of water quality factors in agricultural reservoirs and multipurpose dams. Agricultural reservoirs show the high relationship between Chl-a and other water quality factors while the correlation among COD, BOD, and SS is strong in multipurpose dams. Agricultural reservoirs have the high relationship between various water quality factors in season such as Chl-a and pH ($R^{2}=0.294$) in Spring, pH and water temperature ($R^{2}=0.246$) in Summer, and Chl-a and BOD ($R^{2}=0.435$) in Fall, and between COD and BOD ($R^{2}=0.370$) in Winter, respectively, for Sapgyo reservoir while Chl-a and T-P ($R^{2}=0.739$) in Spring, T-P and SS ($R^{2}=0.876$) in Summer, and Chl-a and SS ($R^{2}=0.600$) in Fall, and between COD and SS ($R^{2}=0.998$) in Winter, respectively, for Seokmun reservoir. Boryeong dam has the strong relationship between T-P and SS ($R^{2}=0.511$) in Spring while the relation between COD and SS is high in other seasons with the values of $R^{2}$ of 0.362, 0.665, and 0.500 in Summer, Fall, and winter, respectively. The first and second water quality factors in relationship are COD and BOD in Sapgyo and Seokmun reservoirs, which is similar to the characteristics in Winter for multipurpose dams. Chl-a has no relationship with other water quality factors in Boryeong dam in operation for both flood control and low water regulation purposes. The result of this research is expected to provide contributions to the seasonal water quality control and analysis on characteristics for each reservoir by monitoring.

• Korean Journal of Environmental Biology
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• v.29 no.2
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• pp.107-112
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• 2011

The relationships between the phytoplankton community and sizes of reservoirs are investigated from 29 reservoirs in Yeongsan and Seomjin River Basins, Korea. As a microalgal flora, a total of 371 species of phytoplankton were identified. There were spatial and seasonal variations in standing crops and species diversity of phytoplankton. Statistical analysis showed that the size of reservoirs did not affect greatly on the community of phytoplankton. Species diversity and standing crops were higher in reservoirs of smaller surface area. However, there were no distinctive relationships between the size of basins of reservoirs and standing crops, species diversity, and chlorophyll $a$ concentrations. Relationships between the constructed years of reservoirs and standing crops, species diversity, and chlorophyll $a$ concentrations also showed very low level.

• Journal of Korean Society on Water Environment
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• v.20 no.4
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• pp.313-320
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• 2004

In this study, variable characteristics of drinking water and the influences on underground water reservoirs, rooftop water tanks, and service water pipes in the building were assessed. The influence of underground water reservoir material and water capacity on water quality also were assessed. The results are the following as; First of all, the drinking water passing through underground water reservoirs or service water pipes in the building, averagely metal component concentration more increased from percent of 41.3 to percent of 74.2 totally than other items of water quality. On the other hand, both residual chlorine and total solid highly decreased 65.6 percent and 35.3 percent, respectively. Therefore, it was thought that water quality could be getting worse for microorganism re-growth by residual chlorine reduction, and total solid also could be a cause for extraneous matters accumulated in water reservoir. Secondly, the variations on water quality of each stage for water supply system in the building were higher in water service pipes connected from rooftop water tanks to the tap than in underground water reservoirs. In addition to, among of twelve items on water quality, ten items on water quality except dissolved oxygen and residual chlorine increased. Therefore, it was thought that the influence of water service pipes connected from rooftop water tanks to the tap on water quality were higher than other stages of water supply system in the building. Thirdly, in case of materials of underground water reservoir, it was likely that the variation on water quality by stainless steel and concrete materials got some similar. In case of water capacity, the variations on water quality of underground water reservoirs over $1,000m^3$ higher than those under $1,000m^3$. That reasons was likely that the retention time(49.72 hours averagely) of underground water reservoirs over $1,000m^3$ was two times longer than it of those under $1,000m^3$(23.37 hours). Therefore, it was thought that the influence on water quality by materials were some similar, but in case of water capacity, the influence of underground water reservoirs were higher.

• Korean Journal of Ecology and Environment
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• v.37 no.2 s.107
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• pp.213-226
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• 2004

The present study was conducted to analyze the pattern of eutrophication of Korean reservoir with Chl. a concentration and morpho-physical parameters, and to valuate water quality characteristics of the classified types. The collected data from 486 reservoirs were classified as four types, with the Chl- a concentration (25 ${\mu}g\;L^{-1}$) and the ratio of water storage/surface area (mean depth, 7.5 m). According to OECD criteria and trophic state index based on Chl-a concentration, 34.3 and 72.8% of selected reservoirs appeared to be eutrophic, respectively. Characteristics of TYPE ll reservoirs generally showed high Chl-a concentration, relatively old age, small DA/LA ratio, short Hydraulic retention time, large paddy field and field to watershed ratio, and high pollutant loading compared to other types of reservoirs. The difference of TP concentration was greater than that of TN concentration in reservoir water among classified four types. Based on TN/TP ratio (by weight), phosphorus was limiting nutrient in all types and more closely related with Chl- a concentration than nitrogen. Significant decrease of Chl- a concentration with increase of TN/TP ratio observed only in reservoirs with Chl-a concentration > 25${\mu}g\;L^{-1}$. Although drainage area is believed to be a factor that is related to the generation load of pollutants in the watershed, it did not show any significant relationship with water quality parameters. Morphometric characteristics such as depth and age of reservoir as well as type of land use patterns in the watershed was among important parameters for the assessment of water quality characteristics in Korean reservoirs.

• Korean Journal of Ecology and Environment
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• v.55 no.2
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• pp.175-183
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• 2022

In this study, 46 reservoirs in South Korea were characterized based on heavy metal concentration in sediments. We analyzed the relationship between heavy metal concentrations, physicochemical water quality and hydromorphological factors in each reservoir. Study reservoirs were classified into five groups of reservoirs, by hierarchical cluster analysis based on the similarities of heavy metal concentration. Group 1 had the most severe sediment heavy metal contamination among the groups, whereas Groups 2 and 3 showed low levels of heavy metal contamination. Group 4 displayed high value of Ni, and Group 5 showed high contamination of Pb, Cu, Cr, Ni, and Hg. Groups 1 and 5, which had high concentration of heavy metals in sediments, showed a high density of mines in the catchment of reservoirs. Heavy metal concentration was high in reservoirs with large capacity or the ones located at higher elevation, and also highly related with number of mines in the catchment of reservoir. This study can contribute to the systematic management of sediment heavy metals in reservoirs.

• The Korean Journal of Quaternary Research
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• v.32 no.1_2
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• pp.1-29
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• 2018

We investigated the seasonal variation of diatoms from the modern bottom floor sediments of the reservoirs distributed in the southern part of the Korean Peninsula. The studied reservoirs include each three reservoirs from Southeastern part, Central Southern part and Southwestern part, respectively, to compare the dominant diatom assemblages that are ecologically controlled by local environments. In the Southeastern region, Aulacoseira spp., Fragilaria crotonensis, Fragilaria tenera, Gomphonema gracile, G. parvulum and Gyrosigma attenuatum were dominant species. Aulacoseira spp., Cymbella tumida, Cymbella turgidula, Diploneis finnica and Fragilaria crotonensis were dominant taxa in the Central Southern regions. In the southwestern region, Aulacoseira spp., Fragilaria crotonensis, Gomphonema parvulum and Stenopterobia curvular were predominated. Of which Aulacoseira spp. were predominant species at all reservoirs. In addition most of dominants are saproxenous taxa living in the clean water area, and the water quality of these reservoirs is considered to be less polluted water. As a result of seasonal comparison of diatom productivity, the first productivity is higher in summer than in winter. However, diatom valve abundance in the southeastern reservoirs was fewer from the samples collected at May than February.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.4
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• pp.437-444
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• 2004

To control algal bloom in reservoirs in Korea, artificial circulation systems have been applied. Diffuser block aeration systems have been increasingly used in Korean reservoirs especially for shallow ones. However, there has been no sound theoretical background for the design and operation of the system. Also there has not been sufficient post-installation studies to validate the effectiveness of the system. As a result, it has been repeatedly reported that the success of the system is not certain. Proper consideration on thermal stratification regimes of reservoirs and flow dynamics induced by bubble plumes are essential elements in design processes of the aeration system. This paper discusses the current methods in the design of diffuser type aeration system and suggests a new design method based on fluid mechanical theory. Example calculations were discussed using observed data of the Yeoncho Dam and it seems that the results represent the current situation successfully.

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.78-83
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• 2012

Man-made reservoirs over 95% in Korea are shallower than 10 meters in depth, which is apt to cause eutrophication. This study has characterized long-term trends in water quality factors for the selected six reservoir points in the Kum River watersheds, and then estimated the seasonal trophic state index for each reservoir. The reservoir trophic state was evaluated at four trophic levels using the Korean trophic state index, TSIKO. It is observed from seasonal results for six reservoirs that the highest value of the trophic state index is estimated in summer while the trophic state index value is low in spring and winter seasons. Especially, the Boryeong Lake has a relatively lower trophic state index since this reservoir has been managed properly for water withdrawal and irrigation. It is expected that the seasonal trophic state index resulted from this study can contribute toward long-term water quality improvement plans for reservoirs.

• Journal of Microbiology
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• v.42 no.3
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• pp.181-187
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• 2004

Cyanobacteria are the dominant phototrophic bacteria in water environments. Here, the diversity of cyanobacteria in seven Korean reservoir waters where different levels of algal blooms were observed during the summer of 2002, was examined by T-RFLP analysis. The number of T-RF bands in the HaIII T-RFLP profiles analyzed from those water samples ranged from 20 to 44. Of these, cyanobacteria accounted for 6.1 to 27.2％ of the total bacteria. The water samples could be clustered into 2 groups according to the Dice coefficient of the T -RF profiles. The eutrophic Dunpo and oligotrophic Chungju reservoirs were selected, and several representative clones from both reservoir waters analyzed for the nucleotide sequences of their 16S rDNA. The major clones were found to belong to the Microcystis and Anabaena species in the waters from the Dunpo and Chungju reservoirs, respectively, which was in agreement with the T-RFLP result. That is, the Microcystis and Anabaena species were dominant in the eutrophic and polluted Dunpo and oligotrophic Chungju reservoir waters, respectively. These results indicated that there is a correlation between prevalence of cyanobacterial species and levels of pollution in reservoir waters.

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.5
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• pp.73-80
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• 1995

The uses of stage-storage curve function are diverse in irrigation reservoirs. The curve functions would be used to determine the optimal size of spillway length and the inundation area above full water level based on the flood routing in reservoirs. In addition, the curve function would he used to transform the stage to the storage for the reservoir water management, in which the storage is the supply water. Besides those, the curve is necessary for the planning of dredging, the estimation of the effective and the dead storage, the drought management by reservoir, etc. The curve function data, however, are almost unavailable for these purposes. According to the statistics, about 74% of the 2, 900 resevoirs which are maintained by Farm Land Improvement Association have no more effective data. Therefore, the simulation of the curve function could be better alternative. The curve functions were simulated derivating the regression equations based on the basin relief ratio and the effective depth. The results of the verification show the enough reliability of the application to generate the curve function in some reservoirs which do not have the surveyed stage-storage data. Also, even though the averaged curve function would be applicated without the basin relief ratio data, the result shows that the simulated curve is closer to the real one than the linear function by only the existing effective storage data.