• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.1
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• pp.89-96
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• 1993

The conventional water budget analysis methods for major water works do not take the spatial variation of available water resources into account. There has also been a tendency of over-estimation of water supply capacity when a significant inter-basin water transfer is involved. Therefore, a revised water budget analysis methodology is proposed which can take care of the spatial variation of the water resources available within the basin and with the inter-basin transferable water. For the purpose of present study, the Saemangeum project area is taken for the analysis, which includes both the Dongjin and the Mangyungs River basin, one of the regions with the most complex water utilization.

• The Korean Journal of Zoology
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• v.36 no.4
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• pp.535-544
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• 1993

Sinca early 1930' Colitis taenia striate were introduced to the Donsgjin in Chollabukdo, where it hybridized with an endemic subspecies C. tiutheri. Protein electrophoresis revealed high levels of hybridization with intensive backcrossing occupied approximately 20 kilometers of the river. This is roughly one-half of tech historic range of the endemic species. The average frequency of introduced alleles of three diagnostic loci ranged 0.03-0.46 among 11 sites in tech svrnpatric area. Clinal patterns in allele frequencies suggest C. tiutheri were introduced in an upper reaches of the Dongjin and downstream dispersal of the introduced alleles followed. There is little linkasedisequilibrium between the diagnostic loci, suggesting the nuclear genomes of tech two subspecies are randomly associated. The evidence presented here and previously supports recognition of C. t. striata and C. t. lutheri as the typical subspecies.

• Ocean and Polar Research
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• v.30 no.4
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• pp.509-518
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• 2008

Distribution of bacterial abundance and production was investigated in seawater around Saemangeum dike 7 times during March, $2007{\sim}July$, 2008. In the inner area of the dike, salinity variation was great due to river runoff from Mangyung and Dongjin Rivers and high chlorophyll a (chl a) concentrations up to $124.3{\mu}g\;l^{-1}$ was found. In the outer area of the dike, salinity was higher than in the inner area of the dike, and chl a was lower up to 10 times than in the inner area of the dike. Thus, the area of Saemangeum showed meso- to hypereutrophic conditions. Bacterial abundance and production ranged from 0.3 to $4.3{\times}10^9\;cells\;l^{-1}$ and from 5.2 to $570 pmol\;l^{-1}h^{-1}$ in outer area of the dike, respectively, while in the inner area of the dike bacterial abundance and production was 3 to 4 times higher ($0.4{\sim}12.7{\times}10^9\;cells\;l^{-1}$ and $12.3{\sim}1309\;pmol\;l^{-1}h^{-1}$, respectively) than those in the outer area. In both areas, bacterial abudance and production was highest in summer and lowest in winter. However, the variations of bacterial parameters was very large in each season. These large variations seemed to be related with the supply of organic matter. Bacterial abundance and production showed significant negative correlations with salinity in the inner area, suggesting that allochthonous organic matter input by river runoff could be an important factor in regulating the distribution of bacterial abundance and production. In addition, bacterial production also correlated positively with chl a in the inner area, suggesting that autochthonous substrate might be another regulating factor of bacterial growth in the area. These results suggest that the supply of both allochthonous organic substrates introduced by river runoff and autochthonous substrates produced by phytoplankon could be important in regulating bacterial growth and utilization of organic matter in the area. Thus, to manage water quality in the inner area of dike, it seems to be important to lower the load of both organic and inorganic nutrients from adjacent rivers.

• Journal of Korea Water Resources Association
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• v.35 no.4 s.129
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• pp.425-442
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• 2002

The land reclamation area of Saemangeum(Kunsan) is located between $126^{\circ}10'\;E{\sim}126^{\circ}50'\;E\;and\;35^{\circ}35'\;N{\sim}36^{\circ}05'\;N$ at the western coast of the Korean peninsula. The reclamation area of Saemangeum has a range of 5.6m spring tide and the maximum tidal current speed is about $1.41m\;s^{-1}$. In ordinary spring tide. Most of the sediments deposited on the tidal flats are transported from the Geum river, the Mankyung river and the Dongjin river. The soil in this area consists of silty sand with the depth of 10m to 30m. The wind in winter is strong from the direction of northwest. Saemangeum coastal area is being constructed 33km the sea dike and 40,100ha reclamation area. The purpose of this study Is to find the residual circulations in four seasons before and after the dike construction by a robust diagnostic and prognostic numerical model.

• Korean Journal of Ecology and Environment
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• v.51 no.1
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• pp.60-70
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• 2018

The distribution of benthic macroinvertebrates was investigated at 1,157 sites of 7 main water systems in Korea, including 442 sites of Han River system (Namhan River, Bukhan River, Han River main stream, Anseongcheon, etc.), 305 sites of Nakdong River system (Nakdong River, Hyeongsan River, Taehwa River, etc.), 199 sites of Geum River system (Geum River, Sapgyocheon, Mangyeong River, Dongjin River, etc.) 102 sites of Seomjin River system (Seomjin River), 102 sites of Yeongsan River system (Yeongsan River, Tamjin River, etc.), and 7 sites of Jeju stream system. A total of 151 families were found in the whole survey sites, including 141 families in Han River, 122 in Nakdong River, 115 in Geum River, 106 in Seomjin River, 113 in Yeongsan River, and 50 in Jeju. Chironomidae (20.8%) was the most dominant species in Korea, followed by Hydropsychidae (17.1%), Baetidae (12.6%), Tubificidae (10.3%), Heptageniidae (8.6%), Ephemerellidae (6.3%), Asellidae (2.7%), Leptophlebiidae (2.4%), Planariidae (1.7%), and Tipulidae (1.6%). Substrates compositions consisted of large sand (22.6%), large gravel (18.4%), silt (10.5%), and boulder (8.2%). The mean stream width was 133.5 m and the mean watercourse width was 61.7 m. The mean water depth and velocity were 30.2 cm and $33.1cm\;s^{-1}$, respectively. Results of cluster analysis based on distributional characteristics of benthic macroinvertebrates were divided into six groups according to the frequency of benthic macroinvertebrate taxa which appeared in the study area. Finally, altitude, current velocity and substrate composition were the most influencial factors determining the distribution patterns of macroinvertebrate communities.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.4
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• pp.258-271
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• 2010

In order to figure out hydrodynamic and water quality changes after completion of dike construction of the Saemangeum, which behaves as a semi-enclosed estuarine lake, numerical simulations based on fine grid structure by using EFDC were intensively carried out. In this study some limitations of precedent study has been improved and gate operation were considered. Also 3 phases such as air-water-sediment interaction modeling was considered. It is clear that inner mixing of the Saemangeum is dominated by Mankyeong and Dongjin riverine discharges rather than the gate opening influence through the Lagrangian particle tracking simulations. Vertical DO structure after the dike completion shows steep gradient especially at Dongjin river estuary due to lessen of outer sea water exchange. Increasing SOD at stagnantly changed man-made reservoir might cause oxygen deficiency and accelerating degradation of water quality. According to TSI evaluation test representing eutrophication status, it shows high possibility of eutrophication along Mankyeong waterway in spite of dike completion, while the index is getting high after final closing along Dongjin waterway. Numerical tests with gate operations show significant differences in water quality. Thus it should be noted that proper gate operation plays a major role in preserving target water quality and management for inner development plan.

• Korean Journal of Weed Science
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• v.2 no.2
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• pp.169-174
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• 1982

The distribution of major aquatic weeds in irrigation and drainage canals along Dongjin river and the degree of infestation of aquatic weeds were investigated throughout Korea, and chemical control of aquatic weeds was also studied. The major aquatic weed species in irrigation and drainage canals along Dongjin river were Leersia japonica, Ceratophyllum demersum, Zijania latifolia, Nuphar japonicum, Phragmites communis, Vallisneria asiatica, Trapa natans, Myriophyllum verticillatum, and Potamogeton crispus. Zijania latifolia, Phragmites communis, and Leersia japonica were troublesome weeds among emerged weeds throughout Korea. Caratophyllum demersum was most serious weed and Myriophyllum verticillatum, Potamogeton crispus, Vallisneria asiatica, and Potamogeton oxyphyllus were also heavily infested among submerged weeds. Leersia japonica was controlled by paraquat at 73.5g/10a glyphosate at 91.5g/10a, and fluridone at 74.7g/10a, Zijania latifolia by paraquat at 220.5g/10a, glyphosate at 366.0g/10a, and fluridone at 74.7g/10a, and Ceratophyllum demersum and Potamogeton crispus by 2,4,5-TP at 540g/10a and fluridone at 1008/10a.

• Korean Journal of Environmental Biology
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• v.37 no.2
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• pp.177-188
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• 2019

The objective of this study was to analyze the distribution patterns of two exotic disturbing fish species (largemouth bass, Micropterus salmoides and bluegill, Lepomis macrochirus), their physical habitat features, and chemical water qualities from 13 sites of Dongjin River. The relationships between the fish distributions and water chemistry and physical habitat characteristics (i.e., bottom substrate) were evaluated by comparing dominant vs. absent regions of largemouth bass and bluegill. The relative abundance of the two species decreased sharply with decreased in the water quality in terms of BOD, PO₄-P and pH, but not with NO₃-N and conductivity. The bluegill showed no difference in habitat preference between the two regions with regard to the bottom structure, while the largemouth bass had significant differences in the bottom structures of silt, coarse gravels and boulders. The dominant species were Zacco platypus (14.6%), Lepomis macrochirus (14.0%), and Micropterus salmoides (9.8%) in the order of relative abundance, indicating that exotic species (24% in total) dominated the fish community, perhaps ensuing large ecological disturbances on the ecosystem. In conclusion, the results of this study suggest that the distribution of the two exotic species may be largely influenced by water quality of organic matter and nutrient pollutions.

• Journal of Korea Water Resources Association
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• v.48 no.12
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• pp.1065-1075
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• 2015

In the estuary where the structure such as river-mouth weir has been installed, the flow is developed very complicatedly due to river water from upstream, tide of the sea and floodgate operation. Especially, if basin outlets more than one exists in one estuary, the boundary conditions will be significantly more complex form. Saemangeum(SMG) project area in Korea is the most typical example. There are Mankyung river and Dongjin river in upstream. The water of them inflows into SMG project area. In the downstream, river flow was drained from inland to sea over the SMG sea dike through the sluice. The connecting channel was located between Mankyung and Dongjin basins. It functions not only as transportation by ship in ordinary period but also as flood sharing by sending flood flow to each other in flood period. Therefore, in order to secure the safety against flood, it is very important to understand the flood sharing capacity for connecting channel. In this study, the flood control effect was analyzed using numerical simulation. Delft3D was used to numerical simulation and simulated period was set up with neap tide, in which the maximum flood stage occurred due to poor drainage. Actually, three connecting channels were designed in land use plan of the SMG Master Plan, but they were simplified to a single channel for conciseness of analysis in this study. According to the results of numerical analysis, the water level difference between two basins was increased and the maximum flood stage at dike sluice was also upraised depending on decrease of conveyance. And the velocity induced by same water level difference was decreased when the conveyance became smaller. In certain conveyance above, there was almost no flood control effect. Therefore, if the results of this study are considered for design of connecting channel, it will be expected to draw the optimal conveyance for minimizing dredging construction cost while maximizing the flood control effect.

• Korean Journal of Environmental Biology
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• v.38 no.1
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• pp.146-159
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• 2020

The objective of our study was to analyze the distribution and composition of fish species and their community characteristics in agricultural waterways in the six water systems-Mankyung River, Seomjin River, Namhae Region, Tamjin River, Yeongsan River, and Dongjin River-during 2017-2018. Little is known about the distributions and community characteristics of the aquatic biota of agricultural waterways in Korea, even if the water bodies have important roles as spawning areas or habitats for fish. In this study, we identified 3,633 fish individuals in the waterways, belonging to 53 species, eleven families, and six orders (dominant species: Tanakia koreensis, T. lanceolate) and 7,108 fish individuals in the main rivers, belonging to 57 species, fifteen families, and nine orders. Moreover, three endangered wildlife (designated by the Ministry of Environment, Korea)-T. somjinensis, Acheilognathus majusculus and Coreoperca kawamebari-were found in the waterways. By fish guild analysis, we found that many waterways had a lower proportion of sensitive species and a higher proportion of omnivore species than those of the main rivers, which indicates a feature of a disturbed environment. In addition, by grouping with environmental variables, we found the group of waterways with high substrate complexity had a higher diversity index (Shannon index) and a lower dominance index (Simpson index) than that of simple substrate complexity. Overall, our study represents the characteristics of fish habitats in agricultural waterways and suggests the need to manage them and study further.