• Korean Journal of Environmental Biology
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• v.36 no.4
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• pp.665-671
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• 2018

This paper represents an investigation into the pattern of carbon transportation and composition on an open estuary in the transition zone between the river and marine environment in Tamjin River where stream water flows into the Gangjin Bay. To conduct the study, seven plots were established along an environmental gradient from river and estuary to the ocean. Surface water samples were collected thrice during the summer rainfalls and non-flooding seasons in 2017. The samples were then measured for the concentrations of dissolved organic carbon ([DOC]), particulate organic carbon ([POC]) and dissolved inorganic carbon ([DIC]). An analysis of the results showed that [POC] did not increase in the river even during the summer rainfall. However, [DOC] increased resulting in a higher [DOC]:[POC] ratios for the non-flooding season compared to summer rainfall events. On the other hand, the marine site of the estuary bay showed the highest [DIC] which was stable relative to those of river sites. The results suggest that in an open estuary zone, river and ocean supplied the open estuary zone with different types of carbon materials; mainly DOC supplied from the river and DIC sourced from the ocean.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.161-166
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• 2004

Research for deposits in Nakdong eatuary that research about Nakdong eatuary's sediment flows out in Nakdong-kang so far had been progressed but research about deposits that is flowed in open sea is insufficient. Observed Nakdong eatuary's characteristic of sediment transfer through observation during the second during Buteo 20 days on February 6, 2004 in this research Resuspension bed load Flux appeared high the first result St.4 point and St.5 point. St.4 branch had much bed load amount that is flowed in the east, and bed load that St.5 branch is flowed in the south appeared much Tendency such as the first showed in the second result, but compare with the first result and St.5 branch had much bed load that is transfer in end. Bed load that is transfer in observation result Nakdong river was less. As this, can know that amount of sediment that is transfer in open sea more than deposits that is transfer in Nakdong river is much Is expected to exert effect that deposits that is transfer in open sea is high in Nakdong estuary's topography change. Specially, observation result is expected that Nakdong estuary's deposition tendency becomes Jinwoodo southern and Shinho southern.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.2
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• pp.53-69
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• 2011

Classification of estuaries based on their multi-component and multidisciplinary processes is important for the systematic management of estuaries. In this study, an integrated GlS-based analysis system including high resolution aerial photographies and topographic maps was used to classify 463 estuaries based on estuarine circulation pattern, geomorphological feature, natural habitat distribution and characteristics of land use. These estuaries were divided into two basic types, open and closed. Two hundred and thirty five systems were open estuaries comprising of forty one mountainous type (OM), eighty sevcn sandpit type (OS) and one hundred seven funnel type (OF). Each type of open estuary was further classified into three types based on habitat distribution and land use characteristics resulting in total ninc types of open estuaries. Two hundred and twenty eight estuaries were closed systems comprising of one hundred and forty four blocked type (CB directly) and eighty four lake type (CL, indirectly). CB type estuary was further classified into three types based on habitat distribution and land use characteristics. This estuarine classification scheme can be applied to provide a framework for effective management strategies of individual estuaries to estimate the management priority and strategy.

• Journal of Ocean Engineering and Technology
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• v.9 no.1
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• pp.120-131
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• 1995

Numerical simulations on the suspended sediment transport in the Nakdong Estuary are carried out Uncoupled flow model and diffusion model of which the governing equations are two-dimensional depth integrated equations are used int his study. Four cases are tested in this numerical simulations in which the Gaduk waterway open boundary condition and Nakdong Estuary barrage boundary condition are considered as the boundary conditions. The simulated results are compared with the measured data which were obtained by NEDECO at hadan site on 1981.2.19. and by Dong-A university at one station in the study area on 1993.4.3. and show a good agreement with them. The construction of the Nakdong Estuary Barrage may affect to reduce the current near Jinudo an Daemadeung and the suspended sediment inflowed from the upstream in the wet season seems to be transported to the Dadae.

• Journal of Ocean Engineering and Technology
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• v.32 no.3
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• pp.192-201
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• 2018

In this study, a qualitative evaluation of the morphological changes in the seabed surrounding Jinwoo-Island due to the construction of the new Busan port were determined through a numerical simulation. Various scenarios for the discharge of the Nakdong river estuary dam and construction stage of the new Busan port were established and utilized for an indirect and qualitative investigation through simulation using the numerical model implemented in this study. It was concluded through a qualitative study that the morphological changes in the seabed surrounding Jinwoo-Island were typical estuary seabed changes due to the discharge of the Nakdong river estuary dam and waves from the open sea. The effects from the construction of the new Busan port were relatively small.

• Ocean and Polar Research
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• v.31 no.3
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• pp.239-246
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• 2009

Long-term observations were conducted between 1997 and 2002 to examine the variability of the vertical temperature structure in the Youngsan Estuary, southwest Korea, in summer. The observed hydrographic data revealed that the temperature minimum layer in the middle depth persisted through the entire summer of 2000 but was rarely observed in other years. The variability in the vertical structure might be affected by the air temperature during the previous winter and the density difference between the open sea and the estuary. In 2000, the air temperature in the previous winter was lowest and the horizontal density difference during summer was largest. The large horizontal density difference probably produced more active driving of warm water along the bottom, which would have intruded into the Youngsan Estuary. Furthermore, the cold previous winter would have provided a better condition for maintaining cold temperatures in the middle water layer for a longer period.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.2
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• pp.113-123
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• 2005

Samples were collected to investigate the effect of salinity change on biological interaction between primary producers and herbivores in water column of the Youngsan estuary (Mokpo Harbor) at 8 stations from October 2003 to September 2004. The highest river freshwater inputs were introduced into the estuary from the Youngsan dike during summer (June and July 2004). Ranges of salinity were between 6 and 28.9 psu when the gates of dike were open whereas the ranges were between 24.4 and 30.3 psu when the gates were closed. Algal bloom occurred in February and July when the gates were not open at the upper region of the Youngsan estuary and the bloom was dominated $(70\%)$ by large cells of phytoplankton $(micro-sized;>20{\mu}m).\;Nano-sized (2-20{\mu}m)$ and pico-sized phytoplankton $(<2{\mu}m)$ were dominant in October, November 2003, June, August and September 2004 when the gates were open suggesting that size structure was affected by river discharge from the dike. Micro-and meso-zooplankton (herbivores) displayed the similar pattern to that of phytoplankton. The biomass of zooplankton was higher when the gates were closed than when the gates open and also the biomass was higher at the upper region of the harbor system. This results suggest that freshwater inputs affect size structure and biomass of phytoplankton by changing salinity, nutrient inputs, turbidity or light level In water column resulting in the change of the interaction between primary producters and herbivores in the Youngsan estuary.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.49-59
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• 2022

Total of 325 estuaries in Korea were surveyed to analyze the effect of presence of sluice gate on the estuary environment and fish community from 2016 to 2018. Fish community in closed and open estuaries showed differences generally, and the relative abundance (RA) of primary freshwater species in the closed and migratory species in the open estuaries were high. The result of classifying species by habitat characteristics in closed and open estuaries showed similar tendencies at the estuaries of south sea and west sea. The relative abundances of primary freshwater species in the closed estuaries at the estuaries of south sea and west sea were the highest, but estuarine and migratory species were high in both closed and open estuaries at the estuaries of east sea. Primary freshwater species showed higher abundances in the closed estuaries with reduced salinity due to blocking of seawater since they are not resistant to salt. However, primary freshwater species in open estuaries at east sea was higher than that of the closed estuaries, which is considered to be the result of reflecting the characteristics (tide, sand bar, etc.) of the east sea. Korea Estuary Fish Assessment Index (KEFAI) was showed to be higher at open estuaries than closed in all sea areas (T-test, P<0.001), the highest KEFAI was observed in closed estuaries at south sea, and open estuaries in east sea. Fish community of closed and open estuaries in each sea areas showed statistically significant differences (PERMANOVA, East, Pseudo-F=3.0198, P=0.002; South, Pseudo-F=22.00, P=0.001; West, Pseudo-F=14.067, P=0.001). Fish assemblage similarity by sea areas showed a significant differences on fish community in closed and open estuaries at east sea, south sea, and west sea (SIMPER, Group dissimilarity, 85.85%, 88.36%, and 88.05%). This study provided information on the characteristics and distribution of fish community according to the types of estuaries. The results of this study can be used as a reference for establishing appropriate management plans according to the sea areas and type in the management and restoration of estuaries for future.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.2 no.1
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• pp.1-10
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• 1990

Experimental studies oil the density currents were made in order to investigate their hydraulic conditions in the estuary. Interfacial forms in the flow direction became sharply with increasing densimetric Froude number in the estuary which arrested saline wedge exists. Interfacial thicknesses were almost constant in the open channel, while they abruptly increased out of channel and they also decreased as overall Richardson number increases. Densimetric Froude number of river mouth showed that it was not necessarily 1.0 and varies with the upper layer thickness. On the other hand, water level there tended to increase with increasing relative densities. It is observed in the Sumjin River Estuary that a strong density front has been formed between freshwater and ocean waters.

• Journal of the korean society of oceanography
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• v.38 no.2
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• pp.80-86
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• 2003

The horizontal distributions of $^{224}Ra$ (half life=3.4 days) and $^{223}Ra$ (half life=11.3 days) were measured in surface seawaters of the Nakdong River estuary and the South Sea of Korea in April and October 2002. In order to determine these short-lived Ra isotopes, we used a delayed coincidence counter which is much more rapid and accurate than traditional methods. In an estuarine mixing zone (salinity, ~l6 ppt), the activities of $^{224}Ra\;and\;^{223}Ra$ were much greater than what would be expected from a mixture of freshwater and seawater in the Nakdong River estuary. This excess Ra may be a result of Ra desorption from fresh sediments originating from the river upstream. However, in the more open areas of the Nakdong River estuary (salinity>30 ppt) and the South Sea of Korea, $^{224}Ra\;and\;^{^{223}Ra$ activities decreased exponentially as a function of distance offshore. Using the decrease of $^{223}Ra$ with distance offshore in the South Sea of Korea, we estimated the apparent horizontal eddy diffusivities. The apparent eddy diffusion coefficients in South Sea of Korea are calculated to be approximately $3500-8000\;\textrm{m}^2/sec$.