• Journal of Environmental Science International
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• v.30 no.6
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• pp.487-500
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• 2021

To evaluate the geochemical characteristics and assess the pollution in surface sediments of the Nakdong River estuary, two sites adjacent to the estuary bank (Hh1 and Hh2) and one site at the upper part of the estuary bank (Hh3) were investigated. The surface sediments were analyzed for their contents of metals (Cu, Pb, Ni, Cr, Zn, and Al), organic matter (IL, COD, TOC, and TN), and grain size from 2018 to 2020. As a result of the pollution assessment, there was little anthropogenic contamination by most of the metals. The surface sediments in Hh2 had comparatively abundant silt and clay, whereas the other sites were mainly composed of sand. The organic index and contents of organic matter were highest at Hh2. Multivariate statistical analyses (cluster analysis and Pearson correlation analysis) showed that the contents of organic matter and pollution were associated with fine sediment. These results suggest that the geochemical characteristics were changed by the estuary bank built in the research area and that the increase in fine sediment attributable to the low-energy environment resulted in an increase in organic matter pollution.

• 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.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.154-159
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• 2001

Nakdong estuary is located at south-eastern coast of the Korea. A lot of sediment from upper river was deposited at this area. It has caused many problems such as changes in topography and tidal current. In this paper, field observation data on tidal currents and sediments were investigated as well as historical topographic changes by dredging and reclamation of the foreshore. Then, the numerical model considered the settling velocity of the suspended solids according to the particle size was applied to examine the characteristic of deposition. The results are as follows : 1. Changes of characteristics of deposition were caused by topographic changes of Nakdong estuary 2. Characteristics of deposition were influenced by river plume and tidal currents. 3. Numerical model which considers settling velocity reappeared distribution of deposition by particle-size. 4. Used model is only resonable for discussion in the quality, so, it is strongly suggested that the new model development is needed including the quatitative deposition processes.

• Ocean and Polar Research
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• v.29 no.1
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• pp.69-80
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• 2007

This paper attempts to measure the environmental value of the Nakdong-river estuary, which is ecologically important but confronted with the threat of development. Especially, in order to elicit the environmental values of its four attributes, contingent valuation method(CVM) based on multi-attribute utility theory is applied and the CVM survey was rigorously designed to comply with the guidelines for best-practiced CVM studies. We surveyed a randomly selected sample of 400 and 350 households in Busan and six large cities(Seoul, Incheon, Daegu, Daejeon, Gwangju, and Ulsan), respectively and asked respondents questions in person-to-person interviews about how they would willing to pay for the estuary conservation and management program. Respondents overall accepted the contingent market and were willing to contribute a significant amount(2,457 won in Busan and 3,560 won in six large cities), on average, per household per year, which implies that there exists a large difference between the two. The aggregate values of the Nakdong-river estuary in Busan and six large cities amount to 2.92 and 22.32 billion won, respectively, per year. In addition, expanding the values to Korea produces 51.34 billion won per year. The quantitative values can be utilized in planning and decision-making about development versus conservation of the estuary.

• Journal of Environmental Science International
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• v.17 no.12
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• pp.1331-1341
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• 2008

For providing basic data on estuary conservation and pattern of vegetation succession of sand bar, the flora of delta was investigated from March 2004 to August 2006 in the Nakdong River estuary of Korea. The flora in the eight surveyed areas was composed of total 159 taxa that belonged to 46 families, 123 genera, 133 species, 1 subspecies, 20 varieties, and 5 forms. Among them, naturalized plants and evergreen broad trees were 31 taxa and 5 taxa, respectively. The communities of main species at delta of estuary were composed of 16 species such as Rosa rugusa community, Scirpus triqueter community, Phragmites communis community, Carex kobomugi community, Digitaria ciliaris community. Especially, Rosa rugusa community which are important to establish the southern limit line of distribution as the northern factor was distributed through Jinwoodo. The succession of main vegetation community in the new delta (Doyodeung) was in order of Carex scabrifolia, Scirpus triqueter, Phragmites communis, Imperata cylindrica var. koenigii and Miscanthus sinensis var. purpurascens. Therefore, the succession order of the surveyed area seems to predict the pattern of the vegetation succession of another deltas in Nakdong River estuary.

• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.651-658
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• 2008

Estuary barrier is a hydraulic structure constructed to supply safely water as protecting chlorine penetration of sea water. However, the barrier brings about a problem which decreases original functions of estuary because hydraulic ecology was disrupted as obstructing natural water exchange between fresh water and sea water. It is important to supply Enough fresh water in the estuary ecosystem. But it is possible to reduce the problems brought from barrier throughout efficient water gate operation of estuary barrier. It was shown in this study that the environmental effect of estuary in Nakdong river was investigated according to the control of water level. Also, the basic information about the effective water gate operation was provided. The analysis results showed that the release rate of estuary was increased about 20% as changing the operational water levels. This helps supplying fresh water durably to the mixing zone. Also, CE-QUAL-W2 model was utilized to assess water quality. The values of BOD and COD were not changed in estuary area. From the result, it was analyzed the effect of water quality according to the water gate operation was not indicated.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.4
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• pp.372-389
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• 2008

In this study, we formed a detailed grid at the estuary area of the Nakdong and collected the surface sediments. Particle size analysis and comparison with existing data were conducted to investigate the characteristics of seasonal and long-term changes in the sediments. As a result of investigation, the distribution of the sediments showed a great change per season and was greatly influenced by the quantity of outfall discharge at the Nakdong estuary barrier and the incident wave climate. The sandy sediments showed dominant movement toward the front of Jinwoodo west of the estuary area of the Nakdong due to the influence of the ENE wave, the annually-dominant wave. And the muddy sediments showed deposition by being moved toward the deep open sea along with a current. The present conditions of the sediments at the estuary area of the Nakdong showed great differences from the results of previous studies.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.21 no.3
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• pp.91-102
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• 2016

The spatio-temporal variations of the dissolved methane concentration were investigated and the methane budget was estimated in the Nakdong Estuary in January, September, and November of 2014. Dissolved methane showed seasonal variation (21~874 nM) with high concentration in summer due to enhanced temperature and fresh water discharge. Decreasing trends of dissolved methane from the river to the estuary were consistent in all seasons showing the main source of the estuarine methane is river discharge. However, the decreasing trends were modified seasonally due to the local sources such as organic-rich sediments in intertidal zone or near the estuarine barrage. Dissolved methane concentration in the Nakdong Estuary was high, compared to other estuaries probably due to the well developed wetland in Nakdong-river system and stagnation effect from barrages and dams. Dominant sink for the Nakdong estuarine methane was outflux into the atmosphere. Relatively long residence time (produced by barrier island and estuarine dam) in the estuary might provide the enough time for the outgassing.

• Journal of Korea Water Resources Association
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• v.56 no.3
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• pp.165-171
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• 2023

The Nakdong Estuary Barrage is a tidal river environment where freshwater and seawater meet. This requires systematic monitoring of both surface water discharged from the estuary barrage and submarine groundwater discharge. In this study, upstream hydrograph and water balance analysis were used to calculate the change in water storage and discharge of the Nakdong Estuary Barrage. Submarine groundwater discharge was also calculated based on remote sensing-based digital elevation model data and hydrological modeling data, and compared with the estimated surface water discharge for analysis. Our proposed method can be efficiently applied to water resource management by utilizing remote sensing-based altimeter data other than field measurement. Because submarine groundwater discharge plays a significant role on the coastal environment as well as surface water discharge from an estuary barrage, studies on groundwatersurface water interactions in a river estuary should be sufficiently considered in monitoring the ecosystem of the Nakdong Estuary Barrage.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.22 no.4
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• pp.172-186
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• 2017

Current study is a part of the efforts to assess the estuarine barrage effects on the coastal ecosystem induced by the Si flux changes. Surface sediments from Seomjin and Nakdong estuary and sediment cores from Nakdong estuary was analysed to investigate the effect of estuarine barrage on the distribution of grain size, organic matter (loss on ignition: LOI) and biogenic silica (BSi). The samples of Seomjin estuary were collected in March, 2015 and those of Nakdong estuary were collected in November, 2014. Generally, the longitudinal distribution of grain size, LOI and BSi in Seomjin estuary, natural estuary, was gradually changed. However mud (silt and clay), LOI and BSi increased from station mid-estuary where tide reaches year-round. The distribution of grain size, LOI and BSi in Nakdong estuary, however, were entirely different between inside and outside of estuarine barrage. The mud percentage and LOI were low and consistent in inside of the barrage except R05, inside of right gate, yet those of outside of the barrage were higher and varied by adjacent sluices. Mud, LOI and BSi of ND1 and ND2 decreased immediately after the construction of Nakdong estuarine barrage due to disturbance of sediment and decrease of sediment supply. To exclude the physical effects by the barrage, BSi excess ($BSi_{exc}$) was calculated using regression equation of BSi-LOI and BSi-mud of Seomjin estuary. $BSi_{exc}$ of Seomjin estuary decreased gradually from upper estuary to lower estuary. $BSi_{exc}$ of Nakdong estuary were positive in inside of the barrage and negative in outside of the barrage. BSi retention and shift of species composition of diatom by the barrage would affect $BSi_{exc}$ distribution. Before the construction of Nakdong estuarine barrage, $BSi_{exc}$ of ND2 was negative and consistent owing to high mud sedimentation. After the construction, $BSi_{exc}$ of ND2, however, fluctuated due to continuous disturbance of sediment due to construction of Eulsuk bridge and East gate.