• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.1
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• pp.13-20
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• 2013

An emergy concept was used to evaluate the contributions of the Youngsan River Estuary to the Korean economy from systems and ecosystem service perspectives. Total emergy input to the estuary was $9.42{\times}10^{20}$ sej/yr with the chemical potential of river inflow accounting for 73% of the total and tidal energy for the remaining 27%, reflecting the unique environmental characteristics of estuaries where rivers meet sea. From the systems perspective, the estuary ecosystem contributed 179.9 billion em\/yr (14.91 million em\/ha/yr or 13,526 em$/ha/yr). Four ecosystem services of the Youngsan River Estuary were selected for the emergy evaluation: fishery production, pollutant removal, aesthetic function, and scientific research information. Aesthetic function contributed the most to the Korean economy with 179.9 billion em\/yr, followed by fishery production (101.1 billion em\/yr), pollutant removal (32.6 billion em\/yr), and scientific research information (934 million em\/yr). Emergy-based values of the selected ecosystem services of the estuary were higher than those calculated by economic methodologies.

• Journal of the Korean Society of Marine Environment & Safety
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• v.14 no.2
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• pp.119-125
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• 2008

The aim of this study was to determine the characteristics of wave transformation in the shallow water of the Nakdong River estuary due to variations in air pressure, air temperature, wind speed, and wind direction. We analyzed the correlation between weather factors and wind waves in offshore regions near Geoje Island and the Nakdong River estuary in April and May 2007. The weather and wind wave data were obtained from the automatic ocean observation buoy near Geoje Island operated by the Korean Meteorological Administration (KMA). For the estuary region, the wind wave information was the result of field observations, and weather data were obtained from the Busan Meteorological Station. Field observations of water waves in April and May showed that the maximum wave height decreased by about 2.2 m. M oreover, wave height decreased significantly by about 1.3 m due to the reduction in wave energy caused by the water waves propagating from Geoje buoy to the Nakdong River estuary. We conclude that offshore or wind waves coming into the Nakdong River estuary showed considerable height variation due to the prevailing weather conditions, especially wind speed and direction. In particular, headwinds tended to decrease the wave size in inverse proportion to the wind speed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.2B
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• pp.109-119
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• 2011

In this study, the flow characteristics of Han River Estuary were investigated by using a two-dimensional numerical model according to the assumption of shift and modification of the Shingok submerged weir. The two-dimensional analysis has contributed to our understanding of the hydraulic effects induced by shift of the weir on the topography, especially wetlands. The tide and flow discharge of 2007 were adopted as an input data for the simulation. The tidal data contained both spring and neap tide, and the flow discharge condition was divided into monsoon and normal seasons. The boundaries of this study were Hangang Bridge, Tongil Bridge, and Yu island. The simulation results showed that influence area of seawater changed depending on the weir shift, and the water level at particular station fluctuated according to the condition of tide and flow discharge.

• Ocean and Polar Research
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• v.27 no.2
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• pp.135-148
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• 2005

Macrobeilthic fauna were collected using a van Veen grab $(0.1m^2)$ to investigate the spatial characteristics of the macrobenthos community at 28 stations near the Nakdong River estuary, Southeast Korea, in September 2001. A total of 203 species were sampled with a mean density of $1,554 ind./m^2$ and a biomass of $252.3 gWWt/m^2$. Annelids were the dominant faunal group in terms of species and density, with 68 species and a mean density of $1,031ind./m^2$, which comprised 33.5% and 66.3% of the total benthic animals, respectively. Based on density, three Polychaetes were dominant Tharyx sp· $(420ind./m^2)$, Lumbrineris longifolia $(143ind./m^2)$, and Sternaspis scutata $(118ind./m^2)$, along with a bivalve Theora fragilis $(129 ind./m^2)$. On cluster analysis, the benthic community was classified into four groups based on the species composition: Group-1 occurred in disturbed areas, Group-II in coastal regions, Group-III in central mariculture grounds, and Group-IV offshore. Environmental factors (mean gain size, organic carbon, and depth) were primarily correlated with the macrobenthos community structure. A benthic pollution assessment based on the macrobenthos community structure showed that Group-I and Group-II were located in a coastal area that had been severely disturbed by construction of Busan new port and various pollutants, Group-III was gradually polluted, while offshore Group-IV was the most stable.

• Journal of Environmental Science International
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• v.32 no.12
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• pp.943-953
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• 2023

This study analyzed the ecological characteristics of the wetland protection area at tthe Nakdong River through vegetation and biota surveys, which showed that brackish water meets fresh water, a unique ecological environment has been created, biodiversity is high, and diverse habitats are distributed. Eleven plant communities, including four woody communities and seven grass communities, are distributed along the coast, and a total of 514 species, including 11 endangered wildlife species, were identified in terms of species diversity. Among them, the species diversity of the Eulsuk-do area was found to be relatively higher than that of other Barreir Islands areas. The presence of a population of Sterna albifrons on Sinja-do and a population of Eremias argus on Jinwo-do, an area outside the boundaries of the wetland protection area, confirmed the conservation value of the wetlands and the need to expand the boundaries of the wetland protection area. It is judged that this information can be used as basic information for a systematic conservation and management plan for the wetland protection area at the Nakdong River Estuary and as basic data to support the establishment of a policy.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.5
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• pp.383-392
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• 2011

The basic research of the estuarine circulation at Gyeong-Gi bay has not been well studied up to now, although coastal development pressures have been continuously increased. To understand the oceanographic phenomena at the Han River estuary, it's essential to understand the propagation characteristic of tidal wave which is the strongest external forcing in this region. In this study, we investigate the tidal wave propagation characteristics along the 3 major channels using observation data and numerical model. It is found that 3 channels are all hyper-synchronous and the most important physical factor controlling the tidal wave propagation is topographical convergence of estuary shape and friction. The result of analytic solution at ideal channel considering the topographical convergence and friction show that the contribution of physical role of convergence and friction varies at 3 different channel. And the ratio of convergence and friction at Yeomha channel is four times larger than Seokmo channel. Because of this effect, the location of maximum amplitude at Yeomha channel is showed up downward than Seokmo channel. The ratio of decreasing amplitude and increasing phase per unit distance between stations is bigger than Seokmo channel. Although 3 major channel show a hyper-synchronous pattern, Yeomha shows more frictionally dominant channel and Seokmo channel is more dominantly affected by convergence effect.

• Economic and Environmental Geology
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• v.33 no.5
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• pp.417-424
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• 2000

We applied SP monitoring and resistivity surveys using the pole-pole electrode array to seawater leakage problems in the Youngsan estuary dam and the Eoeun embankment to estimate and detect the zone of seawater leakage. The embankment is generally affected by tidal variation and has low resistivity characteristics due to the high saturation of seawater. For this reason, SP monitoring and the pole-pole array resistivity surveys, which are relatively more effective to the conductive media, were carried out to delineate the leakage zones of sea water through the embankment. We checked out electrical conductivity (EC) and temperature variations along the inner part of Youngsan estuary dam to detect the zone of seawater leakage and found that the measured EC value agreed to that of seawater in the leakage zone and the temperature was lower than that of the vicinity of leakage zone. SP monitoring results were coincided with tidal variations at each embankment. At the leakage zones in the Youngsan estuary dam and the Eoeun embankment, SP anomalies are in the range of -60~-85 mV and -20~-50 mV, respectively, and true resistivity values obtained by 2-D inversion are 3~15 ohm-m and below 0.3 ohm-m, respectively. Both SP monitoring and the pole-pole array resistivity method are found to be quite effective for investigation of seawater leakage zones in the embankment.

• Korean Journal of Environmental Biology
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• v.38 no.2
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• pp.254-270
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• 2020

We conducted a seasonal field survey to analyze the distribution patterns of a phytoplankton community and biological oceanographic characteristics in the Geum river estuary in 2018. The results showed that the phytoplankton community consisted of 58 genera and 116 species, showing a relatively simple distribution. It was controlled by diatoms at 70.2%, a low number of species in winter and spring, and a high number in summer and autumn. The phytoplankton cell density ranged from 10.0 to 2,904.0 cells mL^-1, with an average layer of 577.2 cells mL^-1, which was low in autumn and high in winter. The seasonal succession of phytoplankton dominant species was mainly centric diatoms from winter to summer, including Thalassiosira nordenskioeldii, Cerataulina bergonii, and Skeletonema costatum-ls in winter, S. costatum-ls and C. bergonii in spring, and Eucampia zodiacus and Th. nordenskioeldii in summer. However, the autumn species depended upon the regions, with the inner bay dominated by the centric diatom, Aulacoseira cf. granulata, the mixed areas by S. costatum-ls, and the open sea by the dinoflagellate, Lingulodinium polyedra. According to principal component analysis (PCA), the phytoplankton community was greatly affected by the inflow and expansion of freshwater, including high nutrients, which are introduced annually through the rivermouth weir in Geum river estuary. However, the estuary, which is strongly affected by annual freshwater, was limited to areas near Geumran Island, which is adjacent to the river-mouth weir.

• Journal of Environmental Impact Assessment
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• v.4 no.1
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• pp.65-78
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• 1995

The resident attitude for preservation and development of amenity in Eulsuk island and its downstream area at estuary of Nakdong river in Korea were investigated by the questionnaires and the field surveys. Based on the results, the characteristics of this study area are the natural ecological preservation area, natural environmental preservation area and curtural assets for migratory birds. And there are a estuary bank, a Dadae beach and a Molundae park. Special amenities are (1) the light (sunrise, sunset etc), (2) the water(river, sea etc.), (3) the air(fresh wind, beautiful sound etc.), (4) the land space(beautiful view, recreation field, reed area, pine forest etc.) and (5) the stream(dancing of migratory birds, water flow, folk dance, history remains etc.). But at present, the environmental qualities as health, aesthetics safety, amenity and culture are deteriorated by development. So the number of migratory birds are decreasing. The residents desired that in future this area be use for the recreation space, the park and the natural leaning fields etc, as well as the restoration of destroyed resources.

• Journal of the Korean Society of Marine Environment & Safety
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• v.14 no.3
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• pp.189-195
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• 2008

This study analyzed the characteristics of sea water transport between Busan New-port and the Nakdong River estuary. A current meter was placed on a pier bridge and the current velocity was analyzed to determine the flow direction. Water temperature, salinity, turbidity, and tide were also measured to determine the characteristics of sea water and to describe the tidal current between the two regions. The results indicated that the dominant outflow direction of the ebb tidal current was from the Nakdong River estuary to Busan New-port. Conversely, during a flood tide, the dominant direction was from Busan New-port to the Nakdong River estuary. The maximum current speed during the first and second field measurements was about 13.18 and 30.80 cm/ sec, respectively. During the first field measurement, the total volume of sea water transport was $184.71\;m^3/sec$ and the residual volume transport was $+59.74\;m^3/sec$. By contrast, during the second field measurement, the respective values were $331.15\;m^3/sec$ and $28.88\;m^3/sec$.