• Journal of Environmental Impact Assessment
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• v.8 no.3
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• pp.13-22
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• 1999

Tidal flow and water quality were simulated in this paper to assess environmental impact caused by pier construction projects in Onsan harbor system. The Surfacewater Modeling System (SMS) was applied to the Onsan harbor system, where coastal reclamation and dredging were planned to build the piers. A finite element mesh was constructed and refined to cover the complicated geometry of the Onsan harbor and the proposed reclamation area. The time variable change of tidal height at harbor inlet was given as an input condition to tidal simulation. The water quality simulation was based on the discharge rate of suspended solids at the reclamation area. The simulation results have shown reasonable agreements with real situations in both tidal flow and water quality. According to the proposed plan, tidal flow and water quality were predicted during and after the pier construction. The tidal simulation study showed that there would be no discernible change of tidal current in the harbor except for the dredged area. The water quality simulation, however, predicted that suspended solids would increase significantly near the reclaimed and dredged areas during construction.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1239-1241
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• 2003

This paper presents the results of Landsat-TM imagery applications for detecting spatial variations of the water environments in the Saemankeum (STLR) project areas. The simulated tidal flow patterns from a two -dimensional hydro - dynamic model and water quality data from STRL project were used for relationships with the satellite data. Unsupervised classification of the tidal water body reflects the overall flow patterns at a flooding tide. Regressive equations for water quality parameters were derived and used for supervised classifications. The results were found to be useful to synoptically evaluate the water environments during the construction stages of the STLR project.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.246-252
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• 2000

The water quality in Yeongil Bay is getting worse due to the sewage and the waste water from the surrounding industrial complex The study aims to simulate the current system that is necessary to built ecosystem model for the optium water quality control and clarify the correlation of current system characteristics with water quality in Yongil Bay. To clarify the characteristics of coastal water movement system and verify the applicability of the 3-D model, the current system was simulated using 3-D baroclinic model considered tidal current and density effects. As the results of numerical experiments, it is proved the 3-D model is the most appliable on the Yongil Bay where current flows slowly and the flow direction is varied by depths. From the results of simulation considered tidal current only, It am be clearly said the water in Yongil Bay flows in through the surface layer and flows out through the bottom layer. And the fresh water from the Hyongsan river and the heated discharge from POSCO have little effect on the current structure in Yonggil Bay, but have and important effect upon the density structure by diffusion of heat and salt. And the water quality distribution is closely related with the current structure characteristics as well as the tidal residual current system.

• Journal of Ocean Engineering and Technology
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• v.21 no.2 s.75
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• pp.42-49
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• 2007

It has been known that shallow-water regions, such as tidal flats, sea grass and sea weed beds have water purification capability, and they also serve as nursery grounds for many fishes. On the other hand, tidal flat areas are economically attractive sites for reclamation, to be used for developing industries. When developing shallow-water areas, we have to propose a plan to mitigate the environmental impact associated with such a development plan. However, it is difficult to estimate the affects on the ecosystem and water purification, and the literature related to this matter is insufficient. In order to evaluate the ability of coastal tidal flat and to predict the future changes, it is necessary to develop a reliable prediction technique and construction of data by using a field investigation. In this study, we carried out a numerical model test for the tidal flat ecosystem, using the pelagic system and the benthic system, simultaneously, in order to show a change in the tidal flat ecosystem. The flow of nitrogen, phosphorus and carbon has been identified as a primary consideration of marine ecosystem components, and the capability of water purification and the change of the tidal flat were predicted using this flow. In order to make a more reliable prediction, a field investigation to determine tide, current and creatures of the object coastal area has been done. The purification capability of this shallow-water region is estimated from the model results. According to the results of experiments, the tidal flat has a capability of water purification (Sink) of 11mgN/m2/day, but the other area has a load (Source) of 20mgN/m2/day. As a result, we could confirm that the tidal flat of an object coastal area plays an important role in water purification.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.22-30
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• 2007

Nihonbashi River takes more time to discharge water pollution because it runs low-lying areas and is easy to affect tidal flow from downstream. After rainfall, the water environment of the river has become worse. Even though the river is located in the important metropolitan area in Tokyo, it dose not have any connection with people's lives. We took Nihonbashi River as an example to consider methods for river restoration of improving water quality and river environment in densely inhabited urban areas. Especially, the major issue of river restoration is how smoothly and quickly discharges water pollution which flows into with river flow. The conclusion of this project is the effectiveness of improvement of water environment to construct of rock gates in Nihonbashi River and Kanda River to control inflows from upstream and tidal flows from downstream.

• Journal of Korean Port Research
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• v.13 no.1
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• pp.123-132
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• 1999

It is very important to quantitatively assess the movement of sea water and pollutant dispersion before or after constructing shore structures such as breakwater considering marine environment and long-term utilization of those structures. This assesment is possible through the use of simulation models designed to predict water movement and pollutant dispersion in a certain area. In this study the numerical computations were carried out to predict the sea water quality in the Ilgwang Harbor located at the east coast of Pusan. The flow patters were investigated before and after the development of Ilgwang Harbor. The computational models adopting ADI Method (Alternating Direction Implicit Method) were used here and were already verified from the previous studies. As a results of this study the tidal exchange in Ilgwang Harbor after development proved to be worse due to the increased semi-enclosed at the harbor limit. In order to improve the water quality of this area after development a new method was proposed to improve water quality in the semi-enclosed bay by creation and control of tidal residual currents. For this purpose the unsymmetric structures so called bottom roughness were introduced in this study. The simulation was carried out on the basis of the study by Komatsu et. al. and Gug and we made a conclusion that it is possible to generate a new tidal residual current and to increase the tidal exchange by application of bottom roughness arrangement.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.43-51
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• 2005

This paper presents a waste load allocation study for the Incheon coastal environment, where a computer model, called AQUASEA, was applied. A finite element mesh was constructed and refined to cover the complicated geometry of Incheon coastal sea. The tidal height at 13 places of Incheon coastal boundary and flow of the Han River were given as an input condition to the tidal simulation. All pollution sources that discharge into Incheon coast were given as input data to the water quality simulation. The modeled parameters include tidal flow and COD(Chemical Oxygen Demand). The model was calibrated and verified with the field measurements. The model results showed reasonable agreements with field measurements in both tidal flow and water quality. Systems analysis showed that the pollution load from the Han River caused recognizable impacts on the water quality of Incheon coast from Yeomhwa waterway to northern area of Younghungdo. The loads from Incheon City affected water quality from the area below Youngjongdo to the area above Jawalldo. The discharge from the Sihwa Lake caused discernible impacts on the coastal zone from the dike outlet to the Incheon harbor, and pollution loads from Kyungkido affected the sea near the Oido. An effective water quality management plan was developed from the waste load allocation analysis of the validated model, that the maximum waste loads can be discharged without violating the water quality standard given in the Incheon coastal environment.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.1
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• pp.14-23
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• 2001

The characteristics of tidal circulation with Hyungsan River discharges in Youngil Bay by the numerical experiments is elucidated. For the simulation of tidal residual currents related to inflow by the river discharges in Youngil Bay located in the southeastern part of Korean Peninsula, the two-dimensional numerical experiment is peformed. The tidal elevation boundary conditions of the 4 main tidal harmonic constituents (M₂, S₂, K₁ and O₁) on the open boundary and river discharges at the river boundary are considered. The computed results obtained from numerical experiment showed good agreements with the field observation ones. The residual currents generally flow toward the inner bay through the western (Dalman-Gap) and central areas of the bay, and then the currents go toward the outer bay along the eastern shore (Changgi-Gap) of the bay with anti-clockwise circulation. Especially, in the numerical experiment without Hyungsan River discharges, these flow patterns are disappeared. Based on the results, it showed that the Hyungsan River discharges play the dominant role in the patterns of tidal residual currents. This flow pattern of tidal residual currents are important mechanism of water quality, material transport in Youngil Bay.

• Journal of Korean Port Research
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• v.12 no.1
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• pp.95-104
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• 1998

Water pollution in a semi-enclosed sea area such as a bay due to stagnancy of water has been a serious water environmental problem. Recently, some kinds of new methods to activate the tidal exchange between an inner bay and an outer sea area by control of a tidal residual current have been proposed. However, these methods have several problems, that is, I). deterioration in a natural view due to building of huge structures, II). increase of risk of navigation in case of a submerged structure, III). limition of sea area where a tidal current can be controlled and IV). difficulty in removing those structures in case of occurrence of an unexpected impact on water environment. In this paper, a new method is proposed, which can solve all the above problems, to purify water quality in a semi-enclosed bay by creation and control of a pattern of a tidal residual current. The tidal residual current is controlled by unsymmetric structures, which change the properties of resistance according to the direction of flow, arranged on the sea bottom. In this study, several numerical and hydraulic experiments of tidal current and particle-tracking for various arrangements of bottom roughness in a semi-enclosed model bay were carried out. As a result of experiments, it becomes clear that it is possible to generate a new tidal residual current and to activate a tidal exchange by only operation of bottom roughness arrangement.

• Journal of Environmental Impact Assessment
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• v.9 no.3
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• pp.215-228
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• 2000

This paper presents a novel method to predict a flushing rate in an embayment system, which can be utilized to assess an environmental impact caused by harbor construction. The method was successfully applied to the Ulsan-Onsan coastal area. The flushing rate was computed on the basis of water quality changes predicted by US Army Corps of Engineers' RMA-2/RMA-4 models. After calibration and verification to the measured tidal elevation and current velocity, the model was used to estimate the flushing rate in the proposed harbor. The water quality was simulated for 96 hours and the flushing rate was computed. The results indicated that the proposed harbor would significantly reduce the flushing rate in the Onsan harbor, especially at the small embayment area near the south breakwater. The flushing rate was evaluated for several alternatives, of which the tidal flow channel of 1,000 $m^2$ in the south pier appeared to be the best mitigation measure. This study proposes that the prediction of flushing rate would be a novel method to assess a water quality impact caused by harbor construction.