• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.5
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• pp.333-343
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• 2010

In Mokpo coastal zone, the characteristics showing ebb-dominant tidal flow was confirmed by analysis of observed tide and tidal currents, Physical factors occurring ebb-dominant flow were reviewed. Influence of critical depth for drying, bottom shear stress, coastal reclamation, tidal amplitude, nonlinear tide, and eddy viscosity on the change of ebb-dominant flow was investigated by applying a two-dimensional circulation model. The simulation results for a variety of conditions showed that eddy viscosity and critical depth for drying does little or no impact on the generation of asymmetric flow. Strong bottom friction stress makes ebb-dominant flow clearly. Change of tidal flat into land swells ebb- dominant flow, and change of tidal flat into sea disappears ebb-dominant flow. Nonlinear tides play a decisive role in the generation of asymmetrical tidal flow. Non-linear tides should be included in the open boundary conditions of hydrodynamic modeling in the Mokpo coastal zone.

• 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.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.2 no.3
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• pp.1-9
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• 1999

This paper described the results of the characteristics of the near-bottom flow and field analysis of the tidal flats sediment. It was the aim of this paper to grasp current flow of tidal flat's environment and influence factor for environmental change forecast of tidal flats. Field measurement of water velocity, water elevation, bed materials test, and temperature distribution of tidal flat were conducted. Thereafter, current flow, turbidity and temperature distribution of tidal flat sediment have been discussed. The field research results showed that the fluctuating velocity near the seabed before and after its appearance at low tide was strongly affected by the wind wave. The resuspension of the sea-bottom sediment took place with great intensity before and after the appearance of the seabed at low tide. Both the sea water level and the weather condition were a significant influential factors. Such as, temperature and turbidity just on the surface and the shallow layer of seabed sediments were varied largely with time and weather conditions, but that its deeper layers was almost constant. Temperature on the seabed sediments was strongly influenced by irradiance and water depth. The temperature variation of the tidal flat and the variation characteristics of the current flow and turbidity depend greatly on the inhabiting environment of the tidal flat benthic organism.

• 한국해양학회지
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• v.14 no.2
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• pp.71-77
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• 1979

Tidal waves and the fluctuation of current are studied by use of observed data on tidal level, flow velocity and river discharge in the estuarine region of the Nakdong River. Observed data on the tidal level at five stations are used to obtain the fluctuation of amplitude and phase of tides, and the change of the wave speed versus distance from the river mouth. Comnining these tidal data with the vertical distribution of horizontal velocity data, some characteristics of the periodic tidal flow are deduced: (1)Diminishing rates of the tidal amplitude ratio η / η$\_$0/ at high tide were 0.058η$\_$0H/ /Km at neap tides. The constant of phase change, K, was 0.035rad/km. (2)While proceeding landward, the shape of the tidal wave changes from symmetrical to asymmetrical. The traveling speed of the tidal wave crest was estimated to be 3.6∼5.2m/sec, while that of the tidal wave trough was 2.4∼ 3.5m/sec. (3)The flowing speed of the water varies periodically in accordance with the tidal period. The maximum speed of landward flow appeared approximately at two hours before the high tide, while that of seaward flow at two hours before the low tide. (4)The upstream boundary is deduced approximately to be 50km at spring tide and 44km at neap tide from the tidal velocity decreasing. the tidal influence area is estimated approximately to be 65km from the tidal amplitude damping.

• Proceedings of KOSOMES biannual meeting
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• 2018.06a
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• pp.7-7
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• 2018

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.6
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• pp.353-360
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• 2010

The Kyunggi Bay in mid-west of Korea is a relatively large estuarine system that connects the Han River system with Yellow Sea. Due to macro-tidal range of more than 8 m, the urban estuary shows deep tidal channels and wide tidal flats. Since last 30 years, the coastal development is undergoing, yielding noticeable change in environment. Particularly the tidal flat dynamics are generally accepted as being related with tidal residual flows in this area (Kim et al., 2009). We have estimated the annual variation and vertical structure of residual currents with one-year long observed flows in two major tidal channels of Kyunggi Bay. The moving average method and tidal current harmonic analysis yield nearly the same results on residual flow. The residual flow in Jangbong channel ranges from 20 cm/s in summer to 30 cm/s in winter. It is noticeable that the residual flow in Jangbong channel is flood dominant throughout the year, while the flow in Seokmo channel is ebb-dominant residual flow with current speed range of 20-40 cm/s. Due to the baroclinic response of relatively shallow estuary, significant reduction of energy in bottom layers have been observed, indicating the importance of residual circulation to the tidal flat behavior.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.1366-1369
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• 2010

Along with the increasing need of sea development, the hydraulic stability of seabed structure on a soft seafloor ground is becoming an issue in the course of seaside development recently. However, the movement and hydraulic resistance or hydraulic stability of seafloor ground are mutually coupled with various phenomena, and there has been no clear proof for the issue, which makes it difficult to forecast. Furthermore, most researches are focused on hydraulic variables and the conditions of marine external force, while there have been few researches into the assessment in consideration of the type of a seafloor ground and the geotechnical characteristics. In addition, according to the periodic change of the flow direction, possible changes in hydraulic resistance performance of the seafloor deserves all the recognition. But there is no way to measure the hydraulic unstability of the sea ground due to tidal flow quantitatively. In this study, conventional hydraulic resistance measurement apparatus was improved to consider direction change of the current flow. Various artificial clayey soil specimens were made from Kaolinite and Jumunjin standard sand and hydraulic resistance tests were performed by changing the flow direction to validate the effect of the direction change on the scour of the seafloor.

• The Korean Journal of Zoology
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• v.9 no.1
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• pp.1-6
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• 1966

Frequently , large masses of the young short necked clam, Tapes japonica , die at their tidal flats in summer and this phenomenon has not been explained clearly. The purpose of the present investigation is to study the thermal condition and the chlorinity level of tidal flats in which the young clam appears to be injured. A study is also mad efor the burrowing organism in the lower layer of the esturay over which the fresh water flow during the low tide. Observation are made at five places of the tidal flat near Ikawazu Fixheries Laboratory of Tokyo University during the ebb and flow tide period of the spring tide. The diurnal and monthly changes of tidal temperatures and chlorinities are measured. Results of the study are ; 1. The surface temperature of the tidal flat increases with the ebb tide, reaches the highest between 12-14PM, and gradually decreases thereafter. The temperatures of tidal flat below 5 and 10 cm increase gradually until the flow tide reaches the surface. 2. At the spring tide in summer , the diurnal change of surface of the tidal flat temperature is very extensive ; it reaches 37-39$^{\circ}C$ in August. At the depths of 5 and 10 cm the temperature remains at 33 $^{\circ}C$ and 31$^{\circ}C$ , respectively. 3. The chlorinity of the tidal flat is higher during May through June and lower July through August, and this seems to be related to the amount of rainfall. 4. The chlorinity of the surface of tidal flat increases slightly during the ebb and flow tide periods. The observed higher chlorinity of surface of the tidal flat was 18.82% Cl. 5. At near the esturay, the fresh water that overflows the tidal flat affects the chlorinity of the surface but no such influence to the depth of the flat. 6. From above observations, it is assumed that the young short necked clam in the tidal flat could be exposed to the severe change of environmental conditions. The high temperature of the tidal flat in summer and the low chlorinity of it at flood period may be considered as the change in environment.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.516-519
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• 2005

The pilot tidal current power plant is to be constructed at the Uldolmok between Chindo and Haenam, during next year. and extensive coastal engineering research works have been carried out. In this paper we describes some observation results of the tide and tidal current. as well as modeling work in order to investigate the tide and tidal current regime change in relation to the tidal current power plant (TCPP) construction. The special modeling skill in order to consider the turbine operation in the TCPP is developed and applied to the estimation for the flow regime change by the simple layout of the tidal current power plant.

• New & Renewable Energy
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• v.1 no.2 s.2
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• pp.73-78
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• 2005

The pilot tidal current power plant is to be constructed at the Uldolmok between Chindo and Haenam, during next year, and extensive coastal engineering research works have been carried out. In this paper we describes some observation results of the tide and tidal current, as well as modeling work in order to investigate the tide and tidal current regime change In relation to the tidal current power plant [TCPP] construction. The special modeling skill in order to consider the turbine operation in the TCPP is developed and applied to the estimation for the flow regime change by the simple layout of the tidal current power plant.