• 한국해양학회지
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• v.6 no.2
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• pp.92-98
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• 1971

Storm surges caused by typhoon Billie, 28 Aug. ∼ 2 Sep. 1970, on the west and south coasts of Korea are studied with the tidal data. Tracks and frequencies of the typhoons which affected the Korean peninsula and the yearly maximum tidal deviation at tide stations for the past twelve years are also reviewed. It is assumed that most of the typhoons affecting the Korea peninsula cause variations of sea level along almost all of the coast of Korea. Maximum storm surges at each tide station on the south coast appeared to be caused by typhoons during the summer, and by the north westerly monsoon and extraordinary cyclones on the west coast during spring and winter. In the coastal waters of the west coast where depths are shallower and the bottom configuration is flat, sea level variation is mostly caused by atmospheric pressure and wind effect. When a typhoon travels as in case of typhoon Billie, sea level ascends generally on the south coast and it descends on the west coast before the typhoon approaches near to the coasts. Considering the large tidal range on the western and southern coasts, it is assumed that the extraordinary destructive surges can be occurred when the tide is high water. Reviewing the monthly mean sea level variations on the each coast, hazards to be caused by storm surges can more fluently occur during the summer.

• Ocean Science Journal
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• v.40 no.4
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• pp.191-200
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• 2005

In this study an analytical tide model of uniform width with three sub-regions is presented. The three-subregions model takes into account step-like variations in depths in the direction of the channel as a way to examine the $M_2$ tide of the East China Sea (ECS) as well as the Yellow Sea (YS). A modified Proudman radiation condition has been applied at the northern open head, while the sea surface elevation is specified at the southern open boundary. It is seen that, due to the presence of an abrupt change in depth, co-amplitude lines of the $M_2$ tide are splitted to the east and west near the end of the ECS shelf region. Variations in depths, bottom friction and the open head boundary conditions all contribute to the determination of formation of amphidromes as well as overall patterns of $M_2$ tidal distribution. It is seen that increasing water depth and bottom friction in the ECS shelf results in the westward shift of the southern amphidrome. There is however no hint at all of the well-known degenerated tidal pattern being formed. It is inferred that a lateral variation of water depth has to be somehow incorporated to represent the tidal patterns in ECS in a realistic manner. Regarding the radiation factor introduced by Fang et al. (1991), use of a value larger than one, possibly with a phase shift, appears to be a proper way of incorporating the reflected waves from the northern Yellow Sea (NYS).

• Economic and Environmental Geology
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• v.52 no.4
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• pp.299-312
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• 2019

This study analyzed variation of tidal channels associated with Shihwa reclamation project for corresponding observation period based on remote sensing approaches. The project period was subdivided to developing period, closed period, and open period based on developing and management plan of Shiwa lake, and number, length, width, and direction of tidal channels for each period were analyzed using CORONA, Landsat 5 TM, Landsat 7 ETM+, and orthorectified aerial photographs. Number of tidal channels decreased from developing to opening period while $3^{rd}$ order channles did not show noticeable changes. The length of tidal channels decreased during developing to closed period, and increasing trend of $2^{nd}$ and $3^{rd}$ order channels was observed for the opening period. The average widtrh of $2^{nd}$ and $3^{rd}$ order channels decreased from developing to closed period, and increased during open period. The direction of tidal channels showed NW and NE direction in general, while the rose diagram showed deacrased frequency of NE direction and increased frequency of NW direction during the open period. These variations in tidal channels are considered to be related to changes in tidal energy environment, where stable energy environment before the project was changed to disconnection of tidal energy by closed environment, and re-connection of the energy during the open period.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.6
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• pp.733-753
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• 1994

Monthly mean sea levels from 103 tidal stations in Korea, Japan, and Russia are analyzed to study long-period sea level variations. Barometric adjustment are done for all the sea level data, using monthly air pressures at sea levels from meteorological stations near tidal stations. Seasonal variation is dominant in most of study area. It is the largest in the coasts along the Tsushima Current, and the smallest in the Russian coasts. The cross-correlations of seasonal variations are very high between the coasts along the Tsushima Current. In these marginal seas, seasonal variations seem to be related with the Tsushima Current. The phase of seasonal variations is generally getting late from south to north, and also from west to east. On the other hand, longer-period variations(longer than seasonal variation) have the largest amplitudes and the earliest phases in the coasts along the Pacific Ocean, which shows that they propagate from the Pacific Ocean. Shorter-period variations (shorter than seasonal variation) have generally lower cross correlations. Their values do not show any dictinct difference between areas, and show a common tendency that they are inversely proportional to distance. It implies that the shorter period waves are generated all over the study areas, and propagate in all the directions with faster dissipations. The trends of sea levels in the study area are generally negative in the coasts along the Pacific Ocean and positive in the other areas during the period of 1965 to 1985. By the trends, the mean volume transport between Cheju and Sasebo can be reduced by about 1 Sv during the period. The seasonal variation of volume transport obtained by sea level difference is about 2 Sv in the Korea Strait. The values are comparable to previous reports.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.1
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• pp.47-55
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• 2005

Seasonal variations of remineralization and inorganic nitrogen removal capacity were measured from Dec. 2001 to Apr. 2004 in a tidal flat located in south-western pan of Gwanghwa island, Korea by measuring the sediment oxygen demand (SOD) and denitrification. SOD was higher in muddy sediment (Dong-Mak; three year average=$683;m^{-2}d^{-1}$) than sandy sediment(Yeocha; three year average=$457;m^{-2}d^{-1}$). The SOD was high in summer and tended to be lower in winter. During the sediment incubation in Apr. 2002, production of oxygen from sediment was observed implying active benthic photosynthesis. Denitrification was also higher in muddy sediment (Dong-Mak: $5.4;m^{-2}d^{-1}$) than sandy sediment (Yeocha; $3.4;m^{-2}d^{-1}$). The denitrification rate corresponds to the carbon remineralization rate of 9.3 and $5.9\;mg-C\;m^{-2}d^{-1}$ in Dong-Mak and Yeocha, respectively. The denitrification rates were lower compared to rates observed in other coastal area $(0{\sim}200\;{\mu}mole\;m^{-2}h^{-1})$. Although Kwanghwa tidal flat sediments are replete in organic matter, remineralization activity seems to be limited by the availability of labile organic matter. The Kwangwha tidal flat may have potential to effectively remove large load of organic matter. Net remineralization rates were 196 and $132\;mg-C\;m^{-2}d^{-1}$ in Dong-Mak and Yeocha, respectively.

• Journal of Environmental Science International
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• v.11 no.6
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• pp.519-528
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• 2002

This study was to evaluate the impact of river runoff and salt intrusion by tide on nutrient balance of estuary during a complete tidal cycle. 24 hours time series survey was carried out during a spring tide July 2001 on a tidal estuary in the Keum river. Three stations(A,B,C) were set along a transect line of about 10km, which linked the lower part of estuary dyke to the subtidal zone. Surface water was sampled simultaneously at each station every hours f3r the determination of nutrients. Water temperature, pH and dissolved oxygen were measured in situ. Riverine input of silicate and nitrate during ebb tide significantly increased the concentration of all stations. Conversely, during high tide, nutrient concentration were lowered by the mixing of fresh water with sea water Ammonium nitrogen concentration were higher at intertidal zone(Stn.B) due to sewage inflow to Kyeongpo stream and ammonium release under anaerobic conditions. Also, these results was discussed as a biological component that influences the processes of nutrient regeneration within the estuary. Best correlations were found at lower part of estuary dyke(Stn.A) for salinity against DIN(Y=0.121 Sal.+4.97, r2=0.956) and silicate(Y=0.040 Sal.+2.62, r2=0.785). But no significant correlation was found between salinity and ammonium. Unbalanced elemental ratio(N/P, Si/N and Si/P) depended significantly on the import of nutrients (silicate & nitrate nitrogen) from river and stream. The effect of the tidal cycle and river runoff is important that in determining the extend of the variations in nutrient concentrations at all station.

• Ecology and Resilient Infrastructure
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• v.9 no.4
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• pp.247-258
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• 2022

Hampyeong Bay has a narrow seawater channel and a complex topographical structure. The sand content of the tidal flat soil is increasing due to asymmetrical sedimentation. Through the investigation of the vegetation distribution and the use of the line-transect method, sand flats were observed to gradually change the vegetation distribution of salt marshes. Comparing the vegetation area between 2016 and 2022, the obligate halophyte Suaeda maritima decreased by 74% and Zoysia sinica increased by 75%. Z. sinica seems to support the robustness of the dune environment by trapping sediments such as sand in the colony, because the underground rhizomes and stems are highly developed. To establish an effective conservation management plan for tidal flats, an integrated study should be conducted to assess the impact of changes in tidal flat soil and the interaction of vegetation communities in Hampyeong Bay.

• The Korean Journal of Malacology
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• v.15 no.1
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• pp.21-30
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• 1999

This study was carried out to describe the growth of Ruditapes philippinarum on Chohwa and Toksan tidal flat in Kwangyang Bay, from June 1994 to July 1995. On the Chohwa tidal flat, the mean gran size, organic content and chlorophyll-a of the surface sediment were the range of 2.50-4.46 , 4.99-5.11%, 14.53-19.90 $\mu\textrm{g}$ cm$\^$-3/, and on the Toksan tidal flat, 0.83-1.66 , 2.22-2.34%, 6.20-6.90 $\mu\textrm{g}$ cm$\^$-3/, respectively. The shell length of R. philippinarum increased rapidly from spring to summer, and gently from summer to autumn, and ceased during winter. Fresh weight increased during spring and autumn, and decreased during summer and winter. condition factors also showed the same variations of weights. Synthesized annual growth pattern of 4 year classes in shell length fitted the von Bertalnffy growth model well. The annual growth of weight fitted the Gompertz model relatively well. The values of w, initial shell growth rate, and AGR$\sub$max/, maximum weight growth rate, on the Chohwa tidal flat were lower than those on the Toksan tidal flat. Comparing the growth patterns in the same tidal flat, growth rate was higher on the lover tidal flat than those on the higher tidal flat. In conclusion, the Chohwa tidal flat maintaining higher density showed lover growth rate, because of relatively insufficient food supply and inhabiting space.

• Journal of Environmental Science International
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• v.28 no.3
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• pp.341-356
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• 2019

In this study, the impacts of local meteorology caused by tidal changes in the West Sea on ozone distributions in the Seoul Metropolitan Area (SMA) were analyzed using a meteorological model (WRF) and an air quality (CMAQ) model. This study was carried out during the day (1200-1800 LST) between August 3 and 9, 2016. The total area of tidal flats along with the tidal changes was calculated to be approximately $912km^2$, based on data provided by the Environmental Geographic Information Service (EGIS) and the Ministry of Oceans and Fisheries (MOF). Modeling was carried out based on three experiments, and the land cover of the tidal flats for each experiment was designed using the coastal wetlands, water bodies (i.e., high tide), and the barren or sparsely vegetated areas (i.e., low tide). The land cover parameters of the coastal wetlands used in this study were improved in the herbaceous wetland of the WRF using updated albedo, roughness length, and soil heat capacity. The results showed that the land cover variation during high tide caused a decrease in temperature (maximum $4.5^{\circ}C$) and planetary boundary layer (PBL) height (maximum 1200 m), and an increase in humidity (maximum 25%) and wind speed (maximum $1.5ms^{-1}$). These meteorological changes increased the ozone concentration (about 5.0 ppb) in the coastal areas including the tidal flats. The increase in the ozone concentration during high tide may be caused by a weak diffusion to the upper layer due to a decrease in the PBL height. The changes in the meteorological variables and ozone concentration during low tide were lesser than those occurring during high tide. This study suggests that the meteorological variations caused by tidal changes have a meaningful effect on the ozone concentration in the SMA.

• Korean Journal of Remote Sensing
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• v.36 no.6_2
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• pp.1605-1613
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• 2020

The tidal channel is a coastal sedimentary terrain that plays the most important role in the formation and development of tidal flats, and is considered a very important index for understanding and distribution of tidal flat sedimentation/erosion terrain. The purpose of this study is to understand the changes in tidal channels by a period after the opening of the floodgate of the seawall in the reclaimed land of Sihwa Lake using KOMPSAT high-resolution multispectral satellite image data and to evaluate the applicability and efficiency of high-resolution satellite images. KOMPSAT 2 and 3 images were used for extraction of the tidal channels' lineaments in 2009, 2014, and 2019 and were applied to supervised classification method based on Principal Component Analysis (PCA), Artificial Neural Net (ANN), Matched Filtering (MF), and Spectral Angle Mapper (SAM) and band ratio techniques using Normalized Difference Water Index (NDWI) and MF/SAM. For verification, a numerical map of the National Geographic Information Service and Landsat 7 ETM+ image data were utilized. As a result, KOMPSAT data showed great agreement with the verification data compared to the Landsat 7 images for detecting a direction and distribution pattern of the tidal channels. However, it has been confirmed that there will be limitations in identifying the distribution of tidal channels' density and providing meaningful information related to the development of the sedimentary process. This research is expected to present the possibility of utilizing KOMPSAT image-based high-resolution remote exploration as a way of responding to domestic intertidal environmental issues, and to be used as basic research for providing multi-platform-image-based convergent thematic maps and topics.