• Journal of Korea Water Resources Association
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• v.34 no.6
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• pp.597-604
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• 2001

The objective of the paper was to estimate the changes in acreages of tidal flats after the seawall construction at the Asan Bay and the Chunsu Bay from topographic maps, hydrographic charts, and Landsat TM images. The tidal floats from topographic maps published in one year differ significantly from that in the other, which appears to be attributed to the tide levels at the time of photographing. The hydrographic charts showed that tidal flats increase at rates of 22.3 ha/yr at the Asan Bay and 56.6 ha/yr at the Chunsu Bay after the dike construction. Applying the ISODATA method of unsupervised classifications for the Landsat TM images, the tidal flats were identified, and the resulting acreages for each image estimated. The resulting tidal flats increased at the rates of 21.3 ha/yr at the Asan Bay and 47.3 ha/yr at the Chunsu Bay during twelve years after the dike construction. It was found that the rates of the annual increases from the two data are very close and the differences result from the coastal lines at the charts and the TM images.

• Journal of Marine Life Science
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• v.3 no.2
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• pp.59-66
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• 2018

The assessment of level of health of the tidal flats can be evaluate by health of organisms inhabit the tidal flats. It is possible to evaluate the precise health level of organisms inhabit the tidal flats using analysis of expression of biomarker genes. The purpose of this research is to evaluate the health of the tidal flats on the west coast using biomarker genes such as heat shock protein 70 (Hsp70), heat shock protein 90 (Hsp90), glutathione S-transferases (GST) and thioredoxin (TRX). These genes are stress, immune, and antioxidant related genes that can be used to look at the health of an organism through gene expression. In this study, we collected manila clam (Ruditapes philippinarum) in 8 analysis areas on the west coast. Expression of the genes was analyzed by RT-qPCR method. Results showed that, the expression of Hsp70, Hsp90, GST and TRX genes were differentially expressed in the 8 analysis areas. In particular, the expression of Hsp90 and GST or the expression of Hsp70 and TRX were similar. This means that there is a substance that reacts specifically to each gene. Therefore, I think suggest that the based on the results of physicochemical analysis, it can be selected genes suitable for analysis. These results suggest that Hsp70, Hsp90, GST and TRX were played roles in biomarker for assessment of the health of tidal flats.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.574-578
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• 2006

Tidal amplification by construction of the sea-dike and sea-walls had been detected not only near Mokpo Harbor but also at Chungkye Bay which is connected with Mokpo Harbor by a narrow channel. This brings about increase of tidal flat area and in particular increase of surge-wave combined runup during storms. The purpose of this study is to examine an efficient operational model that can be used by civil defense agencies for real-time prediction and fast warnings on wind waves and storm surges. Instead of using commercialized wave models such as WAM, SWAN, the wind waves are simulated by using a new concept of wavelength modulation to enhance broader application of the hyperbolic wave model of the mild-slope equation type. Furthermore, The predicting system is composed of easy and economical tools for inputting depth data of complex bathymetry and enormous tidal flats such as Mokpo coastal zone. The method is applied to Chungkye Bay, and possible inundation features at Mokpo Harbor are analyzed.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.21-24
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• 2001

As one of the phil-environmental alternative plan of Saemankeum project, gradual development is recommended. The procedure of the Saemankeum project start with the completion of 32 km long sea-dikes which contains two discharge gates until the year 2004. Second step is pre-development of Mangyoung area permitting temporary intrusion of sea water, i.e. tides, by the opening of discharge gate until the environmental evaluation on the water quality of this area secures permanent meet to government's water quality standard. Therefore this study is to predict the future condition of this tidal flat with the point of view tidal environments, salt, water quality, soil mechanics, etc. of Mangyoung area when the sea water still passed in the inland reservoir through the discharge gate.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.992-996
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• 2004

천해역(shallow sea area)에서의 조류 형태(tidal flow regime)는 주로 만(bay)이나 해안선(shoreline)의 형태, 해저 지형(bottom topography), 수로(channel), 천퇴(sand bar)나 간석지(tidal flat) 등의 지형적인 요인에 의해 결정된다. 본 연구는 복잡한 지형적 변화 및 천해특성에 기인된 조석(tide)의 현상이 뚜렷이 나타나는 금강하구(Keum River Estuary)를 하구둑(Estuary Dike) 건설 전${\cdot}$후(Before and After Constructed)의 수심(depth)변화 및 유속(current)변화를 수치실험(numerical experiments)으로 고찰했다.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.365-370
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• 2000

Sea dike construction for the tidal flat reclamation works in estuary and coast may change the characteristics of tidal motion and wave conditions in the region. In turn, a new hydraulic condition provides the impacts on sediment transport pattern and forms a new morphological environment. Also, morphological changes during the closure works of sea dike are closely related with a safy of sea dike. Therefore, the prediction of morphological changes is required secure the safe closure work and the economic design of sea dikes. To investigate morphological changes due to sea dike construction, hydrodynamic changes of tides and waves have to be evaluated, then sediment transport and sea bottom changes are computed. Mathematical modelling is required for representation of interrelation of tidal motion, wave and sediment transport. In this study, numerical model MORSYS is applied to compute the hydrodynamics and morphological changes around the closure gap for Saemankuem dike. This model allows a flexible integration of the module for waves, currents, sediment transport and bottom changes.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.4
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• pp.32-41
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• 2001

We measured the fluxes of COD, TN and 55 in addition to composition and quality of sediment in Komso Bay, West Coast of Korea. The fluxes of TN, SS and COD were measured during flood tide and ebb tide in April and August, 2000. Denitrification rates in the sediments was also measured by direct produced $N_2$ gas technique on April and August from 1999 to 2000 in the same sea area. The composition of the sediments were 0.33~5.67 % of sand, 20.2~25.6 of gravel and 68.7~77.0 % of silt. Ignition loss of the sediments were 6.58~7.50 %. The concentration of hydrogen sulfide in the sediments were 0.028~0.326 mg/gㆍdry and oxidation reduction potential of the sediments were -28~-15 mV Diurnal fluxes of COD, total nitrogen, and suspended solids with tidal current and denitrification rate in the tidal flat have been determined in Komso Bay The diurnal net flux of COD was same in April. While 14.4 ton COD/hr of net influx into the tidal flat was recorded in August. The diurnal net influx of total nitrogen was 0.16 ton N/hr in April and 1.13 ton N/hr in August. The diurnal net influx of suspended solids was 0.05 ton SS/hr in April, and also net influx of suspended solids was 0.29 ton SS/hr in August. The overall purification ability of the tidal flat were estimated 0.00~5.69 g COD/$m^2/day$, 0.06~0.45 g N/m²/day and 0.02~0.12 g SS/$m^2/day$ for COD, TN and SS, respectively. Denitrification rate was 0.009~1.720 m mole ${N_2}/m^2/day$ (average 0.702 m mole ${N_2}/m^2/day$) in April and 0.033~0.133 m mole ${N_2}/m^2/day$ (average 0.077 m mole ${N_2}/m^2/day$) in August, 1999. 0.000~l.909 m mole ${N_2}/m^2/day$ (average 0.756 m mole ${N_2}/m^2/day$) in April, 0.000~1.691 m mole ${N_2}/m^2/day$ (average 0.392 m mole ${N_2}/m^2/day$) in August, 2000. Even with a wide range of denitrification rate depending on the sampling location and studied periods, the average denitrification rate was estimated 0.482 m mole ${N_2}/m^2/day$ in the tidal flat of Komso Bay.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.1
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• pp.31-37
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• 2005

To find out temporal variations of net photosynthetic rate (NPR) of intertidal flats, we measured oxygen microprofiles in sediments with oxygen microsensors 4 times from December 2003 to June 2004. The study areas were the intertidial flats in Janghwa-ri and Dongmak-ri, located on the southwestern and the southern parts of Ganghwa-gun, respectively, and in Incheon North Harbor where the content of organic matter was relatively high. During the investigation, oxygen penetration depths in the tidal flats of Janghwa-ri and Dongmak-ri were high in December (mean values of 4.0-4.1 mm). Thereafter, the oxygen penetration depths declined to mean values of 2.2-2.8 mm and 1.6-1.8 mm in the two tidal flats. Interestingly, the oxygen penetration depths in the Incheon North Harbor tidal flat showed a lower range $(0.8{\pm}0.3\;mm;\;mean{\pm}1SD)$ over the period. The maximum NPR in the Dongmak-ri tidal flat was found in March $(11.1{\pm}2.8\;mmol\;O_2\;m^{-2}\;h^{-1})$, and those In Janghwa-ri $(6.1{\pm}4.1\;mmol\;O_2\;m^{-2}\;h^{-1})$ and Incheon North Harbor $(6.4{\pm}1.4\;mmol\;O_2\;m^{-2}\;h^{-1})$ were observed in May. During the period when NPR was most active, the highest oxygen concentration was found at 0.1-0.5 mm depth below the surface sediment, and was on average 1.8-3.2 times higher than the air-saturated oxygen concentration in the overlying seawater. Although we took into account of low in situ light intensity $(400{\mu}Einst\;m^{-2}\;s^{-1})$ during the investigation in June, NPR in the 3 study areas decreased significantly to less than $0.2\;mmol\;O_2\;m^{-2}\;h^{-1})$. Thus, temporal variations of NPR were somewhat different among the tidal flats. Generally, benthic primary producers inhabiting in the uppermost 0.5 mm of the sediment showed a peak photosynthetic activity in the study areas in spring. This is the first domestic report on photosynthetic rates of benthic microflora in the tidal flats with oxygen microsensors, and the use of the microsensor can be widely applied to measurements of benthic primary production of a tidal flat and the oxygen consumption rate of surficial sediments.

• Korean Journal of Remote Sensing
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• v.25 no.4
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• pp.383-389
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• 2009

The main objective of the research is a feasibility study on the intertidal zone using a X-band radar satellite, TerraSAR-X. The TerraSAR-X data have been acquired in the west coast of Korea where large tidal flats, Ganghwa and Yeongjong tidal flats, are developed. Investigations include: 1) waterline and backscattering characteristics of the high resolution X-band images in tidal flats; 2) polarimetric signature of halophytes (or salt marsh plants), specifically Suaeda japonica; and 3) phase and coherence of interferometric pairs. Waterlines from TerraSAR-X data satisfy the requirement of horizontal accuracy of 60 m that corresponds to 20 cm in average height difference while current other spaceborne SAR systems could not meet the requirement. HH-polarization was the best for extraction of waterline, and its geometric position is reliable due to the short wavelength and accurate orbit control of the TerraSAR-X. A halophyte or salt marsh plant, Suaeda japonica, is an indicator of local sea level change. From X-band ground radar measurements, a dual polarization of VV/VH-pol. is anticipated to be the best for detection of the plant with about 9 dB difference at 35 degree incidence angle. However, TerraSAR-X HH/TV dual polarization was turned to be more effective for salt marsh monitoring. The HH-HV value was the maximum of about 7.9 dB at 31.6 degree incidence angle, which is fairly consistent with the results of X-band ground radar measurement. The boundary of salt marsh is effectively traceable specifically by TerraSAR-X cross-polarization data. While interferometric phase is not coherent within normal tidal flat, areas of salt marsh where the landization is preceded show coherent interferometric phases regardless of seasons or tide conditions. Although TerraSAR-X interferometry may not be effective to directly measure height or changes in tidal flat surface, TanDEM-X or other future X-band SAR tandem missions within one-day interval would be useful for mapping tidal flat topography.

• Proceedings of the Malacological Society of Korea Conference
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• 2002.11a
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• pp.17-18
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• 2002