• Korean Journal of Ichthyology
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• v.26 no.2
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• pp.125-132
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• 2014

Seasonal variation and abundance of fish larvae in Han River estuary were determined by analysis of seasonal samples collected from three channels in the Han River estuary from May 2007 to August 2008. During the study, a total of 3,642 fish larvae were collected belonging to 13 taxa. Coilia spp. was the most abundant (48.8%). The highest number of taxa (11 taxa) was collected in the Jangbong channel and abundance was high in the Sukmo channel (2,428 ind./$1,000m^3$). Brackish-water species were prevailed in the Yumhwa channel and the Sukmo channel, while coastal species were abundant in the Jangbong channel. Canonical correspondence analysis revealed that the environmental factors such as water temperature and salinity had a strong relationship with the abundance of major larvae species.

• 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.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.3
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• pp.149-158
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• 2012

This study analyzed cross-sectional variations in residual current and strengths of stratification by observing cross-sectional velocity and salinity during spring tide and neap tide, respectively, for continuous 13-hour periods at 2 observation lines at northern and southern end of Seokmo Channel, which is located west of Ganghwado. Salinity distribution of channel depends on not only neap and spring tide but also impact of salinity. The residual current component was obtained by removing $M_2$ and $M_4$ tidal components that were extracted using the least squares method on 13-hour velocity component. Cross-section of residual velocity at northern and southern end of Seokmo Channel exhibited southward residual components at channel's surface layer, but northward residual current was observed at channel's bottom layer, clearly showing a 2-layer tidal circulation between surface and bottom layers. The variation in location of appearing northward residual current according to changes in spring and neap tidal cycle and its correlation with stratification were analyzed using the Richardson number and Simpsonhunter index. At northern and southern end of Seokmo Channel, northward residual current appears in the location where Richardson number is large, Simpson-hunter index appears as a value greater than 4.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.6
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• pp.390-399
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• 2012

This research observed the cross section current of 7 survey lines in Seokmo Channel of Gyeonggi bay with a lot of freshwater inflow and S-shaped for 13 hours during flood season and neap tide. We indicated the distribution of the current velocity by comprehending the speed and direction of the current velocity of each line during maximum flood, ebb tide and observed the distribution of salinity. Moreover, in order to understand what lateral momentum causes the lateral flow in each survey line, we practiced the momentum analysis through the observation data. As a result, the lateral baroclinic pressure gradient force and vertical friction of the Seokmo channel during neap tide were the strongest, and this is why the flow by the distribution of salinity and stratification most often occurs. In north of the Seokmo channel, where have wide intertidal and a lot of freshwater inflow, the secondary circulation is caused by balance of lateral baroclinic pressure gradient force and other forces, and the vertical friction was strong in the lines with small depth. On the other hand, in the southern part of the Seokmo channel where the water is deep and the waterway is curved, the advective acceleration and centrifugal force become stronger by the geographical causes during ebb and the influence of fresh water. Therefore, the lateral flow in the Seokmo channel was caused by the distribution of the momentum that differs by location, depth, curve, etc.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.4
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• pp.166-175
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• 2010

Seasonal variation in species composition of estuarine fauna in the Han River estuary was determined by analyzing monthly samples collected on the intertidal flat of Ganghwa Island by a fence net from April to December 2009. Total number of species was 57: 34 species of fishes, 20 species of crustacean, 2 species of cephalopods and 1 species of jellyfish. Of a total of 57 species, Portunus trituberculatus (57.2%), Palaemon gravieri (7.1%), Collichthys lucidus (7.0%), Hemigrapsus sanguineus (6.2%) and Exopalaemon carinicauda (4.7%) were predominated in abundance. Diverse species were occurred in spring and autumn, and abundance was high in autumn. Chelon haematocheilus, Synechogobius hasta, Co ilia nasus, P. gravieri and E. carinicauda were classified as the brackish residence species. P. trituberculatus, C. lucidus, Mugil cephalus and Cynoglossus joyneri were coastal migratory species which use the estuary as nursing and feeding grounds. Diadromous species (such as Takifogu obscurus, Anguilajaponica and Eriocheir sinensis) and freshwater fish (Carassius auratus) were also collected.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.2
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• pp.41-51
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• 2013

The tidal creek dependent mass transport characteristic in Gyeong-Gi Bay (west coast of Korea) was studied using field measured data and numerical model. Gyeong-Gi Bay consists of 3 main tidal channels and contains a well-developed vast tidal flat. This region is famous for its large tidal difference and strong current. We aim to study the effect of tidal creek in the tidal flat on the mass exchange between the estuary and the ocean. For numerical application, the application of unstructured grid feature is essential, since the tidal creek has complicated shape and form. For this purpose, the FVCOM is applied to the study area and simulation is performed for 2 different cases. In case A, geographic characteristics of the tidal creek is ignored in the numerical grid and in case B, the tidal creek are constructed using unstructured grid. And these 2 cases are compared with the field measured cross-channel mass transport data. The cross-channel mass transport at the Yeomha waterway mouth and Incheon harbor was measured in June, 9~10 (Spring tide) and 17~18 (Neap tide), 2009. CTD casting and ADCP cross-channel transect was conducted 13 times in one tidal cycle. The observation data analysis results showed that mass transport has characteristic of the ebb dominance Line 1 (Yeomha waterway mouth), on the other hand, a flood dominant characteristic is shown in Line 2 (Incheon harbor front). By comparing the numerical model (case A & B) with observation data, we found that the case B results show much better agreement with measurement data than case A. It is showed that the geographic feature of tidal creek should be considered in grid design of numerical model in order to understand the mass transport characteristics over large tidal flat area.