• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.4
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• pp.262-272
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• 2007

Diurnal and tidal variation in the abundance of the macro- and megabenthic assemblages were studied in the macrotidal flat, Incheon, Korea. The samples were collected by modified otter trawl during 8-9, June 2000. The macro- and megabenthic assemblages comprised a total of 60 species, including 6,309 individuals and 67,835.5 gWWt. As a result, the abundance pattern showed two different categories relating to diel and tidal cycles. First, the diel pattern of these assemblages was subdivided into 3 groups. 1) Diurnal species such as Hexagrammos otakii, Thryssa baelama, Loligo beka, Metapenaeus joyneri. 2) Nocturnal species such as Cynoglossus joyneri, Sebastes schlegeli, Charybdis japonica, Crangon affinis, Trachysalambria curvirostris, Metapenaeopsis dalei. 3)Other species showing no obvious pattern with Johnius grypotus, Platycephalus indicus, Repomucenus richardsonii. However, based on the result of Mann-Whitney U-test, diel patterns of macro- and megabenthos did not reveal any significant differences. Second, tidal variation in the macro- and megabenthic assemblages was significant between ebb and flood tides. Total macro- and megafaunal species number, abundance and biomass were higher in ebb tide$(13^h30',\;16^h30',\;1^h30',\;4^h30')$ than in flood tide$(19^h30',\;21^h30',\;10^h30',\;13^h00')$. As a consequence, the macro- and megabenthic assemblages were clearly influenced by tides but their diel variations were not significantly different.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.1
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• pp.58-66
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• 2010

In this paper, we have constructed high-resolution topographical map of macro-tidal Malipo beach through integration of terrestrial LiDAR measurement and MBES survey data at inter-tidal zone. To acquire the enough information of inter-tidal zone, we have done terrestrial LiDAR measurement mounted on the roof of vehicle with DGPS through go-stop-scan method at the ebb tide and MBES depth surveying with tide gauge and eye staff measurement for tide correction and MSL calculation at the high tide all together. To integrate two kinds of data, we have unified the vertical coordination standard to Incheon MSL. The mean error of overlapped inter-tidal zone is about 2~6 cm. To verify the accuracy of terrestrial LiDAR, RTK-DGPS measurement have done simultaneously and the difference of Z value RMSE is about 4~7 cm. The resolution of Malipo topographical map is 50 cm and it has constructed to DEM (Digital Elevation Model) based on GIS. Now it has used as an input topography information for the storm-surge inundation prediction models. Also it will be possible to use monitoring of beach process through the long-term periodic measurement and GIS-based 3D spatial analysis calculating the erosion and deposition considering with the artificial beach transition and coastal environmental parameters.

• Journal of the Korean earth science society
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• v.31 no.7
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• pp.708-719
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• 2010

The Gochang-gun Dongho macro-tide pocket-type beach, located on the southwestern coast of Korea, is investigated in terms of the seasonal variations of surface sediment and sedimentary environment. Surface sediments of 45 sites in four seasons (May 2006-February 2007) are sampled across three survey lines (15 sites in each survey line). The surface sediments of the Dongho Beach are mainly composed of fine to coarse sands, and the ratio of fine sand is the largest. The average of grain size is the coarsest in the summer. The spatial distribution of surface sediments shows a coast-parallel band of fine and medium sands during three seasons of spring, fall, and winter, whereas medium sands dominated in the northern part of the study area during the summer. These results suggest that a tide is more effective than a wave in the surface sediments of the Dongho Beach during the summer.

• Journal of the Korean earth science society
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• v.33 no.6
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• pp.497-509
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• 2012

The Gochanggun Kwangseungri macro-tide open-coast beach, located in the southwestern coast of Korea, was investigated in terms of the seasonal variations of surface sediment facies and sedimentary environment. Surface sediments of 45 sites in four seasons (May 2006 - February 2007) were sampled along three survey lines (15 sites in each survey line). The surface sediments of the Kwangseungri Beach are mainly composed of fine-grained sands, and its mean grain size is the coarsest in winter. Mud facies partly exists in summer, whereas it is nearly absent in winter. The spatial distribution of surface sediments shows a coast-parallel band of fine and medium sands during spring, fall, and winter. In the northern part, the study area is dominated by fine sands during summer, whereas by coarse sands during winter. These results can be interpreted that tide is more effective than wave on the surface sediment distribution of the Kwangseungri Beach during the summer season.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.5
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• pp.457-464
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• 2001

Algal growth potential (AGP) assay using Cochlodinium polykrikoides was conducted in Saryang Island coast where C. polykrikoides red tide occurred annually from July to October 1998. The effects of macro- and micro-nutrients on the growth of C. polykrikoides were specifically evaluated by the algal assay method. Two different types of growth response of C. polykikoides for the addition of nutrients were clearly obseued. For both before and after C. polykrikoides occurrence, the growth of C. polykikoides was significantly stimulated by the addition of either nitrate or ammonium of $50{\mu]M$ with phosphate of $5{\mu}M$. The addition of a single nutrient had no clear effect on the growth of C. polyhikoides and the addition of trace metals, vitamins, and EDTA etc. did not stimulate the algal growth, also. This result indicates that both N and P potentially limited the growth of C. polyhikoides in this period. However, during a bloom of C. polyhikoides, the growth was unlikely to be stimulated by the addition of both macro- and micro-nutrients. At that time the nutrient concentration of Saryang Island coast was $24.33{\mu}M$ for ammonium, $1.61{\mu}M$ for phosphate, and $0.58{\mu}M$ for nitrate, respectively. The concentrations of nutrients increased, on average, 8.2-fold for ammonium and 4.8-fold for phosphate, decreased 3.3-fold for nitrate compared to both before and after the red tide. This result shows that the growth of C. polykikoides was not limited by the nutrients during the bloom in September. Therefore, our results suggest that the C. polykrikoides red tide may outbreak especially when the water is fertilized due to the increased N and P.

• Journal of Ocean Engineering and Technology
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• v.33 no.1
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• pp.68-75
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• 2019

A low-crested structure (LCS) is an excellent feature not only because it provides shore protection but also because it is fully submerged. However, in order to properly control waves, it is necessary to maintain a certain range of crest height and width in consideration of the wave dimensions at the installation area. According to previous studies, an LCS has some wave breaking effect when the crest width is more than a fourth of the incident wavelength and the crest depth is less than a third of the incident wave height. In other words, if the crest width of the LCS is small or the crest depth is large, it cannot control the wave. Therefore, when an LCS is installed in a large sea area with a great tidal range in consideration of the landscape, waves cannot be blocked at high tide. In this study, the hydraulic performances of a typical trapezoidal LCS with a constant crest height and a low-crested structure with an adjustable crest height, which was called a tide-adapting low-crested structure (TA-LCS) in this study, were compared and evaluated under various wave conditions through hydraulic experiments. It was found that the wave transmission coefficients of the TA-LCS at high tide were lower than the values for the typical LCS based on empirical formulas. In addition, the hydraulic performances of the TA-LCS for wave reflection control were 12.9?30.4% lower than that of the typical LCS. Therefore, the TA-LCS is expected to be highly effective in controlling the energy of incoming waves during high tide even in a macro-tidal area.

• Journal of the Korean earth science society
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• v.36 no.6
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• pp.533-542
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• 2015

The Gochang beach is located in the southwestern coast of Korea along the eastern part of the Yellow Sea, comprising the Donghori, Gwangseungri, and Myeongsasipri beaches from north to south. The Gochang beach is characterized by macro-tide, open-coast, linear shoreline, and sand substrates. This study has investigated annual and seasonal characteristics of surface topography variation and sediment accumulation rate in the Gochang beach. During the five seasons of winter (Feb.), spring (May), summer (Aug.), and fall (Nov.) in 2014 and winter (Feb.) in 2015, the topographic elevation of total 315 sites was measured along three survey lines. It consists of 21 sites at 30 m intervals in each transverse line perpendicular to the shoreline, respectively. Annual accumulation rate of the Gochang beach in 2014 was -0.081 m/yr, indicative of erosional condition. Annual accumulation rates of the comprising beaches represent -0.091m/yr of the Donghori, -0.051 m/yr of the Gwangseungri, and -0.10 m/yr of the Myeongsasipri.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.5
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• pp.393-400
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• 2011

The mass transport is very complicated at the area which has the macro tide and complex geometry such as Gyeonggi bay. Especially, the long period current has a strong influence on the estuarine ecosystem and the long-term distribution of substances. The long period current is caused by several external forcing, whose unique characteristic varies spatially and temporally. The variation characteristics of long period current is analysed and its generation mechanism is studied. The tidal nonlinear constituents such as overtide and compound tide are generated due to nonlinear interaction and it causes mean sea level setup. The tidal wave propagating up into estuary is transformed rapidly by decrease of cross-sectional area and depth. Therefore the mean sea level is getting rise toward upriver. The high and low tide level is similar between down-river(Incheon) and up-river(Ganghwa) during neap tide when the tidal deformation is decreased. The tidal phase difference between two tidal stations causes a periodic fluctuation of sea level difference. The low water level of Ganghwa station during spring tide does not descend under EL(-)2.5 m, but the low water level of Incheon fall down under EL(-)4.0 m. The variation of tidal range and its sea level are increased during spring tide. It is found that the long period current $M_{sf}$ is quite similar to that of sea level difference between the two tidal stations. It means that the sea surface inclination caused by the spatial difference of tidal deformation is important forcing for the generation of long period current.

• Journal of the Korean earth science society
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• v.23 no.7
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• pp.565-574
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• 2002

Based on previous investigations of aerial photographs and topographical surveys, this study focuses on the sedimentologic features of the Daebudo area including sedimentation processes, sedimentary facies and hydrologic conditions of the erosional coast. A total of 137 surface sediments and one core (by hand auger) sediment were obtained to interpret the depositional environment of the erosional coast in the macro-tidal coast. Surface sediments are distributed from sandy gravel (sG) to silt (Z). Textural parameters are characterized not only by coarse, poorly sorted, positive skewed and multi-modal distribution in the supra-tidal flat, but also finer, relatively well-sorted, symmetric distribution in the intertidal flat. According to the C/M diagram, sediment transport modes of study area are characterized by the mixed mode of suspension and bedload in the upper-, middle-tidal flat and by uniform suspension in the lower-tidal flat due to tidal effect. Vertical sediment distribution of the core, collected near shoreline, shows coarsening-upward, poorly sorted pattern by the input of detritus resulting from coastal erosion. Considering the sedimentological features of the study area, it appears to be composed of a coastal zone changed by not only artificial reclamation, but also by natural processes such as strong wave action due to typhoons and storms during high water level and long/short-term sea level rising. As a result, tide-dominated erosional coasts show that the shore is affected by local, temporal and hydrological conditions near high tide level and that the intertidal flat is represented by a general tide-dominated sedimentary environment.

• Journal of Marine Life Science
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• v.5 no.1
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• pp.25-33
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• 2020

The Asan Bay, which has semi-diurnal tide with macro-tidal range, is affected by both freshwater discharge from the sluice gates in the sea dikes and tidal seawater inputs from the Yellow sea. Understanding water quality change in response to tides is important since tides can impact the short-term variations in physical and chemical water properties as well as the response of biological properties. The diel variations in water quality were seasonally investigated at 2 hour intervals from a fixed station in the Asan Bay. In the results, water temperature and salinity consistently fluctuated in phase or out of phase with tidal height. Especially salinity was positively correlated with tidal height. The concentrations of total suspended solids were higher in the bottom water than in the surface and fluctuated greatly over the tidal cycle recording higher values at low tide than at high tide. Nitrite+nitrate levels also fluctuated out of phase with tidal height and correlated negatively with tidal height. Other nutrients also showed a similar pattern. The pattern was distinct in July when freshwater was discharged before the field sampling. The concentrations of organic materials, total nitrogen and total phosphorus greatly fluctuated over the tidal cycle and were generally out of phase with tidal height. Most materials except particulate organic forms were correlated with salinity indicating that freshwater inputs were sources for the materials similarly to the dissolved inorganic nutrients. The results suggest that water quality (except dissolved oxygen and pH) and nutrients including organic materials was largely affected by tides in the Asan Bay.