• 한국해양학회지
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• v.27 no.1
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• pp.66-77
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• 1992

Tidal sand ridges and sand waves are well developed in the Yellow Sea off Tae-An Peninsula, Korea. Their transport directions were inferred based on high resolution seismic profiles, surficial sediment characteristics and tidal regime. Tidal sand ridges are asymmetric, with long axes parallel to or slightly oblique to the dominant NE-SW tidal current direction. They show steep south and/or southeast flanks, which are in concordance with the apparent direction of internal cross-bedding in the south. Holocene sediments occur in accordance with distributional patterns of tidal sand ridges. These features indicate that Holocene active tidal sand ridges move toward the open sea in southeast, south and southwest direction. Sand waves which are distributed in flat sea floor with depth of about 40-60m show also asymmetric forms with a steep east-to-northeast face. Surficial sediments in the sand wave field are characterized by well sorted fine sands compared with poorly sorted adjacent areas. The sand waves appear to undergo easterly or northeasterly landward movement.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.481-481
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• 2016

하천퇴적물은 물의 순환과정에서 유역으로부터 유입되는 물질에 따라 조성이 변하게 된다. 특히 입자가 작은 토양과 유기성 물질들은 물순환과정에 이동성이 크게 나타나며, 인간에 의해 개발된 지역은 자연상태에 비해 이동하는 물질이 많이 나타나곤 한다. 본 연구에서는 하천에 건설된 보에 대한 퇴적물 조사를 실시함으로서 향후 수질관리에 필요한 기초 자료를 수집하고자 하였다. 본고에서는 금강과 낙동강에 건설된 보의 주요지점에 대한 퇴적물 조사를 실시하고 수질영향을 평가하였다. 조사는 홍수기전과 홍수기후로 구분하여 2회에 걸쳐 실시하였으며 물리적 성상과 화학적 항목에 대한 분석을 실시하였다. 입도분석 결과 금강 주요 10개 지점의 퇴적물 조성은 Sand, Silt와 Clay 성분이 혼합되어 있는 것으로 분석되었으며, 삼각좌표 분류법에 의한 토성은 대부분의 지점이 실트질양토(SiL)로 평가되었다. 완전연소가능량은 0.35~1.37로 전 지점에서 하천 호소 퇴적물 오염평가 기준의 유기물 함량기준 13%보다 높지 않은 것으로 나타났으며 홍수기 전 후에도 거의 유사하였다. 금강에서는 중금속뿐만 아니라 유기물 및 영양염류도 기준보다 낮게 나타났으며, 모든 항목에서 환경부예규인 하천 호소퇴적물 오염평가 기준보다 낮게 평가되었다. 하상 퇴적물이 수질에 미치는 영향을 평가하는 용출실험에서도 유기물 및 중금속 모두 수질에 미치는 영향은 거의 없는 것으로 평가되었다. 낙동강 주요 26지점의 입도분석 결과 퇴적물 조성은 대부분 Sand로 구성되어 삼각좌표 분류법에 의한 토성은 사토(S)로 평가되었다. 홍수기 전 후에 조사한 결과 완전연소가능량은 0.27~2.85으로 전 지점에서 하천 호소 퇴적물 오염평가 기준의 유기물 함량 기준보다 낮았으며 홍수기 전 후에도 거의 유사하였다. 화학적 성상 분석 결과 모든 항목에서 환경부예규인 하천 호소퇴적물 오염평가 기준보다 낮게 평가되었으며, 용출실험에서도 유기물 및 중금속 모두 수질에 영향을 거의 미치지 않는 것으로 평가되었다. 이번 조사는 4대강 건설 후 하상이 안정화 되지 않은 상태로 인해 지점간 특별한 경향성은 확인할 수 없었으며 보다 정확한 결과 도출을 위해서는 장기적인 조사를 통해 평가해야 할 것으로 판단되었다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.1
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• pp.39-47
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• 2020

In order to investigate current characteristics at the Gungpyung beach, which is a macrotidal flat, field measurements were carried out in the summer and winter at the intertidal and the subtidal zones. The distribution of residual current at intertidal flat was dominant in the northward direction in the summer and dominant in the northward and southwestern directions in the winter. The direction and speed of the residual current in the winter are highly correlated with the significant wave height, and the turbidity is also highly correlated with the significant wave height. Therefore, in the winter, high sediment rates are suspended by high waves, and sediments are transporting due to the residual current in the southwest direction. On the other hand, it is expected that the northward residual current is predominant due to the small wave in the summer, and sediment transport does not occur largely due to less suspended sediments. In addition, sediment transport in the southern direction is blocked by the dock, which is the artificial structure, and the erosion occurs in the south side of the dock. The erosion pattern in the macrotidal zone of Yellow sea is dominated by seasonal waves, and blocking of sediments by artificial structure is very important.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.10 no.4
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• pp.187-196
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• 1998

Morphological changes around the groin system in the beach are examined using a numerical model. The model consists of two parts : the hydrodynamic model which calculates the transformation of waves and currents, and the sediment transport model which determines sediment transport rates and bottom topographic changes. The numerical model is applied to single-groin and three-groin systems on a typical plane beach. The changes to the beach system due to waves and currents during 150-day simulation near the groins are calculated using sediment transport rate patterns in the domain. The sand by-passing rate patterns around groins are also evaluated.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.6 no.2
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• pp.150-156
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• 1994

Shoreline change due to the littoral drift in Suyeong bay, especially the Gwanganri and Haeundae beaches, was investigated. Average monthly frequency. speed. and direction of winds blowing from between east and south for the last 15 years were analysed, and offshore significant waves were hindcasted using the JONSWAP model. Wave refractions, shoaling, and breaking weir also investigated for the calculation of littoral drift. At the Gwanganri beach major longshore transport of sands occurs from the southwest to the northeast and the shoreline seems to advance in the northeast while it recedes in the southwest. At the Haeundae beach the sands mainly move from the east to the west and the shoreline retreats in the east and advances in the west.

• Economic and Environmental Geology
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• v.37 no.3
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• pp.311-324
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• 2004

We investigated the contamination and behavior of heavy metals in stream sediments within the watershed of Juam Reservoir. Many abandoned mines within the reservoir can act as a potential contaminant source for water quality. Heavy metal concentrations (Cr, Cu, Ni, Pb and Zn) in stream sediments from watershed are very low, indicating that content of heavy metals in the sediments probably do not affect the water quality in Juam Reservoir. However Pb concentration in the stream sediments increases downward streams, suggesting the possible diffusion of Pb contamination. According to the leaching ratio for stream sediments at a strong acidic condition in the abandoned mine areas, the relative mobility for metals decreases in the order of Pb＞Zn=Cu＞Ni＞Cr, indicating that Pb can have a bad effect upon the water quality in Jum Reservoir. Moreover, if contaminated sediment is placed in the bottom of reservoir (i.e., reducing condition), the relative mobility of Pb is the highest, indicating that Pb in the bottom sediments can be leached to water at interface between water and sediment with changing in physicochemical conditions.

• 한국해양학회지
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• v.27 no.2
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• pp.145-153
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• 1992

From the analyses of 16 bottom sediment samples and current data obtained during field expert ments from August to September 1987, the textural characteristics and transport mode of sand grains of a tidal sand ridge in Gyeonggi Bay are studied. The textural characteristic of the bottom sediments are diverse depending on their location on the tidal sand ridge. Sands on the crest are well sorted. near symmetric in skewness. leptokurtic in kurtosis. and are unimodal in peakedness. On the other hand, Poorly sorted gravelly sands in the trough are coarse skewed in skewness and plartkurtic in kurtosis. The mean values of U/SUB 100/ (velocity at one meter above bottom) and U/SUP */ (boundary shear velocity) are calculated to be 41.4 cm/sec and 2.39 cm/sec, respectively. From the analyses of characteristics of the sediments and currents in the study area, it can be concluded that almost all the sands of the tidal sand ridge (esp. on the crest) are transported as bedload (mainly as saltation).

• Proceedings of the KGS Conference
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• 2003.11a
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• pp.24-28
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• 2003

장기간에 걸친 지형변화를 예측하는 것은 기초과학뿐만 아니라 응용과학 및 해양 공학적인 측면에서 볼 때 매우 중요하다. 퇴적물 이동과 지형변화의 예측은 항만의 수로를 유지하고, 폭풍에 의한 침식을 방제 할 뿐 아니라 지질학적 time-scale에서 퇴적층 형성을 이해함으로서 경제적으로 유용한 석유자원 매장을 밝히는데 도움을 준다. 그렇지만 퇴적역학에 대한 이해가 불충분하고 지형환경 system이 복잡하기 때문에 퇴적물 이동 및 지형변화에 대한3차원 모델을 통한 지형 변화 예측을 실용적으로 사용하기에는 불충분하다. (중략)

• Journal of the Korean earth science society
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• v.31 no.2
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• pp.139-150
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• 2010

This study investigated the depositional environment of the area of Anmyeondo in the mid-western coast of Korea. A total of 142 surface sediments were analyzed, and leveling survey was conducted as well in 12 transects at the sandy tidal flat in the area. The surface sediments are classified into several different types (slightly gravelly Sand, Sand, slightly gravelly sandy Mud, etc.) and they show fining-distribution toward the offshore. Textural parameters are characterized by being coarse, well sorted, positively skewed in the supratidal and intertidal flat, whereas being finer, poorly sorted, negatively skewed in the subtidal flat. According to the C-M diagram, the sediment transport modes are characterized by the mixed mode of bedload and graded suspension in supratidal and intertidal flat, and by graded suspension or uniform suspension in the subtidal flat. Histogram shows a bimodal distribution in the lower subtidal flat which is indicative of two sediment transport modes.

• Journal of the Korean earth science society
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• v.27 no.2
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• pp.221-235
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• 2006

In order to understand the transport mechanism of tidal beach sediments in Deukryang Bay, south coast of Korea, beach profiles, surface sediments, sedimentation rates and hydrodynamic conditions have been investigated. The beach is composed of a steep beach face and gentle low-tide terrace, showing general morphologic characteristics of tide dominated beach. Central beach face of an indented coast becomes flattened in summer, but ridge and runnel system developed in other seasons makes the beach profile rather irregular. These seasonal variations of beach profiles and sedimentation rate indicate that beach sedimentation is mainly controlled by both tide and wave processes. Erosion is prevalent in winter when strong wind wave is dominant, while deposition is dominant in other seasons. However, central beach showed an apparent erosional phase in summer. This is caused by strong waves induced by southerly strong winds occurring ephemerally during the summer. On the other hand, sedimentation rates are -89.2 mm/yr on the central beach and 60.5 mm/yr and 38.2 mm/yr on the sides. This result suggests that sediments are eroded on the central beach and subsequently transported to the both sides. Therefore, the central part of Sumun beach, used as a beach bathing site, will be continuously eroded, if nearby dyke continues to prevent the sediment supply from sources.