• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• 제23권1호
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• pp.39-51
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• 1995

Bidirectional transport trend using the sediment-transport path model was identified in the two areas, sand ridge area and tidal mudflat in Garolim Bay, which is located in the mid-western coast of Korean Peninsular. This model exhibits the two-dimensional view of clear sediment transport trend based on data of changes in sediment statistics such as mean, sorting, and skewness, Garolim Bay was selected to test for the sediment-transport path model developed by McLaren and Bowles [1985]. Line-S, a typical tidal mudflat and representative of the Garolim Bay tidal flats, is well tested by this model, showing a clear seasonal change and coarsening-trend seaward (case C). This indicates that strong ebb currents carried relatively coarser sediments seaward with respect to high energy regime. Seasonally, this energy regime slowly decreases toward the summer in contrast with an increase of energy regime of flood tides, carrying coarser sediments landward (case C) in the summer. However, the Line-D area does not show consistent transport trend with respect to time-series. Separated and scattered events show fining trend landward (case B) in the sand ridge itself. The finining-trend (case B) either seaward and landward is not chiefly important in both the entire Line-D area and sand ridge itself. Also, the coarsening-Trend (case C) landward is not significant in the sand ridge itself. Consequently, in reality, the selection of suitable and representative locations are very important to fit with this model.

• Korean Journal of Hydrosciences
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• 제10권
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• pp.73-83
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• 1999

The intake towers of Buyeo W.T.P. in Keum river have being suffered from the sedimentation problems since the beginning of the operation. Impellers of the intake pumps have to the frequently changed due to the serious surface erosion. Thousands tons of sands are entrapped in the intake towers and equalization chambers of W.T.P. every year. Site surveying and numerical analysis were carried out to suggest an appropriate solution by understanding the general sedimentation regime of Keum river and causes of the sedimentation in the intake towers. Origin of the sediment could be found by the desk and site inspections. The validity of the used numerical models was examined by comparisons between the calculated bydraulic values and the measured ones during the specific periods. The design flow rate for the prediction of the future sedimentation regime of the rever was studied. The efficiency of the sediment control measures was also examined with the verified numerical models. Finally, it was found that the best solution could be a combination of three sediment control measures; increase the clearance between river bed and inlet, construct jetties at 2 kilometers upstream from the intake towers, and put vanes at the right side of the intake towers.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.203-206
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• 2008

There are lots of the narrow pass on alluvial channel of Korea. Most of research about this narrow pass of channel were focused on incremental effect of water level at backwater segment. In the meantime this research showed that it is important to valuate the river-bed variation at backward and forward around narrow pass. The sediment deposit at not only the backward of narrow pass but also the forward affected incremental effect of water level. The sediment deposit at the forward of narrow pass headed by sediment that passed through the narrow passed or scoured right around it.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2016년도 학술발표회
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• pp.196-196
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• 2016

Landslide dam failure presents as a severe natural disaster due to its adverse impact to people and property. If the landslide dams failed, the discharge of a huge volume of both water and sediment could result in a catastrophic flood in the downstream area. In most of previous studies, breaching process used to be considered as a constructed dam, rather than as a landslide dam. Their erosion rate was assumed to relate to discharge by a sediment transport equation. However, during surface erosion of landslide dam, the sediment transportation regime is greatly dependent on the slope surface and the sediment concentration in the flow. This study aims to accurately simulate the outflow hydrograph caused by landslide dam by overtopping through a 2D surface flow erosion/deposition model. The lateral erosion velocity in this model was presented as a function of the shear stress on the side wall. The simulated results were then compared and it was coherent with the results obtained from the experiments.

• Ocean and Polar Research
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• 제24권1호
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• pp.39-45
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• 2002

The seasonal patterns of sediment supply were investigated during the period of June 1999 to June 2000 on a coastal foredune of Seungbong Island, Korea. Sediment supply was determined from measurements of geomorphic changes in the foredune and beach along six lines. Most sands were deposited on the dunefoot and foredune area during the winter and spring, from November to April. The largest amount of sands was deposited along the lines 5 and 6 near the sea-dike in the southern tip of the dune area. In general, the sand on the beach was gradually eroded in spring, summer and fall but deposited in winter. Total sediment accumulation over the study period was $484m^3$ for the foredune and $345m^3$ for the beach. The volume of the foredune increased in the winter and spring, whereas the volume of beach increased in the winter. Variation in sediment deposition appears to be controlled primarily by variations in the seasonal wind regime.

• 한국해양공학회지
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• 제12권2호통권28호
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• pp.111-120
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• 1998

Laboratory settling experiments (column, recirculating flume) were conducted for further understanding of the physical processes of cohesive sediment transport. \In still water experiments, the growth rate of flocculation is dependent upon the initial suspended concentration. Consequently, the settling velocity increases with concentration of flees. In flocculation settling regime, the exponent n in the settling velocity, $w_s=kC^n$, for Nakdong estuary mud was obtained empirically. The exponents were found to be 1.33, and 1.06 for the initial suspended concentrations of 1 g/i and 3 g/t, respectively. In flowing water, experiments for the median settling velocity with Nakdong mud in a recirculating flume were conducted. Settling velocity was found to depend much more strongly on the current velocity than initial concentrations. The temporal variation of suspended concentration increases as current velocity decreases.

• 한국지역지리학회지
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• 제7권2호
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• pp.82-96
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• 2001

본 연구에서는 우리나라의 대표적인 조간대 퇴적지형인 강화도 남단 갯벌을 사례로 서해안 조간대 지역의 퇴적환경을 구명하고 올바른 이용 및 관리방안을 고찰하였다. 연구결과는 다음과 같다. 첫째, 강화도 남단 갯벌은 세계적으로 그 가치가 인정되고 있는 지형 생태적으로 중요한 해안습지이다. 그러나 해안생태계의 자정작용 역할을 하는 염생습지의 대부분은 간척되어 현재는 농경지로 이용되거나 그대로 방치되고 있다. 둘째, 강화도 남단 갯벌의 평균 조석간만의 차는 7.3m로, 조석차를 바탕으로 권역을 구분하면 고위 조간대 중위 조간대 저위 조간대 및 천해로 구분 지을 수 있다. 또한 대부분 간척된 과거 염생습지로 이루어진 육지권역이 포함될 수 있다. 셋째, 연구지역의 퇴적환경을 지시한다고 판단된 표층 퇴적물의 물리적 특성을 분석한 결과 평균 입도 분포는 모래 41.5% 실트 47.3% 점토 11.2%로 나타나서 실트의 비율이 상당히 높은 비율을 차지하고 있는데, 이는 퇴적물의 생태적 특성을 지시하는 것이다. 넷째, 권역별 이용 및 관리방안으로는 (1) 고위 및 중위 조간대는 갯벌 체험학교와 인공 염생습지, 그리고 양식업 대상지로 이용할 수 있으며 오염물질의 유입과 양식장 관리가 중요한 곳이다. (2) 저위 조간대는 특정기간의 갯벌체험과 바다 낚시 대상지로 이용할 수 있으며 조류의 통과시기와 패류의 산란시기에는 각별한 주의가 요구되는 곳이다. (3), 천해는 외해와 인접한 곳으로서 극히 일부 기간의 갯벌 체험과 바다 낚시 대상지로 이용할 수 는 곳이다. (4) 인접 육지부는 방조제를 이용한 철새관찰용 시설물 설치와 갯벌의 생태적 특징을 중심으로 한 홍보물을 설치할 수 있는 생태 관광지 대상지이다. 또 갯벌부로 유입되는 생활하수와 축산폐수의 관리가 중요한 곳이기도 하다.

• 한국환경복원기술학회지
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• 제11권3호
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• pp.74-86
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• 2008

To assessment the disturbances of the Namgang caused by dam construction, upstream area was selected for the reference reach and downstream area was selected for the comparison reach. And these reaches were surveyed and analyzed according to the assessment criteria of the river disturbances.The artificial factors of river disturbances were classified as river improvement works, dam construction and aggregate dredging. The indexes were physical factors as like epifaunal (bottom), embeddedness, velocity/depth regime, sediment deposition, channel flow status, channel alteration, frequency of riffles, bank stability, vegetative protection, riparian zone etc.The assessment results showed 46% of the assessment criteria which was serious status in dam downstream area and 89.5% of it which was excellent status in dam upstream.Finally, the results showed that physical river environment in downstream area was disturbed by the discharge control and the interception of sediment discharge by dam, consequently this disturbance give rise to impact of ecosystem in river.

• 한국환경복원기술학회지
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• 제13권2호
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• pp.95-104
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• 2010

The purpose of this study is to analyze the correlation between physical stream characteristics and bed materials in natural rivers. Accordingly, four natural rivers were selected reference streams, they were Nam river, Sumjin River, Naesung River and Han River. Grain size distributions of bed materials were gravels, cobbles and boulders in Han river and Nam river, were sand, gravels, cobbles and boulders in Sumjin river and were sand in Naesung river. Four reference streams were divided into each two reference reaches (straight and bend) by plan and profile characteristics of naturally meandering stream. Therefore various reference reaches were chosen in the aspect of physical stream characteristics and grain size distributions. The results investigated and analyzed are as follows. The streams that grain sizes distributions of river bed materials were coarse were stable because they had variety of bed slope without sediment deposition, and then the riffles frequency and the physical characteristics were various. Also, velocitydepth regime were various in four kinds, and the response parts for water level change were small, so that channel flow status were stable and excellent condition. On the other hand, sand river that grain sizes distributions of river bed materials were fine had not the variety of parameters as velocity-depth regimes, sediment deposition, channel flow status and riffles frequency, so that the physical stream characteristics were not various.

• Environmental Engineering Research
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• 제19권2호
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• pp.175-184
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• 2014

Weirs are conventional structures that control water level and velocity in streams to facilitate water resource management. Despite many weirs built in streams, there is little information how weirs change hydrology regime and how that translates to sediment and phosphorus (P) responses. This study evaluated the influence of weirs on P retention and mobilization in an urban tributary of the Han River in Korea. Total P concentrations in sediments upstream of weirs were higher than the downstream site, mainly due to the increase of potentially available fractions (labile P and aluminum- and iron-bound P) (p < 0.05). Equilibrium phosphorus concentrations ($EPC_o$) were lower than soluble reactive phosphorus (SRP) concentrations of stream waters, but there was an increasing trend of sediment $EPC_o$ upstream of weirs compared to the downstream site (p < 0.001) indicating a greater potential for P release upstream of weirs. Sediment core incubation showed that SRP release rates upstream of weirs were higher than the downstream site under anoxic conditions of the water column (p < 0.01), but not under oxic conditions. SRP release rates under anoxic conditions were greater than that measured under oxic conditions. Un-neutral pH and increased temperature could also enhance SRP release rates upstream of weirs. We conclude that weirs can increase P retention within stream sediments and potentially promote significant P releases into waters, which in turn cause eutrophication.