• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.4
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• pp.296-304
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• 2010

The shoreline change caused by the construction of shore protection structures are discussed based on the example of Youngrang coast, Sokcho where the coastal erosion control system(CECS), three artificial headlands and two submerged breakwaters are being constructed. The study qualitatively analyzed the shoreline changes of Youngrang coast using available satellite/aerial photographs and camera photographs taken during the construction period of 6 years since 2002 for the artificial headlands construction. The main results from the study are as following. (1) Before the installation of the middle artificial headland, longshore drifts along Youngrang coast are transported in the NW-SE direction according to the seasonally different wave characteristics. (2) During the CECS construction the shoreline is continuously changed by altering the local longshore drift budget. Especially, the middle artificial headland induces considerable change of shoreline by blocking the sediment supply from the southern pocket beach to the northern pocket beach and by accelerating the sediment accretion at the wave shadow zone behind its head. It induces the asymmetry on the net longshore drift causing the significant erosion at the center of the southern pocket beach. (3) The study demonstrates that serious unintended erosion/accretion problem are possibly occurred due to local changes on the wave transformation and the sediment transport by the construction of coastal erosion control system.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.47-47
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• 2011

하도 내 수역이 식생으로의 천이가 진행되고 최종적으로는 육상 식물들이 활착하게 되는 육역화 현상은 하도의 수리학적 문제 및 환경생태적 측면에서 큰 문제를 발생시킬 가능성을 내포하고 있다. 최근 하천복원의 필요성이 강조됨에 따라 물골공법 및 국부세굴 유도형 공법 등 실용성을 포함시킨 다양한 하천 복원공법이 제시되고 있다. 물골공법은 자연적인 물골형상에 의한 유사퇴적방지, 홍수시 유속저감 및 생물서식처를 조성하는 하상 생태복원 공법을 의미하며, 본 연구에서는 수리모형실험 및 3차원 수치모의를 이용하여 다양한 하도육역화 방지 공법 중 물골공법의 효과 및 적용성을 검토하였다. 물골공법의 특성 중 유사퇴적방지의 효율성 분석을 위해 부정류(unsteady state)상태에 대해 연구를 수행하였으며 홍수 이후 수위하강시 고수부지 및 물골 주변에서의 흐름특성을 재현하였다. 수위하강 모의를 위해 임의의 수위하강시간을 선정하여, 수위하강이 진행되는 시간( )을 각각의 수위하강시간으로 무차원 화한 후 무차원된 시간(t/�� )에 따른 흐름특성을 비교 분석하였으며 모의 및 분석결과, 수위하강시간이 80초 이상일 경우 주요 지점에서의 유속의 변화는 무차원된 시간에 대하여 일치하였으며 수리모형실험 및 수치모의에 적용할 수위하강시간으로 선정할 수 있었다. 물골 전구간에 대한 부정류 실험을 위해 LSPIV(Large-Scale Particle Image Velocimetry)장치를 이용하여 수위하강에 따른 물골주변의 흐름특성을 관측하였으며 3차원 수치모의를 통해 검증하였다. 실험 분석결과, 수위하강에 따라 고수부지 위로 흐르는 유수가 물골 내부로 유입되어 물골을 따라 흘러 물골 합류부로 이동하는 것으로 나타났으며, 이는 홍수시 유수와 함께 떠다니는 부유사(suspended load)가 물골로 유입되어 물골 합류부로 이동하므로 물골의 유사배제 가능성을 판단할 수 있었다. 또한 물골의 유사배제능력을 평가를 위해 실험을 통하여 산정된 최대 및 최소 마찰속도(U )와 유사이동 한계곡선을 이용하여 물골의 통한 배제 가능한 유사의 입경을 분석하였다. 분석결과, 최소 2mm에서 최대 4mm로 나타났으며 이 입경 이하인 유사에 대해서는 퇴적되지 않고 물골을 통하여 배제될 수 있을 것으로 예상되었다. 본 연구 결과 물골공법 적용시 수위하강에 따라 물골에서 하도방향으로 유사의 수세(flushing)효과가 나타났으며 유사의 부상 및 이송이 효과적으로 발생하여 고수부지 내 유사퇴적 방지가 효과적인 것으로 판단되었다. 추후 다양한 형상의 물골에 대한 능력검토가 보완된다면 물골설계지침 제안을 위한 자료로 활용 가능할 것이다.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1058-1062
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• 2007

본 연구에서 이동상 모래하천에서 식생의 변화과정을 연구하였다. 연구 대상 하천은 낙동강 상류 하회지구를 대상으로 하였다. 이 지역은 우리나라에서 대표적인 모래하천으로서 지형적인 요인으로 형성된 사행하천의 만곡부에 해당하고 있다. 특히 상류에 댐과 취수보 등 수자원개발시설이 건설되면서 수십 년 동안 물과 유사의 공급이 조절되어 안동시권역에서부터 하류방향으로 향하면서 점차 바뀌어 가고 있는 실정이다. 이 가운데, 이동성을 지니고 있던 사주부에 식생이 유입되고, 식생역이 확장되면서 사주가 고정화되는 경향을 보이고 있다. 이러한 이동상 하도에서 이동사주내 식생역의 발달과정을 파악하기 위하여 사주내 토양의 물리화학적 조사를 수행하였다. 연구 결과, 안동 하회지구내 모래사주에서 식생이 정착 발달 확장 되어가는 과정을 파악할 수 있었다. 하회지구의 식생역의 발달은 시기적으로 홍수기와 비홍수기의 반복적인 출현에 영향을 받고 있었다. 그리고 공간적으로는 홍수기 동안의 유사의 퇴적과 세굴과정과 밀접한 관련이 있는 것을 확인할 수 있었다. 식생역의 확장과정은 이러한 시공간적 상황으로 인해 유발되는 토양의 물리화학적 특성과 높은 상관성이 있음을 확인할 수 있었다.

• Journal of The Geomorphological Association of Korea
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• v.19 no.1
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• pp.29-40
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• 2012

The sand dunes at the lower reach of the Duman river indicate that their distribution patterns and directions conform to the dominant northwestern winter wind. On the riverbed of the Duman river at the surroundings of sand dunes form sandy point bars and mid-stream islands. The geomorphic processes of sand dunes can be classified into two types according to the depositional environments via analyses of the sand grain size and stratigraphic profiles. First, the sand dunes of Hoelyongbong, Kyeongshin-Wonjeong, and the riverside areas of the Duman river, have formed by alluvium of the Duman river which deposits and accumulates on the riverbed, then being wind blown to the nearby sand bars, terraces and higher eroded hills. The second type is the active sand dune of the Bangcheon-Nodongja District which develops similarly as to the formation of the first type, but the fixed sand dunes of the district seem to have formed in the underwater condition.

• Journal of the Korean Geographical Society
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• v.39 no.2
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• pp.269-282
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• 2004

Luminescence dating of a coastal dune from the Shindu dunefield on the T'aean Peninsula shows that deposition of the dune structure began about 500-600 years ago. The lower section of the dune has remained stable since then but the upper part yields an age of about 30 years, suggesting reactivation or additional deposition since the 1970's. The two samples that were collected from the lower part of the dune at depths of 3.5 m and 2.0 m below the surface differ by an age interval of about 50-70 years. This indicates a net depositional rate of around 2.5 cm a year which is relatively slow for a coastal dune. Whilst only one dune structure has been dated for the time being and even though the dunefield was probably established much earlier in the Holocene, the OSL ages obtained demonstrate that some dunes in the area could be younger than 1000 years. Such chronologies point to a dynamic environment where the dune structures are not permanently fixed. Sedimentological properties of the dune sands are consistent with those of particles initially deposited under subaqueous conditions and then later transported by wind.

• The Korean Journal of Petroleum Geology
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• v.10 no.1_2 s.11
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• pp.23-33
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• 2004

The Lago Sofia conglomerate in southern Chile is a lenticular unit encased within mudstone-dominated, deep-sea successions (Cerro Toro Formation, upper Cretaceous), extending from north to south for more than $120{\cal}km$. The Lago Sofia conglomerate is a unique example of long, gravelly deep-sea channels, which are rare in the modern environments. In the northern part (areas of Lago Pehoe and Laguna Goic), the conglomerate unit consists of 3-5 conglomerate bodies intervened by mudstone sequences. Paleocurrent data from these bodies indicate sediment transport to the east, south, and southeart. The conglomerate bodies in the northern Part are interpreted as the tributary channels that drained down the Paleoslope and converged to form N-S-trending trunk channels. In the southern part (Lago Sofia section), the conglomerate unit comprises a thick (> 300 m) conglomerate body, which probably formed in axial trunk channels of the N-5-trending foredeep trough. The well-exposed Lago Sofia section allowed for detailed investigation of sedimentary facies and large-scale architecture of the deepsea channel conglomerate. The conglomerate in Lago Sofia section comprises stratified conglomerate, massive-to-graded conglomerate, and diamictite, which represent bedload deposition under turbidity currents, deposition by high-density turbidity currents, and muddy debris flows, respectively. Paleocurrent data suggest that the debris flows originated from the failure of nearby channel banks or slopes flanking the channel system, whereas the turbidity currents flowed parallel to the orientation of the overall channel system. Architectural elements produced by turbidity currents represent vertical stacking of gravel sheets, lateral accretion of gravel bars, migration of gravel dunes, and filling of channel thalwegs and scoured hollows, similar to those in terrestrial gravel-bed braided rivers. Observations of large-scale stratal pattern reveal that the channel bodies are offset stacked toward the east, suggestive of an eastward migration of the axial trunk channel. The eastward channel migration is probably due to tectonic tilting related to the uplift of the Andean protocordillera just west of the Lago Sofia deep-sea channel system.

• Water for future
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• v.18 no.3
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• pp.235-241
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• 1985

The predictions of the local and regional sand transport of the offshore tidal sand banks tn the west coast of Korea, east of the Yellow San have been performed on the basis of diagrammatical method suggested by Kenyon et al(1981). There is general agreements between these predictions and the earlier predictions(Choi, 1983) of net regional sand transport paths from the numerical simulation of maximum bottom stress vector during the semidiurnal period due to m2 and m4 tides. Further detailed investigations are proposed for the study of Choongang Chontoe where the predicted net sand transport direction is to the dredged navigation channel.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.7
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• pp.854-862
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• 2016

In summer 2010, we measured the concentration of dissolved oxygen (DO) and nutrients in the water collected at the bottom of Cheonsu Bay, off the west coast of Korea. We also measured nutrient fluxes across the sediment-water interface by deploying a fully-automated benthic lander, which collected time-series water samples inside a benthic chamber. We confirmed on-going hypoxia in the northern parts of the bay where polluted lake water was discharged. DO content in the water at the bottom was 2 mg/l, compared to 5 mg/l at the mouth of the bay in the south. Nutrient concentrations showed a trend that was opposite to that of DO. The variation of N/P ratios implies phosphate desorption and a release of nutrients caused by hypoxia. The organic carbon oxidation rate and oxygen consumption rate in the northern parts of the bay were about twice as fast as those at the mouth of the bay. Benthic fluxes of nutrients in the northern part of the bay were 4 to 6 times higher than those at the mouth. Our results imply that it is important to understand the role of hypoxia events to make an accurate estimation of material fluxes across the sediment-water interface.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.2
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• pp.93-102
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• 2011

In this study, experiments on total digestion and sequential extraction were conducted in order to understand total metal contents, and mobility, bioavaliability and toxicity of metals in marine dredged sediment from Busan New Port. The total concentrations of arsenic and heavy metals in the dredged sediment were relatively low as follows: Al (2.36~2.96 wt.%), As (1.6~3.3 mg/kg), Ba (30.0~33.8 mg/kg), Cd (0.12~0.18 mg/kg), Cr (27.5~35.0 mg/kg), Cu (11.3~15.0 mg/kg), Fe (2.91~3.51 wt.%), Mn (324~408 mg/kg), Ni (18.8~23.8 mg/kg), Pb (23.8~31.3 mg/kg), and Zn (70.0~86.3 mg/kg). In addition, it was found that most of Al (87.5~95.9%), As (74.1~93.8%), Ba (71.8~77.6%), Cr (69.5~94.3%), Cu (50.0~78.7%), Fe (70.8~87.6%), Ni (64.5~75.3%), Pb (53.4~64.3%), and Zn (62.5~81.7%) existed in the residual fraction, meaning that those elements might come from natural sources. On the other hand, Cd and Mn were present mainly in the non-residual fraction. Due to low concentrations of toxic heavy metals and high percentage of residual fraction, it could be possible to reuse the dredged sediment for bricks, pavement base material, etc.

• Journal of the Korean association of regional geographers
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• v.22 no.1
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• pp.211-224
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• 2016

Natural lakes are estimated in variety with that's function or value depending on age environment or geographical characteristics. There are many kind of natural lakes, but the kind of natural lake is limited in rivers in korea flowing into East Sea. However, Yeonho lake in Uljin has different geographical characteristics with oxbow lake or lagoon which is common in korea's river flowing into East Sea. Therefore the purpose of this study is to analyze geographical characteristics due to the process of Yeonho's formation. Further more research for protecting wetland is needed to adequately preserve, depending on the geomorpologic process. To analyze geographical characteristics, it was essential to compare and analyze topographical map of 1918 1956 2012 and I pictured estinated line of bedrock and longitudinal section of Nam-dae cheon(Riv) Yeonho cheon(Riv). In addition, I denoted flooded areas through design flood level of Nam-dae cheon(Riv) Yeonho cheon(Riv) and analyzed particle size distribution of deposited sediment due to consider deposit environment. The results of study are as follows. In conclusion, Yeonho lake is floodbasin which was not researched at river flowing into East Sea. Through this study, my opinion is that floodbasin can be formed in the river that is steep and short. I argue that preservation methods will be seeked by geomorphologic process of floodbasin and development of downtown.