• Journal of The Geomorphological Association of Korea
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• v.19 no.2
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• pp.123-132
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• 2012

In this study, we analyzed sedimentation and erosion environment around Halmiseom on Anmyeon Island using wind direction and wind speed data, gain size analysis data and datum-point measured values. To observe changes in sedimentation and erosion environment around Halmiseon, we installed datum points at 12 locations around Halmiseom and carried out at total of 32 field measurements from May 16th, 2010 to May 8th, 2012. The field measurement results showed that H-3, H-4, H-5 and H-9 points are dominated by sedimentation environment, and H-7, H-8, H-10, H-11 and H-12 points are dominated by erosion environment. Meanwhile, sedimentation and erosion appeared alternately at H-2 and H-6 points. These results indicate that a bank installed in the southwest side of Halmiseom prevented sand of the beach from moving to the northeast side, leaving the sand of the beach being deposited at the sites, and the northeast side, where sand was not provided from beach ridge of Halmiseon was dominated by sedimentation. That is, the southwest side of Halmiseom was dominated by sedimentation, but the northeast side was dominated by erosion in general. However, the opposite trends were observed at H-9 point of the northeast side and H-12 point of the southwest side. According to analysis, since H-9 point is located at the end of sand spit connected to Halmiseom, the supply of sediments by a tidal current is possible. On the other hand, it was difficult to analyze the cause of erosion in case of H-12 point located at the sand dune due to the short measurement period.

• Journal of the Korean Geographical Society
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• v.40 no.4 s.109
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• pp.416-427
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• 2005

This paper aims to investigate morphological changes of deltaic barrier islands in the Nakdong Estuary and especially their spatial variations after barrage construction. We analyzed shorelines, geometrical centroids, and areas to reveal the changes of barrier islands. Here, we suggest three interesting points from this study. First, each individual barrier island in the Nakdong estuary goes through a different stage of the geomorphic cycle. The frontal barrier islands such as Sinja-do and Doyo-deung grow because they are located in front of the gates of the barrage. Sediments in water out of the gates are moved to offshore and then reworked by coastal processes such as waves and tides. Second, on the contrary, Baekhap-deung located behind Doyo-deung now diminishes indicating that sediments mainly move to the frontal growing island. Third, there is no morphological change in several barrier islands far away from the main flow of the Nakdong river such as Jinwoo-do, Daema-deung, and Jangja-do. In conclusion, barrier islands in the Nakdong estuary show distinct spatial variations. As a barrier island is closer to the main channel or is in the frontal location, there happens a very dynamic change in the morphology of the island.

• Journal of Korean Society of Disaster and Security
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• v.11 no.1
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• pp.7-14
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• 2018

The Benangkimi wetland, which serves as a stopover place for migratory birds in the Dadohae Marine National Park in Wando-gun, Jeollanam-do, is a place where various species and a large number of migratory birds are observed. In order to provide an effective and scientific management plan for the habitat environment of migratory birds, we carried out field survey of Benangkimi wetland. The field survey and survey on habitat use of migratory birds were conducted in parallel to obtain the basic data of hydraulics and hydrology. The hydraulic and hydrological survey of Benangkimi wetland was conducted 1-2 times a year during the period of 2015-2016 (two years). It was classified into 4 sectors according to the topography and geology, rainfall, hydraulic characteristics, and wetland conditions. The 3 sectors same as the migratory birds survey sector and the 1 sector as the inflow of the wetland were analyzed. The survey also focused on small migratory birds arriving at Benangkimi wetland during the spring and autumn season. As a result of investigating the population and species in each section, the habitat environment was different according to the water depth, sediment thickness and salinity. Migratory birds prefer hydraulic and hydrological characteristics. This study will be used for the scientific management of Benangkimi wetland, which serves as a stopping point for migratory birds, and it will contribute to basic data of ecology - hydraulics by examining the relationship between habitat environment and hydrological data.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.516-516
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• 2023

하천 만곡부 외곽 하안부의 빠른 유속은 침식을 유발하고 내측의 느린 유속은 토사 퇴적의 원인이 된다. 이는 하천 지형을 지속적으로 변화시키는 원인이 되고 나아가 하천 주변의 환경뿐만 아니라 안정성에도 문제를 일으킨다. 하천의 안정성과 수생태계 보존을 위해서는 수제와 같은 인공 구조물을 설치하여 하도의 안정을 유지할 수 있다. 수제는 후류에 느린 유속을 발생시켜 침식을 예방하고 제방과 하안을 보호한다. 그러나 수제 주변에서 발생하는 강한 와류는 국부 세굴을 유발하여 구조물의 안정성을 저해하기도 한다. 본 연구에서는 이동상 수리실험을 통해 수제 주변에서 발생하는 국부 세굴 및 후류에서의 하상 변동을 측정하였다. 수리실험은 길이 10 m, 폭 0.44 m, 높이 0.59 m인 수로에서 D50 = 2.98 mm인 모래를 사용하였고 하상변동은 하상이 평형상태에 이르렀을 때 물의 흐름을 멈추고 측정하였다. 실험 결과를 바탕으로 평형상태의 하상변동과 시간 변화에 따른 세굴심 변화를 도출하였다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.2
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• pp.105-118
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• 2000

Anchored measurements (12.5 hr) of suspended sediment concentration and other hydrodynamic parameters were carried out at two stations located at the entrance to Hampyung Bay in summer (August 1999). Tidal variations in water temperature and salinity were in the range of 26.0-27.9$^{\circ}C$ and 30.9-31.5, respectively, indicating exchange offshore and offshore water mass. Active tidal mixing processes at the entrance appear to destroy the otherwise vertical stratification in temperature and salinity in spite of strong solar heating in summer. On the contrary, suspended sediment concentrations show a marked stratification with increasing concentrations toward bottom layer. Clastic particles in suspended sediments consist mostly of very fine to fine silt (4-16 ${\mu}$m) with a poorly-sorted value of 14.7-25.9 ${\mu}$m. However, at slack time with less turbulent energy, flocs larger than 40 ${\mu}$m are formed by cohesion and inter-collision of particles, resulting in a higher settling velocity. Strong ebb-dominated and weak flood dominated tidal currents, in the southwestern and the northeastern part, respectively, result in a seaward residual flow of -10${\sim}$-20 cm $s^{-1}$ at station H1 and a bayward residual flow less than 5.0 cm $s^{-1}$ at station H2. However, mean concentration of suspended sediments at station H1 is higher at flood (95.0-144.1 mg $1^{-1}$) than in ebb (75.8-120.9 mg $1^{-1}$). On the contrary, at the station H2, the trend is reversed with higher concentration at the ebb (84.7-158.4 mg $1^{-1}$) than that at the flood (53.0-107.9 mg $1^{-1}$). As a result, seaward net suspended sediment fluxes ($f_{s}$) are calculated to be -1.7 ${\sim}$-$15.610^{3}$ kg $m^{-2}$ $s^{-1}$ through the whole water column. However, the stations H1 and H2 show definitely different values of the flux with higher ones in the former than in the latter. Alternatively, depth-integrated net suspended sediment loads ($\c{Q}_{s}$) for one tidal cycle are also toward the offshore with ranges of 0.37${\times}$$10^{3}$ kg $m^{-1}$ and 0.21${\times}$$10^{3}$ kg $m^{-1}$, at station H1 and H2, respectively. This seaward transport of suspended sediment in summer suggests that summer-time erosion in the Hampyung muddy tidal flats is a rather exceptional phenomenon compared to the general deposition reported for many other tidal flats on the west coast of Korea.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.3
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• pp.541-547
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• 2017

In Yongwon channel, its natural flow of seawater is blocked by the construction of Busan Newport including the container berth. The channel was transformed into a narrow and long one, where it is possible that ships are only allowed to pass through the north-side channel of Gyeonmado located at the point of river mouth to Songjeongcheon. So it is considered that the changes in the terrain characteristics of Yongwon channel is likely to alter the circulation of sea water, thereby changing its water quality. Contaminants are accumulated from the sediment release. In this study, before and after dredging the sediment release test was performed. As a result, after the sediment dredging is performed, the reduction rate was higher at the same point. The results show that the water quality can be improved by dredging. Each group (A~C) reduction rate of the evaluation of the reduction rate of 4.64% T-N, 18.00%, 18.59%, respectively. T-P rate of 24.75% reduction, 24.17%, 44.08%, respectively. COD reduction rate was 18.57%, 19.76%, 38.08%, respectively. These results can be used as basic data for controlling the contamination by dredging in Yongwon channel.

• Journal of Korea Water Resources Association
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• v.33 no.2
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• pp.181-193
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• 2000

This paper presents the flow and the suspended sediment movement over ripples for oscillatory flows. A new numerical model system is developed, and applied to a laboratory experimental condition of regular waves and a fictitious condition of irregular waves. The flow field is obtained from a programme proposed by Kim et. al.(1994), which is a modified version of SOLA based on SMAC scheme. The sub-model solves the continuity and Reynolds momentum equations in the x-z plane. The wave orbital velocities, shear stresses, and pressure are all reasonably reproduced by the model. The model results on the vertical velocity component show good agreement with the measurements. The suspended sediment transport sub-model is newly set up to solve the advection-diffusion equation of suspended sediment using a split method, and involving a special shear entrainment from the whole ripple surface. The calculated suspended sediment concentrations for regular waves show reasonable agreement with measurements at Deltaflume. The model results for random waves show that the suspended sediment concentration is higher than those for regular waves and that the sediment diffuses higher than for regular waves with the significant wave height and the peak wave period of the irregular waves.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.207-211
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• 2011

하천공사의 매립 및 준설 시 뿐만 아니라 최근에는 호우 시에도 발생하는 고농도 오탁수의 유출 확산으로 인하여 주변 수역의 수산자원 및 자연환경에 심각한 영향을 미치고 있다. 특히 유사는 하천과 호소에 유입되어 탁도를 증가시켜 수자원의 이용가치를 저하시키며, 박테리아나 각종 미생물의 이동 매개체가 되고 있다. 또한 퇴적된 유사는 유량이 증가하면 다시 침식되어 부유상태가 되며 이때에 영양염류나 독성물질이 재용출 되기도 하는 등 하천의 물리 및 토양환경의 장 단기적인 변화를 유발하는 원인이 된다. 결국 유사는 다양한 방식으로 하천과 호소의 생태환경에 큰 변화를 초래한다. 부유토사의 발생 가능한 피해의 범위와 정도는 유역의 부유토사 발생율과 하천, 호소 퇴적물의 성분종류와 입도분포, 그리고 유속에 따라 결정된다. 따라서 탁수의 영향범위를 예측하고, 악영향이 예측될 경우에는 탁도를 저하시킬 수 있는 오탁물질의 저하기법을 적용하여 그 대책을 수립하여야 한다. 현재 정부가 역점을 두고 있는 4대강 살리기 사업 중 하나인 하천 준설 사업 시 발생되는 고농도 오탁수는 주변 수역의 수자원 및 자연환경에 심각한 영향을 미치므로 자연환경의 보존, 해양자원을 보호하기 위하여 오탁물질의 제어가 반드시 필요한 실정이다. 기존의 오탁 저감시설이나 방법의 경우 오탁물질의 확산을 제어하는데 한계가 있고 오탁물질의 종류와 관계없이 일률적으로 시공함으로서 오탁제어 효과가 의문 시 되고 있다. 이러한 문제점을 개선하기 위하여 오탁물질의 확산 범위를 줄이고 침강효율을 높이는 방법을 찾아 오탁확산 제어 효율을 개선할 필요가 있다. 본 연구에서는 오탁물질 제어 시 2차 응집물로 인한 오염이 발생하는 않는 천연광물 제올라이트를 이용한 실내실험을 통하여 고농도 탁수의 탁도 저감효율을 파악하여 고농도 탁수의 탁도 저감에 대한 제올라이트의 적용 가능성을 살펴보았다. 4대강 살리기 사업 중인 OO강 OO공구의 OO보 현장에서 하천 준설 시 발생하는 고농도 탁수를 이온을 첨가한 제올라이트를 이용하여 확산제어에 관한 효과를 검토한 결과 2,000NTU 정도의 고농도로 유하하는 탁수에 대하여 제올라이트 혼합 후 20분이 경과한 시점에 제거효율이 90%이상으로 제올라이트의 탁수저감 효과가 대단히 크다는 것을 알 수 있었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1084-1088
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• 2007

국내에서 농업용수 취수, 수위 유지 등의 목적으로 18,000 개의 크고 작은 보가 하천에 설치되어 있으나 농경지의 도시화, 비닐하우스 단지화 등 토지이용의 변화와 대형 저수지의 축조/양수장 설치 등에 따른 취수 시설물의 통합 및 보체의 노후화 등으로 매년 50-150개의 보가 본래의 기능을 상실하여 용도 폐기되고 있다. 그러나 폐기된 보들이 철거 되지 않고 하천에 존치되어 하천생태통로의 단절, 수질 악화 등의 문제가 지속적으로 야기되고 있다. 외국의 경우에는 1970년대부터 본격적으로 기능을 상실한 보, 소형댐 등은 물론 일부 기능이 있는 하천횡단 시설물을 철거하여 하천환경복원을 추진하고 있다. 우리나라의 경우에는 최근 들어 기능을 상실한 보나 소형 댐 등에 한하여 하천생태통로 및 생태환경 복원 차원에서 철거의 필요성이 대두되기 시작하였다. 실제 철거도 이루어지고 있으나 체계적인 연구나 가이드라인 없이 지자체에 의해 이루어지고 있는 실정이다. 보는 하천을 횡단하는 구조물로 보의 상류에 저류지가 형성되고 많은 양의 퇴적물이 쌓여 그에 따른 하상의 단차가 형성된다. 이런 보가 철거됨으로 인해 막대한 양의 유사가 이동하게 되고, 철거 형태에 따라 하상 침 퇴적이 발생하고 그 위치나 양에 따라 하천 형태가 변할 수 있다. 이런 변화를 예측하여 철거에 따른 문제 등을 사전에 방지할 수 있는 기술이 필요하고, 철거에 대한 가이드라인 등이 마련되어야 할 것이다. 본 연구는 한강 제 1지류인 곡릉천에 위치한 곡릉2보의 철거에 따른 하상 변동, 하천 형태 변화 등 물리적 영향을 조사하고, 보 철거 후 장 단기적인 하도 및 하상 변동 등을 예측하는 기술을 개발하는 것이다. 연구 대상 보인 곡릉2보의 철거에 따른 모니터링 결과, 하상의 종단 변화는 그리 크게 생기지 않았으며 보 상 하류 횡단면에서 변화가 다소 큰 것으로 나타났다. 또한, 하상 재료의 부분적 변화도 발견되었으나, 전반적인 하천의 변화는 크지 않은 것으로 나타났다.

• Economic and Environmental Geology
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• v.43 no.1
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• pp.1-12
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• 2010

Geochemical approaches on the two recovered piston cores were performed to understand the characteristics of organic matters and the influence of the sea level variation of the East Sea in the Hupo Basin since the Holocene. The analyzing results on organic components (TOC and TN), and isotopic compositions of organic matters showed the variation to core locations and sampling depths. In core 08HZP-01, their values were gradually changed with depth from 4 mbsf to seafloor. However, rapid variation was observed at the boundary of 4.71 mbsf (meter below seafloor) in core 08HZP-03. Based on TOC/TN, $\delta^{13}C_{org}$ and $\delta^{15}N_{org}$, the origin of organic matters in the Hupo Basin can be divided into three groups; 1) predominant marine algae, 2) $C_3$ land plant, and 3) mixture of $C_3$ land plant and marine/freshwater algae. It is likely that the vertical and spatial variations of organic and isotopic compositions reflect the shifts in sedimentary environment (including sediment transportation) by ocean currents and sea-level changes and others during the Holocene period.