• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.1
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• pp.52-62
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• 2014

As a case study of the changed aquatic environment due to an estuary dam, the Geum River Estuary Dam System (GREDS) has been investigated for the last two decades. We sought the similarities and differences in the disrupted aquatic environment between the estuarine and lacustrine sides of the GREDS. Both sides of the GREDS shared similar aquatic disruptions, such as elongated hydraulic residence times, deteriorated water quality, highly accumulated organic-rich sediments, and considerable siltation of river-transported materials prior to reaching coastal waters. The disruptions of water quality such as high nutrients concentration and frequent bloom of blue-green algal are much more noticeable in the reservoir than in the estuary. However serious siltation problem has been reported from the estuary, which will possibly threaten the proper functioning of the natural Kunsan Estuarine System.

• Journal of Korean Society of Forest Science
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• v.102 no.2
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• pp.161-169
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• 2013

This study was carried out to examine characteristics of physical and chemical current status and problems of Salix spp. communities based on growth characteristics by tree age and height of the tree species in around Namgang Dam reservoir area. Tree density in 4 survey areas was 5,284 trees/ha, but all areas need to control high tree density. Tree crown area in 4 survey areas was 9,786.4 $m^2/ha$ and crown area of Salix spp. was the most dominant among tree species in watershed of the Jinyang lake. Mean soil depth in 4 survey areas was 65.5 cm higher in the sedimental deposit soil (78 cm) than in forest soil (12.5 cm) near the watershed. Soil bulk density was also higher in the sedimental deposit soil than in forest soil because of poor porosity in the sandy sediment. Soil pH was higher in sedimental deposit soil (A, B horizon:pH 6.7) than in forest soil (A horizon:pH 5.3; B horizon:pH 5.2) because of originated from non-point source polution and detergent of domestic sewage. The results suggest that growth of Salix spp. could be poor because of low fertility with low cation exchange capacity in sedimental deposit soil.

• Journal of The Geomorphological Association of Korea
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• v.15 no.2
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• pp.25-35
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• 2008

Typhoon Ewiniar and Bilis followed by heavy rainfall in July 2006 triggered massive slope failures and debris flows along the Osaek valley within Seoraksan National Park. Since national road 44 is constructed along the fault-line, the susceptibility of hazard in the area is very high. Debris flows in Osaekcheon are mobilized from landslides near the ridgelines and peaks when heavy rainfall elevates pore pressure and adds weight to the hillslopes, causing failure. Stream flows falling onto the existing colluvium or channel-margin deposits also trigger debris flows. Steep slopes constructed along the road and thin regolith in the slope is the main reason for the landslide in the upper stream. In middle reaches of stream, under-fit drainage utilities and narrow bridges cause the overflow, this then triggers debris flow. Overflowing and erosion in the channel margin deposits is main reasons for the debris flow. The intensities and frequencies of heavy rainfall are certain to increase, so early warning and management system for the landslide-related hazard is urgently needed.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.86-86
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• 2011

1922년 R. L. Parshall이 고안한 파샬플륨은 현재 사용되고 있는 개수로 유량계로서는 가장 많은 실험자료를 보유하고 있다. 위어에 비해 설치가 어렵고 경제성이 떨어지는 단점도 있지만 설치 후에는 상대적으로 다른 시설보다 토사이동이 원활하다는 장점이 있어 하수 및 폐수 등의 유량측정에 많이 적용되고 있다. 용담저수지의 주요 지천인 금강본류와 구량천 2곳에는 국가가 관리하는 수위관측소가 있다. 설치지점의 지명을 따 동향수위관측소와 천천수위관측소로 운용되고 있으며, 동향수위관측소 약 170 m 하류와 천천수위관측소 약 2.5 km 상류 2곳에 갈수기 유량조사를 위한 파샬플륨이 설치되었다. 동향파샬프륨과 천천파샬플륨은 갈수기 유량을 고려하여 Iso 9826의 파샬플륨 번호 10(Parshall flume No. 10)과 유사한 규격(설치당시 목부(Throat)폭 5ft))으로 설계되었으며, 플륨으로 흐름을 유도하는 유입부(Entrance section) 좌 우 횡단방향에 보를 연결하여 상대적으로 하폭이 넓은 자연하천에 적용하였다. 수년간의 현장운용 결과, 파샬플륨의 가장 큰 장점이었던 원활한 토사이동이 보로 인해 차단되고, 누적된 토사가 흐름을 왜곡시킴으로서 플륨내 수위로부터 환산한 유량값에 비교적 큰 오차를 발생시 킬 수 있음을 알게 되었다. 본 연구는 이러한 문제의 원인이 상류에 누적된 토사에 있음을 규명하고 대처방안을 제시하기위해 동향파샬플륨을 대상으로 수행되었다. 플륨을 통한 유량자료의 신뢰도는 (1) 플륨내 정밀유량측정, (2) 50 m 하류에서의 도섭법에 의한 유량측정 그리고 (3) 130 m 하류에서의 도섭법에 의한 유량측정을 통하여 비교 및 검증하였다. 조사결과 플륨내 수위는 상류에 퇴적된 토사로 인해 일정하지 않으며 이로 인해 유량에 오차가 발생하고 있음이 확인되었다. 또한 본 연구에서는 자연하천에서의 파샬플륨 적용을 위해 토사이동을 고려한 설비의 구조개량을 병행하였다. 새로운 형태의 파샬플륨은 '에코플륨'이라 명명하였으며 원활한 토사이동과 인공구조물에 의한 자연경관 훼손을 방지할 수 있는 두 가지의 효과가 기대된다. 현재 실물모형의 제작이 완료되어 실내실험을 수행하고 있으며, 머지않은 장래에 현장설치가 가능하다고 판단된다.

• Journal of the Mineralogical Society of Korea
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• v.19 no.4 s.50
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• pp.259-264
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• 2006

This work carried out to analyze the physicochemical properties and investigate the assessment of heavy metal contamination of stream sediments of the Yudeung and the Gab streams in the Daejeon area. The pH of stream sediments of the Yudeung stream shows the range of weak acid and weak alkaline. Most of stream sediments contain about 80% sand grain and have low water and cation retention capacity. Hence the stream sediments are not suitable fur various plans to grow up. The analysis of heavy metals in the stream sediments shows that the concentration of Pb, Cr and Cd increases from upstream to down stream. It is likely that the trend has a relationship with the water. Contamination of stream water. The authors recommend that clay materials be replenished in the stream sediments to increase the self-purification capacity and to make the suitable condition for growing up of various plants, and that water quality of the stream which can Influence into the contamination of stream sediments be monitored.

• The Journal of Engineering Geology
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• v.33 no.1
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• pp.201-211
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• 2023

This study investigated the damage range of the debris flow to predict the amount of collapsed soil in a landslide event. The height of the collapsed slope and the distance traveled by the collapsed soil were used to predict the total trajectory distance using a random walk model. Debris flow trajectory probabilities were calculated through 10,000 Monte Carlo simulations and were used to calculate the damage range as measured from the landslide scar to its toe. Compiled information on debris flows that occurred in the Cheonwangbong area of Mt. Jirisan was used to test the accuracy of the proposed random walk model in estimating the damage range of debris flow. Results of the comparison reveal that the proposed model shows reasonable accuracy in estimating the damage range of debris flow and that using 10 m × 10 m cells allows the damage range to be reproduced with satisfactory precision.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.138-138
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• 2023

본 연구에서는 유목과 연행침식을 고려한 토석류 수치모형을 개발하여 2011년 발생한 우면산 산사태의 관측데이터를 기반으로 수치모의를 수행하였다. 토석류 모형개발을 위해 천수방정식 기반의 침수모형인 Nays2DFlood 모형에 혼합유사농도의 이송확산, 토석류 지면전단응력, 연행침식모듈을 추가하였으며 유목생성과 유목거동 모의를 위해 입자법 기반의 유목동력학 모형을 결합하였다. 개발된 모형을 검증하기 위해, 민감도분석을 수행하였으며, 모의결과, 우면산 산사태 당시 래미안 APT에 피해를 끼친 충격수심과 충격유속, 최종 토석류 체적을 양호하게 재현한 것으로 판단된다. 또한 토석류를 구성하는 토사입경이 작을수록 토사점성에 의한 전단응력의 증가로 토석류 유속과 수심이 감소했지만 연행침식량이 증가하였으며, 토사입경이 증가하면 유속과 수심이 증가하고 연행침식량은 감소한 것으로 나타났다. 또한 본 연구에서 개발된 토석류 거동모형은 토사입경, 침식 및 퇴적계수 등의 다양한 토석류 매개변수가 요구되기 때문에, 이러한 물성치 데이터가 현장 또는 실내실험에서 충분히 확보되어야 모형의 정확도가 향상될 것으로 판단된다. 따라서, 향후 연구에서는 본 연구에서 고찰된 모형의 적용성과 한계점을 고려하여 토석류 거동을 예측모의 한다면 보다 세부적으로 토석류와 유목거동을 예측분석해 볼 수 있을 것으로 사료된다. 또한 본 연구의 결과는 기후변화로 인한 강우발생의 불확실성과 이로 야기되는 토석류 발생을 사전에 예측하여 토석류 저감대응방안을 구축하는 일환으로 활용 될 수 있을 것으로 기대된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.339-339
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• 2011

4대강 살리기 프로젝트 중 하나인 금강살리기 사업은 현재 금강 상류로부터 금남보, 금강보, 부여보가 건설중에 있다. 이러한 보의 건설을 통해 물 부족 해결 및 용수확보, 홍수조절 등 하천에서 중요한 역할을 담당하게 될 것이다. 하지만 보의 건설에 따른 다양한 하천환경의 변화가 발생될 수 있으며, 특히 하천의 흐름이 차단됨에 따라 보 건설 전 후의 하상변화가 발생될 것으로 판단되며 하상변화에 대한 지속적인 모니터링이 필요하다. 본 연구에서는 금강의 보 건설 구간 중 부여보의 상 하류에 하상변동 및 퇴적 토사의 입도 변화양상과 보 주변의 하천변화를 2010년 1년 동안 사전조사와 분기별 1회씩 총 5회에 걸쳐 모니터링을 수행하였다. 그 결과 부여보 상류의 경우 평균 하상고의 차이가 0.17m로 하상변화가 미미하였으며, 하상단면 형상 또한 변화가 크지 않았다. 한편, 보 하류의 경우 평균 하상고의 차이는 1.05m로 큰 차이가 나타났다. 이는 하류지역에 준설작업과 상류 지역의 토사 및 퇴적물의 이동으로 인해 하상변화가 크게 나타난 것으로 사료된다. 하상재료의 경우 전체 조사기간 모두 나쁜입도로 나타났으며 이는 현재 부여보 건설중 계속적인 준설작업으로 인한 하상교란 때문인 것으로 판단된다.

• Journal of Korean Society of Forest Science
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• v.79 no.3
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• pp.269-277
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• 1990

In planning the disaster prevention by the erosion control facilities, it is essential to focus on the microtopography of the channel bed and the chronological process of sedimental movement in the torrential streams. For this purpose, the microtopographical change of the channel bed and the effects of the erosion control facilities in the mountain torrents were analyzed by the experimental channel and the field survey of the torrents where low-dam series had been constructed in the channel. The results of this experiment showed that the effects of construction of the low-dam series on the channel bed fixiation were the prevention of the local scouring in the experimental channel and the expansion of flow channel width and deposit space. The results are summarized as follows : 1. When the low-dam series were constructed over the whole channel bed (L'/L=1), the conning water and the sediment were seperated, simultaneously resulting in deposition of sediment and reduction of the tractive force for the running water. Therefore, the F.A. (Fluctuation area in cross-section: value was decreased to about 65% compared with that of non-work (L'/L=0). 2. The efficiencies of the low-dam series on the channel width were increased with an increment in length of working space. After the construction of low-dam series on the whole channel bed (L'/L=1), flow channel width was increased to about 1.53 times compared with that of non-work (L'/L=0). 3. It needs a deposition area to store the sediment with decrease in tractive force. The low-dam series in the experimental channel widened the deposition area about 2.10 times compared with that of non-work.

• Journal of Korea Water Resources Association
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• v.43 no.11
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• pp.995-1009
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• 2010

Accelerated soil erosion due to extreme climate change, such as increased rainfall intensity, and human-induced environmental changes, is a widely recognized problem. Existing soil erosion models are generally based on the gross erosion concept to compute annual upland soil loss in tons per acre per year. However, such models are not suitable for event-based simulations of erosion and deposition in time and space. Recent advances in computer geographic information system (GIS) technologies have allowed hydrologists to develop physically based models, and the trend in erosion prediction is towards process-based models, instead of conceptually lumped models. This study aims to propose an effective and robust distributed rainfall-sediment yield-runoff model consisting of basic element modules: a rainfall-runoff module based on the kinematic wave method for subsurface and surface flow, and a runoff-sediment yield-runoff model based on the unit stream power method. The model was tested on the Cheoncheon catchment, upstream of the Yongdam dam using hydrological data for three extreme flood events due to typhoons. The model provided acceptable simulation results with respect to both discharge and sediment discharge even though the simulated sedigraphs were underestimated, compared to observations. The spatial distribution of erosion and deposition demonstrated that eroded sediment loads were deposited in the cells along the channel network, which have a short overland flow length and a gentle local slope while the erosion rate increased as rainfall became larger. Additionally, spatially heterogeneous rainfall intensity, dependant on Thiessen polygons, led to spatially-distinct erosion and deposition patterns.