• Ecology and Resilient Infrastructure
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• v.2 no.2
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• pp.161-166
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• 2015

The inappropriate hydraulic design criteria on the new revetment technique for the ecological river restoration project happens to lead to economic loss during the flood season. In this study, the hydraulic stability of the developed non-toxic revetment was evaluated at a maximum discharge of $3.0m^3/s$ and a maximum velocity of 3.0 m/s in a real scale experimental channel. The vertical movement of the non-toxic revetment block was in the range of ${\pm}3mm$ mm in the experimental conditions. The results show that the non-toxic revetment block was sufficiently hydraulically secured.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.95-95
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• 2018

최근 하천관리 정책은 단편적인 홍수방어뿐만 아니라 맑은 물을 안전하게 확보하고 건강한 생태계가 유지되는 하천으로 관리하는 방향에 주안점을 두고 있다. 그러나 치수 목적의 하천관리 기술에 비하여 하천환경관리를 위한 기술은 요소기술 개발 및 적용으로 산재되어 있어, 체계가 정립되지 못하고 실무 적용에서도 활용에 한계가 있는 실정이다. 따라서 본 연구에서는 치수, 이수, 하천환경 목적의 다차원 하천관리를 위하여 하천복원의 기술적 체계를 기술수준의 정도를 기준으로 단계별로 정립하였다. 첫 단계는 수문특성, 수리특성, 하상변동/유사특성, 생물/화학특성의 분석이다. 이 단계에서는 각 특성의 현황과 하천복원 방법에 따른 물리특성 변화를 분석하는 것이다. 다음 단계는 하천복원에 따른 정량적인 기대효과 분석이다. 수위저감 및 안정하도 확보, 수질개선, 생물서식처 효과분석 등이 수행된다. 마지막 단계는 하천복원 등의 관리계획에 의한 기대효과 전망이다. 사회경제적 가치, 생물종 다양성 확대가치 등이 분석항목에 포함된다. 각 단계에서는 계량 가능한 지표를 설정하여 계획의 성과를 비교한다. 제안된 다차원 하천복원 기술적 프레임웍을 통해 하천사업에 따른 물리, 생물, 사회, 경제 등 다양한 분야의 구조를 통합한 방법론을 제시함으로써 하도개선 위주의 획일적인 하천복원사업에 변화를 주고, 더 나아가 하천공간 복원 등 적극적인 하천복원사업이 활성화되길 기대한다.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.1
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• pp.53-61
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• 2021

Distribution of fish community depends largely on environmental disturbance such as habitat change. In this study, we evaluated the impact of environmental variables and microhabitat patch types on fish distribution in Yudeung Stream at 15 sites between early May and late June 2019. We used non-metric multidimensional scaling to examine the distribution patterns of fish in each site. Gnathopogon strigatus, Squalidus gracilis majimae, Zacco koreanus, and Zacco platypus were associated with riffle and boulder areas, whereas Iksookimia koreensis, Acheilognathus koreensis, Coreoleuciscus splendidus, Sarcocheilichthys nigripinnis morii, and Odontobutis interrupta were associated with large shallow areas. In contrast, Cyprinus carpio, Carassius auratus, Lepomis macrochirus, and Micropterus salmoides were found at downstream sites associated with large pool areas, sandy/clay-bottomed areas, and vegetated areas. On the basis of these results, we suggest that microhabitat patch types are important in determining the diversity and abundance of fish communities, since a mosaic of different microhabitats supports diverse fish species. As such, microhabitat patches are key components of freshwater stream ecosystem heterogeneity, and a suitable patch composition in stream construction or restoration schemes will support ecologically healthy food webs.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.492-492
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• 2023

담수 생물종 시식역의 보전을 위해 하천 연결성 유지와 회복이 중요하지만, 하천관리에 있어 이를 고려하기 위한 기초자료나 관련 연구가 부족한 실정이다. 특히 인공장벽(artificial barrier) 영향에 대한 대부분의 연구는 어류이동에 초점을 두고 있거나, 그 공간적 범위를 제한하는 경향이 있다. 본 연구는 강과 하천을 연속체 개념으로 접근하여 생태학적 과정을 방해할 수 있는 모든 인위적 구조물을 인공장벽으로 간주하고, 댐과 저수지, 보와 같이 하천의 종적 연결성을 저해하는 3개 유형의 인공 구조물에 대해 공간자료를 구축하였다. 수치지형도로부터 하천중심선과 수리시설물(보), 호소 및 저수지 경계를 교차(intersection) 분석하여 유형별 구조물의 위치 정보를 추출하고, 기존 자료와의 비교·검증을 통해 자료의 신뢰성을 도모하였다. 인공장벽에 대한 공간자료는 구조물의 유형에 따라 국가하천과 지방하천, 소하천으로 구분하고 낙동강 대권역 내 총 195개 표준유역에 대해 밀도(barrier density)를 계산하였는데, 여기서의 밀도는 하천 연장에 대한 총 인공장벽의 수로 정의(barriers/km)된다. 본 연구의 주요 결과는 낙동강 유역 내 인공 장벽의 밀도와 유형, 하천별 공간분포에 대한 정량적 평가를 포함하고 있으며, 이를 기반으로 수생태계 연결성 회복을 위한 하천관리방안을 모색하고자 하였다. 분석 방법과 결과 등 자세한 내용은 발표를 통해 제시될 예정이다.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.42-42
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• 2021

한강 자연성 회복은 사회환경을 고려한 한강의 생태적 기능회복과 복원, 자연의 복원력을 기반으로 한 사람이 공생 공존하는 새로운 관계로의 전환점을 의미하고 있다. 본 연구에서는 한강 유역권 산·학·연 관계자 100명을 대상으로 설문조사를 실시하여 한강 자연성 회복 비전과 추진전략을 도출한 결과, '맑은 물이 흐르는 강'(1순위), '더불어 사는 강'(2순위), '생명이 숨쉬는 강'(3순위), '살아 움직이는 강'(4순위)으로 정책방향을 수립할 수 있었다. 또한 설문조사의 결과를 바탕으로 AHP 및 델파이 분석을 통해 한강 상류, 중류(서울권, 경기권), 하류별 자연성 회복 평가지표간 가중치를 산정하여 주요 추진과제를 선정하였다. 상류유역에서는 비점오염원 관리를 통한 환경오염 감소, 중류 유역에서는 도심하천의 수질관리강화 및 물 순환 체계 개선, 하류 유역에서는 생물다양성 확보 및 상·하류 지역 협력을 통한 상수원 수질 개선의 방안 필요의 결과가 도출되었다. 본 연구를 통하여 한강의 하천관리정책은 이수·치수 중심의 하천조성에서 하천생태복원 및 강과 사람과의 공존과 공생이 조화를 이룬 하천조성으로 관점이 변화되었음을 확인할 수 있었으며, 가중치 평가를 통한 최적 조합의 하천 관리방안이 도출되었다.

• Geomechanics and Engineering
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• v.39 no.2
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• pp.171-179
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• 2024

Gravity wall combined with anchoring frame beam is widely adopted to support a high slope under complex geomorphic condition, in which the rigid gravity wall is adopted as a lower structure and the flexible anchoring frame beam serves as an upper structure. The seismic anchor force and the seismic active earth pressure are two essential issues for the seismic design of combined retaining structure in high seismic intensity area. In this study, an analytical model of combined retaining structure is established based on the upper bound theorem of limit analysis, and the formulas for seismic anchor force and seismic active earth pressure of combined retaining structure are derived. The results are optimized by using the global optimization algorithm. The proposed method is verified by a comparison with previous method. Moreover, the influence of main parameters on seismic anchor force and seismic active earth pressure is analyzed to facilitate the seismic design of such combined retaining structure.

• Journal of Wetlands Research
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• v.13 no.3
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• pp.535-545
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• 2011

This study was carried out to suggest the baseline data necessary for vegetation restoration by naturalness assessment of riverine wetland within stream corridor. We selected stream reach both of near nature and urbanized by Nonsan stream and Hongchun river as experimental site. Composition of vegetation community and land use pattern between two sites indicated considerable difference, which imply for many different watershed property and process disturbed each other at river ecosystem. Naturalness of the sampled reaches showed that near nature is in better condition for riverine wetland than urbanized of all two sites. However, the prevalence index of Hongchun river within its natural state was lower than that of Nonsan stream, because the index included some vegetation communities occurred at upland fringe and bank slope. In conclusion assessment system using prevalence index would be considered an effective method for evaluating of natural states of riverine wetland.

• Journal of Korea Water Resources Association
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• v.40 no.5
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• pp.359-369
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• 2007

In this study the evaluation method for riverine naturalness proposed previously by other researcher has been modified to assess stream naturalness of small scaled streams. Two evaluation items have been added to the previously proposed method. That is, the modified method for evaluating naturalness of small scaled streams contains 16 evaluation items with two categories - river morphology and river environments. The three evaluation items have been improved based on the results of stream configuration and characteristics investigation. To prepare evaluation index for channel configuration of small scaled stream, 55 small scaled streams have been selected to analyze sinuosity, wavelength, etc. It has been shown that the values of sinuosity are around 1.2 and one wavelength appears approximately every 500 m in the sample streams. An equation implied diversity for width of normal flow has been proposed to add the evaluation index for diversity of channel width. The every 500 m 1,000 m along small scaled stream is also recommended through the investigation as the interval of evaluation unit. The modified method has been applied to the DangWang stream to estimate the effect of stream rectification project. It has shown that the proposed method would appropriately reflect channel morphology and environments before and after the rectification project.

• Journal of the Korean Society of Safety
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• v.32 no.4
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• pp.46-52
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• 2017

Sediment exchange in river has been affected by artificial changes such as dredging and abnormal climate changes like intense rainfall. Over last decades in Korea, there were many constructions, restoration or rehabilitation in rivers. Therefore, deposition and erosion become more actively occurred than before, which may threaten the river safety such as flood defense. For safety's sake, the dredging of river bed, which is considered as the most typical measure, has been increased to extend hydraulic conveyance compared with previous conditions. However, since it might change the sediment mechanism, there would be another risk at which unexpected side effects such as headward erosion could be occurred. Particularly, sedimentation at abrupt expansion region is able to lead to hydraulic characteristics like water elevation in the upstream region in the beginning of dredging, which, however, has been barely studied in this field. Therefore in this study, the relationship between sediment mechanism at dredging section and hydraulic characteristics in upstream region were presented through numerical simulations in the idealized abruptly widen channel using Delft3D. The ideal channel of 2,000 m length with each side angle of 45 degrees at abruptly widen expansion region was employed to consider the sediment angle of repose. The sensitivity analysis was performed on the dimensionless factors consisted of upstream and downstream depths($h_u$, $h_d$), width($w_u$, $w_d$), water level(H), flow rate(Q) and discharge of sediment($Q_s$). And the sedimentation amount at dredging and the upstream hydraulic characteristics were investigated through that analysis. It showed that $h_d/h_u$, $H/h_u$ and $w_d/w_u$ were more influential in sequence of effect on sedimentation amount, while $h_d/h_u$, $w_d/w_u$ and $H/h_u$ on upstream region. It means that $h_d/h_u$ was revealed as the most significant factors on sedimentation, also it would most highly affect the rising of water level upstream.

• Journal of Korea Water Resources Association
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• v.38 no.2
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• pp.143-153
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• 2005

Recently, the concern of groynes that provide us with various ecological environment and improvement of scenary near river as well as hydraulic improvement has greatly increased for naturalized river and ecological river restoration. However there is no adequate design guidelines in Korea. Furthermore there is lack of research for installation of groynes in Korea. Thus, in this study, we have conducted hydraulic modeling test for kinds of groyne and changes of permeability and made a study of the analysis for installation factor of groyne. Experimental conditions were the fixed bed model for flow pattern of groyne tip and separation length about changes of groyne length and permeability. The Experiments were conducted to measure velocity and drift angle at groyne tip. The main study kas measured the groyne tip velocity for a factor of scour and drift angle for velocity increase at center of channel. We have suggested the equation about groyne tip velocity rate(tip velocity/ approach velocity) and area rate(groyne area/ flow area). And In recirculation zone of groyne downstream, To study the basic data of groyne about installation interval has analyzed the change of separation length and incidence angle. We have suggested the equation about separation length rate(separation length/ groyne length), changes of permeability and installation angle.