• Journal of Korea Water Resources Association
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• v.55 no.10
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• pp.801-810
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• 2022

This study investigates the evolution processes of alternate bars in the channel with bank stability by vegetation by laboratory experiment. Laboratory experiments are conducted to elucidate the behavior of alternate bars by the influence of riparian vegetation on the rivers with erodible banks. To control bank stability of the channel, the actual vegetation, alfalfa, is grown by adjusting the density of alfalfa on the flood plain. As the vegetation density increases in the flood plain, the bank erosion rates and the channel widening rates decrease and the bank stability increases. The alternate bars migrate slow downstream over time. Moreover, the bars in a channel with strong banks migrate rapidly, which is related with the aspect ratio, that is, width to depth ratio. The bar wavelength decrease with vegetation density. Our laboratory experiments show that the behavior of bars differ according to bank strength.

• The Korean Journal of Ecology
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• v.24 no.5
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• pp.273-280
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• 2001

We investigated the flora and vegetation structure of exotic plants along stream geomorphology and disturbance factors in the riparian zone of Seunggi stream, Incheon. Total 53 exotic plant species were found in the riparian corridors of Seunggi stream. The percentage of exotics ranged from 25% to 33% of total species richness, and its mean value was 24% in the whole riparian area. The percentage of exotics reflected the vulnerability of riparian zones to plant invasions by disturbances, and it could be used as an indicator of riparian system dysfunction. The distinct distribution patterns of exotic plants did not found in the lateral topographic features of the stream. Invasion and proliferation of the exotic plants were somewhat remarkable at terraces and bank slopes of the stream. Among various disturbance factors, plowing and trampling were important on the invasion of exotic plant species of Seunggi stream.

• Ecology and Resilient Infrastructure
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• v.2 no.2
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• pp.154-160
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• 2015

This paper presents the field investigation of deposition and erosion relief of a riverfront using vegetation. The results obtained were as follows: Phragmites japonica showed 0.2 m of deposition and 0.3 m-0.4 m of erosion relief of river front by the critical velocity of 1.0 m/s-1.2 m/s. P. communis showed 0.1 m-0.4 m of deposition and 0.2 m-0.3 m of erosion relief by the critical velocity of 0.6 m/s-0.7 m/s. Salix gracilistyla showed 0.1 m-0.2 m of deposition and 0.4 m-0.5 m of erosion relief by the critical velocity of 1.2 m/s-1.4 m/s. Miscanthus sacchariflorus showed 0.1 m-0.4 m of deposition and 0.1 m-0.2 m of erosion relief by the critical velocity of 0.6 m/s-0.7 m/s. S. gracilistyla had the greatest role, while M. sacchariflorus had the lowest role for erosion relief. These results showed that aquatic plants had an effective role in sustaining a stable channel.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.347-355
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• 2015

최근 활발한 하천개발을 통하여 하안에는 많은 식생도입이 주류를 이루고 있다. 통상 하안에 자생하고 있는 조밀한 식생은 수리학적 저항이 증가되고 통수능이 감소되어 수위상승을 초래한다. 본 논문에서는 수리 해석 모형을 활용하여 중소규모 3개소의 하천을 대상으로 자연 상태와 조밀한 식생 분포에 해당하는 11가지 조도계수 모델조건을 적용하여 수리특성 변화를 분석하였다. 각 하천별 전 구간에서 식생에 의하여 하천정비계획에서 분석된 수위보다 1.2~2.7m가 상승하는 것으로 분석되었다. 각 하천별로 계획된 여유고 0.6~1.2m를 감안하면 계획홍수 이상의 강우가 발생될 경우 적절한 대책수립이 필요한 것으로 분석되었다. 분석 결과에 의하면, 하천변 식생이 활착되면 하천의 규모, 하상경사에 관계없이 수리학적 흐름 특성은 매우 민감하게 변화되는 것을 알 수 있었다.

• Journal of Korea Water Resources Association
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• v.47 no.4
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• pp.321-330
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• 2014

This study was performed to investigate relation between riparian vegetation and environmental factor and to predict riparian vegetation succession in Nakdong river, which is typical sand river in Korea Peninsula. We searched 5 natural levee and installed 84 quadrats in Nakdong river near by Andong city. Also, We analyzed flora, vegetation cover degree, topography, soil moisture, organic content, pH, electrical conductivity and soil texture. According to the result of CCA (canonical correspondence analysis), which considered both investigated vegetation data and environmental factor, vegetation were divided down three groups, and each group was difference by height above ordinary water level, organic content and sand. In addition, the most powerful factor was indicated the height above ordinary water level.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1365-1369
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• 2010

본 연구에서는 자연하안 조성을 위한 공법 설계시 공법의 적용 위치, 규모, 제원 등을 선정하기 위한 수문학적 정보 및 하천의 수문학적 특성에 적합한 식생을 선정하기 위한 수심, 침수기간 정보를 제공하기 위한 기법을 제시하였다. 이를 위해 장기 유출모형인 SWAT 모형을 적용하였으며, 자연하안 조성 공법 중 하나인 방틀이 시험 적용된 평창강을 대상으로 수문학적 특성을 분석하기 위한 유황 분석을 실시하였다. 평창강의 상안미 수위관측소 상류부에 위치한 방틀 시험지점의 유황을 분석하기 위해 상안미 수위관측소 상류유역을 대상유역으로 하여 상안미 수위관측소의 관측유량과 비교를 통해 신뢰성 있는 검보정을 마친 모형을 이용, 1989년부터 2008년까지 20년간의 유출분석을 실시하였다. 모의된 20년간의 일유출자료를 토대로 방틀 시공 단면의 유황곡선을 도시하여 유량특성을 분석하였으며, 유량을 수심으로 환산하여 대상 단면의 침수기간별 수심분포를 산정하였다. 또한 대상 단면의 하안을 침수기간별로 구분하여 하안의 높이에 따라 적정한 식생의 종류를 선정할 수 있는 자료를 생성하였다. 이와 같은 정보의 제공은 공법 설계에 필수적으로서 본 해석기술의 주요한 성과 및 활용성이라고 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.395-395
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• 2021

우리나라에서는 최근 이상기후로 인해 평균 기온이 높아지고, 여름철에 집중된 강우 특성으로 인하여 하천의 하도와 하도내 식생영향에 따른 수위-유량관계곡선식의 변동성이 높아지고 있다. 하도 내 식생과 하천의 흐름은 서로 영향을 주기 때문에 하도내 식생은 하천 흐름 특성에 핵심적인 요소로 볼 수 있다. 하도의 변동성은 단면 측량 등으로 확인 할 수 있으나, 하도내 식생은 주변 환경에 따라 매년 다르게 나타나기 때문에 이에 대한 모니터링이 필수적이다. 본 연구에서는 만경강 유역에 위치한 전주시(서천교)관측소를 대상으로 2017년~2018년, 2020년의 하도 내 수중식생과 하안 영역의 식생 성장과 소멸 및 식생사주의 모니터링 결과를 바탕으로 수위-유량관계 변화를 분석하였다. 2017년은 하도 내 식생의 성장과 소멸에 따라 저수위 구간에서 다수의 기간분리가 발생하였으며, 중수위 구간은 기간분리가 발생하지 않은 것으로 분석되었다. 2018년과 2020년은 하도 내 수중식생의 성장과 소멸로 인항 저수위 기간분리 이외의 하안영역의 식생 성장과 소멸에 따른 통수능 변동으로 인하여 중수위 기간분리가 추가로 발생하였고, 식생사주에 대한 지속적인 모니터링을 통하여 중수위 구간분리를 추가 검토하였다. 결과적으로 본 연구에서는 하도 내의 식생영향에 따른 유량측정성과를 확보하였으며 확보한 유량측정성 통한 신뢰도 높은 수위-유량관계곡선식을 개발하였고 이를 통해 생산된 유량자료는 정확도가 매우 높은 것으로 분석되었다.

• Ecology and Resilient Infrastructure
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• v.8 no.2
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• pp.79-87
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• 2021

Because active interactions occur among vegetation, hydrology, and geomorphology in riparian systems, any changes in one of these factors can significantly affect the other two. In this study, we evaluated these interactions at four sites (two in Gajeong and two in Hahan) along the Seomjin-gang River that was substantially devastated by an extreme flood in 2020. We examined the relationship between the riparian vegetation and the hydraulic characteristics of the flood using remote sensing, hydraulic modeling, and field surveys combined. The evaluation results showed that the floods caused a record-breaking rise of up to 43.1 m above sea level at the Yeseong-bridge stage gauge station (zero elevation 27.4 m) located between the Gajeong and Hahan sites, with the shear stress being four times higher in Hahan than in Gajeong. Additionally, the water level during the flood was estimated to be a maximum of 1 m higher depending on the location in the presence of riparian plants. Furthermore, both sites underwent extensive biological damage due to the flood, with 78-80% loss in vegetation, with preferential damage observed in large willow species, compared to Quercus acutissima. The above findings imply that all plant species exhibit different vulnerabilities towards extreme floods and do not induce similar behavior towards events causing a disturbance. In conclusion, we developed strategies for effectively managing riparian trees by minimizing flood hazards that could inevitably cause damage.

• Journal of Korea Water Resources Association
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• v.46 no.9
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• pp.909-919
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• 2013

This study examines the hydraulic characteristics, the channel changes, the behavior of bars, and bank stability by means of laboratory experiments. Three sets of laboratory experiments are conducted to elucidate the influence of riparian vegetation of the channels with erodible banks. Flow velocity is decreased in the vegetated zone, the mobility of lower channels is decreased. The double Fourier analysis of the bed waves shows that 1-1 mode (alternate bar) is dominant at the initial stage of the channel development. As time increases, 2-2 and 2-3 modes (central or multiple bars) are dominant due to the increased width to depth ratio. As the vegetation density is increased, the number of bars are increased, bank stability increases. The variation of sediment discharges is affected by vegetation density. The braided intensity is decreased with vegetation density. As the vegetation density is increased, the correlation coefficient of bed topography and bed relief index is increased.

• Korean Journal of Environment and Ecology
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• v.26 no.3
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• pp.437-445
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• 2012

The study performed the implementation monitoring of the revegetation methods applied to the test-bed of Simgok Stream in Incheon to identify the effect of water level and inundation period on the vegetation coverage of the stream bank revegetation methods. The categories of monitoring included the plant species and plant coverage for each method, physicochemical property of soil, water level and water quality. The result of monitoring revealed that plant growth conditions of all revegetation methods of each stream bank were good in the first survey as of May 2010. However, in the second survey of June 2011 when inundation period was less than a week, plant growth conditions and coverage of revegetation methods were partially bad. In the third survey as of August 2011 when inundation period was longest as 8 weeks during survey period, most vegetations did not survive except for Phragmites communis. But plant species number and plant coverage were increased gradually in the forth survey as of October 2011 when inundation period was less than 2 weeks so water level decreased more than that of third survey. Accordingly, the correlation analysis among number of plant species and plant coverage on stream bank, which applied revegetation method, water level and inundation period was performed for quantitative analysis. The result revealed that number of plant species and plant coverage has a negative correlation with water level and inundation period, but inundation period had higher correlation with plant occurrence than water level.