• Journal of Korean Society of Rural Planning
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• v.17 no.2
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• pp.23-32
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• 2011

The purpose of this study is to produce basic planning criteria required in ecological restoration and improvement works of streams in rural area through the application of stream assessment methods (water quality, soil environment, and ecological function assessment) at 6 study sites of Han River basin. The investigation results were as followings; 1) There were the evaluation items like a manure use, salt degree, river peripheral tree, which did not fitted to apply to domestic streams, in the SVAP (Stream Visual Assessment Protocol) and NRCS Riparian Assessment that were evaluation models developed in USDA. The area inhabitants with a little knowledge and education personally seems to utilize the evaluation methods through improvement partly with an aspect that evaluation is slightly easy. 2) From the stream assessment results, the construction of diverse pools, large woody debris and isolated backwater pool are needed to improve a few of problems observed at the mostly study sites. The result of NRCS Riparian Assessment showed that the improvement of stream bank vegetative communities is needed by planting tree with deep-binding root masses, and managing of noxious weeds and exotic undesirable plants. 3) Summing up, the assessment results showed that the assessment scores were higher at upstream than downstream, the stream with totally maintenance than that with partly maintenance, the stream with slope bank than that with vertical bank, and the stream with a flood plain than that without a flood plain. So, the direction of stream maintenance projects must be set by consideration of those results.

• The Korean Journal of Ecology
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• v.26 no.3
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• pp.97-102
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• 2003

This study was carried out to understand the variation of bird community by eco-park development of urban stream, Yangjae stream, Seoul, from Jan. 1996 to Dec. 2001. After the development, slight change in the bird community happened; for example, the number of species increased(r²=0.729, p<0.05), but there was not any variation in the total number of birds(r²=0.050, p>0.05). Especially, the number of individuals in herons and ducks rose. We suggest that the change as caused by restoration of low revetment vegetation and artificial pond vegetation in flood plain. However, the number of sandpipers, plovers and wagtails inhabiting on the sands and gravels in stream fell down. It seems that it would be caused by construction of bicycle path on the flood plain. The number of songbirds was tended to go down to 2000, but increased in 2001. The decrease of songbirds might be attributed to irregular removals of bush. We suggested that riparian vegetation restoration and artificial ponds positively affected birds inhabitation, but bicycle path and irregular elimination of a bush negatively affected.

• Journal of Wetlands Research
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• v.12 no.1
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• pp.15-22
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• 2010

We measured net primary productivity, annual accumulation of organic carbon and leaf decomposition of Salix community in the flood plain of the Han River and the Nakdong River. Net primary productivity, annual accumulation of organic carbon of the Salix community were 22.5ton/ha/yr(16.7ton/ha/yr-31.2ton/ha/yr) and 9.7ton C/ha/yr(7.5ton C/ha/yr-14.0ton C/ha/yr) respectively, which showed the highest values among the woody plant communities reported in the Korea. It means that planting Salix in the flood plain of the river is the best way to remove carbon dioxides. The faster leaf decomposition occurred around, under and the herb of Salix community in order. Leaf decomposition rate of Salix was higher than that of mesophytes, but lower than that of hydrophytes.

• 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.

• Korean Journal of Remote Sensing
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• v.34 no.5
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• pp.787-799
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• 2018

Accurate and effective mapping is critical step to monitor the spatial distribution and change of flood inundated area in large scale flood event. In this study, we try to suggest methods to use low spatial resolution satellite optical imagery for flood mapping, which has high temporal resolution to cover wide geographical area several times per a day. We selected the Sebou watershed flood in Morocco that was occurred in early 2010, in which several hundred $km^2$ area of the Gharb lowland plain was inundated. MODIS daily surface reflectance product was used to detect the flooded area. The study area showed several distinct spectral patterns within the flooded area, which included pure turbid water and turbid water with vegetation. The flooded area was extracted by thresholding on selected band reflectance and water-related spectral indices. Accuracy of these flooding detection methods were assessed by the reference map obtained from Landsat-5 TM image and qualitative interpretation of the flood map derived. Over 90% of accuracies were obtained for three methods except for the NDWI threshold. Two spectral bands of SWIR and red were essential to detect the flooded area and the simple thresholding on these bands was effective to detect the flooded area. NIR band did not play important role to detect the flooded area while it was useful to separate the water-vegetation mixed flooded classes from the purely water surface.

• Water for future
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• v.27 no.4
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• pp.115-121
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• 1994

In tidal rivers, the water level is affected by a tidal wave. The latter creates higher flood stages that enlarge the flood plain areas and increase potential damages. In such rivers, the water level is not solely a function of the flow discharge but rather a joint function of both the discharge and tidal phenomena. This paper attempts at formulating a relation between tital water level and river flow discharge that can be used for the predictions of water level in coastal rivers. Numerical applications were performed on the HaDong and the SongJung Station in Sumjin river with satisfactory results. The correlation coefficients between the tide(M) and the water stage(Z) at the HaDong Station is 0.558, and SongJung is 0.016. From this result, the water level at HaDong Station is greatly affected by a tide, whereas songJung is not.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.40-40
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• 2015

최근 기후변화로 인해 홍수의 발생빈도와 홍수량이 증가하고 있으며, 여름철 집중호우 및 태풍에 의해 하천의 둔치가 침수됨으로써 다양한 침수피해를 야기한다. 대하천 사업 이후 하천의 둔치를 활용한 체육시설, 자전거도로 및 생태공원과 같은 친수시설들이 조성되었으며 태풍으로 인한 하천의 홍수위 상승은 이러한 친수시설에 대한 직접적인 피해를 가져올 수 있다. 따라서 이와 같은 침수피해를 예측하기 위해서는 둔치를 포함한 복단면에서의 흐름해석을 통한 수리학적 영향을 분석해야하며, 둔치에서의 흐름양상은 주수로에 비해 수심이 얕고 흐름에 대한 저항이 크기 때문에 2차원 수리해석이 바람직한 것으로 제안되고 있다. 2차원 수리해석에 있어 하천의 홍수위 상승과 하강으로 인해 발생하는 둔치구간에서의 마름과 젖음 현상은 수치해의 발산을 야기하며, 이러한 문제를 해결하기 위해 다양한 마름/젖음 해석 기법에 대한 연구들이 진행되어 왔으며 일반적으로 마름/젖음에 대한 문제를 해결하는 방법은 마름/젖음에 상관없이 모든 부분에서 방정식을 푸는 박막기법과 해석영역으로부터 마름 부분을 제거하는 이동경계법으로 나눌 수 있다. 본 연구에서는 단기간에 수위가 급변하는 태풍사상에 대한 둔치에서의 홍수위험도를 평가하기 위해 마름/젖음 해석이 가능한 2차원 유한차분모형인 Nays2D 모형을 이용하여 마름/젖음에 대한 과거 선행연구들의 결과와 적용된 모형의 결과를 비교하여 모형의 적용성을 검증하였고, 검증된 모형을 강정-고령보에서부터 달성보 사이 구간에 적용하여 수리학적 영향을 분석하였다. 또한, 모형의 결과를 이용하여 홍수위험지수를 산정하였으며, 이를 통해 둔치구간에서의 홍수위험도 평가를 실시하였다.

• Korean Journal of Environment and Ecology
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• v.29 no.1
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• pp.62-68
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• 2015

In order to get basic data for flood plain restoration, we surveyed the woody vegetation in Korean natural rivers and analyzed the species' characteristics with regards to patterns of richness and diversity. These characteristics were higher in hard wood forests than those in soft wood forests, such as Salix spp. community. Futhermore, they were the highest in the Prunus sargentii-Pinus densiflora community(H' 1.095), and the lowest in the Carpinus laxiflora community(H' 0.118) among the hard wood forests. Species' richness diversity were the highest in the Salix gracilistyla community, but the lowest in the S. koriyangi community or S. koreensis community among the soft wood forests. With regards to the dominant index, just one community is over 0.9, 13 communities are between 0.3-0.7 and 15 communities are less than 0.3. The Salix koreensis community was the highest at 0.931, and Prunus sargentii-Pinus densiflora community was the lowest at 0.13. Species' richness and diversity was significantly correlated with tree layer coverages and degree of slope. These results mean that in order to increase plant species diversity in flood plains planted hard woody trees, such as oaks and fir, are needed to suit environmental conditions with steeper slope and lower canopy coverage.

• Korean Journal of Environment and Ecology
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• v.25 no.2
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• pp.189-210
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• 2011

As a part of improving the effect of stream restoration, the study selected 90 domestic natural streams that are not damaged and researched their riparian vegetations. Among them, the results of streams, whose naturalized ratio were more than 5 % and valley type flood plains were not developed, were excluded. By using the results of final 49 streams, plant communities and companion species that commonly appeared in high frequency, depending on stream type, were drawn. The result revealed that Quercus mongolica community, Hemiptelea davidii community and Salix koreensis community were representative in the mid-northern district (latitude: N $37{\sim}37.9^{\circ}$) with Salix koreensis community in the central district (latitude: N $36{\sim}36.9^{\circ}$) and Quercus serrata community in the southern district (latitude: $34{\sim}35.9^{\circ}$). For the stream type depending on altitude, Quercus serrata community and Phragmites japonica community were representative in the altitude of 200~500 m and there was no stream, in which flood plain is developed naturally, in the altitude of more than 500 m. In addition, the study drew representative communities depending on width of stretches of water at mean water level indicating the size of stream. Quercus serrata community was major vegetation at sites which are less than 20 m wide and Salix koreensis community was common at sites which are more than 20 m and less than 100 m wide of stretches of water at mean water level. Meanwhile the major vegetations at sites which are more than 100 m wide were Salix koreensis community, Morus bombycis community and Salix nipponica community. The study selected the kind of tree for planning riparian forest in flood plain by stream type on the basis of the result and suggested tree planting pattern that can be used in actual work by referring to the result of hydraulic review.

• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.2
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• pp.153-163
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• 2005

This paper presents two case studies for tunnelling in Bangkok: a subway tunnel site and a flood diversion tunnel site. The first case study is related to ground displacement response for dual tunnel Bangkok MRT subway. The MRT subway project of Bangkok city consists of dual tunnels about 20 km long with 18 subway stations. The tunnels are seated in the firm first stiff silty clay layer between 15-22 m in depth below ground surface. The behavior of ground deformation response based on instrumentation is presented. The back analysis based on plain strain FEM analysis is also presented and agrees with field performance. The shear strain of FEM analysis is in the range of 0.1-1% and in accordance with the results of self boring pressuremeter tests. Meanwhile, the second case study is related to the EPB tunnelling bored underneath through underground obstruction. The Premprachakorn flood diversion tunnel is the shortcut tunnel to divert the flood water in rainy season into the Choapraya river. The tunnel was bored by means of EPB shield tunnelling in very stiff silty clay layer at about 20-24 m in depth. During flood diversion tunnel bored underneath the existing Bangkok main water supply tunnel and pile foundation of the bridge, instrumentation was monitored and compared with predicted FEM analysis. The prevention risk potential by means of predicting damage assessment is also presented and discussed.