• Title/Summary/Keyword: saltation

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Aggregate Distribution and Wind Erosion in Grass Land of the New Incheon International Airport (인천 신공항 잔디밭 조성지 토양의 입단분포 및 풍식 예측량 산정)

  • Jung, Yeong-Sang;Yoo, Sun-Ho;Choi, Byung-Kwon;Joo, Young-Kyoo;Bang, Jeong-Ho;Park, Chol-Soo
    • Korean Journal of Soil Science and Fertilizer
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    • v.31 no.4
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    • pp.315-323
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    • 1998
  • Soil aggregate distribution and its relation to wind erosion were examined for the surface soil of the experimental plots for grasses in the New Incheon International Airport, of which soil was reclaimed with sea sands in the Youngjong Island. The soil aggregate with the size between 0.10 and 0.84mm was 74 percents. The 6 percents of the soil aggregates were non-erodible. With this aggregate distribution the wind erodiblity of the soil, I. was $380Mg\;ha^{-1}\;yr^{-1}$ with I value and climatic factor calculated for the dry period from November to May, $45.2Mg\;ha^{-1}\;yr^{-1}$ of the surface soil were estimated to be eroded. The erodible particles with 0.37mm diameter could fly to 17.8, 29.9 and 49.8 meters by saltation at wind speed of 7, 9 and $15m\;s^{-1}$, respectively. The wind erosion could be reduced by increasing vegetation coverage and applying hydrophyllic soil conditioner.

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Numerical Analysis of Modified Seabed Topography Due to the Presence of Breakwaters of Varying Reflection Characteristics using Physics-based Morphology Model [SeoulFoam] (방파제 형식에 따른 반사율 변화가 해저지형에 미치는 영향 수치해석: 물리기반 지형모형 SeoulFoam을 중심으로)

  • Cho, Yong Jun
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.33 no.4
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    • pp.168-178
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    • 2021
  • Numerical simulations were implemented to look into the modified seabed topography due to the presence of breakwaters of varying reflection characteristics. The numerical model was composed of OlaFlow, an OpenFoam-based tool box, and a physics-based morphology model [Seoul Foam]. In doing so, the interaction between the seabed, which undergoes deformation due to siltation and scouring, and the incoming waves was described using Dynamic Mesh. The rubble-mound, vertical, and curved slit caisson breakwaters with varying reflection characteristics resulted in standing waves that differ from each other, shown to have a significant influence on the seabed topography. These results are in line with Nielsen's study (1993) that sands saltated under the surface nodes of standing waves, where the near-bed velocities are most substantial, convected toward the surface antinodes by boundary-layer drift. Moreover, the crest of sand waves was formed under the surface antinodes of standing waves, and the trough of sand waves was formed under the surface antinodes. In addition, sand wave amplitude reaches its peak in the curved slit caisson with a significant reflection coefficient, and the saltation of many grains of sand would cause this phenomenon due to the increased near-bed velocity under the nodes when the reflection coefficient is getting large.