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Experimental Study of Vegetated Flows in the Stream-scale Natural Channel

자연형 수로 내 식생흐름 분석을 위한 실험적 연구

  • Ryu, Yong-Uk (Pukyong National University) ;
  • Kim, Jihyun (Korea Institute of Civil Engineering and Building Technology) ;
  • Ji, Un (Korea Institute of Civil Engineering and Building Technology) ;
  • Kang, Joongu (Korea Institute of Civil Engineering and Building Technology)
  • 류용욱 (부경대학교 해양공학과) ;
  • 김지현 (한국건설기술연구원 국토보전연구본부) ;
  • 지운 (한국건설기술연구원 국토보전연구본부) ;
  • 강준구 (한국건설기술연구원 국토보전연구본부)
  • Received : 2019.08.09
  • Accepted : 2019.08.29
  • Published : 2019.10.01

Abstract

This study experimentally investigated the effects of high and low densities of vegetation patches on the flow characteristics in a stream-scale outdoor experimental channel with rooted willows. Stream-scale experiments on vegetated flows were carried out for an emergent condition of vegetation. Vegetation patches were arranged by alternate bar formation and the flows in vegetated and non-vegetated sections were compared. Three-dimensional flow structure was measured by ADV (Acoustic Doppler Velocimeter) and the vertical distributions of longitudinal velocity were mainly analyzed from the measurements at various points. Flow velocities show different patterns depending on the density of vegetation patches. The difference in flow velocity between in the vegetated and non-vegetated sections appear to large in the dense patches and the flow becomes complicated at the downstream edge of the patch. Despite the upstream flow disturbed by the first patch, the flows over the second patch show the similar pattern.

하천 내 흐름에 대한 식생 밀도의 영향을 조사하기 위해 버드나무가 활착된 하천 규모의 자연형 수로에서 유동 측정 실험을 수행하였다. 식생 내 흐름에 대한 하천 규모 실험은 식생의 반 잠김 조건에 대해 수행되었다. 수로 내 식생대(vegetation patch)는 교차로 형성된 사주의 형상으로 배열되었고 식생 구간과 비식생 구간에서의 흐름을 비교하였다. 3차원 유동 구조는 초음파 유속계(Acoustic Doppler Velocimeter)에 의해 측정되었고 종방향 속도의 연직 분포는 다양한 지점에서의 측정값으로부터 분석되었다. 유속은 식생대의 밀도에 따라 다른 양상을 보여 주는데, 식생 구간와 비식생 구간에서의 흐름 속도의 차이는 밀집된 식생대 주변에서 크게 나타나며 흐름 분포의 형태는 식생대의 하류방향 하단에서 복잡한 모습을 나타낸다. 하류에 위치한 식생대 주변의 흐름은 상류에 설치된 식생대에 의해 교란된 흐름에도 불구하고 유사한 분포를 보여준다.

Keywords

References

  1. Baptist, M. J. (2005). Modelling floodplains biogeomorphology, Ph.D thesis, Delft University of Technology, Faculty of Civil Engineering and Geoscience, Section Hydraulic Engineering, Delft.
  2. Baptist, M. J., Babovic, V., Rodriguez Uthurburu, J., Keijzer, M., Uittenbogaard, R. E., Mynett, A. and Verwey, A. (2007). "On inducing equations for vegetation resistance." Journal of Hydraulic Research, Vol. 45, No. 4, pp. 435-450. https://doi.org/10.1080/00221686.2007.9521778
  3. Camporeale, C., Perucca, E., Ridolfi, L. and Gurnell, A. M. (2013). "Modeling the interactions between river morphody-namics and riparian vegetation." American Geophysical Union, Review of Geophysics, Vol. 51, No. 3, pp. 379-414.
  4. Crosato, A. and Saleh, M. S. (2011). "Numerical study on the effects of floodplain vegetation on river planform style." Earth Surface Processes and Landforms, Vol. 36, No. 6, pp. 711-720. https://doi.org/10.1002/esp.2088
  5. Jang, C. L. and Shimizu, Y. (2007). "Vegetation effects on the morphological behavior of alluvial channels." Journal of Hydraulic Research, Vol. 45, No. 6, pp. 763-772. https://doi.org/10.1080/00221686.2007.9521814
  6. Morvan, H., Wright, N., Tang, X. and Crossley, A. (2008). "The concept of roughness in fluvial hydraulics and its formulation in 1D, 2D and 3D numerical simulation models." Journal of Hydraulic Research, Vol. 46, No. 2, pp. 191-208. https://doi.org/10.1080/00221686.2008.9521855
  7. Paul, M., Henry, P. Y. T. and Thomas, R. E. (2013). "Geometrical and mechanical properties of four species of northern European brown macroalgae." Coastal Engineering, Vol. 84, pp. 73-80. https://doi.org/10.1016/j.coastaleng.2013.11.007
  8. Straatsma, M., van der Perk, M., Schipper, A. M., de Nooij, R. J. W., Leuven, R. S. E. W., Huthoff, F. and Middelkoop, H. (2013). "Uncertainty in hydromorphological and ecological modelling of lowland river floodplains from land cover classification errors." Environmental Modelling & Software, Vol. 42, pp. 17-29. https://doi.org/10.1016/j.envsoft.2012.11.014
  9. Thomas, R. E., Johnson, M. F., Frostick, L. E., Parsons, D. R., Bouma, T. J., Dijkstra, J. T., Eiff, O., Gobert, S., Henry, P. Y., Kemp, P., Mclelland, S. J., Moulin, F. Y., Myrhaug, D., Neyts, A., Paul, M., Penning, W. E., Puijalon, S., Rice, S. P., Stanica, A., Tagliapietra, D., Tal, M., Torum, A. ans Vousdoukas, M. I., (2014). "Physical modelling of water, fauna and flora: knowledge gaps, avenues for future research and infrastructural needs." Journal of Hydraulic Research, Vol. 52, No. 3, pp. 311-325. https://doi.org/10.1080/00221686.2013.876453
  10. Tsujimoto, T. (1999). "Fluvial processes in streams with vegetation." Journal of Hydraulic Research, Vol. 37, No. 6, pp. 789-803. https://doi.org/10.1080/00221689909498512
  11. van Dijk, W. M., Teske, R., van de Lageweg, W. I. and Kleinhans, M. G. (2013). "Effects of vegetation distribution on experimental river channel dynamics." WRR, Vol. 49, No. 11, pp. 7558-7574. https://doi.org/10.1002/2013WR013574
  12. Van Oorschot, M., Kleinhans, M., Geerling, G. and Middelkoop, H. (2015). "Distinct patterns of interaction be-tween vegetation and morphodynamics." Earth Surface Processes and Landforms, Vol. 41, No. 6, pp. 791-808. https://doi.org/10.1002/esp.3864
  13. Vargas-Luna A., Crosato, A. and Uijttewaal, W. S. J. (2015). "Effects of vegetation on flow and sediment transport: comparative analyses and validation of predicting models." Earth Surface Processes and Landforms, Vol. 40, No. 2, pp. 157-176. https://doi.org/10.1002/esp.3633
  14. Warmink, J. J., van der Klis, H., Booij, M. J. and Hulscher, S. J. M. H. (2011). "Identification and quantification of uncer-tainties in a hydrodynamic river model using expert opinions." Water Resources Management, Vol. 25, No. 2, pp. 601-622. https://doi.org/10.1007/s11269-010-9716-7