Journal of Korea Water Resources Association (한국수자원학회논문집)

Korea Water Resources Association (한국수자원학회)
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Numerical analysis of deposition and channel change in the vegetation zone

식생대에서 유사의 퇴적과 하도변화 수치모의 분석

  • Hwang, Hyo (Department of Civil Engineering, Korea National University of Transportation) ;
  • Jang, Chang-Lae (Department of Civil Engineering, Korea National University of Transportation) ;
  • Kang, Minseok (Institute of Agricultural Science, Chungnam National University)
  • 황효 (한국교통대학교 토목공학과) ;
  • 장창래 (한국교통대학교 토목공학과) ;
  • 강민석 (충남대학교 농업과학연구소)
  • Received : 2022.09.22
  • Accepted : 2022.11.24
  • Published : 2023.01.31
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Abstract

This study analyzed the bed load transport and channel change on the vegetation zone through laboratory experiments and numerical simulations. To examine the effect of vegetation zone in the laboratory experiment, artificial vegetation zones made of acrylic sticks were installed in the experimental channel, and discharge conditions were adjusted to examine the bed load transport and channel change in the vegetation zone. Next, numerical simulations were performed by applying the same conditions as those of the laboratory experiment to the Nays2D model, a two-dimensional numerical model, and the applicability of the numerical model was examined by comparing the results with the results of the laboratory experiment. Finally, by applying a numerical model, the bed load transport and channel change according to the change in vegetation density were examined. As a result of examining the bed load transport and channel change in the vegetation zone according to the discharge condition change by applying the laboratory experiment and the numerical model, the results of the two application methods were similar. As the discharge increased, bed load from the upper stream was deposited inside the vegetation zone. On the other hand, on the other side of the vegetation zone, the flow was concentrated and erosion occurred. Also, the range of erosion increased in the downstream direction. As a result of examining the bed load transport and channel change according to the change in vegetation density, as the vegetation density increased, the bed load from the upper stream was deposited inside the vegetation zone. On the other hand, due to the increase in vegetation density, the flow was concentrated to the opposite side of the vegetation zone, erosion occurred.

본 연구에서는 실내실험과 수치모의를 통해 식생대에서의 소류사 이동 및 하도 변화를 분석하였다. 실내시험에서 식생대의 영향을 검토하기 위해 아크릴 봉으로 제작한 인공 식생대를 실험수로에 설치하였으며, 유량 조건을 조정하여 유량변화에 따른 식생대에서의 소류사 이동 및 하도 변화를 검토하였다. 다음으로 실내실험과 동일한 조건을 2차원 수치 모형인 Nays2D모형에 적용하여 수치모의를 수행하고, 그 결과를 실내실험 결과와 비교하여 수치모형의 적용성을 검토하였다. 마지막으로 적용성을 검토한 수치모형을 적용하여 식생밀도의 변화에 따른 소류사 이동 및 하도의 변화를 검토하였다. 실내실험과 수치모형을 적용하여 유량변화에 따른 식생대에서의 소류사 이동 및 하도 변화를 검토한 결과, 두 적용 방법의 결과가 유사하게 나타났다. 유량이 증가함에 따라 상류에서 유입된 소류사가 식생대 내부에 퇴적되었으며, 식생대 반대편에는 흐름이 집중되어 침식이 발생하였다. 또한 시간이 지날수록 하류방향으로 침식범위가 증가하였다. 식생밀도의 변화에 따른 소류사 이동 및 하도의 변화를 검토한 결과, 식생대의 식생밀도가 증가할수록 상류에서 유입된 소류사가 식생대 내부에 퇴적되었다. 또한 식생밀도의 증가로 인하여 흐름이 식생대의 반대편으로 집중되어 식생대 반대편 하도의 침식이 발생하였다.

Keywords

Acknowledgement

이 논문은 2022년도 정부(교육부)의 재원으로 한국연구재단의 지원을 받아 수행된 기초연구사업임(NRF-2021R1I1A3048276).

References

  1. Ahadiyan, J., Adeli, A., Bahmanpouri, F., and Gualtieri, C. (2018). "Numerical simulation of flow and scour in a laboratory junction." Geosciences, Vol. 8, No. 5, 162.
  2. Asahi, K., Shimizu, Y., Nelson, J., and Parker, G. (2013). "Numerical simulation of river meandering with self-evolving banks." Journal of Geophysical Research: Earth Surface, Vol. 118, No. 4, pp. 2208-2229. https://doi.org/10.1002/jgrf.20150
  3. Bennett, S.J., Wu, W., Alonso, C., and Wang, S.S.Y. (2008). "Modeling fluvial response to in-stream woody vegetation: Implications for stream corridor restoration." Earth Surface Processes and Landforms, Wiley, Vol 33, No. 6, pp. 890-909. https://doi.org/10.1002/esp.1581
  4. Choufu, L., Abbasi, S., Pourshahbaz, H., Taghvaei, P., and Tfwala, S. (2019). "Investigation of flow, erosion, and sedimentation pattern around varied groynes under different hydraulic and geometric conditions: a numerical study." Water, Vol. 11, No. 2, 235.
  5. Gran, K., and Paola, C. (2001). "Riparian vegetation controls on braided stream dynamics." Water Resources Research, AGU, Vol. 37, No. 12, pp. 3275-3283. https://doi.org/10.1029/2000WR000203
  6. Jang, C.L. (2006). "Topographical changes and vegetation of rivers." Water for Future, KWRA, Vol. 39, No. 12, pp. 52-58.
  7. Jang, C.L. (2012). "Laboratory experiment of changing bars in the vegetated channels." Journal of the Korean Society of Civil Engineers, KSCE, Vol. 38, pp. 1830-1833.
  8. Jang, C.L. (2013). "Experimental analysis of the morphological changes of the vegetated channels." Journal of Korea Water Resources Association, KWRA, Vol. 46, No. 9, pp. 909-919. https://doi.org/10.3741/JKWRA.2013.46.9.909
  9. Jang, C.L. (2016). "Experimental study on the sediment sorting processes of the bed surface by geomorphic changes in the vegetated channels." Journal of Korea Water Resources Association, KWRA, Vol. 49, No. 1, pp. 73-81. https://doi.org/10.3741/JKWRA.2016.49.1.73
  10. Jang, C.L. (2017). "Numerical Simulation of flow characteristics and channel changes with discharge in the sharped meandering channel in the Naeseongcheon, Korea" Ecology and Resilient Infrastructure, Vol. 4, No. 1, pp. 24-33.
  11. Jang, C.L., and Shimizu, Y. (2007). "Vegetation effects on the morphological behavior of alluvial channels." Journal of Hydraulic Research, IAHR, Vol. 45, No. 6, pp. 763-772. https://doi.org/10.1080/00221686.2007.9521814
  12. Jang, C.L., Baek, T.H., Kang, T., and Ock, G. (2021). "Numerical analysis of morphological changes by opening gates of Sejong Weir." Journal of Korea Water Resources Association, KWRA, Vol. 54, No. 8, pp. 629-641. https://doi.org/10.3741/JKWRA.2021.54.8.629
  13. Ji, U., and Jang, E. (2014). "Numerical analysis of flow and bed changes due to tributary inflow variation at the confluence of the Namhan river and the Geumdang stream." Journal of Korea Water Resources Association, Vol. 47, No. 11, pp. 1027-1037. https://doi.org/10.3741/JKWRA.2014.47.11.1027
  14. Kang, K.H., Jang, C.L., Lee, G.H., and Jung, K. (2016). "Numerical analysis of the morphological changes by sediment supply at the downstream channel of Youngju dam." Journal of Korea Water Resources Association, KWRA, Vol 49, No. 8, pp. 693-705. https://doi.org/10.3741/JKWRA.2016.49.8.693
  15. Kim, H.S. (2013). Impact of finite vegetation patches on flow and bed morphology in open channels. Ph.D. dissertation, Hokkaido University, Hokkaido, Japan.
  16. Kondolf, G.M., and Wolman, M.G. (1993). "The sizes of salmonid spawning gravels." Water Resources Research, AGU, Vol. 29, No. 7, pp. 2275-2285. https://doi.org/10.1029/93WR00402
  17. Lopez, F., and Garcia, M.H. (2001). "Mean flow and turbulence structure of open-channel flow through non-emergent vegetation." Journal of Hydraulic Engineering, ASCE, Vol. 127, No. 5, pp 392-402. https://doi.org/10.1061/(asce)0733-9429(2001)127:5(392)
  18. Meyer-Peter, E., and Muller, R. (1948). "Formulas for bed-load transport." Journal of Hydraulic Research, IAHR, Vol. 3, pp. 39-64.
  19. Nepf, H.M., and Vivoni, E.R. (2000). "Flow structure in depth-limited, vegetated flow." Journal of Geophysical Research, Wiley, Vol. 105, No. C12, pp. 28547-28557. https://doi.org/10.1029/2000JC900145
  20. Park, M.H., and Kim.H.S.(2019) "Numerical simulation of bed change at the confluence of the Gamcheon and Mihocheon." Journal of the Korean Society of Civil Engineers, KSCE, Vol. 6, No. 4, pp. 328-338.
  21. Strickler, A. (1923). Beitrage zur frage der geschwindigkeitsformel und der rauhigkeitszahlen fur strome. Kanale und Geschlossene Leitungen. Bern, Switzerland.
  22. Tal, M., and Paola, C. (2010). "Effects of vegetation on channel mor phodynamics: Results and insights from laboratory experiments." Earth Surface Process Landforms, Wiley, Vol. 35, No. 9, pp. 1014-1028. https://doi.org/10.1002/esp.1908
  23. Thorne, C.D., and Furbish, D.J. (1995). "Influences of coarse bank roughness on flow within a sharply curved river bend." Geomorphology, Elsevier, Vol. 12, No. 3, pp. 241-257. https://doi.org/10.1016/0169-555X(95)00007-R
  24. Tsujimoto, T. (1999). "Fluvial processes in streams with vegetation." Journal of Hydraulic Research, ASCE, Vol. 37, No. 6, pp. 789-803. https://doi.org/10.1080/00221689909498512
  25. Yokojima, S., Kawahara, Y., and Yamamoto, T. (2015). "Impacts of vegetation configuration on flow structure and resistance in a rectangular open channel." Journal of Hydro-environment Research, Elsevier, Vol. 9, No. 2, pp. 295-303. https://doi.org/10.1016/j.jher.2014.07.008
  26. Yoon, T.H., Lee, J.S., and Shin, Y.J. (2002). "Flow variation in open channel due to presence of vegetation zone." Journal of the Korean Society of Civil Engineers, KSCE, Vol. 22, No. 2. pp. 143-149.
  27. Zong, L., and Nepf, H.M. (2010). "Flow and deposition in and around a finite patch of vegetation." Geomorphology, Elsevier, Vol. 116, No. 3, pp. 363-372. https://doi.org/10.1016/j.geomorph.2009.11.020
  28. Zong, L., and Nepf, H.M. (2012). "Vortex development behind a finite porous obstruction in a channel." Journal of Fluid Mechanics, J. Fluid Mech, Vol. 691, No. 25, pp. 368-391. https://doi.org/10.1017/jfm.2011.479