Laboratory study of the effect of vegetation arrangement and density on flow resistance coefficient
Subject Areas : Marine structures
سمیرا سلمان زاده
1
()
منوچهر فتحی مقدم
2
()
جواد احدیان
3
()
سید محسن ساجدی
4
()
Keywords: تراکم, Staggered arrangement, Resistance coefficient, flexible vegetation, drag force, ضریب مقاومت, آرایش زیگزاگی, پوشش گیاهی انعطافپذیر, نیروی درگ,
Abstract :
This paper has been done by considering the hydraulic conditions of the river flow and the morphological conditions of the vegetation along the river and floodplain. The hydrodynamic drag force was measured directly by use of loadcell in the presence of flexible vegetation. Accordingly, all experiments were performed in a flume named "knife edge flume" with 8.3 m length, 0.8 m width and a 0.55 m height. Flexible non-submerged vegetation models with 3 densities (30, 50 and 100%) and staggered arrangement in three relative water depths (0.6, 0.8 and 1) were tested. In this study, vegetation density changed with increasing distance and leaf area of models. The results showed that the drag force significantly depends on the density of vegetation as one of the measurable morphological features of the plant. Density results can be used as a useful criterion in estimating the resistance due to the presence of plant roughness in the river.
Aberle, J. And Jarvela, J. (2015). Hydrodynamics of vegetated channels. Rivers–physical, fluvial and environmental processes. Springer.
Afzalimehr, H. And Subhasish, D. (2009). Influence of bank vegetation and gravel bed on velocity and Reynolds stress distributions. International Journal of Sediment Research, 24, pp: 236-246.
Armanini, A., Righetti, M. And Grisenti, P. (2005). Direct measurement of vegetation resistance in prototype scale. Journal of Hydraulic Research, 43(5), pp:481-487.
Ebrahimi, N. G., Fathi-Moghadam, M., Kashefipour, S., Saneie, M. And Ebrahimi, K. (2008). Effects of flow and vegetation states on river roughness coefficients. Journal of Applied Sciences, 8, pp: 2118-2123.
Fathi-Moghadam, M. And Kouwen, N. (1997). Nonrigid, nonsubmerged, vegetative roughness on floodplains. Journal of Hydraulic Engineering, 123, pp:51-57.
Jarvela, J. (2002). Flow resistance of flexible and stiff vegetation: a flume study with natural plants. Journal of hydrology, pp: 269, 44-54.
Koloseus, H. J. And Davidian, J. (1966). Free-surface Instability Correlations: And Roughness-concentration Effects on Flow Over Hydrodynamically Rough Surfaces. US Government Printing Office.
Kothyari, U. C., Hashimoto, H. And Hayashi, K. (2009). Effect of tall vegetation on sediment transport by channel flows. Journal of Hydraulic Research, 47, pp:700-710.
Kouwen, N. And Fathi-Moghadam, M. (2000). Friction factors for coniferous trees along rivers. Journal of hydraulic engineering, 126, pp: 732-740.
Krzeminska, D., Kerkhof, T., Skaalsveen, K. And Stolte, J. (2019). Effect of riparian vegetation on stream bank stability in small agricultural catchments. Catena, 172, pp:87-96.
Lei, J. And Nepf, H. (2021). Evolution of flow velocity from the leading edge of 2-D and 3-D submerged canopies. Journal of Fluid Mechanics, 916.
Liu, C. And Shen, Y.M. (2008). Flow structure and sediment transport with impacts of aquatic vegetation. Journal of Hydrodynamics, 20, pp: 461-468.
Nepf, H. M. (2012). Hydrodynamics of vegetated channels. Journal of Hydraulic Research, 50, pp:262-279.
Pasche, E. And Rouve, G. (1985). Overbank flow with vegetatively roughened flood plains. Journal of Hydraulic Engineering, 111, pp:1262-1278.
Stephan, U. And Gutknecht, D. (2002). Hydraulic resistance of submerged flexible vegetation. Journal of Hydrology, 269, pp: 27-43.
Tsujimoto, T. (1999). Fluvial processes in streams with vegetation. Journal of hydraulic research, 37, pp:789-803.
Wilson, C., Hoyt, J. And Schnauder, I. (2008). Impact of foliage on the drag force of vegetation in aquatic flows. Journal of Hydraulic Engineering, 134, pp:885-891.
Wynn, T. And Mostaghimi, S. (2006). The effects of vegetation and soil type on streambank erosion, southwestern virginia, usa 1