عنوان مقاله [English]
Understanding how velocity profile changes in vegetated rivers are important in accurately estimating discharge, shear velocity, and flow resistance. Therefore, in this study, velocity profiles of four direct reaches of mountain rivers with vegetation patches in Fars and Bushehr provinces have been investigated. Data collection in this study started in March 2021 and ended in May 2021. Measurements in this study include surveying, velocity measurement, and bed sampling. Investigation of 71 velocity profiles measured in the selected reaches showed that despite the high aspect ratio () in the studied reaches, in 39% of the profiles, the Dip phenomenon occurred, indicating that the aspect ratio is not the only factor influencing the Dip phenomenon. In addition, The Dip parameter was higher in profiles near to vegetastion pacthes. Also, by investigating the logarithmic law in velocity profiles, it was found that the logarithmic law is well applicable in reaches with vegetation patches, and the upper limit of the validity of the logarithmic law up to 58% of the flow depth was obtained. This value has been reported in laboratories for velocity data up to 20% of flow depth.
Afzalimehr, H., & Anctil, F. (2000). Accelerating shear velocity in gravel-bed channels. Hydrological Sciences Journal, 45(1), 113–124.
Afzalimehr, H., Barahimi, M., & Sui, J. (2019). Non-uniform flow over cobble bed with submerged vegetation strip. Proceedings of the Institution of Civil Engineers-Water Management, 172(2), 86–101.
Brierley, G. J., & Fryirs, K. A. (2013). Geomorphology and river management: applications of the river styles framework. John Wiley & Sons.
Chow. V.T. (1959). Open Channel Hydraulics. McGraw-Hill.
Clauser, F. H. (1954). Turbulent boundary layers in adverse pressure gradients. Journal of the Aeronautical Sciences, 21(2), 91–108.
Cotton, J. A., Wharton, G., Bass, J. A. B., Heppell, C. M., & Wotton, R. S. (2006). The effects of seasonal changes to in-stream vegetation cover on patterns of flow and accumulation of sediment. Geomorphology, 77(3–4), 320–334.
Derakhshan, S., Afzalimehr, H., & Singh, V. P. (2021). Effect of Vegetation Patch Distribution on the Flow Resistance.
Emadzadeh, A., Chiew, Y. M., & Afzalimehr, H. (2010). Effect of accelerating and decelerating flows on incipient motion in sand bed streams. Advances in Water Resources, 33(9), 1094–1104.
Fazlollahi, A., & Afzalimehr, H. (2013). Validation of Spatially Averaging Method for Using the Law of the Wall over Concave Bed Form (pool). Journal of Hydraulics, 8(2), 19–28.
Gibson, A. F. (1909). On the depression of the filament of maximum velocity in a stream flowing through an open channel. Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character, 82(553), 149–159.
Keulegan, G. H. (1938). Laws of turbulent flow in open channels (Vol. 21). National Bureau of Standards USA.
Kironoto, B. A., Graf, W. H., & REYNOLDS. (1995). Turbulence characteristics in rough non-uniform open-channel flow. Proceedings of the Institution of Civil Engineers-Water Maritime and Energy, 112(4), 336–348.
Kothyari, U. C., Hayashi, K., & Hashimoto, H. (2009). Drag coefficient of unsubmerged rigid vegetation stems in open channel flows. Journal of Hydraulic Research, 47(6), 691–699.
Lei, J., & Nepf, H. (2016). Impact of current speed on mass flux to a model flexible seagrass blade. Journal of Geophysical Research: Oceans, 121(7), 4763–4776.
López Alonso, R., Barragán Fernández, J., and Colomer, M. (2009). "Flow resistance equations for mountain rivers." Investigación agraria. Sistemas y recursos forestales, 2009, vol. 18, núm. 1, p. 81-91.
Mohammadzade miyab, N. (2014). Influence of aspect ratio in estimating hydrodynamic drag coefficient under declaratory flow over gravel-bed channels and vegetated bank. Isfahan University of Technology (in persian).
Moradian, M., Afzalimehr, H., Heidarpour, M., & Haribzadeh. (2013). Investigates the log law under uniform flow over a gravel-bed. 9th International River Engineering Conference (in persian).
Muhammad, M. M., Yusof, K. W., Mustafa, M. R. U., Ghani, A. A., Abdurrasheed, A. S., Sholagberu, A. T., Argungu, A. S., & Abubakar, U. A. (2021). Hydrodynamics of Flow over Axonopus Compressus (Cow Grass) as a Flexible Vegetation. Proceedings of the International Conference on Civil, Offshore and Environmental Engineering, 103–110.
Naderi, M., Afzalimehr, H. A., & Sohrabi, S. (2021). Investigation of Three-parameter Flow Resistance Model in Coarse-Bed Rivers (Case Study: Deryuk River). Iranian Journal of Soil and Water Research, 52(5), 1423–1435 (in persian).
Pasquino, V., & Gualtieri, P. (2017). Flow resistance of submerged rigid vegetation: Focus and validation on two layer approach. Proceedings of the 37th IAHR World Congress, Kuala Lampur, Malaysia, 13–18.
Song, T. (1995). Velocity and turbulence distribution in non-uniform and unsteady open-channel flow (No. THESIS). EPFL.
Song, T., and Chiew, Y. M. (2001). Turbulence measurement in nonuniform open-channel flow using acoustic Doppler velocimeter (ADV). Journal of Engineering Mechanics, 127(3), 219–232.
Wang, J., Shi, F., Chen, P., Wu, P., & Sui, J. (2015). Impact of bridge pier on the stability of ice jam. Journal of Hydrodynamics, 27(6), 865–871.
Wolman, M. G. (1954). A method of sampling coarse river‐bed material. EOS, Transactions American Geophysical Union, 35(6), 951–956.