Effects of Flow Unsteadiness on the Transport of Bimodal Bed Material

Year 2023, Volume: 34 Issue: 6, 99 - 128, 01.11.2023

Gökçen Bombar , Aysegul Ozgenc Aksoy , Mehmet Şükrü Güney

https://doi.org/10.18400/tjce.1226516

Cited By: 1

Abstract

The grain size distribution of the transported bed load was experimentally investigated under unsteady flow conditions with bimodal mixture of sand and gravel in a laboratory flume. Five various triangular hydrographs were generated. A clockwise behavior for the total bed load versus shear velocity was observed meaning that the bed load during rising limb was higher than that of falling limb. It was found that the percent finer at the plateau of bimodal sediment size distribution curve had higher values during the initial and final phases compared to those obtained during the peak time. At all plateaus, the percent finer values related to the hydrograph peak discharge were in the same order of magnitude with that of the bed material. The sand content of the transported bed material initially decreased, then maintained a constant value during a certain time interval and finally returned to its original value. The sand percent of the bed load decreased in the falling limb showing a counterclockwise loop and the duration of the hydrograph did not affect the results considerably. The greater the peak flow rate of the hydrograph, the greater was the hysteresis. The bimodality index was calculated for all transported sediment samples and it was revealed that its initial and final values were less than that of the bed material but it was approximately the same elsewhere. The 5% finer sediment amount was nearly equal during rising and falling limbs. It was revealed that D50 value of the bed load decreased in the rising limb showing a clockwise loop. The hysteresis was not considerably changed according to the hydrograph characteristics. The clockwise type hysteresis was also observed for the size group of D95. The lag increased as the peak flow rate increased. A strong relation was found between the dimensionless total bed load Wt* and the total work index Wk as well as Wk and the ratio WR/WF. The correlations between the dimensionless total bed load and the unsteadiness parameters P, and Pmod were very weak, whereas a high value of determination coefficient was obtained with the unsteadiness parameter Pgt, implying an appreciable interdependence.

Keywords

Unsteady flow, mixed gravel and sand, bimodal sediment, bed load, unsteadiness parameter, hysteresis

Supporting Institution

TÜBİTAK

Project Number

109M637

References

• Bombar, G., 2009, Experimental and numerical investigation of bed load transport in unsteady flows, October 2009, PhD Thesis, Dokuz Eylül University Graduate School of Natural And Applied Sciences.
• Bombar, G., Elçi, Ş., Tayfur, G., Güney, M.Ş., Bor, A., 2011, Experimental and numerical investigation of bedload transport under unsteady flows, Journal of Hydraulic Engineering. posted ahead of print February 25, 2011. doi:10.1061/(ASCE)HY.1943-7900.0000412
• De Sutter, R., Verhoeven, R., Krein, A., 2001, Simulation of sediment transport during flood events: laboratory work and field experiments. Hydrological Sciences-Journal-des Sciences Hydrologiques, 46(4), 599-610.
• Duan, Z., Chen, J., Jiang, C., Liu, X., and Zhao, B., 2020, Experimental Study on Uniform and Mixed Bed-Load Sediment Transport under Unsteady Flow Appl. Sci. 2020, 10, 2002; doi:10.3390/app10062002
• Gumgum, F., Guney, M.S., 2021, Effect of Sediment Feeding on Live-Bed Scour around Circular Bridge Piers, Civil Engineering Journal, Vol. 7, No. 05, pp 906-914, DOI:10.28991/cej-2021-03091699
• Güney, M.Ş., Bombar G.,Aksoy A.Ö., 2013, Experimental study of the coarse surface development effect on the bimodal bed load transport under unsteady flow conditions, Journal of Hydraulic Engineering, Vol. 13, No. 1, pp 12-21. DOI: 10.1061/(ASCE)HY.1943-7900.0000640.
• Gunsolus, E.H., Andrew, B.D., 2017, Effect of morphologic and hydraulic factors on hysteresis of sediment transport rates in alluvial streams River Res Applic. 2018;34:183–192. DOI: 10.1002/rra.3184
• Gunsolus, E.H., Binns, A.D. 2017, Effect of morphologic and hydraulic factors on hysteresis of sediment transport rates in alluvial streams, River Research and Applications, Vol. 34, No. 2, pp 183-192 . DOI:10.1002/rra.3184
• Houssais, M., Lajeunesse E., 2012, Bedload transport of a bimodal sediment bed, Journal of Geophysıcal Research, Vol. 117, F04015, DOI:10.1029/2012JF002490,
• Khosravi, K., Chegini, A.H.N., Binns, A.D., Daggupati, P. and Mao, L., 2019, Difference in the bed load transport of graded and uniform sediments during floods: An experimental investigation Hydrology Research | 50.6
• Kuhnle, R.A., 1992, Bed load transport during rising and falling stages on two small streams, Earth Surface Processes and Landforms, Vol 17, 191-197
• Lee, K.T., Liu, Y.L., Cheng, K.H. 2004, Experimental investigation of bedload transport processes under unsteady flow conditions, Hydrological processes, 18(13), pp. 2439-2454.
• Li, Z., Qian, H., Cao, Z., Liu, H., Pender, G., Hu, P., 2018, Enhanced bedload sediment transport by unsteady flows in a degrading channel International Journal of Sediment Research 33 327–339 https://doi.org/10.1016/j.ijsrc.2018.03.002
• Mao, L., 2012, The effect of hydrographs on bed load transport and bed sediment spatial arrangement, Journal of Geophysical Research Atmospheres, Vol. 117, F03024, DOI:10.1029/2012JF002428
• Mao, L., 2018, The effects of flood history on sediment transport in gravel-bed rivers Geomorphology 322 (2018) 196–205 https://doi.org/10.1016/j.geomorph.2018.08.046.
• Melville, B., Sutherland, A. 1988, Design method for local scour at bridge piers, Journal of Hydraulic Engineering, Vol. 114, No. 10, pp 1210–1226.
• Mrokowska, M.M. and Rowinski, P.M., 2019, Impact of Unsteady Flow Events on Bedload Transport: A Review of Laboratory Experiments Water 2019, 11, 907; doi:10.3390/w11050907
• Müller, E.N., Batalla R.J., Bronstert A., 2008, Modelling bedload transport rates during small floods in a gravel-bed river. Journal of Hydraulic Engineering 134, 1430-1439
• Nanson, G.C., 1974, Bedload and suspended load transport in a small, steep, mountain stream, Am. Journal Sci., 274, 471-486.
• Przyborowski L., Nones M., Mrokowska M., Książek L., Phan C.N., Strużyński A., Wyrębek M., Mitka B., Wojak S., 2022, Preliminary evidence on laboratory experiments to detect the impact of transient flow on bedload transport, Acta Geophysica, https://doi.org/10.1007/s11600-022-00743-5Parker G, 2008, “Chapter 3, Transport of Gravel and Sedıment Mıxtures”, ASCE Manual 54, http://hydrolab.illinois.edu/people/parkerg/_private/Man54/Man54Chap3WholeText.pdf
• Parker’s Morphodynamics Web Page, (2006a, Calculator for statistical characteristics of grain size distributions: http://hydrolab.illinois.edu/people/parkerg/_private/e-bookExcel/RTe-bookGSDCalculator.xls
• Parker’s Morphodynamics Web Page, 2006b, Characterization of Sediment and Grain Size Distributions: http://hydrolab.illinois.edu/people/parkerg/_private/e-bookPowerPoint/RTe-bookCh2SedimentGSD.ppt
• Perret, E., Berni, C., Camenen, B., Herrero, A., Abderrezzak, K.E. 2018, Transport of moderately sorted gravel at low bed shear stresses: The role of fine sediment infiltration. Earth Surf. Process. Landforms, 43, 1416–1430.
• Plumb, B.D., Juez, C., Annable, W.K., McKie1, C.W., and Franca, M.J., 2020, The impact of hydrograph variability and frequency on sediment transport dynamics in a gravel-bed flume Earth Surf. Process. Landforms 45, 816–830 (2020) DOI: 10.1002/esp.4770
• Qu, Z., 2002, Unsteady open-channel flow over a mobile bed, PhD Thesis, EPFL, Thesis no 2688
• Reid, I., Frostick L.E., Layman J.T., 1985, The incidence and nature of bedload transport during flood flows in coarse-grained alluvial channels, Earth Surface Processes and Landforms, Vol 10, 33-44
• Saadi, Y., 2008, Fractional Critical Shear Stress at incipient motion in a bimodal sediment, Civil Engineering Dimension, Vol 10, No 2, pp 89-98
• Sambrook Smith G.H., 1996, Bimodal fluvial bed sediments: origin, spatial extent and processes, Progress in Physical Geography, Vol 20, No 4, pp 402-417, DOI: 10.1177/030913339602000402
• Smith Nicholas Ferguson, 1997, Measuring and defining bimodal sediments: Problems and implications, Water Resources Research, Vol 33, pp 1179-1185
• Tabarestani, M., Zarrati, K. 2015, Sediment transport during flood event: a review Int. J. Environ. Sci. Technol. 12:775–788 DOI 10.1007/s13762-014-0689-6
• Tian, S. and Wang Z., 2009, Bimodal sediment distribution and its relation with the river ecology in the Dadu River Basin, Advances in Water Resources and Hydraulic Engineering, pp 1049-1054
• Wang, L., Cuthbertson, A., Pender, G., 2013, Experimental investigation on temporal lag effect of graded sediment transport in unsteady flows Proceedings of 2013 IAHR Congress © 2013 Tsinghua University Press, Beijing
• Wang, L., Cuthbertson, A., Pender, G., Cao, Z., 2014, The Response of Bed-load Sediment Transport and Bed Evolution under Unsteady Hydrograph Flows, River Flow 2014 Conference: River Flow 2014 – the 7th International Conference on Fluvial Hydraulics At: Lausanne, Switzerland September 2014 DOI: 10.1201/b17133-215
• Wang, L., Cuthbertson, A., Pender, G., Cao, Z., 2015, Experimental investigations of graded sediment transport under unsteady flow hydrographs International JournalofSedimentResearch30(2015)306–320 http://dx.doi.org/10.1016/j.ijsrc.2015.03.010
• Wang, L., Wang, D., Cuthbertson, A.J.S., Zhong, D., and Pender, G., 2021a, Hysteretic Implications for Graded Bed Load Sediment Transport in Symmetrical Hydrograph Flows. Front. Environ. Sci. 9:800832. doi: 10.3389/fenvs.2021.800832
• Wang, L., Cuthbertson, A.J.S., Zhang, S.H., Pender, G., Shu, A.P., Wang, Y.Q., 2021b, Graded bed load transport in sediment supply limited channels under unsteady flow hydrographsWaters, K.A., and Curran, J.C., 2015, Linking bed morphology changes of two sediment mixtures to sediment transport predictions in unsteady flows, Water Resour. Res., 51, 2724–2741, doi:10.1002/2014WR016083.
• Wilcock, P.R., 1988, Methods for estimating the critical shear stress of individual fractions in mixed-size sediment, Water Resources Research, Vol 24, No 7, pp 1127 – 1135
• Wilcock, P.R., 1993, Critical shear stress of natural sediments, Journal of Hydraulic Engineering, Vol 119, No 4, April, pp 491 – 505
• Wilcock, P.R., Kenworthy S.T., Crowe J., 2001, Experimental study of the transport of mixed sand and gravel, Water Resources Research, Vol 37, No 12, pp: 3349-3358
• Wilcock, P.R., 2001, Toward a practical method for estimating sedimenttransport rates in gravel-bed rivers, Earth Surf. Processes Landforms, 26(13), 1395–1408, doi:10.1002/esp.301.
• Wilcock, P.R., and Kenworthy S., 2002, A two-fraction model for the transport of sand/gravel mixtures, Water Resour. Res., 38(10), 1194, doi:10.1029/2001WR000684.
• Yarnell, S.M., Yager, E., Sasha, L., 2016, Impacts of Hydrograph Shape on Sediment Transport in a Gravel-Bedded Stream, Extended Abstract 11th ISE 2016, Melbourne, Australia