Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Grain shape effects in bed load sediment transport

An Addendum to this article was published on 15 November 2023

Abstract

Bed load sediment transport, in which wind or water flowing over a bed of sediment causes grains to roll or hop along the bed, is a critically important mechanism in contexts ranging from river restoration1 to planetary exploration2. Despite its widespread occurrence, predictions of bed load sediment flux are notoriously imprecise3,4. Many studies have focused on grain size variability5 as a source of uncertainty, but few have investigated the role of grain shape, even though shape has long been suspected to influence transport rates6. Here we show that grain shape can modify bed load transport rates by an amount comparable to the scatter in many sediment transport datasets4,7,8. We develop a theory that accounts for grain shape effects on fluid drag and granular friction and predicts that the onset and efficiency of transport depend on the coefficients of drag and bulk friction of the transported grains. Laboratory experiments confirm these predictions and reveal that the effect of grain shape on sediment transport can be difficult to intuit from the appearance of grains. We propose a shape-corrected sediment transport law that collapses our experimental measurements. Our results enable greater accuracy in predictions of sediment transport and help reconcile theories developed for spherical particles with the behaviour of natural sediment grains.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Competing effects of grain shape on bed load sediment transport.
Fig. 2: Granular materials used in the experiments.
Fig. 3: Comparison of grain shape theory with laboratory flume data.

Similar content being viewed by others

Data availability

The experimental flume data and measurements of grain properties and code used to support the conclusions and generate the figures in the main text and extended data items are available in an online repository. Flume data: https://doi.org/10.7910/DVN/GBSC2U; grain properties: https://doi.org/10.7910/DVN/31KT36; main text figures: https://doi.org/10.7910/DVN/5PYJFP; and extended data items: https://doi.org/10.7910/DVN/NQ33ODSource data are provided with this paper.

References

  1. Simon, A., Bennett, S. J. & Castro, J. M. (eds). Stream Restoration in Dynamic Fluvial Systems (AGU, 2013); https://doi.org/10.1029/gm194.

  2. Perron, J. T. et al. Valley formation and methane precipitation rates on Titan. J. Geophys. Res. Planets 111, E11001 (2006).

  3. Garcia, M. H. Sedimentation Engineering: Processes, Measurements, Modelling and Practice (American Society of Civil Engineers, 2008).

  4. Gomez, B. & Church, M. An assessment of bedload sediment transport formulae for gravel bed rivers. Water Resour. Res. 25, 1161–1186 (1989).

    Article  ADS  Google Scholar 

  5. Parker, G., Klingeman, P. C. & McLean, D. G. Bedload and size distribution in paved gravel-bed streams. J. Hydraulics Div. ASCE 108, 544–571 (1982).

    Article  Google Scholar 

  6. Shields, A. Anwendung der Aehnlichkeitsmechanik und der Turbulenzforschung auf die Geschiebebewegung (Mitt. Preuss. Versuchsanst. Wasserbau Schiffbau, 1936) [English translation by Ott W. P. & van Uchelen, J. C. (US Dept. Agric. Soil Conser. Serv. Coop. Lab., 1936)].

  7. Wong, M. & Parker, G. Reanalysis and correction of bed load relation of Meyer-Peter and Müller using their own database. J. Hydraul. Eng. 132, 1159–1168 (2006).

    Article  Google Scholar 

  8. Frey, P. & Church, M. How river beds move. Science 325, 1509–1510 (2009).

    Article  CAS  PubMed  Google Scholar 

  9. Church, M. Bed material transport and the morphology of alluvial river channels. Annu. Rev. Earth Planet. Sci. 34, 325–354 (2006).

    Article  ADS  CAS  Google Scholar 

  10. Dietrich, W. E. et al. Fluvial gravels on Mars: Analysis and implications. In Gravel‐Bed Rivers: Processes and Disasters (eds Tsutsumi, D. & Laronne, J. B.) 755–783 (Wiley, 2017).

  11. Grotzinger, J. P. et al. A habitable fluvio-lacustrine environment at Yellowknife Bay, Gale Crater, Mars. Science https://doi.org/10.1126/science.1242777(2014).

    Article  PubMed  Google Scholar 

  12. Nienhuis, J. H. et al. Global-scale human impact on delta morphology has led to net land area gain. Nature 577, 514–518 (2020).

    Article  ADS  CAS  PubMed  Google Scholar 

  13. Alcántara-Ayala, I. Geomorphology and disaster prevention. In Geomorphological Hazards and Disaster Prevention (eds Alcántara-Ayala, I. & Goudie A. S.) 269–278 (Cambridge Univ. Press, 2009); https://doi.org/10.1017/cbo9780511807527.022.

  14. Whyte, D. C. & Kirchner, J. W. Assessing water quality impacts and cleanup effectiveness in streams dominated by episodic mercury discharges. Sci. Total Environ. 260, 1–9 (2000).

    Article  ADS  CAS  PubMed  Google Scholar 

  15. Gilvear, D. J. Fluvial geomorphology and river engineering: future roles utilizing a fluvial hydrosystems framework. Geomorphology 31, 229–245 (1999).

    Article  ADS  Google Scholar 

  16. Raymond Pralong, M., Turowski, J. M., Rickenmann, D. & Zappa, M. Climate change impacts on bedload transport in alpine drainage basins with hydropower exploitation. Earth Surf. Processes Landforms 40, 1587–1599 (2015).

    Article  ADS  Google Scholar 

  17. Meyer-Peter, E. & Müller, R. Formulas for Bed-Load Transport. In Proceedings of the 2nd Meeting of the International Association for Hydraulic Structures Research 39–64 (Inter. Assoc. Hydraul. Res., 1948).

  18. Reid, I. & Jonathan, B. L. Bed load sediment transport in an ephemeral stream and a comparison with seasonal and perennial counterparts. Water Resour. Res. 31, 773–781 (1995).

    Article  ADS  Google Scholar 

  19. Low, H. S. Effect of sediment density on bed-load transport. J. Hydraul. Eng. 115, 124–138 (1989).

    Article  Google Scholar 

  20. Masteller, C. C., Finnegan, N. J., Turowski, J. M., Yager, E. M. & Rickenmann, D. History‐dependent threshold for motion revealed by continuous bedload transport measurements in a steep mountain stream. Geophys. Res. Lett. 46, 2583–2591 (2019).

    Article  ADS  Google Scholar 

  21. Ockelford, A.-M. & Haynes, H. The impact of stress history on bed structure. Earth Surf. Process. Landf. 38, 717–727 (2012).

    Article  ADS  Google Scholar 

  22. Cassel, M. et al. Bedload transport in rivers, size matters but so does shape. Sci. Rep. 11, 508 (2021).

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  23. Demir, T. The Influence of Particle Shape on Bedload Transport in Coarse-bed River Channels. PhD thesis, Durham Univ. (2000).

  24. Dudill, A. et al. Comparing the behaviour of spherical beads and natural grains in bedload mixtures. Earth Surf. Process. Landf. 45, 831–840 (2020).

    Article  ADS  Google Scholar 

  25. Jain, R., Tschisgale, S. & Fröhlich, J. Impact of shape: DNS of sediment transport with non-spherical particles. J. Fluid Mech. 916, A38 (2021).

    Article  ADS  MathSciNet  CAS  MATH  Google Scholar 

  26. Ferguson, R. I. & Wathen, S. J. Tracer-pebble movement along a concave river profile: virtual velocity in relation to grain size and shear stress. Water Resour. Res. 34, 2031–2038 (1998).

    Article  ADS  Google Scholar 

  27. Warburton, J. & Demir, T. Influence of bed material shape on sediment transport in gravel-bed rivers: a field experiment. In Tracers in Geomorphology (ed. Foster, I. D. L.) 401–410 (Wiley, 2000).

  28. Cleary, P. W. The effect of particle shape on simple shear flows. Powder Technol. 179, 144–163 (2008).

    Article  CAS  Google Scholar 

  29. Yager, E. M., Schmeeckle, M. W. & Badoux, A. Resistance is not futile: grain resistance controls on observed critical shields stress variations. J. Geophys. Res. Earth Surf. 123, 3308–3322 (2018).

    Article  ADS  Google Scholar 

  30. Komar, P. D. & Li, Z. Pivoting analyses of the selective entrainment of sediments by shape and size with application to gravel threshold. Sedimentology 33, 425–436 (1986).

    Article  ADS  Google Scholar 

  31. Burkalow, A. V. Angle of repose and angle of sliding friction: an experimental study. GSA Bull. 56, 669–707 (1945).

    Article  Google Scholar 

  32. Dietrich, W. E. Settling velocity of natural particles. Water Resour. Res. 18, 1615–1626 (1982).

    Article  ADS  Google Scholar 

  33. Smith, D. A. & Cheung, K. F. Settling characteristics of calcareous sand. J. Hydraul. Eng. 129, 479–483 (2003).

    Article  Google Scholar 

  34. Dioguardi, F. & Mele, D. A new shape-dependent drag correlation formula for non-spherical rough particles: experiments and results. Powder Technol. 277, 222–230 (2015).

    Article  CAS  Google Scholar 

  35. Göğüş, M., İpekçi, O. N. & Kökpina, M. A. Effect of particle shape on fall velocity of angular particles. J. Hydraul. Eng. 127, 860–869 (2001).

    Article  Google Scholar 

  36. Middleton, G. V. & Southard, J. B. Sediment gravity flows. In Mechanics of Sediment Movement (eds Middleton, G. V. & Southard, J. B.) Ch. 8 (SEPM, 1984); https://doi.org/10.2110/scn.84.03.0008.

  37. Lamb, M. P., Dietrich, W. E. & Venditti, J. G. Is the critical Shields stress for incipient sediment motion dependent on channel‐bed slope?. J. Geophys. Res. Earth Surf. 113, F02008 (2008).

    Article  ADS  Google Scholar 

  38. Parker, G. Self-formed straight rivers with equilibrium banks and mobile bed. Part 2. The gravel river. J. Fluid Mech. 89, 127–146 (1978).

    Article  ADS  MATH  Google Scholar 

  39. Novák-Szabó, T. et al. Universal characteristics of particle shape evolution by bed load chipping. Sci. Adv. 4, eaao4946 (2018).

    Article  ADS  PubMed  PubMed Central  Google Scholar 

  40. Bodek, S. & Jerolmack, D. J. Breaking down chipping and fragmentation in sediment transport: the control of material strength. Earth Surf. Dynam. 9, 1531–1543 (2021).

  41. Riazi, A., Vila-Concejo, A., Salles, T. & Türker, U. Improved drag coefficient and settling velocity for carbonate sands. Sci. Rep. 10, 9465 (2020).

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  42. Dufek, J., Manga, M. & Patel, A. Granular disruption during explosive volcanic eruptions. Nat. Geosci. 5, 561–564 (2012).

    Article  ADS  CAS  Google Scholar 

  43. Akhshik, S., Behzad, M. & Rajabi, M. CFD–DEM model for simulation of non-spherical particles in hole cleaning process. Part. Sci. Technol. 33, 472–481 (2015).

    Article  CAS  Google Scholar 

  44. Yang, Y., Peng, H. & Wen, C. Sand transport and deposition behaviour in subsea pipelines for flow assurance. Energies 12, 4070 (2019).

    Article  CAS  Google Scholar 

  45. Alihosseini, M., & Thamsen, P. U. Experimental and numerical investigation of sediment transport in sewers. In Proc. ASME 2018 5th Joint US–European Fluids Engineering Division Summer Meeting V003T17A005 (ASME, 2018); https://doi.org/10.1115/FEDSM2018-83274.

  46. Katterfeld, A. & Wensrich, C. Understanding granular media: from fundamentals and simulations to industrial application. Granul. Matter 19, 83 (2017).

    Article  Google Scholar 

  47. Carrigy, M. A. Experiments on the angles of repose of granular materials. Sedimentology 14, 147–158 (1970).

    Article  ADS  Google Scholar 

  48. Dai, B. B., Yang, J. & Zhou, C.-Y. Micromechanical origin of angle of repose in granular materials. Granul. Matter 19, 24 (2017).

    Article  Google Scholar 

  49. Mead, S. R., Cleary, P. W. & Robinson, G. K. Characterising the failure and repose angles of irregularly shaped three-dimensional particles using DEM. In Proc. Ninth Int. Conf. CFD in the Minerals and Process Industries (eds Solnordal, C. B. et al.) (CSIRO, 2012).

  50. Wiberg, P. L. & Smith, J. D. Calculations of the critical shear stress for motion of uniform and heterogeneous sediments. Water Resour. Res. 23, 1471–1480 (1987).

    Article  ADS  Google Scholar 

  51. Parker, G. Transport of gravel and sediment mixtures. In Sedimentation Engineering (ed. Garcia, M.) 165–251 (ASCE, 2008); https://doi.org/10.1061/9780784408148.ch03.

  52. Maurin, R., Chauchat, J. & Frey, P. Revisiting slope influence in turbulent bedload transport: consequences for vertical flow structure and transport rate scaling. J. Fluid Mech. 839, 135–156 (2018).

    Article  ADS  MathSciNet  CAS  MATH  Google Scholar 

  53. Vanoni, V. A. and Norman, H. B. Laboratory Studies of the Roughness and Suspended Load of Alluvial Streams. Report No. E-68 (California Institute of Technology, 1957).

  54. Buffington, J. M. & David, R. M. A systematic analysis of eight decades of incipient motion studies, with special reference to gravel‐bedded rivers. Water Resour. Res. 33, 1993–2029 (1997).

    Article  ADS  Google Scholar 

  55. Krumbein, W. C. Measurement and geological significance of shape and roundness of sedimentary particles. J. Sediment. Res. 11, 64–72 (1941).

    Article  CAS  Google Scholar 

  56. Blott, S. J. & Pye, K. Particle shape: a review and new methods of characterization and classification. Sedimentology 55, 31–63 (2008).

    Article  Google Scholar 

  57. Riazi, A. & Türker, U. The drag coefficient and settling velocity of natural sediment particles. Comput. Part. Mech. 6, 427–437 (2019).

    Article  Google Scholar 

  58. Metcalf, J. R. Angle of repose and internal friction. Int. J. Rock Mech. Min. 3, 155–161 (1966).

    Article  Google Scholar 

  59. Al-Hashemi, H. M. B. & Al-Amoudi, O. S. B. A review on the angle of repose of granular materials. Powder Technol. 330, 397–417 (2018).

    Article  Google Scholar 

  60. Bradski, G. & Kaehler, A. Learning OpenCV (O’Reilly, 2008).

Download references

Acknowledgements

We thank C. Johnson and M. Jellinek for logistical support, M. Rushlow, M. Cantine, A. Perron and M. Perron for assistance with grain shape measurements, and M. Church for discussions of grain shape and flume experiments. Research was sponsored by the Army Research Laboratory and was accomplished under grant number W911NF-16-1-0440. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Laboratory or the US Government. The US Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein. S.J.B. was partly supported by a grant from the NASA FINESST programme. The experimental facility was constructed using a Canadian Foundation for Innovation Leaders Opportunity Fund grant to J.G.V.

Author information

Authors and Affiliations

Authors

Contributions

E.D., J.T.P., K.K. and J.G.V. conceived the project. E.D. developed the grain shape theory with input from J.T.P. E.D., J.T.P., J.G.V., S.J.B. and R.B. performed laboratory flume experiments. E.D. and J.T.P. measured grain density, shape, drag coefficients and grain friction coefficients. E.D., J.T.P., S.J.B. and Q.Z. analysed the experimental data. E.D. and J.T.P. wrote the paper with input from all other authors.

Corresponding author

Correspondence to Eric Deal.

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature thanks Rebecca Hodge, Chris Paola and Manousous Valyrakis for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data figures and tables

Extended Data Fig. 1 Free body diagram of a single grain on a bed with inclination θ.

Force vectors shown correspond to forces in equations (4) and (5).  The various forces are a gravitational force, Fg, a buoyant force, Fb, a fluid drag force, FD, a lift force, FL, a bed contact force, Fc, and a frictional force, Ff.

Extended Data Fig. 2 Effects of different aspects of grain shape on fluid drag coefficient.

The measured drag coefficient of a grain settling in still water, CDsettle, relative to the calculated drag coefficient of the volume-equivalent sphere, Co, as a function of the Corey shape factor, a measure of gross grain shape. Coloured points show the materials used in our flume experiments and the additional materials in Extended Data Fig. 3a–e. Grey lines are fits to a large compilation32 of single-grain settling experiments that have been sorted by grain angularity, a measure of small-scale grain shape. Sketches in key show idealized grains of different angularity. Red dashed line is the trend 1/Sf for comparison. Error bars show one standard error of the mean.

Extended Data Fig. 3 Additional granular materials and their shape properties.

a, Tempered glass chips. b, Shell fragments. cf, Natural gravels 2–5, respectively, with differences in gross grain shape, angularity and surface properties. All materials have similar average sizes and densities to each other and to the five granular materials used in the flume experiments (Extended Data Table 1). g, Normalized coefficient of friction, μ*, as a function of the Corey shape factor for the five granular materials used in the flume experiments and the six additional granular materials shown in af. h, Normalized coefficient of drag, C*, as a function of Corey shape factor for the same 11 granular materials as in g. i, The ratio of the two normalized coefficients from g and h, C*/μ*, as a function of Corey shape factor for the same 11 granular materials as in g and h. The parameters C* and μ* tend to vary similarly for many of the measured materials, such that their ratio is close to one. However, several materials have ratios of C*/μ* distinctly different from one. This highlights the difficulty of guessing the net effect of grain shape on sediment transport based on qualitative inspection of grains. Error bars show one standard error of the mean.

Extended Data Fig. 4 Competing effects of grain shape on bed load sediment transport.

Same as Fig. 1, but including the six granular materials in Extended Data Fig. 3. a, Comparison of bulk coefficient of static friction with a measure of grain circularity, Sc = 4πA/P2, where A is the projected grain area and P is the projected perimeter (values closer to 1 indicate more-circular grains), for a compilation of observations47,48,49 and the materials measured here. b, Comparison of the still-water-settling drag coefficient, CDsettle, normalized by the drag coefficient for a sphere of the same volume (Methods) with another measure of grain shape, the Corey shape factor, Sf = c/(ab)1/2, where a, b, and c are the long, intermediate, and short axes of a grain (values closer to 1 indicate more-spherical grains), for a compilation of observations32 and the materials measured here. The coefficients of both friction and drag decrease with increasingly spherical grains. Error bars show one standard error of the mean.

Extended Data Fig. 5 Schematic diagram of laboratory flume.

Measurements of bed and water surface slope were made in the middle 2.5 m of the flume, where there were no visible entry or exit effects on grain motion. The flume is inclined 3°, but the sediment bed can develop a slope that is either steeper or less steep than the flume.

Extended Data Fig. 6 Shape distributions of granular materials with variable grain shapes.

ac, Histograms of the three axes (a, b, and c) used to characterize grain shape. df, Corresponding histograms of the Corey shape factor. n is the sample size for each grain type.

Extended Data Fig. 7 Distributions of settling velocities for the grain types used in flume experiments.

n is the sample size for each grain type.

Extended Data Fig. 8 Measurement of the angle of repose of experimental materials.

a, Spheres. b, Faceted ellipsoids. c, Rounded chips. d, Painted natural gravel. Painted gravel was used in the experiments to aid automated grain identification. e, Rectangular prisms. Blue and red lines are the right and left edges of the pile silhouette extracted with image analysis. Yellow lines are least-squares fits to these edges used to estimate the angle of repose. Vertical red line at the centre of each image is a plumb line used to determine the direction of gravity.

Extended Data Fig. 9 Comparison of boundary shear stress estimates from different methods.

For a subset of the flume experiments with spheres, flow velocity was measured using laser particle image velocimetry (PIV). a, Profiles of fluid velocity in the downstream direction as a function of distance above the grain bed (blue dotted lines), offset on the x-axis for visual clarity, are fit with the law of the wall (black lines), u = (u*/κ)ln(30z/do), where κ = 0.4 is the von Karman constant, do is the grain diameter, and u* = √(τ/ρ) is the shear velocity, which yields an estimate of the shear stress. The law of the wall is fit to the part of each profile between 20% and 80% of the maximum velocity (solid blue lines). b, Plot of the nondimensional bed shear stress estimated from τ = ρgRS against the nondimensional shear stress estimated from the Law of the Wall (blue points) and the shear stress calculated by applying a wall correction factor53 to the original estimates of τ = ρgRS (green points) for flume experiments with glass spheres. c, Same as b, but for the flume experiments with natural gravel, and without PIV-derived shear stress. Dashed lines are least-squares fits. The wall-corrected shear stress estimates for spheres and natural gravel are within error of each other and of the PIV-derived estimates. The average wall correction factor for the two grain types is (2.7 + 2.1)/2 = 2.41. Error bars show best estimate of uncertainty in shear stress estimates. For PIV-derived estimates this is the uncertainty of the log-linear fits in a; for the other estimates, it is the propagated standard error of the mean.

Extended Data Table 1 Grain properties

Supplementary information

Supplementary Video 1

A video of spheres undergoing low-intensity bed load transport. Dimensionless shear stress is τ* = 0.056, and dimensionless transport rate is q* = 0.018.

Supplementary Video 2

A video of natural gravel 1 undergoing low-intensity bed load transport. Dimensionless shear stress is τ* = 0.081, and dimensionless transport rate is q* = 0.025.

Supplementary Video 3

A video of spheres undergoing moderate-intensity bed load transport. Dimensionless shear stress is τ* = 0.106, and dimensionless transport rate is q* = 0.185.

Supplementary Video 4

A video of natural gravel 1 undergoing moderate-intensity bed load transport. Dimensionless shear stress is τ* = 0.148, and dimensionless transport rate is q* = 0.230.

Supplementary Video 5

A video of faceted ellipsoids undergoing moderate-intensity bed load transport. Dimensionless shear stress is τ* = 0.127, and dimensionless transport rate is q* = 0.262.

Supplementary Video 6

A video of rectangular prisms undergoing moderate-intensity bed load transport. Dimensionless shear stress is τ* = 0.123, and dimensionless transport rate is q* = 0.224.

Supplementary Video 7

A video of rounded glass chips undergoing moderate-intensity bed load transport. Dimensionless shear stress is τ* = 0.124, and dimensionless transport rate is q* = 0.262.

Supplementary Video 8

A video of spheres undergoing high-intensity bed load transport. Dimensionless shear stress is τ* = 0.160, and dimensionless transport rate is q* = 0.598.

Supplementary Video 9

A video of natural gravel 1 undergoing high-intensity bed load transport. Dimensionless shear stress is τ* = 0.206, and dimensionless transport rate is q* = 0.543.

Source data

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Deal, E., Venditti, J.G., Benavides, S.J. et al. Grain shape effects in bed load sediment transport. Nature 613, 298–302 (2023). https://doi.org/10.1038/s41586-022-05564-6

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41586-022-05564-6

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing