The morphology of an alluvial river channel is the consequence of sediment transport and sedimentation in the river. Morphological style is determined chiefly by the caliber and quantity of sediment delivered to the channel, although modulated by channel scale. Yet the relations between sediment transport and river morphology have received only limited, qualitative attention. In this review, the problem is studied by defining sediment transport regimes on the basis of the Shields number, a nondimensional measure of the capacity of the channel to move sediment of a given caliber. The problem is also approached from an inverse perspective by which the quantity and character of sediment deposits are used to infer details about the variation of sediment transport and sedimentation along a channel. Coupling the two approaches establishes a basis to gain new insights into the origins of alluvial channel morphology.

http://geofaculty.uwyo.edu/neil/teaching/4880_files/ChurchAnnRev2006.pdf

Bed material transport and the morphology of alluvial river channels

[1] Dunes are present in nearly all fluvial channels and are vital in predicting flow resistance, sediment transport, and deposition within many rivers. Progress in understanding the fluid dynamics associated with alluvial dunes has been significant in the last 15 years and has witnessed huge advances in field, laboratory, and numerical investigations. Progress has been made in detailing the principal features of mean and turbulent flow over asymmetric dunes that possess flow separation in their leesides and how these forms affect both downstream boundary layer structure and stress partitioning over the dune. Additionally, the links between sediment transport over dunes and instantaneous coherent flow structures are being increasingly understood, with the feedback of dune three-dimensionality upon flow and sediment dynamics over these bed forms beginning to be recognized as vital. Such research now provides an outstanding background for beginning to address areas of greater complexity that will enable a fuller understanding of these important natural features. This review paper summarizes the principal features of mean and turbulent flow over alluvial sand dunes. Five areas are then highlighted and discussed as a possible focus for future research: (1) the influence of dune leeside angle upon flow processes in the dune wake and downstream flow field, (2) the influence of three-dimensionality in dune shape upon the generation of turbulence and distribution of bed shear stress, (3) flow field modification resulting from bed form superimposition and amalgamation, (4) the scale and topology of dune-related turbulence and its interactions with sediment transport and the flow surface, and (5) the influence of suspended sediment on the dune flow field and dune morphology.

/pdf/the-fluid-dynamics-of-river-dunes-a-review-and-some-future-2nrjtixo1r.pdf

The fluid dynamics of river dunes: A review and some future research directions

[1] Dunes are present in nearly all fluvial channels and are vital in predicting flow resistance, sediment transport, and deposition within many rivers. Progress in understanding the fluid dynamics associated with alluvial dunes has been significant in the last 15 years and has witnessed huge advances in field, laboratory, and numerical investigations. Progress has been made in detailing the principal features of mean and turbulent flow over asymmetric dunes that possess flow separation in their leesides and how these forms affect both downstream boundary layer structure and stress partitioning over the dune. Additionally, the links between sediment transport over dunes and instantaneous coherent flow structures are being increasingly understood, with the feedback of dune three-dimensionality upon flow and sediment dynamics over these bed forms beginning to be recognized as vital. Such research now provides an outstanding background for beginning to address areas of greater complexity that will enable a fuller understanding of these important natural features. This review paper summarizes the principal features of mean and turbulent flow over alluvial sand dunes. Five areas are then highlighted and discussed as a possible focus for future research: (1) the influence of dune leeside angle upon flow processes in the dune wake and downstream flow field, (2) the influence of three-dimensionality in dune shape upon the generation of turbulence and distribution of bed shear stress, (3) flow field modification resulting from bed form superimposition and amalgamation, (4) the scale and topology of dune-related turbulence and its interactions with sediment transport and the flow surface, and (5) the influence of suspended sediment on the dune flow field and dune morphology.

The fluid dynamics of river dunes : A review and some future research directions : Marine sandware and river dune dynamics

ASCE Manual 54 , Sedimentation Engineering, prepared under the leadership of Professor Vito A. Vanoni, has provided guidance to theoreticians and practitioners’ world wide on the primary topic of sediment problems involved in the development, use, and conservation of water and land resources. First published in 1975, Manual 54 gives an understanding of the nature and scope of sedimentation problems, of the methods for their investigation, and of practical approaches to their solution. It is essentially a textbook on sedimentation engineering, as its title accurately refl ects. Manual 5 4 was the fi rst and most comprehensive text of its kind and has been circulated throughout the world for the past 30 years as the most complete reference on sedimentation engineering in the world. It has recently been published again as the Classic Edition (Vanoni 2006). In the spirit of its predecessor, this chapter of Manual of Practice 110 , Sedimentation Engineering, aims at presenting the state of the art concerning the hydraulics of sediment transport in fl uvial systems based on the knowledge gained in the last three decades. A concerted effort is made to relate the mechanics of sediment transport in rivers and by turbidity currents to the morphodynamics of lake and reservoir sedimentation, including the formation of fl uvial deltas.

Sediment Transport and Morphodynamics

. Gilbert, G.K. (1885) The topographic features of lake shores. US Geol. Surv., 5th Ann. Rept, 69–123. Gilbert, G.K. (1890) Lake Bonneville. US Geol. Surv. Monogr. 1. Goodbred, S.L., Jr and Kuehl, S.A. (1998) Floodplain processes in the Bengal Basin and the storage of Ganges-Brahmaputra river sediment: an accretion study using Cs and Pb geochronology. Sediment. Geol., 121, 239–258. Goodbred, S.L., Jr and Kuehl, S.A. (1999) Holocene and modern sediment budgets for the Ganges-Brahmaputra River system: evidence for highstand dispersal to fl ood-plain, shelf, and deepsea depocenters. Geology, 27, 559–562. Goodbred, S.L., Jr and Kuehl, S.A. (2000a) The signifi cance of large sediment supply, active tectonism, and eustasy on margin sequence development: Late Quaternary stratigraphy and evolution of the Ganges-Brahmaputra delta. Sediment. Geol., 133, 227–248. Goodbred, S.L., Jr and Kuehl, S.A. (2000b) Enormous GangesBrahmaputra sediment discharge during the strengthened early Holocene monsoon. Geology, 28, 1083–1086. Gould, H.R. (1970) The Mississippi delta complex. In: Deltaic Sedimentation: Modern and Ancient (J.P. Morgan, Ed.). SEPM Spec. Publ. no. 15, pp. 3–30. Harris, P.T., Baker, E.K., Cole, A.R. and Short, S.A. (1993) A preliminary study of sedimentation in the tidally dominated Fly River Delta, Gulf of Papua. Cont. Shelf Res., 13, 441– 472. Harris, P.T., Pattiaratchi, C.B., Keene, J.B., Dalrymple, R.W., Gardner, J.V., Baker, E.K., Cole, A.R., Mitchell, D., Gibbs, P. and Schroeder, W.W. (1996) Late Quaternary deltaic and carbonate sedimentation in the Gulf of Papua foreland basin: response to sea-level change. J. Sediment. Res., 66, 801–819. Harris, P.T., Heap, A.D., Bryce, S.M., Porter-Smith, R., Ryan, D.A. and Heggie, D.T. (2003) Classifi cation of Australian clastic coastal depositional environments based upon a quantitative analysis of wave, tidal, and river power. J. Sediment. Res., 72, 858–870. Haruyama, S. and Phai, V.V. (2002) Coastal change in the Southern Song Hong Delta. J. Geogr., 111, 124–132 (in Japanese with English abstract). Hayes, M.O. (1979) Barrier island morphology as a function of tidal and wave regime. In: Barrier Islands from the Gulf of St Lawrence to the Gulf of Mexico (S.P. Leatherman, Ed.). Academic Press, New York, pp. 1–27. Hori, K. and Saito, Y. (2003) Morphology and sediments of large river deltas, J. Geogr., 112, 337–359 (in Japanese with English abstract). Hori, K., Saito, Y., Zhao, Q., Cheng, C., Wang, P., Sato, Y. and Li, C. (2001a) Sedimentary facies and Holocene progradation rates of the Changjiang (Yangtze) delta, China. Geomorphology, 41, 233–248. Hori, K., Saito, Y., Zhao, Q., Cheng, C., Wang, P., Sato, Y. and Li, C. (2001b) Sedimentary facies of the tide-dominated paleoChangjiang (Yangtze) estuary during the last transgression. Mar. Geol., 177, 331–351. Hori, K., Saito, Y., Zhao, Q. and Wang, P. (2002) Architecture and evolution of the tide-dominated Changjiang (Yangtze) River delta, China. Sediment. Geol., 146, 249–264. Hori, K., Tanabe, S., Saito, Y., Haruyama, S., Nguyen, V. and Kitamura, A. (2004) Delta initiation and Holocene sea-level change: example from the Song Hong (Red River) delta, Vietnam. Sediment. Geol., 164, 237–249. Hovius, N. (1998) Controls on sediment supply by large rivers. In: Relative Role of Eustasy, Climate, and Tectonism in Continental Rocks (K.W. Shanley and P.J. McCabe, Eds.). SEPM Spec. Publ. no. 59, pp. 3–16.

Large Rivers : Geomorphology and Management

The branches of the River Rhine in the Netherlands, characterized by a sand–gravel bed in the upstream part and a sand bed in the downstream part of the river system, show migrating dunes, especially during floods. In the last 20 years, these dunes have been studied extensively. High-resolution echo-sounding measurements of these dunes, made with single and multibeam equipment, were analysed for three different sections of the Rhine river system during several floods. This analysis was done to quantify the growth, decay and migration rates of the dunes during floods. In addition, the migrating dunes were used to calculate bedload transport rates with dune tracking. The results of dune growth and decay and migration rate are shown to be very different for the various sections during the various floods, and these differences are related to differences in grain size of the bed and to differences in the distribution of discharge over the main channel and the floodplain. The relations are used to show that the growth and migration rate of dunes, and the calculated bedload transport rates during the rising stage of a flood wave can be predicted from the mobility of the bed material with simple power relations.

The response of subaqueous dunes to floods in sand and gravel bed reaches of the Dutch Rhine

Detailed field measurements during the 1998 flood of the Rhine River in The Netherlands show that both Manning \in and Darcy—Weisbach friction factor \if increase with discharge. The changes in bedform roughness height and friction factors are attributed to the increased dune height during floods. There is a near-peak hysteresis in the dune height measurements. At a given discharge, dunes are significantly larger after than before the peak discharge. The trend is most apparent for the Bovenrijn with weaker variations for the Waal. The methods of Engelund and Vanoni—Hwang provide similar estimates of form drag. When combined with van Rijn’s method to estimate grain resistance, both methods tend to overpredict the measured bed friction factor after the peak discharge. These methods perform best when field bedform measurements are available to estimate form drag. The composite effect of primary and secondary dunes should be considered in the analysis of resistance to flow.

https://www.engr.colostate.edu/%7Epierre/ce_old/Projects/Paperspdf/Julien-Klaassenet%20alASCE2002.pdf

A. W. E. Wilbers

Papers

The response of subaqueous dunes to floods in sand and gravel bed reaches of the Dutch Rhine

Case Study: Bed Resistance of Rhine River during 1998 Flood

Dune Growth, Decay and Migration Rates during a Large‐Magnitude Flood at a Sand and Mixed Sand–Gravel Bed in the Dutch Rhine River System