Stability of Armour Layers in Rivers

by Arved J. Raudkivi, Prof.; Dept. of Civ. Engrg., Univ. of Auckland, Auckland, New Zealand,
Robert Ettema, Research Engr.; Iowa Inst. of Hydr. Research, Iowa City, Iowa 52242,

Serial Information: Journal of the Hydraulics Division, 1982, Vol. 108, Issue 9, Pg. 1047-1057

Document Type: Journal Paper


The importance of both the overpassing and the embedding of river bed particles is demonstrated by experiments. When a single layer thick armouring layer of uniform d1 size particles on a bed of uniform finer d2 size particles is broken at one location the stability of the remainder of the armour layer depends on the tendency of the d1 particles to embed into the surface of d2 particles. If a d1 size particle is seated in the exposed position on the surface of the d2 sized bed sediment it may, by virtue of its exposure to the flow, be preferentially entrained and it may then overpass the finer bed sediment. Alternatively, the d1 particle may be too large for overpassing and it will become embedded. Armour layers composed of particles which embed, tend to be more stable.

Subject Headings: Particle size distribution | Overpasses and underpasses | Particles | River bank stabilization | Bed materials | Sediment | Overland flow | Entrainment

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