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Fig. 3.8: The tree-lined but abandoned channel in the lower part of the photograph shows the former course of the Murrumbidgee at this meander bend.

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Fig. 3.9: The areas of sediment accumulation, usually on the inside of bends, highlight where flow swings from left to right in Yaven Yaven Creek.  This rhythmical swing in flow from one side of the channel to the other is responsible for initiating erosion on the apex of bends and ultimately the channel migrates.

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Fig. 3.10: The arrow shows an abandoned channel which may become inundated during high flows. Note the exposed deposits of sediment on the inside corners of the meander. Yaven Yaven Creek, tributary of Murrumbidgee, SE Australia.

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Fig. 3.11: The red arrows show the line of highest velocity known as the thalweg.  This swings from side to side causing erosion at the apex of bends and deposition on point bars on the inside of bends. Yaven Yaven Creek, tributary of Murrumbidgee, SE Australia.

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Fig. 3.12: Flow from a pool (left) to a riffle (right) then another pool (top middle), Afon Trannon, mid-Wales.

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Fig. 3.13: Flow from a riffle (left of orange stage board) to a pool (centre) then to the start of another riffle (left), Afon Trannon, mid-Wales.

It is still not exactly clear why rivers meander.  If you place a drop of water onto a flat pane of glass and tilt it slightly, you will see the drop of water moving from side to side as it flows.  This may help explain the initiation of meandering.  Recent research suggests that the accumulation of coarse sediment on channel beds tends to deflect the flow to one side or the other.  This initiates erosion, meandering and point bar formation.  Riffles (areas of shallower water) usually exist between meander bends while deeper pools form between riffles.

Download a PowerPoint file (308 K)  containing a movie showing channel change on the Afon Trannon, mid-Wales via sequential air photos from 1948, 1963, 1976, 1988 and 1995.

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Essential Reading

** Ferguson RI. 1981. Channel form and channel changes, in Lewin J (ed) British Rivers, London, Allen & Unwin.  Chapter 4, 106-121.

** Knighton D. 1998. Fluvial Forms and Processes, London, Arnold.  Chapter 6 Channel changes through time,  261-307.

* Stott TA. 2000. The River and Waterway Environment for Small Boat Users: An Environmental Guide for Recreational Users of Rivers and Inland Waterways, Nottingham, British Canoe Union. Chapter 1.2, 27, Chapter 2.2, 122-126..

Further Reading

*** Hooke JM. 1997.  Styles of channel change,  in CR Thorne, RD Hey and MD Newson (Eds.) Applied Fluvial Geomorphology for River Engineering and Management, 237-268.

*** Leeks GJL, Lewin J, Newson MD. 1988. Channel change, fluvial geomorphology and river engineering: The case of the Afon Trannon, Mid-Wales’, Earth Surface Processes and Landforms 13, 207-223.

*** Mount NJ, Zukowskyj PM, Teeuw RM, Stott TA. 2002. Assessing River Channel Destabilisation Using Aerial Photography, Digital Photogrammetry and GIS, in: Leuven RSEW, Poudevigne I, Teeuw RM. (eds.) Application of Geographic Information Systems and Remote Sensing in River Studies, Buckhuys, Lieden, 41-62.