http://www.paleocurrents.com/castle_rock/docs/meandering_riv...
http://www.searchanddiscovery.net/documents/Shell/images/p2....
Natural levees Natural levees are very low, asymmetrical ridges which flank the flood-stage channel of a stream. The crest of the natural levee is near the channel, and the levee slopes gently toward the backswamps. The width of the natural levee is from 60 to over 700 times its height. The height varies with the size of the stream; Mississippi natural levees are approximately 15 feet high and Brazos levees are about 5 feet high Natural levees consist of very fine sands9 silts, and clays which are deposited by channel overflow waters. Coarser materials are deposited on the levee crest, and progressively finer materials on the levee backslopes and in flood basins. Although soil development and vegetation destroy much of the bedding' very small ripple lamination is common in natural levee deposits Natural levees within stream meander belts, together with the higher point bar deposits' form alluvial ridges which are the highest parts of alluvial valleys.


--------------------------------------------------
Note added at 17 hrs (2009-05-05 07:33:18 GMT)
--------------------------------------------------

These are still alluvial ridges formed originally as natural levees (whether or not they occur in swamp (peatlands) or not.

Het bedijken van de grote rivieren is aan het eind van de 11de eeuw begonnen. Door deze bedijking werden de waterstromen meer en meer gefixieerd en kwam er een eind aan de natuurlijke ontwikkeling van stroomruggen. Tot de 10e eeuw lagen de nederzettingen uitsluitend op de hoger gelegen stroomruggen.
http://home.hccnet.nl/jan.arkesteijn/landschap/llinks.html

A natural levee is an narrow ridge of alluvium deposited at the side of the channel. During high discharge periods when the stream floods, coarse sediment settles out near the stream channel and grades to finer material further away. The over bank deposits of alluvium are often rich sources of nutrients for soils developed on the floodplain. Because floodplain soils are usually quite fertile, humans have inhabited them for years. To prevent flooding, artificial levees are built close to the channel, typically higher than natural levees. Confining the flood discharge to a small area increases the velocity of flow. The levees of the Mississippi River increase the flow velocity near the mouth as it enters the Gulf of Mexico. As a result, sediment is shot into the Gulf rather than being deposited near the mouth building the river's famous 'bird's foot' delta.http://www.uwsp.edu/geO/faculty/ritter/geog101/textbook/fluv...

he Nsonge Wetland : The Nsonge Floodplain is a 67 ha floodplain wetland draining north-east into the Mooi river. Land use in its catchment is agriculture, conservation and recreation, and the wetland is used for grazing livestock. It is characterised by an alluvial ridge that rises up to 1 m above the surrounding hummocky swamp. Meander scars and ox-bow lakes occur mostly in the lower end of the floodplain. http://wetlands.sanbi.org/project_details.php?id=76


--------------------------------------------------
Note added at 18 hrs (2009-05-05 08:06:41 GMT)
--------------------------------------------------

Hi Olly,

I think you are confused by the idea that the stroomrug is actually the bed of the river - this is not actually the case. The stroomrug forms as a result of flooding (natural levee) or can be a series of ridges indicating the movement of the river bend on the convex side (inside of the bend) as the river bed shifts. I rather suspect that the piece you are translating wrongly indicates that this is a stroomrug - the river bed would still be enclosed in either riverbanks or in levees, especially in an area that was probably subject to flooding. Raised river beds occur where the levees increase in height and deposits on the river bed cause it to rise too.

--------------------------------------------------
Note added at 18 hrs (2009-05-05 08:50:02 GMT)
--------------------------------------------------

I think you need to use the word 'abandoned river bed ridge' in that order because the river bed is no longer a river bed hence 'abandoned' and to distinguish this from other alluvial ridges you need to indicate that it is a river bed ridge. I'm in two minds as to whether you still need to use the word raised if you use ridge - probably not. The ontology should be obvious from the rest of the sentence.



--------------------------------------------------
Note added at 20 hrs (2009-05-05 10:16:28 GMT)
--------------------------------------------------

I would not use raised river bed as that is a different topological feature - the bed of the river rises due to sedimentation on the river bed (usually in a sluggish river where the valley floor is very flat). The layers of sediment raise the level of the river bed and consequently cause the natural levees to rise as well (the Mississipi River in Louisiana is a typical example) The surrounding land is much lower than the level of the river and are constantly in danger of flooding. That was the problem with Hurricane Katrina. The river level rose above the level of the levees and caused much of the flooding in New Orleans.
This is an abandoned river bed ridge (i.e. caused by the subsidence of the surrounding peat bogs) leaving the abandoned river bed standing above the surrounding area - Imagine a river in a peat bog. If the rainfall in the area dries up then the river dries up too and the peat bog begins to shrink. That leaves the abandoned river bed standing proud above the surrounding area.



--------------------------------------------------
Note added at 20 hrs (2009-05-05 10:46:34 GMT)
--------------------------------------------------

Olly, a raised river bed is fundamentally different and implies that there is still water flowing through it. As a geography graduate I have to go with the abandoned river bed ridge.