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Author Topic: Why Do Rivers Bend ?  (Read 8606 times)

Offline neilep

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Why Do Rivers Bend ?
« on: 14/06/2008 21:11:30 »
Dear River Dwellers and Riverologists,

Rivers are great aren't they ?...They truly are my all time favourite natural streams of flowing water !

Look...here's one !



Being delivered Tuesday !

Notice something else though ?...it's got a bend in it !..in fact most rivers (as far as I know ) have bends in them !

Why's that then ?...Why do rivers have bends ?.....surely bends should be extraneous to a rivers locomotion !

*le sigh*...Saturday night and I don't know the answer !.....so wish I knew !!...hmmpth !!...you're probably all out clubbin....chillin....dancing....groovin !!....but I know ewe envy me stuck here with my brats kids whilst wifey is out !! >:(

Thanking ewe

Hugs and shmishes


Neil
Bent River Enquirer !!  (hmmmmm....lol)

xxxxxxxxxxxxxxxxxx





 

Offline Karen W.

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Why Do Rivers Bend ?
« Reply #1 on: 14/06/2008 21:50:44 »
I would think the geography of the land would have something to do with it. Perhaps rain and wind weather etc, may have over time allowed changes in the surface of the earth and eroded enough that those changes eventually are enough to form the bends as it may have been the path of least resistance.. eh???
« Last Edit: 15/06/2008 00:57:10 by Karen W. »
 

Offline jysk

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Why Do Rivers Bend ?
« Reply #2 on: 14/06/2008 23:40:20 »
Fast moving water carries sediment in suspension and when we slow that moving water, the sediment drops out of suspension.

So, I think mechanism of stream building goes something like this;

Water speeding around the stream's outer bank causes erosion, exaggerating the bend. (Liberating and carrying away sediment). Simultaneously, water creeping around the inner bank slows down, deposits new material(Building a bar), and exaggerates the bend further. As more material gets deposited on the inner bar, more of the stream's volume gets forced to the outside. As the channel narrows, the water speeds up, and the outside bend suffers even more. 

Geographic and geologic factors aside, wherever the flow of water slows enough to drop it's load out of suspension, would be the start of a stream's change in direction.

Mike
 

Offline jysk

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Why Do Rivers Bend ?
« Reply #3 on: 14/06/2008 23:51:23 »
Oh, one more thing that I think is kind of neat;

Doubling the speed of water, increases it's ability to carry sediment 6 times!

Mike
 

Offline Karen W.

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Why Do Rivers Bend ?
« Reply #4 on: 15/06/2008 00:55:51 »
That is a cool explanation.. well done!
 

Offline JimBob

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Why Do Rivers Bend ?
« Reply #5 on: 15/06/2008 04:32:07 »
water does not naturally flow in a straight line. Ideal water flow is known as laminar flow and is quite rare. It is an ideal engineers strive to achieve in some circumstances but rarely achieve.

The norm, turbulent flow, is characterized by eddies in the water flow. These eddies cause small variations of faster and slower flow in different parts of a stream. So the faster water causes faster erosion. these faster eroding parts of flow become the outer part of streams and the slower become the inside of the bends in a stream.

Tis is a gross over-simplification. But succinctly put - streams bend because water doesn't flow in a straight line.
 

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Why Do Rivers Bend ?
« Reply #5 on: 15/06/2008 04:32:07 »

 

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