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Author Topic: Which way direction do (most) rivers flow?  (Read 69363 times)

dalya

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Which way direction do (most) rivers flow?
« on: 01/06/2004 13:45:54 »
So, which way direction do (most) rivers flow in -north-to-south or south-to-north?  And does it differ if you are north or south of the equator?  What are the major forces that determine the direction of water flow?

Incidentally, I would like to point out that since these questions have been asked to settle a very heated dispute, only answers that support my argument will be accepted as valid.  

Thanks for anyone who can help.
« Last Edit: 04/07/2004 07:55:51 by Exodus »

qpan

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Re: Which way direction do (most) rivers flow?
« Reply #1 on: 01/06/2004 18:23:39 »
lol- surely the direction of flow is hardly dependant on north or south at all? Although the earth does bulge around the equator, river flow will very much depend on the geography of the area, which is not really correlated to north, south, west or east at all!

"I have great faith in fools; self-confidence my friends call it."
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« Last Edit: 01/06/2004 18:24:05 by qpan »

Dan B

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Re: Which way direction do (most) rivers flow?
« Reply #2 on: 01/06/2004 20:09:32 »
The water (as with everything else) will try to find a minima in its potential enegy....

Roughly translated: DOWNHILL!!!!! and GRAVITY!!!!

« Last Edit: 01/06/2004 20:10:35 by Dan B »

dalya

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Re: Which way direction do (most) rivers flow?
« Reply #3 on: 04/06/2004 14:00:56 »
Yes but let's just say it is downhill for the first third of the river then straight for the next third and uphill for the final third, by that logic there would be no net flow at all -it would just pool in the middle third.

I thought something similar though -which is that the water flowed in a direction that minimised the pressure behind it.  That of course can be based on the geography of the exact area (hilliness and all), but more importantly it would be the amount of water.  And since there is more water at the poles, there would be a general trend to flow away from them ie southwards in the northern hemisphere and northwards in the southern hemisphere.  I do realise there are some serious flaws in this suggestion,though.

My co-debater suggested that water flow was somehow determined by differece in the earth's magnetic field but I think that sounds like total nonsense.

More commentaries please.

tweener

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Re: Which way direction do (most) rivers flow?
« Reply #4 on: 04/06/2004 14:59:09 »
OK, lets analyze this.  Start with the really big rivers.

In North America, the Mississippi flows South, the Rio Grande flows Southeast, the Colorado flows Southwest, the Columbia flows West, and the Yukon and others in Canada flow pretty much North.  I don't know the relative sizes of the rivers, but on average, I would say the average is headed South based on the Mississippi.

In South America, the amazon flows East, and most rivers south of there also flow east.  The western side of the continent (from the divide) is very small, so not much water flows West.  So, the average is definitely East.

My geography is weak for the eurasian continent and australia and i don't have easy access to a map right now. - someone else help out now!

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John - The Eternal Pessimist.

gsmollin

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Re: Which way direction do (most) rivers flow?
« Reply #5 on: 04/06/2004 16:40:09 »
In the north of Europe and Asia, the rivers all flow north. One of Russia's long standing goals has been to acquire a warm-water port.

But without sifting through a lot of geography to come up with an "average" answer, I see a trend: In the northern parts of the continent, the rivers flow towards the north. In the southern parts they flow south, etc., etc. In all cases, they flow from the inland parts of the continent, towards the coast. In a word, they flow DOWNHILL.


Dan B

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Re: Which way direction do (most) rivers flow?
« Reply #6 on: 04/06/2004 19:28:14 »
hahahahahaha. Dalya, how the hell could water flow uphill without being pumped?

qpan

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Re: Which way direction do (most) rivers flow?
« Reply #7 on: 04/06/2004 21:58:32 »
Pressure differences can cause water to go uphill, but due to the nature of rivers, the pressure at the surface of the water is atmospheric as the water is exposed to the atmosphere (meaning you can't really have much of a net pressure difference over a significant length of river). Therefore, the ability of the water to climb hills is very limited, but it does happen (assuming the water has enough kinetic energy) due to the high surface tension of water. I certainly would not expect a river to go uphill for any significant stretch.

"I have great faith in fools; self-confidence my friends call it."
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qpan

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Re: Which way direction do (most) rivers flow?
« Reply #8 on: 05/06/2004 22:19:42 »
See these sites for more details:
http://web.mit.edu/jeffa/Public/web/jump.htm
http://www.lmnoeng.com/Channels/HydraulicJump.htm

"I have great faith in fools; self-confidence my friends call it."
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gsmollin

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Re: Which way direction do (most) rivers flow?
« Reply #9 on: 06/06/2004 02:38:23 »
Rivers flow upstream in tidal areas, when the tide is coming in. However, the net flow is still downstream.

dalya

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Re: Which way direction do (most) rivers flow?
« Reply #10 on: 15/06/2004 12:47:11 »
All right.  Point taken.  I was sure I learned that the general trend was for water to flow southwards in the Northern hemisphere and northwards in the southern.

Exodus

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Re: Which way direction do (most) rivers flow?
« Reply #11 on: 30/06/2004 06:58:31 »
quote:
Originally posted by Dan B

The water (as with everything else) will try to find a minima in its potential enegy....

Roughly translated: DOWNHILL!!!!! and GRAVITY!!!!





alongside this, lets not forget the importance of the geology, an easily eroded rock like a sandstone is more likely to gully than a granite for example so the river will therefore be partially responsible for its flow direction through erosion?

Jel

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Re: Which way direction do (most) rivers flow?
« Reply #12 on: 10/03/2005 22:14:15 »
There is, however, a certain circularity in the logic here: rivers flow downhill because they flow to the sea: the sea is, however, the result of the rivers flowing downhill.
Just for fun, therefore, and begging readers' pardon for totally unscientific method, with the saving grace of hoping to promote some unorthodox engineering, I refer readers to http://www.forteantimes.com/articles/178%5Fbackwards.shtml

gsmollin

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Re: Which way direction do (most) rivers flow?
« Reply #13 on: 11/03/2005 14:16:23 »
Those "gravitational anomalies" are optical illusions. There are no true gravitational anomalies large enough to make a car coast uphill. There are small ones caused by mountains, but the effects are tiny.

I don't find any circular logic, but I do find a circular water cycle.

 

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