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Mixing of fluid streams in rivers

  1. Jan 27, 2013 #1
    Walking round a local amenity area today brought this photo of a side stream cut off by the local river in spate flowing past from left to right in the picture.

    The river water is reddy brown and the side stream grey-green.
    The two waters are not mixing as can be seen by the well defined boundary.

    Attached Files:

  2. jcsd
  3. Jan 28, 2013 #2
    This happens at many confluences, the most recent I've personally seen is at the confluence of the Monongahela and Allegheny rivers in Pittsburgh, PA. It's pretty neat to see.
  4. Jan 28, 2013 #3


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    What would you have expected it to look like?

    The grey green needs to somehow transition to the reddish brown?

    Maybe I don't get your question.
  5. Jan 28, 2013 #4
    Obviously not since I didn't have one.

    I just thought that some might be interested.

    I can certainly see some features of hydraulics theory in play can you?

    The most obvious is that the side stream flow has essentially ceased.
  6. Jan 28, 2013 #5


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    Ah! Ok. My bad. Sorry.

    No I don't think that's true. I think it is still flowing. The interface makes you think it isn't.
  7. Jan 28, 2013 #6
    It is difficult to impossible to show true (as opposed to arty) movement in a still photo.

    I can assure you that the water in the side stream was essentially still. Normally its level would not be that high and it would run out quite quickly into the river.
  8. Jan 28, 2013 #7


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    The main stream was flowing very fast?
  9. Jan 28, 2013 #8
    That's what I said. The nearby river gauging station was running above the weir.

    Perhaps this English term is new to you?

    Here are some typical flood pictures from November.

    Last edited by a moderator: Sep 25, 2014
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