Mixing of fluid streams in rivers

Studiot

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 Thumbnails

 

Travis_King

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.

rollingstein

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.

Studiot

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.

rollingstein

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.

Studiot

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.

rollingstein

The main stream was flowing very fast?

Studiot

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.

http://www.youtube.com/watch?v=dasKGb6xev8