Turbulent flow on the Wiza

 

Here's the Wiza last month on the factory corner on Station Road. The water is about to take a 90 degree turn to the right of picture. There was a prominent line of foam coming down which was gently rotating as shown. A will be slow moving water and B faster. This produces shear forces and then reflection from the bank at the turn must be adding to the rotation. I'm guessing that the rotation mixes air in to produce the foam.