Looking at the sides of the channel you can see that they get lower towards the "top". I can see how the channel is flat on the floor and that the supporting ve

Looking at the sides of the channel you can see that they get lower towards the "top". I can see how the channel is flat on the floor and that the supporting vertical struts are simply cut to the correct height for the camera's perspective. I'm at a complete loss as to how the water drops onto the wheel though.