You are walking by a stream, and you notice that a leaf had fallen on the surface of it. As the leaf floats down the stream, you notice that the velocity of the leaf as it flows down the river changes (see figure below), and you deduce that the velocity of the stream at the three points, I, II, III, in the stream shown. What can you deduce about the depth----of the stream at these three points? The level of the water in the stream is the same at all three points, and the length of the velocity vector in the figure gives the speed of the river at each point