A watershed has an orderly flow pattern. The pattern is dendritic
or branching, as it flows from the headwaters to a larger body of water.
When one stream flows into a larger stream or river they are called tributaries.
The smallest channels in a watershed with no tributaries are called
first order streams. A second order stream is when two first order
streams join. If you look at the stream order diagram, you can see the
creation of a fifth order stream channel. Fifth to sixth order streams
are usually larger rivers, while first and second order are often small,
steep, or intermittent.