The channel on the image shows a meandering river. This basically means that the river managed to erode the banks and it has taken a snake-like shape, better known as meander. A river that exhibits such a thing is a mature river. This can be supported by the fact that the river needs long time to be able to erode the surrounding area, especially when it comes to flatter land. A young river will be mostly straight and will have its flow determined by the landscape around it, but a mature river has had the time to make its own path, to erode parts o the landscape, and take a certain shape, in this case a meander.
