Over the long profile of the river, it is steeper near the source, where there is a lot more material for the river to cut through to reach its base level. As you go further down the river it has cut further down towards base level and is beginning to cut laterally (sideways) as well. The slope angle of the river decreases. By the time you reach the lower stages of the river it almost flows over a flat surface, as it meanders its way towards the sea.
The cross profile of the river channel changes throughout the course of the river. In the upper section the channel tends to be quite narrow, and comparatively deep. The bottom and sides are littered with many boulders and rocks, causing a great deal of friction for the water flowing past them. This slows the water down and means that this is where the river is flowing the slowest.
In the mid course of the river has a wider channel, which is deeper than the one in the upper reaches, and the water flows faster, as it has less material to slow it down. The river may begin to meander in this section.
The lower course sees the river flowing at its fastest until it slows down when it meets the sea. The channel is very wide, deep in places where the water is flowing quickest, and smooth sided.
|Upper Course||Mid Course||Lower Course|
|Long Profile||Steeply sloping towards the lower sections of the river.||Shallow slopes towards the mouth of the river.||Almost at sea level, very gently sloping towards its mouth.|
|Cross Profile||Steep sided v-shaped valley. Thin river channel, deep in places.||V-shaped valley remains with a wider valley floor and the river begins to meander across it. The river channel begins to widen and become deeper.||Wide, shallow valley, with large flood plains and meanders. The river channel is wide, deep and smooth sided.|