Rivers and valleys
River features and land uses vary along the course of a river. Conflicts can arise between the different land uses and solutions must be adopted to minimise these disputes.
River stages
A river is often divided into three parts or stages and has features that are specific to each stage.
The table below explains the main features of each stage.
| Stage | Main activity | Main features |
|---|---|---|
| Upper course (steep gradient) | Vertical (downward) erosion | Source, tributaries, V-shaped valley, interlocking spurs, waterfalls, rapids, gorges |
| Middle course (gentle gradient) | Lateral (sideways) erosion starts, transportation | River beaches (slip-off slopes), meanders, river cliffs |
| Lower course (very low gradient) | Deposition | Floodplains, oxbow lakes, levées, delta, estuary |
River landscape
The following three diagrams show various types of river landscape.
- Source - the point at which the river starts.
- Interlocking spurs - where the river winds between ridges.
- Gorge - a deep valley caused by the wearing back of a waterfall.
- Waterfall - often occur where the river crosses a band of harder rock.
- V-shaped valley - produced in the upper course because the river cuts down faster than the surrounding slopes are eroded.
- Meander - the river starts to erode from side to side.
- River cliff - the river moves faster on the outside of the bend and cuts into the valley side. The erosion undercuts the ground causing it to collapse, leaving a cliff.
- River beach - (slip-off slope) the river moves more slowly on the inside of the bend. It cannot carry the larger pebbles and these are dropped here.
- Oxbow lake - during floods the river cuts through the neck of a large meander. The outside bend is left as a shallow lake.
- Floodplain - the river is flowing in a very wide, flat valley. When it floods, it spreads over the floodplain.
- Levée - during floods the overflowing river is slowed as it leaves its bed. Silt is deposited along the banks first. Over the years the deposits build up into high ridges.
- Estuary - the open mouth of the river, where it meets the sea.