The River Tees, located in the north-east of England, is a great example of how river landscapes change from source to mouth. From the high Pennines to the North Sea, the River Tees flows over 120 km and shows clear changes in its channel shape, valley profile, gradient, discharge, velocity, and sediment.
The upper, middle and lower course of the River Tees
In the upper course of a river, typically found in mountainous or upland areas, rivers have the lowest energy due to limited discharge. Vertical erosion dominates, deepening the river valley. Erosional processes such as hydraulic action, abrasion, and attrition are most active. Transportation mainly occurs via traction and saltation due to the large size of sediment. The valley is steep and V-shaped, with interlocking spurs.
In the middle course, the river gains more energy as discharge increases with added tributaries. Lateral erosion becomes dominant, widening the channel. Transportation mainly involves suspension and some saltation, and deposition begins to occur on the inside bends of meanders. The river valley becomes wider with a gentler slope.
In the lower course, the river is at its most powerful with high discharge and energy. The gradient is very gentle, and deposition becomes the dominant process. The channel is wide and deep, and the river carries fine, suspended sediment. The valley is broad with features like floodplains, levees, and oxbow lakes.
| Feature | Upper Course | Middle Course | Lower Course |
|---|---|---|---|
| Channel Shape | Narrow, shallow | Wider, deeper | Very wide, very deep |
| Valley Profile | Steep-sided V-shaped | Gentle U-shaped | Broad, flat floodplain |
| Gradient | Very steep | Moderate | Gentle |
| Discharge | Low | Increasing | Highest |
| Velocity | Slow | Moderate | Fast |
| Sediment Size | Large, angular | Smaller, rounded | Fine, well-rounded |
