River transportation involves three categories of load: bedload, suspended load, and dissolved load. A river obtains about 90% of its load from weathering and mass movement down river valley slopes, and 10% from erosion of its bed and banks. A river's ability to transport load depends on factors like the location and supply of material, volume of water, and amount of energy available.

1. River Transportation

2. Load The word load is used to describe the rock particles that are carried by a river. There are three categories: Bedload – large particles carried only at times when the river has much energy. Suspended load – small particles that can be carried by the water, making it look muddy. Dissolved load – minerals carried by solution that are not visible.

3. A river obtains its load from two main sources: About 90% comes from the movement of material down the slopes of the river valley by weathering and mass movement. 10% comes from the erosion of the bed and banks of the river channel.

5. River capacity – the total amount of load that a river can carry at any one time. Capacity increases as discharge increases. River competence – the maximum size or weight of material a river can transport. In times of flood, a river’s competence will increase – it will be able to carry bigger particles. Capacity and competence increase downstream, as discharge increases, and during times of flood.

6. Processes of River Transportation Traction – large boulders are rolled along the river bed. Saltation – pebbles, sand and gravel bounce along the river bed. Suspension – fine particles are carried by the water, making the river look muddy. Solution – minerals that are dissolved in the water, and therefore not visible . Animation –click here!

7. The Hjusltrom Curve

8. The Hjulstrom curve is a graph that shows the relationship between the velocity of a river and the particle sizes that may be transported. It shows the velocity needed to pick up material of a certain size (velocity needed for erosion to take place), and the settling velocity when deposition will occur.

9. Particles eroded Particles deposited Particles transported