Drainage basin + processes

Drainage basin

   - An open system draining water from Earth's surface.

   - Unique in shape, size, rock type, relief, and land use.

List five features of a drainage basin.

Watershed, source, confluence, tributary, mouth.

What are the four processes of river erosion?

• Hydraulic action - The force of the water, which removes material from the bed and banks of the river

• abrasion - When the materials carried by the river scrape away the banks and bed

• attrition - When the material being carried by the river hits each other, the pieces become rounder and smaller

• corrosion (solution) - When rocks are dissolved in slightly acidic water

Vertical and lateral erosion

• Vertical erosion: Increases depth (upper course).

• Lateral erosion: Increases width (middle/lower course).

What are the four processes of transportation?

- Traction: Rolling large materials.

   - Saltation: Bouncing smaller materials.

   - Suspension: Carrying lighter materials in flow.

   - Solution: Dissolving materials in water.

What causes deposition in rivers?

    - Reduced discharge (low rainfall or upstream abstraction).

    - Decreased gradient, slower flow, river entering sea/ocean.