The Drainage Basin (Edexcel IGCSE Geography)

The Drainage Basin

• A drainage basin is an open system

• Every drainage basin is unique and is different in shape and size, with different rock types, relief and land use

Drainage basin features

• All drainage basins have some features in common:

  • Watershed

  • Source

  • Confluence

  • Tributary

  • Mouth

Channel network

• Every drainage basin is covered by a network of tributaries which connect to the main river channel. The number of tributaries in a drainage basin is referred to as the drainage density:

  • Drainage basins with lots of tributaries have a high drainage density

  • Drainage basins with few tributaries have a low drainage density

• The drainage density is the result of the soil and rock under the surface

• Where the rock or soil is impermeable this leads to high drainage density because the water cannot infiltrate

  • This means it flows over the surface in tributaries

• Where the rock or soil is permeable water can infiltrate leading to low drainage density