Drainage Basin (Cambridge International IGCSE Geography)

The Drainage Basin Process

Spec point — 2.2.2

The Drainage Basin Processes

Drainage basin

• A major part of the hydrological system, drainage basins drain all the water which lands on the Earth's surface
• 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

    • This is the boundary between drainage basins

  • Source

    • The furthest point from the mouth where the river starts can be an upland lake, spring or glacier

  • Confluence

    • The place where two or more streams/rivers meet

  • Tributary

    • A stream or river flowing into a larger stream or river

  • Mouth

    • Where the rivers enter the sea/ocean or sometimes a lake

Drainage Basin Features

Channel network

• Every drainage basin is covered by a network of tributaries that 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

Worked Example Study Fig. 1, which shows information about flows through the drainage basin

(i) What is meant by transpiration?

[1 mark]

Final answer: Answer

• The changing of water to water vapour by plants/evaporation of water by plants/trees/vegetation [1]

(ii) Identify the processes that take place at X , Y and Z in Fig 1.

[3 marks]

Final answer: Answer

• X = Overland flow/surface runoff [1]
• Y = Through flow [1]
• Z = Ground (water) flow [1]