The Hydrological Cycle

Question 1

Explain an overview of Drainage Basins.

Answer 1

Water doesn’t come into or leave planet Earth - it’s continuously cycled between the oceans and the atmosphere, returning to the ocean when it falls as rain (or other forms of precipitation e.g. snow). This is known as the global hydrological cycle. The global hydrological cycle is a closed system - there are no inputs or outputs.

There are also local hydrological cycles e.g. drainage basin hydrogloical cycles:

1. A river’s drainage basin is the area surrounding the river where the rain falling on the land flows into that river. This area is also called the river’s catchment.
2. The boundary of a drainage basin is the watershed - any precipitation falling beyond the watershed enters a different drainage basin.
3. Drainage basins are open systems with inputs and outputs.
4. Water comes into the system as precipitation and leaves via evaporation, transpiration and river discharge.