The Drainage Basin & the Water Cycle
Geography: Cambridge International GCSE (2027 Exams), topic 1.5.1
Rivers are Part of the Water Cycle
Rivers have an important part to play in transporting water over land in the water cycle.
Precipitation
- Precipitation falls from the sky as rain, snow, sleet or hail.
- Some rain falls on plants and trees and is absorbed by them - this is called interception.
Water on the ground
- Some rain falls onto the ground and flows to the river over the surface. This is called overland flow or surface runoff.
- Some water will soak into the soil. This process is called infiltration.
- Some water will flow through the soil, which we call through flow. It reaches the river.
- Water may soak into the bedrock by a process called percolation.
Groundwater
- Water may flow towards the river through the bedrock. This is called groundwater flow.
- Groundwater is water that fills the pores of bedrock.
- The bedrock will have spaces in it between grains which we call pores (like pores in your skin).
- Where the pores are saturated in the bedrock there is no space for air.
- The line that separates saturated bedrock from unsaturated bedrock is called the water table.
Evaporation
- Water may be evaporated back into the atmosphere if it is heated.
- Water can also be evaporated from trees and vegetation which we call transpiration.
Test yourself on The Drainage Basin & the Water Cycle
What is the line that separates saturated bedrock from unsaturated bedrock called?