The Characteristics & Processes of Rivers
Water on Earth
- Only 2.5% of the water on Earth is freshwater
- 68.7% of freshwater is stored in glaciers and ice sheets and 30% is groundwater
- The remaining 1.3% of freshwater is in rivers, soil moisture, lakes and the atmosphere
- All water is part of the hydrological cycle
Sources of Water
Hydrological cycle
- The hydrological cycle is a closed system
- Water is constantly recycled through the system
- Within the hydrological cycle, there are stores and transfers (flows)
The Hydrological Cycle
- Stores are those places where water is held for a period of time. These include:
- Water in the atmosphere in the form of water vapour or water droplets in clouds
- Surface stores such as puddles, lakes, rivers and reservoirs
- Interception is how precipitation is prevented from reaching the ground, usually by being caught on leaves or branches
- Aquifers are permeable rocks such as limestone and sandstone which can hold water
- Ice and snow
- Seas and oceans
- Flows are the ways in which water is moved around the hydrological cycle. They include:
-
- Evaporation
- Condensation
- Transpiration
- Evapotranspiration
- Precipitation
- Overland flow
- Infiltration
- Percolation
- Through flow
- Groundwater flow
-
Exam Tip
Remember that percolation and infiltration are not the same. Percolation happens after the water has infiltrated the soil.
Worked example
Which of the following statements are correct?
Tick two statements in the table below:
[2]
| Tick | |
| Overland flow occurs under the surface of the land | |
| Water percolates from the surface into the soil | |
| Groundwater flow moves water through the rocks | |
| Water flows to the river on the surface by through flow | |
| Interception occurs when water vapour is evaporated | |
| Infiltration occurs when water soaks into the soil |
- Answer:
- Ground water flow moves water through the rocks [1]
- Infiltration occurs when soil soaks into the soil [1]
