7.1.1
Global Hydrological Cycle
The Global Hydrological Cycle
The Global Hydrological Cycle
There is a fixed amount of water on the Earth. This is called a closed system because water cannot enter or leave the Earth and its atmosphere. The three components of the cycle are stores, flows and processes.
Global stores
Global stores
- When we talk about stores we include all water stored as either water vapour, ice, saline or freshwater.
- Examples of global stores of water include:
- Oceans.
- Lakes.
- Aquifers (underground lakes).
- The cryosphere (glaciers and ice sheets).
Local stores
Local stores
- Examples of local stores of water include:
- Vegetation storage.
- Surface storage.
- Soil moisture.
- Groundwater storage.
Flows
Flows
- Flows are how water moves from one store to another:
- Infiltration.
- Throughflow.
- Percolation.
- Stem flow.
- Base flow.
- Channel flow.
- Surface runoff.
Processes
Processes
- The following processes drive the flows between the stores:
- Precipitation.
- Evaporation.
- Transpiration.
- Cryosphere (glaciers and ice sheets) exchanges.
- Runoff.
Sizes of Water Stores
Sizes of Water Stores
Water is found on earth as a gas called water vapour, as liquid water, and as solid ice. Although the amount of water in each store changes over the year, each store has a relative size.
Total global water supply
Total global water supply
- 96.5% of Earth's water is in the oceans and seas.
- 2.5% of Earth’s water is in freshwater (not salty).
- 0.9% of Earth’s water is in other saline (salty) water sources.
Freshwater
Freshwater
- Freshwater is water that is not salty.
- 68.8% of Earth's freshwater is in the cryosphere (glaciers, ice caps).
- 30% of Earth's freshwater is groundwater.
- 1.2% of Earth's fresh water is surface water.
Surface water
Surface water
- Water on the Earth's surface is split between the following places:
- 69% of Earth's surface water is in ground ice and permafrost.
- 20% of Earth's surface water is in lakes.
- 3.8% of Earth's surface water is in soil moisture.
- 3.0% of Earth's surface water is in the atmosphere.
- 2.6% of Earth's surface water is in swamps and marshes.
- 0.5% of Earth's surface water is in rivers.
- 0.26% of Earth's surface water is in the biosphere (living things).
1Tectonic Processes & Hazards
1.1Tectonic Processes & Hazards
1.2Natural Disasters
1.3Natural Disaster Case Studies
1.4Trends & Patterns
2Option 2A: Glaciated Landscapes & Change
2.1Glaciated Landscapes Over Time
2.2Periglacial Landscapes
2.3Glacial Processes
2.4Glacial Landforms
3Option 2B: Coastal Landscapes & Change
3.1Coastal Landscapes
3.2Coastal Erosion & Deposition
3.3Coastal Risks
4Globalisation
4.1Globalisation
4.2Negatives of Globalisation
4.3Global Shift
4.5Culture
4.6Measuring Development
5Option 4A: Regenerating Places
5.1Types of Economies
5.2Function of Places
5.3Regeneration
5.4Regeneration Case Studies
6Option 4B: Diverse Places
6.1Population Structure
6.2Past & Present Connections
6.3Urban & Rural Spaces
6.4Diversity
6.5Urban & Rural Case Studies
6.6Case Study - Tower Hamlets
6.7Case Study - Sturton-le-Steeple
7The Water Cycle & Water Insecurity (A2 only)
7.1Hydrological Processes Global to Local
7.2Influences on the Water Cycle
7.3Water Insecurity
8The Carbon Cycle & Energy Security (A2 only)
8.1The Carbon Cycle
8.2Energy Consumption
8.3Alternative Energy
8.4Growing Demand for Resources
9Superpowers (A2 only)
9.1Superpowers
9.2Hard & Soft Power
9.2.1Hard & Soft Power
9.2.2Emerging Powers - China Rivalry
9.2.3Emerging Powers - Chinese Sources of Power
9.2.4Emerging Powers - Brazil
9.2.5Emerging Powers - Russia
9.2.6Emerging Powers - India
9.2.7Theories of Development
9.2.8Power Case Studies: Chinese One Belt One Road
9.2.9Power Case Studies: Pakistan Nuclear Arms
9.2.10Power Case Studies: OPEC
9.3IGOs, TNCs & Alliances
10Option 8A: Health & Human Rights (A2 only)
10.1Human Development
10.2Role of Governments & IGOs
10.3Human Rights
10.4Interventions
11Option 8B: Migration & Identity (A2 only)
11.1Globalisation & Migration
11.2Consequences of Migration
11.3Nation States
11.4Responses to Global Migration
Jump to other topics
1Tectonic Processes & Hazards
1.1Tectonic Processes & Hazards
1.2Natural Disasters
1.3Natural Disaster Case Studies
1.4Trends & Patterns
2Option 2A: Glaciated Landscapes & Change
2.1Glaciated Landscapes Over Time
2.2Periglacial Landscapes
2.3Glacial Processes
2.4Glacial Landforms
3Option 2B: Coastal Landscapes & Change
3.1Coastal Landscapes
3.2Coastal Erosion & Deposition
3.3Coastal Risks
4Globalisation
4.1Globalisation
4.2Negatives of Globalisation
4.3Global Shift
4.5Culture
4.6Measuring Development
5Option 4A: Regenerating Places
5.1Types of Economies
5.2Function of Places
5.3Regeneration
5.4Regeneration Case Studies
6Option 4B: Diverse Places
6.1Population Structure
6.2Past & Present Connections
6.3Urban & Rural Spaces
6.4Diversity
6.5Urban & Rural Case Studies
6.6Case Study - Tower Hamlets
6.7Case Study - Sturton-le-Steeple
7The Water Cycle & Water Insecurity (A2 only)
7.1Hydrological Processes Global to Local
7.2Influences on the Water Cycle
7.3Water Insecurity
8The Carbon Cycle & Energy Security (A2 only)
8.1The Carbon Cycle
8.2Energy Consumption
8.3Alternative Energy
8.4Growing Demand for Resources
9Superpowers (A2 only)
9.1Superpowers
9.2Hard & Soft Power
9.2.1Hard & Soft Power
9.2.2Emerging Powers - China Rivalry
9.2.3Emerging Powers - Chinese Sources of Power
9.2.4Emerging Powers - Brazil
9.2.5Emerging Powers - Russia
9.2.6Emerging Powers - India
9.2.7Theories of Development
9.2.8Power Case Studies: Chinese One Belt One Road
9.2.9Power Case Studies: Pakistan Nuclear Arms
9.2.10Power Case Studies: OPEC
9.3IGOs, TNCs & Alliances
10Option 8A: Health & Human Rights (A2 only)
10.1Human Development
10.2Role of Governments & IGOs
10.3Human Rights
10.4Interventions
11Option 8B: Migration & Identity (A2 only)
11.1Globalisation & Migration
11.2Consequences of Migration
11.3Nation States
11.4Responses to Global Migration
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