02 - The water cycle as a system (stores)

Question 1

Is the Global Water Cycle an open or a closed system?

Answer 1

It is a closed system

Question 2

Describe the Global Water Cycle?

Answer 2

• The hydrological cycle begins with evaporation where water vapour from the ocean is lifted then cools and condenses in the atmosphere to form clouds.
• Moisture is then transported around the globe and returns to the surface as precipitation.
• When reaching the ground, some water will evaporate back into the atmosphere whilst some of the water may percolate through the surface to form groundwater.
• The balance of water that remains on the surface of the earth is called runoff and emptied into lakes, rivers and streams which carry it back to the oceans for the process to start again. This is therefore a closed system.

Question 3

What are the stores of water in the Global Hydrological System?

Answer 3

• Oceans
• Icecaps
• Groundwater
• Rivers and Lakes
• Soil Moisture
• Atmospheric Moisture

Question 4

What are the different water stores in the water cycle?

Answer 4

Oceans, atmosphere, land, groundwater, rivers, soil moisture, atmospheric moisture, and freshwater and other surface water.

Question 5

What are the 3 key concepts to understand cycling in a systems framework?

Answer 5

1. Stores - the amount of material of interest (e.g. water) held within a part of the system. 2. Fluxes - measurements of the rate of flow of material between the stores. 3. Processes - the physical mechanisms that drive the flux of material between stores.

Question 6

At what spatial scales might the water cycle change over?

Answer 6

The global water cycle can change at various spatial scales, such as at the local or regional level.

Question 7

What is the % of earth’s water and residence time of Oceans

Answer 7

Oceans

Percentage: 96.9%

Residence time: 3600 years

Question 8

What is the % of earth’s water and residence time of Icecaps

Answer 8

Icecaps:

Percentage: 1.9%

Residence time: 15000 years

Question 9

What is the % of earth’s water and residence time of Groundwater

Answer 9

Groundwater:

Percentage: 1.9%

Residence time: Up to 10,000 years

Question 10

What is the % of earth’s water and residence time of Rivers and Lakes

Answer 10

Rivers and Lakes:

Percentage: 0.01%

Residence Time: 2 weeks to 10 years

Question 11

What is the % of earth’s water and residence time of Soil Moisture?

Answer 11

Soil Moisture

Percentage: 0.01%

Residence time: 2-50 weeks

Question 12

What is the % of earth’s water and residence time of Atmospheric Moisture?

Answer 12

Atmospheric Moisture:

Percentage: 0.001%

Residence Time: 10 days

Question 13

What percentage of total water does freshwater make up?

Answer 13

2.5%