Factors Affecting Change in the Water Cycle

Question 1

What be Ines more important in periods of drought?

Answer 1

Groundwater flow because it is a long term transfer and not affected by short term weather extremes

Question 2

What is the issue with heat during times of drought?

Answer 2

Heat and dry air causes initial high rates of evapotranspiration.

However, this declines as water on the ground dries up and trees transpire less.

Question 3

How is vegetation different in the summer compared to the winter?

Answer 3

In summer, vegetation grows rapidly increasing interception and transpiration.

In winter, vegetation dies back which reduces interception and transpiration.

Question 4

How is soil water different in summer compared to winter?

Answer 4

In summer, dry soils encourage infiltration, but hard baked soil encourage overland flow.

In winter, soils may become saturated, leading to overland flow.

Question 5

How does urbanisation affect the water cycle?

Answer 5

Due to the replacement of vegetation to concrete and tarmac, water cannot infiltrate the soil, which increases overland flow and makes flooding more likely.

Soil water and groundwater stores are reduced.

Question 6

What is water abstraction?

Answer 6

The extraction of water from rivers or groundwater aquifers.

Question 7

Before deforestation, what is the water cycle like?

Answer 7

Before deforestation,

• much of the high precipitation is returned to the atmosphere by evapotranspiration
• overland flow is minimal
• most of the water that reaches the forest floor infiltrates into the soil and travels slowly to the river by throughflow, maintaining a steady flow in the river

Question 8

On a local scale, what is the water cycle like after deforestation?

Answer 8

After deforestation,

• precipitation stays the same
• evapotranspiration is lower because the replacement vegetation has smaller leaves and roots, and is less dense
• overland flow and throughflow increase because of the lack of vegetation. This leads to increased discharge and flashiness - and can cause local flooding

Question 9

If a diagram showed that after deforestation, the total precipitation remains the same amount, what does this suggest?

Answer 9

If deforestation does not cause decreased rainfall via atmospheric feedbacks, discharge will likely be significantly increased throughout the local area (as the evapotranspiration rate is lower).