The Human impact

Question 1

Name 5 land use changes that can modify catchment flows and stores

Answer 1

• Deforestation
• Afforestation
• Urbanisation
• Abstraction
• Water storage

Question 2

How does deforestation modify catchment flows?

Answer 2

It reduces interception and infiltration, increasing overland flow.
This reduces lag times.

Question 3

How does deforestation modify catchment stores?

Answer 3

Can eliminate the transpiration/condensation part of the cycle. Also, areas affected can be subject to reduced groundwater stores. This can lead to desertification as soil dries up.

Question 4

How does afforestation modify catchment flows?

Answer 4

Increases interception and infiltration, reducing overland flow. This increases lag times.
Also, through flow will increase due to the soil being more porous.

Question 5

How does afforestation modify catchment stores?

Answer 5

Trees encourage greater levels of soil moisture storage, as porosity increases.
Trees act as a store of water, which they can release through transpiration.

Question 6

How does urbanisation modify catchment flows?

Answer 6

Creates impermeable soils, reducing infiltration - increasing overland flow.
However this can lead to flooding issues

Question 7

How does urbanisation modify catchment stores?

Answer 7

Impermeable surfaces inhibit groundwater recharge as precipitation cannot infiltrate.
As a result, dams are required to supply sufficient water for the populace

Question 8

How can the issues caused by urbanisation be solved?

Answer 8

• Channels can be altered, diverting floodwaters away from settlements
• Banks are reinforced to ensure lateral erosion doesn’t cause damage to buildings or infrastructure
• Channel may be widened or deepened to increase water carrying capacity

Question 9

What is abstraction?

Answer 9

The process of taking water from a ground source, usually for irrigation or to produce drinking water.

Question 10

How does abstraction alter river flows/stores

Answer 10

If the water table is close to the surface, evaporation of water leaves salts behind - forming an impermeable curst.

Question 11

What are two processes that can convey water back underground?

Answer 11

• Artificial recharge (replenish water in aquifers)
• Aquifer storage and recovery (store water which is later recovered)