Factors affecting change in the water cycle

Question 1

Natural (physical) factors

Answer 1

• Extreme weather events e.g drought
• Seasonal changes

Question 2

Drought

Answer 2

California drought (2012-16)
* Rivers and lakes dried up, agricultural activity declined
* Vegetation dies or is destroyed, affects water cycle processes e.g transpiration
* Reduction of water stores in rivers and lakes
* Groundwater flow is important as its long term and not affected by short term extreme weather
* Soil dry out and store is reduced, throughflow ceases

Question 3

Seasonal changes in Summer

Answer 3

• Little rainfall but storms are more frequent
• Vegetation grows rapidly, increased interception + transpiration
• High temperatures encourage rapid evaporation
• Dry soils encourage infiltration but also encourage overland flow
• Low channel flow conditions

Question 4

Seasonal changes in Winter

Answer 4

• Greater quantities of rainfall
• Vegetation dies reducing interception and transpiration
• Lower temperatures reduce evaporation rates
• Soils become saturated, leading to overland flow
• High channel flow conditions

Question 5

Human activity

Answer 5

• Land use change (deforestation and urbanisation)
• Farming Prcatices
• Water abstraction
• Irrigation

Question 6

Deforestation

Answer 6

The removal of trees for human resources or land use
* Leads to increased surface runoff and soil erosion
* Reduces interception stores
* Reduces soil water stores
* Reduces evapotranspiration

Question 7

Urbanisation

Answer 7

Replacing vegetated ground with impermeable concrete or tarmac
* Reduces infiltration, increasing overland flow
* Increases flood risk
* Soil water and groundwater stores are reduced
* Reduces evapotranspiration

Question 8

Farming practices

Answer 8

Farmers are able to control the local water cycle through irrigation and land drainage
* Soils covered with plants have higher infiltration and soil water rates, reducing surface runoff
* Ploughing breaks surface increasing infiltration
* Pastoral farming compacts soil, reducing infiltration and increasing runoff
* Arable farming can increase increase interception and evapotranspiration

Question 9

Water abstraction

Answer 9

Water is removed from rivers or groundwater aquifers for human use
* Reduces volume of water in surface stores
* Leads to aquifer depletion
* Increases dry seasons and can lead to drought
* Low flow conditions

Question 10

Irrigation

Answer 10

Agricultural technique that brings water to land in places with inconsistent rainfall
* There are 3 types: spray, flood/furrow and drip
* Waste water is contaminated with pesticides that return to river
* Removes water from channel decresing flow