pivot irrigation washington farming.jpeg
pivot irrigation washington farming.jpeg

Environmental impacts of agriculture and irrigation


Examine the environmental impact of agriculture and irrigation on water quality: salinisation, agro-chemical run-off, the pollution of groundwater and the eutrophication of lakes, rivers and wetlands

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Environmental impacts of agriculture and irrigation


Examine the environmental impact of agriculture and irrigation on water quality: salinisation, agro-chemical run-off, the pollution of groundwater and the eutrophication of lakes, rivers and wetlands

IMPACTS

  • salinisation of soils due to increased evaporation of surface water (worse in areas with a negative water balance like arid or semi-arid areas)
  • reduction of the water table as water is removed

MAIN POINTS

  • Irrigation techniques range from flood > spray > drip
  • Irrigation occurs in low to high income countries
  • 50% of all agricultural land is irrigated
  • 39% of water in the US is used for irrigation
 
 
 

salinisation

 

eutrophication

eutrophication: excessive richness of nutrients in a lake or other body of water, frequently due to run-off from the land, which causes a dense growth of plant life.

Prior to the start of the Olympic sailing competition in Qingdao in 2008, the algae had to be removed from the water surface by hand.

 
 
 

CASE STUDY: Mexico Dead Zones

 

exam practice

Explain two ways in which agriculture and/or irrigation on flood plains can affect water quality. [6 marks]

 

mark scheme

Explanations are likely to refer to two of the following – salinisation, eutrophication, the impacts of agro-chemicals, effluent run-off. In each case, award [1 mark] for the identification and up to [2 marks] for the explanation/developed exemplification.

The most likely focus for candidates will be:

Eutrophication [1 mark] occurs when fertilisers/nitrates are washed into a lake/river [1 mark]. Algae grow, and then die, leading to oxygen depletion [1 mark].