Resource booklet: The Colorado River basin (written for this paper; data approximate)
Figure 1: The Colorado River supplies water to about 40 million people in seven US states and Mexico, and irrigates around 2 million hectares of farmland. About 70–80% of the water used goes to agriculture.
Figure 2: Water allocations under the 1922 Colorado River Compact were based on unusually wet years. Average flow in the 20th century was around 18 billion m³ per year; since 2000 it has averaged closer to 15 billion m³.
Figure 3: Lake Mead, the largest reservoir, fell to about 27% of capacity in 2022. Federal shortage declarations led to cuts for Arizona and Nevada.
Figure 4: Stakeholder views:
• A farmer in Imperial Valley: 'We hold the oldest rights. Our alfalfa feeds cattle across the country.'
• A Las Vegas water manager: 'We've cut our use per person by nearly half since 2002 with turf removal and recycling.'
• A Native American tribal leader: 'Many of our homes still lack running water, though our rights are among the most senior in the basin.'
• A Mexican environmental scientist: 'The river rarely reaches the sea. The delta wetlands have nearly disappeared.'
Figure 5: Climate projections suggest a further 10–30% decline in flow by 2050 due to higher temperatures increasing evaporation and reducing snowpack.
Resource booklet: The Colorado River basin (written for this paper; data approximate)
Figure 1: The Colorado River supplies water to about 40 million people in seven US states and Mexico, and irrigates around 2 million hectares of farmland. About 70–80% of the water used goes to agriculture.
Figure 2: Water allocations under the 1922 Colorado River Compact were based on unusually wet years. Average flow in the 20th century was around 18 billion m³ per year; since 2000 it has averaged closer to 15 billion m³.
Figure 3: Lake Mead, the largest reservoir, fell to about 27% of capacity in 2022. Federal shortage declarations led to cuts for Arizona and Nevada.
Figure 4: Stakeholder views:
• A farmer in Imperial Valley: 'We hold the oldest rights. Our alfalfa feeds cattle across the country.'
• A Las Vegas water manager: 'We've cut our use per person by nearly half since 2002 with turf removal and recycling.'
• A Native American tribal leader: 'Many of our homes still lack running water, though our rights are among the most senior in the basin.'
• A Mexican environmental scientist: 'The river rarely reaches the sea. The delta wetlands have nearly disappeared.'
Figure 5: Climate projections suggest a further 10–30% decline in flow by 2050 due to higher temperatures increasing evaporation and reducing snowpack.
1(a)3 marks
Using Figure 2, calculate the percentage fall in average flow since 2000 compared with the 20th-century average.
1(b)6 marks
Explain how rising temperatures reduce flow in the Colorado River.
1(c)9 marks
Using Figure 4, analyse the conflicting views of stakeholders about water in the Colorado basin.
2(a)4 marks
Explain why the 1922 Compact contributes to water insecurity today.
2(b)8 marks
Examine the strategies used by cities such as Las Vegas to reduce water use.
2(c)16 marks
Evaluate the view that climate change will be the biggest threat to water security in the Colorado basin by 2050.
324 marks
Using the resource booklet and your own knowledge, evaluate the options for managing water in the Colorado basin and recommend the most sustainable approach.
Finished?
Answer every question to finish (7 left), or finish when the time’s up.
Score 0 / 70 · 0 of 7 marked
This paper is written by Plasmo in the style of the Edexcel A-Level Geography exam. It is not a past paper and is not produced or endorsed by the exam board.