Edexcel IGCSE Geography
Management of River Environments
The big idea: water is unevenly shared across the planet — some places have too little, some have too much (flooding), and how humans manage supply, quality, and flood risk determines who suffers and who thrives.
Summary — What This Chapter Covers
Water Uses, Demand & Supply
Only 2.5% of Earth's water is freshwater. Demand is rising fast due to population, industry, farming and tourism.
Water Deficit & Surplus
Some regions (Middle East, Australia) don't have enough water; others (Canada, Amazon) have plenty. Water stress and scarcity are measurable thresholds.
Water Quality
Agriculture, industry and domestic sources all pollute rivers in different ways, with different impacts on ecosystems and humans.
Storage & Supply of Clean Water
Water is collected (dams, wells, boreholes), transferred (pipelines), sometimes desalinated, treated, then delivered — a chain that's far weaker in developing countries.
Causes of Flooding
Flooding happens when river capacity is exceeded — driven by human factors (deforestation, urbanisation) and physical factors (relief, rock type, weather) that shorten lag time.
Flood Prevention
Hard engineering (dams, levees) vs soft engineering (river restoration, wetlands) — plus case studies of river management in Spain and China.
1. Water Uses, Demand & Supply
Where is Earth's water actually stored?
Here's the thing that surprises most students: even though 71% of Earth's surface is covered in water, 97.5% of it is saline (salty) seawater — completely useless for drinking or farming without expensive treatment. That leaves just 2.5% as freshwater.
But don't get excited yet — most of that freshwater is locked away where humans can't easily reach it:
Total water on Earth (100%)
|
|-- Saline (97.5%) --- oceans, seas
|
`-- Freshwater (2.5%)
|
|-- Locked away (1.6%) --- glaciers & ice caps (68.7% of freshwater)
| groundwater (30.1% of freshwater)
|
`-- Accessible to humans (0.9%)
|-- Lakes 20.9%
|-- Ground ice/snow 6.9%
|-- Soil moisture 3.8%
|-- Atmospheric water 3.0%
|-- Swamps/marshes 2.6%
|-- Rivers 0.44%
`-- Biological water 0.26%
So the water humans can realistically use — rivers, accessible groundwater, lakes — is a tiny sliver of a tiny sliver. That scarcity is why water management matters so much.
Quick Fact to Lock In
Only about 0.9% of all freshwater (and just 0.44% of that is in rivers) is realistically accessible to humans. Everything else is frozen, underground, or salty.
Practice Question
Explain why, despite 2.5% of Earth's water being "freshwater," water scarcity is still a major global issue.
How water use differs between rich and poor countries
This is one of the most testable ideas in this topic, so let's make sure it really sticks. Globally, water use splits 69% agriculture, 19% industry, 12% domestic. But that global average hides a massive difference depending on how developed a country is:
| Sector | Developed Countries | Developing / Emerging Countries |
|---|
| Agriculture | 30% | 82% |
| Industry | 69% | 10% |