Knowledge Organiser: Water Security and Management
Key Terms
- Water security: reliable access to sufficient, safe water for health and development
- Physical scarcity: insufficient water due to climate (North Africa, Middle East)
- Economic scarcity: water exists but can't be accessed — poverty, no infrastructure
- Virtual water: water embedded in traded goods (1 kg beef = 15,000 litres)
- Over-abstraction: withdrawing faster than replenishment (Aral Sea)
- Appropriate technology: low-cost, community-managed (fog catchers, sand dams)
- Eutrophication: algal bloom from fertiliser run-off, depletes oxygen
Aral Sea (Over-Abstraction)
- Once 4th largest lake in the world
- Soviet irrigation diverted feeder rivers from 1960s
- By 2007: shrunk to 10% of original size
- 60,000 fishing jobs lost; fleet stranded on dry land
- Toxic dust storms from exposed, chemical-saturated lakebed
- World's worst water management disaster
Three Gorges Dam (China)
- Yangtze River, completed 2006; cost $25 billion
- 22.5 GW electricity — 2% of China's supply
- Major flood control — Yangtze flooding deaths reduced
- 1.2 million people displaced
- Yangtze River dolphin: functionally extinct
- Sediment trapped → delta erosion; landslide risk increased
Small-Scale Solutions
- Fog catchers (Atacama): $500 each; 1-6,000 L/day; no displacement
- Sand dams (Kenya): $3k-$15k; 300 built; 100,000+ beneficiaries
- Rainwater harvesting: roof collection into tanks; global LIC use
- All: community-run, low-cost, no ecological damage
- Limitation: cannot supply cities or large-scale agriculture
POCA Threats
- P: Pollution — run-off, sewage, industrial (2.2bn lack safe water)
- O: Over-abstraction — Aral Sea; groundwater depletion
- C: Climate change — drought, glacier retreat (1bn depend on meltwater)
- A: Access/inequality — economic scarcity, no infrastructure
Cape Town and Conservation
- Day Zero 2018 — reservoirs fell to 26%; taps nearly switched off
- Consumption cut from 200L to 50L/person/day — Day Zero avoided
- UK loses 3 billion litres/day through leaking pipes
- Drip irrigation uses 30-50% less water than flood irrigation
- Metering reduces household use by 10-15%
Common Mistakes
- Confusing physical and economic water scarcity: Physical scarcity means there is not enough water (e.g. Middle East, North Africa); economic scarcity means water exists but cannot be accessed due to poverty or lack of infrastructure — most of sub-Saharan Africa has economic scarcity
- Describing the Aral Sea without explaining the mechanism: Don't just say "the Aral Sea shrank" — explain that Soviet irrigation schemes diverted the Amu Darya and Syr Darya rivers, reducing inflow faster than evaporation could be compensated
- Evaluating large-scale solutions only positively: The Three Gorges Dam provides 22.5 GW electricity but displaced 1.2 million people, made the Yangtze dolphin extinct and traps sediment causing delta erosion — balance is essential
- Ignoring small-scale solutions in evaluation questions: Fog catchers and sand dams are low-cost and community-managed, but cannot supply cities — always compare scale and context when evaluating strategies
Memory Aid
- Use POCA to remember the four main threats to water security in any extended answer:
- P — Pollution: Agricultural run-off (nitrates, phosphates, pesticides), industrial discharge, raw sewage. 2.2 billion people lack safe water partly because of contamination.
- O — Over-abstraction: Withdrawing water faster than it replenishes. The Aral Sea is the most extreme example. Groundwater over-abstraction is happening in India, the US and the Middle East right now.
- C — Climate change: Changing rainfall patterns, glacier retreat, more intense droughts. Cape Town's Day Zero was driven partly by three consecutive drought years linked to climate change.
- A — Access/Inequality: Economic water scarcity — water exists but the infrastructure to deliver it doesn't. More people affected by this than by physical scarcity. Driven by poverty and weak governance.
- And for evaluating management strategies, remember SCALE:
- S — Size: How many people does it reach? A fog catcher serves a village; a dam serves millions.
- C — Cost: Who can afford it? Appropriate tech is accessible to LICs; mega-dams require government finance or foreign investment.
- A — Access and fairness: Who gets the benefit and who bears the cost? Three Gorges benefits distant cities while local communities were displaced.
- L — Long-term sustainability: Does it damage the environment? Can it be maintained? Sand dams last decades with minimal maintenance; large dams have irreversible ecological impacts.
- E — Environmental impact: What is the ecological cost? Fog catchers: near zero. Three Gorges: Yangtze dolphin extinct, delta eroding.