Key Idea: Topic 4.2 explains why freshwater is unevenly distributed, how humans use it (by sector), what causes water scarcity and threatens water security, and how societies respond through management, cooperation, or conflict.
💧 Why freshwater feels scarce
Physical scarcity = not enough water exists. Economic scarcity = water exists but people can’t access/afford it.
🏭 Water use by sector (must memorise)
🛡️ Water security & water scarcity
🧰 Management strategies (supply + demand)
Increase supply: Dams/reservoirs (storage, but ecological/social costs). Desalination (reliable, but expensive + energy-intensive). Groundwater extraction (short-term gain, depletion/subsidence risk). Water transfer schemes (costly, environmental impacts). Rainwater harvesting (local, low-tech).
Reduce demand: Drip irrigation (big efficiency gains). Leak reduction (huge losses in old networks). Water-efficient devices. Greywater recycling. Pricing + education.
High marks: give a mix of supply + demand, and add one drawback per strategy (cost, energy, ecosystems, equity).
⚔️ Conflict vs cooperation
1) Define water security. 2) Physical vs economic scarcity. 3) Sector split (70/20/10). 4) Two supply + two demand strategies with one drawback each.