Physical–Human Interaction: Resources, Hazards and Land Use
This domain examines how people use, modify and are affected by physical systems: resources, hazards and land use.
Core rules
- Resources are classified by renewability and by economic feasibility; a reserve is a known, economically extractable resource. Depletion and substitution are scale-dependent.
- Hazard risk is commonly modelled as Risk = (Hazard × Vulnerability) ÷ Capacity. A hazard is a potential event; a disaster is the realised impact when vulnerability exceeds capacity.
- Land use: von Thünen's model predicts concentric zones of intensity around a market, assuming uniform land, transport and rational farmers. Real patterns diverge because of relief, roads and policy.
- Carrying capacity is the population a system can support sustainably; it changes with technology, consumption and environmental degradation.
Worked example
A flood-prone district has hazard probability 0.2 per year, vulnerability index 0.6 and capacity index 0.3. Risk = (0.2 × 0.6) ÷ 0.3 = 0.4. A levee raises capacity to 0.6: risk falls to (0.2 × 0.6) ÷ 0.6 = 0.2. The calculation shows that reducing vulnerability or raising capacity cuts risk even if hazard probability is unchanged.
Traps
Do not equate a hazard with a disaster. Do not assume all renewable resources are unlimited. Do not apply von Thünen to a market economy without noting its assumptions; transport costs and perishability matter.
Key points
- Risk = (Hazard × Vulnerability) ÷ Capacity.
- A hazard is potential; a disaster is realised impact.
- Reserves are known and economically extractable resources.
- von Thünen predicts intensity rings around a market under simplifying assumptions.
- Carrying capacity changes with technology, consumption and degradation.