Urban environment
A city packs many people, buildings, roads and vehicles in a small area. This brings jobs and services, but also problems:
- Heat: concrete and tar hold heat, so cities are warmer than nearby fields (the urban heat island).
- Air and noise: traffic and industry make smoke and sound.
- Waste and water: a lot of rubbish and waste water to manage.
- Crowding: not enough housing, parks or clean water for everyone.
Good cities add trees and parks, public transport, waste collection, safe water and sewage, and plan where buildings and roads go.
Living environment and health
Where and how we live affects our health. A healthy home has:
- Fresh air: windows or vents so smoke, damp and germs do not stay inside.
- Light: sunlight and good lamps; sunlight also dries damp and helps us feel well.
- Clean water and toilets: stop diseases like diarrhoea.
- Quiet and clean surroundings: less noise, no standing water where mosquitoes breed, safe waste disposal.
- Safe building: no loose wires, strong walls and roof.
Try it: walk through your home and mark where air, light and clean water come in. Which room is weakest?
Disaster prevention and mitigation
A hazard is a natural event such as a flood, earthquake, cyclone or landslide. A disaster happens when a hazard meets people who are not ready. So disaster = hazard + weak preparation.
- Prevention: stop or lower the harm before it happens: embankments, strong buildings, not building on floodplains.
- Mitigation: make the harm smaller: early warnings, shelters, first aid, emergency kits.
- Preparedness: drills, evacuation routes, knowing who to call.
- Response and recovery: rescue, relief and rebuilding better.
Many countries have disaster agencies and give simple rules, for example: drop, cover and hold on in an earthquake; move to high ground in a flood.
Key formulas and definitions
- Disaster = natural hazard + weak preparation
- Flood happens when river level > embankment height
- Safe gap = embankment height - river level
Worked examples
1. A river is 2.2 m high and the embankment is 3 m. What is the safe gap?
3 - 2.2 = 0.8 m. It is safe, but the warning should be watched.
2. Rain pushes the river to 3.4 m with a 3 m embankment. By how much does water cross it?
3.4 - 3 = 0.4 m over the embankment. A flood warning is needed and people should move to shelter.
3. Two towns face the same earthquake. Town A has strong buildings and drills, Town B does not. Which is more likely to have a disaster?
Town B. The hazard is the same, but weak preparation makes the harm bigger.
Common mistakes
- Thinking a flood or earthquake is always a disaster. It is a hazard until people are harmed.
- Mixing prevention and mitigation. Prevention stops harm; mitigation makes harm smaller.
- Closing all windows to keep a house warm or dust-free. Fresh air is needed for health.
- Believing trees only look nice. They cool, clean air and hold soil.