Welcome to the World of Urbanisation!
Hi there! Welcome to your study notes for Urbanisation. Cities are more than just buildings and roads; they are living, breathing systems where more than half of the world's population now lives. In this chapter, we will explore why people move to cities, how cities change over time, and the challenges we face in making them great places to live. Don't worry if some terms seem big at first—we'll break them down together step-by-step!
1. What is Urbanisation?
At its simplest, urbanisation is the increase in the proportion of people living in towns and cities compared to the countryside. It is not just about cities getting bigger; it is about a higher percentage of the total population becoming "urban."
Why does it happen?
Urbanisation is driven by two main things:
1. Rural-to-Urban Migration: People moving from the countryside (rural areas) to the city (urban areas). This is usually caused by "Push" and "Pull" factors.
2. Natural Increase: This happens when the birth rate is higher than the death rate. Because cities often have many young adults, more babies are born there!
Memory Aid: The Magnet Analogy
Think of the city as a magnet. Push factors are things that drive you away from your old home (like a lack of jobs), while Pull factors are the "magnetic" things that attract you to the city (like better healthcare or bright lights).
Key Terms to Know:
Push Factors: Negative things about the countryside (e.g., crop failure, war, lack of services).
Pull Factors: Positive things about the city (e.g., better-paid jobs, education, "bright lights" syndrome).
Urban Growth: The physical expansion of a city's area.
Quick Review: Common Mistake!
Don’t confuse urbanisation with urban growth. Urbanisation is about the percentage of people, while urban growth is about the city getting physically larger. You can have urban growth without urbanisation!
Key Takeaway: Urbanisation is a global process where a higher percentage of people live in cities, driven by migration and birth rates.
2. Changing Urban Processes
As cities develop, they go through different stages. It’s like a cycle of life for a city!
Suburbanisation
This is the outward growth of people and services toward the edges of the city. People move to the suburbs because they want more space, less pollution, and "greener" surroundings. This is made possible by better transport, like trains and cars.
Counter-urbanisation
This is when people move out of the city entirely and into smaller villages or rural areas. They might still commute to the city for work, but they live far away to enjoy a quiet life. This often happens in wealthier countries.
Urban Resurgence
Don't worry if this sounds complex! It just means "the city coming back to life." After years of people leaving, some city centers are "reborn" through regeneration. Old factories might be turned into luxury apartments or trendy shopping malls. Example: The London Docklands or the Jewelry Quarter in Birmingham.
Memory Aid: The S.U.C. Rule
Suburbanisation = Moving to the Side (edges).
Urban Resurgence = Upward trend (coming back).
Counter-urbanisation = Moving Counter (opposite) to the city.
Key Takeaway: Cities aren't static; they grow outwards (suburbs), lose people to the countryside (counter-urbanisation), and can be reborn (resurgence).
3. Megacities and World Cities
In Geography, size matters, but so does influence!
Megacities
A megacity is a city with a population of over 10 million people.
Examples: Tokyo, Mumbai, Lagos, and New York.
Most megacities are now growing in LICs (Low-Income Countries) and NEEs (Newly Emerging Economies) because of rapid rural-to-urban migration.
World Cities
A world city (or global city) isn't just about population; it’s about power. These cities are hubs for international finance, trade, and politics. They "run" the global economy.
Examples: London, New York, and Tokyo.
Did you know?
A city can be a Megacity but NOT a World City! For example, Dhaka has over 10 million people (Megacity), but it doesn't have the global financial power of London (World City).
Key Takeaway: Megacities are about quantity (people), while World Cities are about quality (influence and money).
4. Urban Climate: The "Heat Island" Effect
Have you ever noticed that it feels warmer in the middle of a city than in a park? This is the Urban Heat Island (UHI) effect.
Why are cities hotter?
1. Absorption: Concrete and tarmac absorb heat during the day and release it at night.
2. Human Activity: Cars, air conditioning, and factories all pump out heat.
3. Lack of Water: In the countryside, plants "sweat" (evapotranspiration), which cools the air. Cities have fewer plants and more drains, so the water disappears quickly.
Urban Wind and Precipitation
- Wind: Buildings can create "wind canyons" where air is forced into narrow gaps, making it very gusty.
- Rain: Cities actually get more rain than the countryside! The extra heat causes air to rise (convection), and pollution particles give water droplets something to "sit" on to form clouds.
Analogy: The Toaster Effect
Imagine the city is like a toaster. The buildings are the heating elements that stay hot long after you turn them off, and the pollution is like the crumbs that trap the heat inside.
Key Takeaway: Cities create their own "microclimate" that is generally warmer, rainier, and less humid than surrounding rural areas.
5. Urban Drainage and Waste
Cities have a big problem: they are made of impermeable surfaces (surfaces that don't let water through, like concrete).
The Problem: Flash Flooding
In a forest, rain soaks into the ground. In a city, rain hits the concrete, rushes into drains, and fills up rivers instantly. This causes hydrographs (graphs of river flow) to have a "short lag time" and high peaks.
The Solution: SUDS
SUDS stands for Sustainable Urban Drainage Systems. These are "green" ways to manage water, such as:
- Green Roofs: Growing plants on top of buildings to soak up rain.
- Permeable Paving: Gaps in the pavement to let water soak into the soil.
- Retention Ponds: Small man-made lakes to hold water during a storm.
Urban Waste Management
Cities produce mountains of trash! We manage it through:
- Landfill: Burying it (running out of space!).
- Incineration: Burning it (creates energy but also pollution).
- Recycling: Turning old things into new things.
Key Takeaway: Managing water and waste sustainably is the biggest challenge for modern city planners.
6. Sustainable Urban Development
How do we keep cities running without destroying the planet? This is Urban Sustainability.
The Three Pillars of Sustainability:
1. Social: Are people happy? Is there good housing and healthcare for everyone?
2. Economic: Are there enough jobs? Can people afford to live there?
3. Environmental: Is the air clean? Are there green spaces (parks)?
Quick Review: Features of a Sustainable City
- Public Transport: Excellent buses and trains so people don't use cars.
- Carbon Neutrality: Using solar or wind power.
- Waste Reduction: Encouraging 100% recycling.
- Affordable Housing: Ensuring teachers and nurses can afford to live near their work.
Key Takeaway: A sustainable city meets the needs of people today without making life harder for people in the future.
7. Final Tips for Success
- Use Case Studies: When answering exam questions, always mention a real city. For example, use Curitiba (Brazil) for sustainability or London for urban resurgence.
- Check the Command Word: If the question says "Evaluate," you must give both the good and the bad points.
- Don't Panic: If you forget a term, describe it! If you forget "permeable," just say "surfaces that let water through."
You've got this! Keep reviewing these notes, and you'll be an urbanisation expert in no time!