城市与城市土地利用的格局与过程

In 1980 China made Shenzhen, a county of farms and fishing villages next to Hong Kong, one of its first Special Economic Zones 经济特区. About 300,000 people lived there. Factories came for the low costs and the closeness to Hong Kong's port and banks; millions of workers came from the countryside for the jobs. The 2020 census counted 17.56 million people in Shenzhen. Its site had not changed; its situation, as the gate between China and the world economy, changed everything.

Urbanization 城市化 is the growth in the share of people living in cities. It began with the agricultural surplus that freed some people from farming, and accelerated with the Industrial Revolution.

• Urbanization rate rises fastest in developing countries today, driven by rural-to-urban migration.
• A suburb 郊区 is a residential area on the edge of a city; suburbanization 郊区化 and sprawl 城市蔓延 spread cities outward.
• Site 地点 (the physical features of a place) and situation 区位 (its location relative to other places) explain why a city grew where it did.

Worked example: Shanghai. Its site is flat, low land on the Huangpu River, which gave a sheltered harbour. Its situation is at the mouth of the Yangtze, China's longest river, so goods from a huge inland region pass through it to the sea. The situation explains why Shanghai became China's biggest port and trading city; the site explains the problems too, such as flooding and soft ground for tall buildings.

Some cities have influence far beyond their own country.

• World cities 世界城市 (also called global cities) — such as New York, London, and Tokyo — are command centres of the global economy, finance, and culture.
• Globalization links cities into networks; a decision in one world city can affect jobs on the other side of the planet.

Cities within a country follow patterns of size and spacing.

• The rank-size rule 位序规模法则 says the nth-largest city is 1/n the size of the largest (the 2nd city is half the largest, the 3rd a third, and so on).
• A primate city 首位城市 is far larger than all others (Paris, Bangkok), dominating its country.
• Central place theory 中心地理论 (Christaller) explains the spacing of settlements: larger centres are fewer and farther apart and offer higher-order goods; their market area is the surrounding region they serve.

Worked example: the rank-size rule. A country's largest city has 12 million people. The rule predicts the 2nd city at 12 ÷ 2 = 6 million, the 3rd at 12 ÷ 3 = 4 million and the 4th at 12 ÷ 4 = 3 million. If the real 2nd city has only 1.5 million, the largest city is eight times bigger than it, not twice: that is a primate pattern, like Thailand, where Bangkok is far bigger than any other city.

Worked example (a real AP exam question). "Compare the concept of a metacity with the concept of a world city." (2024) A full-mark answer: "A metacity is defined by size — a continuous urban area of more than 20 million people — while a world city is defined by influence, acting as a command centre for the global economy. A city such as Tokyo can be both, but a large metacity in a poorer country may not be a world city." The command word Compare needs an explicit point of difference (size versus influence), not two separate definitions sitting side by side.

Three classic models describe how North American cities are arranged inside.

• Concentric zone model 同心圆模型 (Burgess) — rings around the Central Business District (CBD) 中央商务区, from inner-city to commuter suburbs.
• Sector model 扇形模型 (Hoyt) — land use grows outward in wedges along transport routes.
• Multiple nuclei model 多核心模型 (Harris–Ullman) — the city has several centres (nodes), not just one CBD, as it grows and specialises.

Later models explain other kinds of city:

Inside the city, land use and density change from centre to edge.

• Density is highest near the CBD (tall buildings, high land prices) and falls outward — the bid-rent curve again.
• Zoning 分区规划 laws separate land uses (residential, commercial, industrial).
• Infrastructure 基础设施 — roads, water, power, transit — must grow with the city; where it lags, informal settlements 非正规住区 (slums) may form.
• Residential density has three broad types: low (detached houses with gardens, mostly in suburbs), medium (row houses and small apartment blocks) and high (tall apartment towers, usually near the centre or along transit lines).

Planners use data and design to make cities work better.

• Smart-growth 精明增长, mixed-use development, and transit-oriented design fight sprawl and car dependence.
• Greenbelts 绿带 limit outward growth; urban renewal 城市更新 rebuilds decayed areas, but can cause gentrification 中产阶级化 that displaces poorer residents.
• Census and geospatial data guide where to put schools, transit, and services.
• Quantitative data 定量数据 are numbers (census counts, rents, traffic counts); qualitative data 定性数据 are words and images (interviews with residents, photos, field notes). Planners need both: numbers show how many people a change affects, interviews show how it affects them.

Rapid urban growth brings problems:

• Social: housing shortages, segregation, and the displacement caused by gentrification.

• Environmental: air and water pollution, the urban heat island 城市热岛 effect, waste, and heavy resource use. Old factory sites with polluted ground, called brownfields 棕地, must be cleaned (remediated) before they can be reused for homes or parks.
• Economic: strained budgets, congestion, and the cost of extending infrastructure to sprawling edges.

Sustainable cities try to grow up rather than out, invest in public transit, and mix homes with jobs and services.

Free-response parts are scaffolded by their command verbs. Identify needs a term or example; describe needs its features; explain needs a because: how or why, with a real example.

Answer (a), (b) and (c).

(a) Identify ONE factor that makes a city a world (global) city.

(b) Describe the concentric zone model of urban structure.

(c) Explain ONE effect of suburbanisation on a city.

Model answer.

• (a) Headquarters of transnational corporations and major financial markets, as in London or New York.
• (b) The city forms rings around a central business district, from a zone of transition and working-class housing outward to higher-income residential zones and commuters.
• (c) As people and businesses move to the suburbs, the central city can lose tax revenue, which reduces money for services such as schools and public transport.

• Separate a city's site (physical setting) from its situation (position relative to others).
• Apply the rank-size rule (the nth city is about 1/n of the largest) and spot a primate city.
• Match a city description to the right model: concentric zone, sector, or multiple nuclei.
• Link land value to density — costly central land is used by building upward.
• Discuss change with suburbanization, sprawl, and gentrification, and smart-growth responses.