- Urbanisation is the process by which there is an increase in the proportion of people living in urban areas.
- Some common indices used to define towns are
- Population size
- Population density
- Level of administration
- The UN has refused to classify settlements as towns/rural areas and has instead chosen to classify them by size.
The Growth of Towns and Cities
- The earliest towns were around the Mediterranean Sea. Babylon is the oldest recorded town.
- Urbanisation was a significant way of life in the Western World by 1AD
- Before the industrial revolution, most towns were small and mainly commercial centers and seaports.
- After the industrial revolution, cities grew very rapidly.
- By 1850, there were 2 "million cities"(cities with a population exceeding one million)-London and Paris.
- The growth of towns experienced a population explosion in the 1950s.
- By 1990, there were 286 "million cities."
The Rank Size Rule
- The Rank Size Rule notes the relationship between the ranks of cities and their populations.
- It was advanced by Zipf in 1941
- The formula is Pn=P1/n where Pn is the population of towns ranked n, P1 is the population of the largest town and n is the rank of the town.
For example, if the largest town has a population of x, the second largest town will have a population of x/2, the 3rd largest will have a population of x/3 and so on.
The Law of the Primate City
- The primate city is the largest most dominant city in a region.
- The degree of primacy refers to the dominance of the largest city over the rest of the country.
- Most LDCs (Less Developed Countries) have a high degree of primacy while most MDCs (More Developed Countries) have a low degree of primacy.
- Factors that affect high primacy include
- Having an underdeveloped economy
- Having an agriculturally dominant economy
- A rapidly expanding population
- A recent colonial history
The Central Place Theory (CPT)
- A Central Place is a settlement which provides one or more services for the population living around it.
- Simple basic services (e.g. grocery stores) are said to be of low order while specialized services (e.g. universities) are said to be of high order.
- Having a high order service implies there are low order services around it, but not vice versa.
- Settlements which provide low order services are said to be low order settlements.
Settlements that provide high order services are said to be high order settlements.
- The sphere of influence is the area of under influence of the Central Place.
- The minimum population size required to profitably maintain a service is the threshold population.
- Factors affecting a fall in the threshold population are
- A decrease in population
- Change in tastes
- Introduction of substitutes
Conclusions That Can be Made About Central Places
- The larger the settlements, the fewer their number
- The larger a settlement, the farther away a similar size settlement is
- The Range increases as the population increases
- The larger the settlement, the higher the order of its services. Deviations to this rule are:
- Tourist resorts that have a small population but large number of functions.
- Dormitory towns that have a large population but a small number of functions.
- Christaller made a number of assumptions such as:
All areas have
- an isotropic (all flat) surface
- an evenly distributed population
- evenly distributed resources
- similiar purchasing power of all consumers
- The theory points out that to prevent spheres of influence overlapping or having gaps, the best shape was a hexagon.
- The breaking point is where the consumer is equidistant from two/more similar services i.e. where the consumer is equally far from two or more centers.
- The formula to calculate it is djk=dij/(1+Square Root of(Pi/Pj)) where djk is the distance from j to k, dij is the distance between two towns, Pi/Pj are the populations of j and i and i is the bigger town.
- This is the distribution of different functions in a city
The Bid-rent Theory
- The Bid Rent Theory suggests different functions will bid differently for land in various parts of the city.
- It suggests the more accessible the site of land, the higher is its value.
Bid Rent Theory Diagram
Factors Influencing Land Values
- Proximity to a secondary shopping center.
- Local Site Characteristics
- Government Policy
Functional Zones Within a City
- The CBD is the central, most accessible, most expensive part of a city
- The Inner City is the area immediately surrounding the CBD. It has adverse social and economic conditions
- The Industrial Zone
- The Residential Zones. These are divided in 3 groups:
- Low Income: 1st generation immigrants and poorer groups.
- Middle Income: 2nd generation immigrants, and wealthier groups.
- High Class Residential: The wealthiest groups
The Models of Urban Structure
- There are three basic models of urban structure
The Burgess Concentric Model
- Burgess developed his model in 1924 based on a study of Chicago city
- He arranged the zones in concentric circles around the CBD as shown in the diagram.
- Land Values Decrease outward from the CBD.
Burgess Concentric Model Diagram
Hoyts Sector Model
- Homer Hoyt proposed The model in 1939
- It was based on a study of 142 American cities
- It arranges the zones in sectors radiating from the CBD
Hoyt's Sector Model Diagram
Peter Mann's Model of a Typical British City
- Peter Mann took Hoyt's and Burgess's models and combined them in his model of a typical British City in 1965.
- He based his model on studies of Sheffield, Nottingham and Huddersfield.
The Multi-Nuclei Theory
- This theory was proposed by Ullmann and Harris in 1945.
- It suggests that a city may have more than one nuclei/center apart from the CBD from which zones develop as shown in the diagram.
Multi Nuclei Theory Diagram
The Urban Field
- The Urban field is the region economically and socially linked to a city.
- It is also referred to as
- Urban Regions:The commuter villages/communities dependent on large towns
- Functional Regions:The regions to/from which a city exports and imports.
- Hinterland:The area served by a seaport