Urbanisation

• 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
  • Function
  • 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 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
  1. A decrease in population
  2. Change in tastes
  3. Introduction of substitutes

  Conclusions That Can be Made About Central Places

  1. The larger the settlements, the fewer their number
  2. The larger a settlement, the farther away a similar size settlement is
  3. The Range increases as the population increases
  4. 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's CPT

• 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.

  Urban Morphology

• 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

  1. Proximity to a secondary shopping center.
  2. Local Site Characteristics
  3. Government Policy
  4. Security

  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:
  1. Low Income: 1st generation immigrants and poorer groups.
  2. Middle Income: 2nd generation immigrants, and wealthier groups.
  3. 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