Christaller’S Central Place Theory

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  1. Christaller’s Central Place Theory & Reilly’s Law of Retail Gravitation Valentina Kasperova IB Geography HL Unit: Settlements
  2. Key Terms To Understand
    • Central Place – A settlement, i.e. hamlet, village or market town
    • Range – Maximum distance people are prepared to travel for a good or service
    • Threshold – Minimum # of people required for a good or service to stay alive
    • Low Order Goods – necessities (bread)
    • High Order Goods – luxuries (computer)
    • Sphere of Influence – Area served and affected by a settlement
  3. Key Assumptions
    • Isotropic Island – area with no variation in relief or climate – flat
    • Rational Behavior – assumption that people minimize distance they travel to obtain a good or service
    • Even Distribution – population and resources
    • All consumers have similar purchasing power
    • Transportation costs are equal in all directions and proportional to distance
  4. Arrangement of Central Places
    • Because transport is equally reachable from all distances, market areas are CIRCULAR (Graph C)
    • HOWEVER – Circular shape results in un-served or other served market areas (grey areas)
    • So, Christaller suggested a HEXAGON shape (Graph D)
    • What this suggests :
    • - within a given area, there will be fewer high order settlements (towns) in relation to lower order settlements
    • - theoretically, settlements are equidistant from each other, higher order settlements further away from each other
  5. Key Principle Threshold & Range Applied
    • In theory – low order goods have a low range and low threshold – less people needed to support it, smaller the distance people are willing to travel
    • Low range and low threshold goods are sold in SMALL TOWNS, VILLAGES etc.
    • Higher ranges and higher thresholds are sold in LARGE TOWNS
    • Same true for services – small town likely to have only general doctor, city a hospital ect.
  6. Intro – Gravitational Models
    • Based on Newton’s law of gravity
    • As size of one town increases, so does the movement between them
    • However, further apart towns are, the less movement ? distance decay
    • Models can be used to predict:
      • Traffic flows
      • Migration between 2 areas
    • For our purposes, the concept of breaking points is essential – customer preferences caused by distance
  7. Breaking Points Reilly’s Gravitation Model Applied
    • Gravitational models say: along a route between Point A and Point B there will be a breaking point
    • People on left side of the breaking point would shop in Town A, while people on right side of it would shop in Town B
    • Operates on assumption that larger towns attract more people ? logical behavior
    • See attachment for applied examples
    Explanation of Equation M ab = Distance of breaking point from Town B D ab = Distance between Town A & B P a = Population of Town A P b = Population of Town B
  8. Limitations to Gravity Models
    • Limitations regarding these two assumptions
      • Larger the town, the stronger the attraction
      • People purchase in a logical way
    • Problem is that assumptions do not always have to be true
    • Examples:
      • Traffic jam on way to larger town, difficult and expensive parking
      • Smaller town might have fewer but higher quality shops
      • Smaller center might be more comfortable: cleaner, modern, safer
      • Some people might have to depend on public transport ? difficult
    • Basis is assumptions are UNREALISTIC – people aren’t predictable
  9. A Little Visual… Important Note: The borders basically are the breaking points between the settlements
  10. Limitations to CPT
    • Large areas of flat land rarely exist (i.e. Netherlands) ? transport is “uneven”
    • More types of transport – costs cannot be proportional to distance
    • People and wealth are not evenly distributed
    • People do not always go to the nearest place
    • Purchasing power of people differs
    • Perfect competition is unreal – some make more than others
    • Shopping habits have changed – People travel larger distances to buy lower order goods (i.e. hypermarkets)
    • Theory sees central place as having a particular function ? in reality, places have several which change over time
    • The model is
    • In today’s world
  11. So Why Do We Have/Use It ... ?
    • Theory has helped geographers and planners to locate new services and plan settlements (i.e. Tesco)
    • Valuable information can come from analysis of the model’s results vs. reality ? explaining the difference