Christaller’S Central Place Theory
- 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
- 11. The model is COMPLETELY UNREALISTIC In today’s world
- 12. 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 NEVER FIT REALITY INTO THE MODEL, FIT THE MODEL INTO REALITY