Central Place Theory (CPT) is an attempt to explain the spatial arrangement, size, and number of settlements. The theory was originally published in 1933 by a German geographer Walter Christaller who studied the settlement patterns in southern Germany. In the flat landscape of southern Germany Christaller noticed that towns of a certain size were roughly equidistant. By examining and defining the functions of the settlement structure and the size of the hinterland he found it possible to model the pattern of settlement locations using geometric shapes. Assumptions: Christaller made a number of assumptions such as: All areas have • • • • • •
an isotropic (all flat) surface an evenly distributed population evenly distributed resources similar purchasing power of all consumers and consumers will patronize nearest market transportation costs equal in all directions and proportional to distance no excess profits (Perfect competition)
Explanation of some terms: Central Place, low order, high order, sphere of influence 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 under influence of the Central Place. Details of the theory The theory consists of two basic concepts: •
-- the minimum population that is required to bring about the provision of certain good or services
range of good or services
-- the average maximum distance people will travel to purchase goods and services
From these two concepts the lower and upper limits of goods or services can be found. With the upper and the lower limits, it is possible to see how the central places are arranged in an imaginary area. Arrangement of the Central places/ settlements:: As transport is equally easy in all direction, each central place will have a circular market area as shown in C in the following diagram:
However, circular shape of the market areas results in either un-served areas or over-served areas. To solve this problem, Christaller suggested the hexagonal shape of the markets as shown in D in the above diagram. Within a given area there will be fewer high order cities and towns in relation to the lower order villages and hamlets. For any given order, theoretically the settlements will be equidistance from each other. The higher order settlements will be further apart than the lower order ones. The three principles in the arrangement of the central places: Christaller noted three different arrangements of central places according to the following principles: 1. The marketing principle (K=3 system); 2. The transportation principle (K=4 system); 3. The administrative principle (K=7 system). 1. The marketing principle The following diagram shows the arrangement of the central places according to the marketing principle. There are ___________ orders of central places. (note: There can be many orders of settlement.) (a) First order service center providing first order services (b) Second order service center providing second order services. (c) Third order service center providing third order services
The different orders of settlements arrange themselves in a hierarchy. Generally speaking lower is the order, larger is the number of settlements and higher the order, greater is the area served.
If the arrangement of the settlements is according to the principle k=3, the theoretical number of settlements will progressively divides the previous order by 3 as shown in the following...