- Urban hierarchy
Urban hierarchy a term that relates the structure of
town s within an area. It can typically be illustrated by dividing towns into four categories:
* 1st Order Towns
* 2nd Order Towns
* 3rd Order Towns
* 4th Order Towns1st Order Towns provide the bare minimum of essential services, such as bread and milk. The services which 1st Order Towns provide require only a very low
threshold population to survive, which make them suited to small communities. Services which require more customers to remain viable are not found in 1st Order Towns.3rd and 4th Order Towns are larger cities and communities. They are home to services which people are willing to travel longer distances to get to, as they are more important or rarer. The services in 3rd and 4th Order Towns require large threshold populations to survive, which is why they are only found in more developed areas.
It is clear, therefore, that there should be more 1st Order Towns than 4th Order Towns, as 1st Order Towns only require a small number of people in their
hinterland to remain viable.German
geographer Walter Christaller proposed the concept of the K-Ratio to describe the number of towns in one order in relation to the next. While Christaller's model is rarely found, it still provides a useful rule for the establishment of towns.If a country had a K-Ratio of 3, for example, this would mean that there would be 3 times as many towns in the order beneath the current one. For example, if a country had the following number of towns in the relevant orders:
* 1st Order Towns = 27
* 2nd Order Towns = 9
* 3rd Order Towns = 3
* 4th Order Towns = 1The country or area would be said to have a K-Ratio of 3, as a large, 4th Order Town had three 3rd Order towns within its hinterland, nine 2nd Order Towns and twenty-seven 1st Order Towns.
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