What is complementary region? With reference to hierarchy of settlements, describe the different types of complementary regions as proposed by Christaller.

What is a Complementary Region?

A complementary region, in the context of Central Place Theory, is the area over which a central place is able to draw its customers for a specific good or service. It’s essentially the market area of a central place. The size and shape of this region are determined by factors like transport infrastructure, the nature of the good or service (daily needs vs. luxury items), and the distance consumers are willing to travel. The theory assumes that consumers will minimize their travel distance and expense to obtain goods and services.

Hierarchy of Settlements and Christaller’s Complementary Regions

Christaller proposed a hierarchy of settlements based on the range (distance travelled) and threshold (minimum market size) of goods and services offered. He identified four levels: hamlets, villages, towns, and cities. He then linked these settlements to different types of complementary regions based on marketing principles, denoted by ‘K’ values. These K values represent the packing ratio – the number of first-order central places surrounding a higher-order central place.

K=4 – Marketing Principle of Maximum Coverage

This principle aims to maximize the market area covered by central places. The complementary regions of first-order central places (cities) are hexagonal and do not overlap. Second-order central places (towns) are located at the vertices of these hexagons, and so on. This results in four first-order central places surrounding a higher-order central place. It’s considered the most theoretically efficient but less realistic due to the complete separation of market areas.

• Characteristics: Complete market separation, efficient use of space.
• Suitable for: Goods with a large range and low frequency of purchase (e.g., automobiles).

K=6 – Marketing Principle of Maximum Market Potential

This principle seeks to maximize the total potential market served. The complementary regions partially overlap, with each first-order central place being surrounded by six second-order central places. This arrangement allows for greater accessibility for consumers, as they have more options within a reasonable distance. This is considered more realistic than K=4.

• Characteristics: Partial market overlap, increased accessibility.
• Suitable for: Goods with a moderate range and frequency of purchase (e.g., furniture).

K=7 – Marketing Principle of Minimum Travel

This principle prioritizes minimizing the average distance consumers have to travel. It involves a more complex arrangement where the complementary regions overlap significantly. Each first-order central place is surrounded by seven second-order central places. This provides the highest level of accessibility but is also the least efficient in terms of spatial coverage.

• Characteristics: High market overlap, minimum travel distance.
• Suitable for: Goods with a small range and high frequency of purchase (e.g., daily groceries).

K Value	Marketing Principle	Market Overlap	Accessibility	Efficiency	Suitable Goods
K=4	Maximum Coverage	None	Low	High	Luxury goods (cars)
K=6	Maximum Market Potential	Partial	Moderate	Moderate	Intermediate goods (furniture)
K=7	Minimum Travel	High	High	Low	Convenience goods (groceries)

It’s important to note that these are idealized models. Real-world settlement patterns are influenced by a multitude of factors, including physical geography, historical development, and political considerations, leading to deviations from the theoretical arrangements proposed by Christaller.