A comprehensive presentation of subchapter 6.2 Urban Trends, from the third chapter of Human Geography, AS Cambridge, Settlements.

1. ASGEOGRAPHYREVISION
SETTLEMENTS
6.3 THECHANGINGSTRUCTURE
OFURBANSETTLEMENTS

2. KEYTERMSANDDEFINITIONS
CBD (Central Business District) is the commercial and geographical
heart of a city.
Concentric zone is a region of an urban area, circular in shape,
surrounding the CBD and possibly other regions of a similar shape,
that has common land use/socio-economic characteristics.
Functional zonation is the pattern of land uses in an urban area
whereby distinctive retail, office, manufacturing and residential zones
can be recognised.
Zone in transition (twilight zone) is the area just beyond the CBD that
is characterised by a mixture of residential, industrial and commercial
land use, tending towards deterioration and blight. The poor quality
and relatively cheap cost of accommodation makes this part of the
urban area a focus for in-migrants, resulting in a rate of population
change higher than in other parts of the urban area.

4. KEYTERMSANDDEFINITIONS
Bid-rent is the decreasing accessibility from the centre of an urban
area, with corresponding declining land values, allowing (in theory) an
ordering of land uses related to rent affordability.
Sector is a section of an urban area in the shape of a wedge,
beginning at the edge of the CBD and gradually widening to the
periphery.
Urban density gradient is the rate at which population density and /
or the intensity of land use falls off with increasing distance from the
centre of the city.
Deindustrialisation is the long-term absolute decline of employment
in manufacturing.

6. KEYTERMSANDDEFINITIONS
Post-industrial city is a city whose economy is dominated by services
and new high-tech industries.
Constrained location theory identifies the problems encountered by
manufacturing firms in congested cities, particularly in the inner
areas.
Rural–urban fringe is the boundary zone where rural and urban land
uses meet. It is an area of transition from agricultural and other rural
land uses to urban use.
Key workers are mainly public sector professional or semiprofessional
workers (e.g. teachers, nurses, police officers, etc.) whose presence is
seen as vital to the safe and efficient functioning of the urban
economy. The problem in London is that their salaries are modest in
relation to the high cost of living in the capital and as a result these
occupations have problems recruiting and retaining staff.

7. KEYTERMSANDDEFINITIONS
Residential mosaic is the complex pattern of different residential
areas within a city reflecting variations in socio-economic status that
are mainly attributable to income.
Spatial competition is the competition for space by different land
uses in various parts of an urban area.
Residential segregation is the division of an urban area into districts
of low-, medium- and high-income housing.

8. TOPICSUMMARY
The first generalisation about urban land use to gain widespread
recognition was the concentric zone model.
The model’s basic concepts were drawn from ecology, with the
physical expansion of the city occurring by invasion and succession,
with each of the concentric zones expanding at the expense of the one
beyond.
Alonso’s theory of urban land rent (1964), generally known as bid-rent
theory, also produces a concentric zone formation, determined by the
respective ability of land uses to pay the higher costs of a central
location.

9. TOPICSUMMARY
Hoyt’s sector model suggested that once variations arose in land uses
near to the centre, they tended to persist as the city expanded.
In the multiple nuclei model, C. D. Harris and E. Ullman (1945) argued
that the pattern of urban land use does not develop around a single
centre but around a number of discrete nuclei.
P. Mann based his land-use model for a typical British city on the
theories of both Burgess and Hoyt, which he tried to apply to
Sheffield, Nottingham and Huddersfield.

11. TOPICSUMMARY
In David Clarke’s model of the North American city, the CBD is
subdivided into core and frame. Outside the low-income inner-city are
three suburban rings divided into sectors of lower-middle, middle and
high income.
Patterns of land use in developing cities are considerably different
from those in developed cities. Models of land use in developing cities
reflect this.
Examination of population density gradients, termed ‘gradient
analysis’, shows that for most cities densities fall with increasing
distance from the centre.

12. TOPICSUMMARY
A range of factors affects the location of urban activities, such as
retailing, manufacturing, office functions, education, health, leisure
and open space.
The demand and supply of land in various locations dictates its price.
However, planning decisions can override market forces.
For the past 50 years or so, manufacturing industry in developed cities
has decentralised to suburban and rural locations. Developing world
cities have followed this trend in more recent years.
Constrained location theory can be used to explain the movement of
manufacturing industry away from inner city locations.

14. TOPICSUMMARY
The location and characteristics of retailing have changed significantly
in most cities in recent decades.
The central business district is the commercial core of an urban area
exhibiting the highest land values. Common changes in many
developed and an increasing number of developing countries have
been the construction of pedestrianised zones, indoor shopping
centres and ring roads around the CBD, with multi-storey car parks.
Residential segregation is very apparent in cities in both the
developed and developing worlds.
Urban renaissance is a common theme running through strategic
planning in most developed and an increasing number of developing
countries.

15. ADDITIONALWORK
1. Look at maps of the urban area you live in or the one closest to
you. Does the arrangement of land use look like any of the models
presented in this chapter of the book?
2. To what extent does the neighbourhood in which you live look like
a residential mosaic?
3. For a CBD that you know or have studied, list the changes that have
occurred.

16. SUGGESTEDWEBSITES
www.geographyfieldwork.com
www.n-aerus.net
www.geographyinaction.co.uk