Settings and forms of urban regions 283types are introduced. The first two (Riverside cities and coastal cities) highlight
thephysiographically determined setting, and its implications for process and
pattern in an urban region. The third category (Metro area and urban-region
ring) focuses on the primary internal form of an urban region, which affects
flows and land use. The fourth grouping (Other diverse types of urban regions)
is effectively a basketful of delicacies waiting to be examined for their inter-
esting patterns and processes. Most of the urban-region types identified in this
section are illustrated in Color Figures2--39.
Afinal section (Effect of and effect on other regions) places an urban region
in the context of other regions, near and far. This emphasizes interactions and
the roleoftheboundary between regions.
Overwhelmingly urban regions manifest a rather rounded compact form,
mainly a result of urbanization from a downtown nucleus plus strong influences
spreading outward over the surroundings. In fact, the basic spatial model for
an urban region is a donut. In thedonut model,the hole represents the all-built
metropolitan area and the delicious portion around the hole is the urban-region
ring (Figure11.1).
Riverside and coastal cities
Riverside cities
The most prominent modification of the basic model form is a slice or
line through the donut’s center, representing a major river. The consequences
and insights from thissliced-donutform,with river bisecting city and metropoli-
tan area, are considerable. Riverwater flows one way, entering the urban region
at a point on its boundary, flowing across the ring, entering the metro area,
leaving the metro area, and flowing out of the region. Thus a mass of clean
waterorpolluted water from an adjacent region enters at a point. Land uses
in the urban-region ring then commonly add agricultural runoff and perhaps
stormwater pollutants to the river water. The metro area normally adds indus-
trial pollutants, sewage outflow, and much more stormwater pollution to the
river. Polluted water extends far downriver across the urban-region ring, and
may continue into the adjoining region.
In addition, the two halves of the urban region tend to tilt toward one
another, with streams flowing across the surfaces to the river. Streams that
flow into the metro area usually disappear, as streamwater combines with pol-
luted stormwater and flows through pipes into the river. Hence the arrangement
of land uses across the region may affect each stream, and each river section,
differently. Upriver of the metro area, riverwater is normally cleanest, so natu-
ralvegetation cover such as forest/woodland in this portion of the region has