cities as systems

8/2/2019 Cities as Systems

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Cities As Systems



What is a System?

• A system is a simplified way of looking at how

things work.

• Systems generally include factors (inputs),

processes (throughputs) and results (outputs).

• The systems approach can be applied to many

aspects of geography, including cities.



Cities as systems: Open linear systems

The Unsustainable City



Inputs

• The inputs may be made up of:

- people, whether daily commuters or more

permanent migrants and immigrants,

- goods such as bricks, bread, furniture and

computer microchips

- services such as water and electricity.



Outputs

• Outputs like:

- waste water and refuse,

- outgoing commuters and migrants- ‘unseen' exports like air pollution.

• Where great amounts of products are

exported without much recycling, this type of system is called an open system.



Why Are These Systems

Unsustainable?

• Such a system may be thought of as

unsustainable in the long term because of the

escalating demands for resources from an

ever-widening area, creating a widening

ecological footprint.



Example: London

• London has experienced great changes in itspopulation which in turn has had implications forthe land area occupied and needs for inputs andoutputs – the basis for any system.

• Sustainability depends on the nature and balanceof the system.

• If the system grows in total numbers, it will

require more inputs and inevitably produce moreoutputs.

• If the system reduces or increases in numbers of working age group, other issues will ensue.



Example: London

•London's total footprint, following Rees's definition,extends to 20 million hectares: around 125 times itssurface area of 159,000 hectares.

• With approximately 12% of the UKs population,7,000,000 people live in London, occupying a surface

area of 158,000 hectares.• The area required for food production at 0.2 hectares

per person is 8,400,000 hectares.

• The forest area required by London for wood products

is 768,000 hectares.• The land area that would be required for carbon

sequestration (fuel production) at 1.5 hectares perperson is 10,500,000 hectares.



• The total London footprint is 19,700,000hectares: 125 times London's surface area.London therefore requires the equivalent of Britain's entire productive land.

• In reality, with its increasingly sophisticated

consumer tastes aided by rapid transporttechnology, this means London is increasing itsimpact on remoter areas: such as obtainingmangoes from Brazil, teak furniture from

Malaysia, copper from Zambia … not to mentionour appetite for increasingly far flung holidaydestinations…



Conclusion

• Large cities are often considered to be

unsustainable systems because they consume

large amounts of resources and produce large

amounts of waste.

• Sustainable urban development aims to meet

the needs of the present generation without

compromising the needs of future generations



• Traditional settlements were delineated and

structured by transport and production

systems based on human or animal power

• A major effect of fossil fuel-based technology

has been that the high density of traditional

cities has given way to urban sprawl creating

an increasing ecological footprint.

Reasons for the Problems



• As cities draw resources from increasing

distances, they also accumulate large amounts

of inert and toxic materials within themselves

– that is to say, pollution.

• Waste gases and water expand the negative

impact of cities at a regional and increasingly

global scales.



Cities as sustainable systems: Circular

metabolism

• In nature, a circular metabolism is developed

whereby every input is also able to renew and

sustain the living environment by recycling the

outputs. In the past medieval cities had

something approaching this relationship, with

the following closely linked nearby: market

gardens, orchards, arable and grazing land,local water supply, forest products and so on.



Cities as systems: Circular Metabolism

The Sustainable City



Looking at the Past to look at the

Future

• Indeed, until the recent and rapid industrially led

growth of the late twentieth century, many

Chinese cities were largely self-sufficient in food.

• They were unique among the world in having

highly developed low technology systems of using

human waste as fertiliser for local farms.

•It must be stressed that any city has an ecologicalfootprint – the question is to what degree?



•

Cities in less economically developedcountries such as India often have a higher ‘re-

use' system than do those in more

economically developed countries.

• In the USA and UK, ‘disposable culture' and

‘built-in obsolescence' permeate society.

• Modern cities have broken the close links with

the local biosphere.



The Key to Sustainability

• In order for cities to become more sustainable

they must change the linear metabolism to a

more circular metabolism, creating a self-

regulating sustainable relationship with the

biosphere.

• To do this they will need to become more

compact cities.



Compact Cities

• Compact cities minimize the amount of

distance travelled, use less space, require less

infrastructure (pipes, cable, roads, etc.), are

easier to a provide public transport network

for, and reduce urban sprawl.



Warning!!

• However if the compact city covers too large

an area it becomes congested, overcrowded,

overpriced and polluted.

• It becomes unsustainable.

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