Describe the city as a system in terms of:
- inputs—energy, water, people, materials, products, food (urban agriculture)
- outputs—solid, atmospheric and liquid waste, noise, people.
Key terms: What is a system?
The system is a type of model. Like urban models (e.g. Burgess Concentric Zone Theory, or Ullman and Harris Multiple Nuclei Model) the system model is used to present a simplified version of reality. It looks at the relationships between components within a unit. The model is usually presented as a flow diagram.
Open system
Open systems are those which have inputs and outputs of energy and matter. An example is the water supply to a house, with water both coming in (as clean fresh water) and out (as waste water and sewerage).
Closed system
Closed systems have inputs and outputs of energy, but not of matter. The global hydrological cycle is an example of this, since energy enters the atmosphere as solar radiation, causing evaporation and thus driving the transfer of water between different states (solid, liquid, gas) and locations. However, there is no input or output of water itself from the hydrological system overall.
Isolated system
These have no inputs or outputs of energy or matter. This is not found in the 'real' world of Geography.
Circular system
Circular systems are open systems, in the context of city studies. Inputs and outputs are minimised due to the process of recycling inside the system. (To put it another way: They occur when the output is recycled as the input, so very little energy or matter actually leaves the system. Because the inputs and outputs are balanced, it can be described as having dynamic equilibrium.)
Linear system
These are open systems, in which the inputs are processed (and flow between components) but the inputs come from another system. The outputs leave to go to another system. If the inputs and outputs are balanced, dynamic equilibrium exists. However, they are usually not perfectly balanced and therefore the system is in danger of falling out of equilibrium, resulting in either a surplus or deficit of materials.
Ecological footprint
A measure of the area of biologically productive land and water an individual, population or activity requires to produce all the resources it consumes and to absorb its waste. It is expressed in a globally comparable, standardized unit called a “global hectare” — a hectare of biologically productive land or sea with world average bioproductivity in a given year.
The system is a type of model. Like urban models (e.g. Burgess Concentric Zone Theory, or Ullman and Harris Multiple Nuclei Model) the system model is used to present a simplified version of reality. It looks at the relationships between components within a unit. The model is usually presented as a flow diagram.
Open system
Open systems are those which have inputs and outputs of energy and matter. An example is the water supply to a house, with water both coming in (as clean fresh water) and out (as waste water and sewerage).
Closed system
Closed systems have inputs and outputs of energy, but not of matter. The global hydrological cycle is an example of this, since energy enters the atmosphere as solar radiation, causing evaporation and thus driving the transfer of water between different states (solid, liquid, gas) and locations. However, there is no input or output of water itself from the hydrological system overall.
Isolated system
These have no inputs or outputs of energy or matter. This is not found in the 'real' world of Geography.
Circular system
Circular systems are open systems, in the context of city studies. Inputs and outputs are minimised due to the process of recycling inside the system. (To put it another way: They occur when the output is recycled as the input, so very little energy or matter actually leaves the system. Because the inputs and outputs are balanced, it can be described as having dynamic equilibrium.)
Linear system
These are open systems, in which the inputs are processed (and flow between components) but the inputs come from another system. The outputs leave to go to another system. If the inputs and outputs are balanced, dynamic equilibrium exists. However, they are usually not perfectly balanced and therefore the system is in danger of falling out of equilibrium, resulting in either a surplus or deficit of materials.
Ecological footprint
A measure of the area of biologically productive land and water an individual, population or activity requires to produce all the resources it consumes and to absorb its waste. It is expressed in a globally comparable, standardized unit called a “global hectare” — a hectare of biologically productive land or sea with world average bioproductivity in a given year.
The city as a system
In his 1997 work 'Cities for a Small Planet', Richard Rogers identified two major city types - the unsustainable, linear city and the sustainable, circular city. They are shown below:
Case study: Is Hong Kong a sustainable/circular city?
The WWF's Hong Kong Ecological Footprint Report 2013 outlines several facts about Hong Kong's sustainability. It is clear that Hong Kong operates as a largely linear system.
STOP PRESS - the 2014 updated report is now available.
The WWF's Hong Kong Ecological Footprint Report 2013 outlines several facts about Hong Kong's sustainability. It is clear that Hong Kong operates as a largely linear system.
STOP PRESS - the 2014 updated report is now available.
Hong Kong is a sustainable city: the argument against
- From 1962 to 2008, HK's per capita ecological footprint increased four-fold
- The average HK resident has a footprint of 4.7gHa, while the available biocapacity is 0.03gHa per person
- In 2008, local ecological assets provided less than 1% of HK's annual ecological footprint (In regular English: HK only produced 1% of the resources it used in 2008, with the rest all being imported - such as food, energy, water and so on)
- Household consumption (compared to government and long-term infrastructure projects) accounts for 78% of HK's footprint
- Hong Kong wastes around 3.584 tonnes of food EVERY DAY - that's 0.5kg of food per person.
- Commercial and industrial sectors (that is, restaurants and food processing factories) are responsible for a third of HK's food waste
- 30% of HK's food footprint comes from seafood, which is highly unsustainable
- HK is the second largest per capita consumer of seafood in Asia
- If everyone in the world lived like a Hong Kong resident, humanity would need 2.6 Earths to sustain our resource needs
Hong Kong is a sustainable city: the argument in favour
It is very important to recognise that while Hong Kong may overuse certain resources such as fossil fuels and food, it does have a highly sustainable public transport infrastructure, and that it is relatively green compared to many urban areas. This is because of the large number of country parks in Hong Kong.
It is very important to recognise that while Hong Kong may overuse certain resources such as fossil fuels and food, it does have a highly sustainable public transport infrastructure, and that it is relatively green compared to many urban areas. This is because of the large number of country parks in Hong Kong.
- 16% of HK's 2008 footprint was for investment in lasting assets. Lasting assets are things like buildings, roads, factories, public transport vehicles and so on. This means that HK is providing for the future. If these assets are good for the environment - such as the new MTR East-West link - they can help reduce the footprint in the future
- HK is getting richer, so it's population is better off. From 1980 to 2008, HK's per capita income relative to world income increased by 14%
- HK is developing socially too. Between 1980 and 2008, HK's Human Development Index value increased from 0.71 ('high') to 0.91 ('very high')
Further resources
Water consumption in Hong Kong
Water supply in Hong Kong
Energy
Crime (click on the links on the destination page, which bring up simple graphs of crime)
Population
Air pollution
Solid waste and recycling, and the lack of recycling
And the source of lots more information, the homepage for Hong Kong Goverment Factsheets.
There is also the work done by students at RCHK on urban stress in Hong Kong, which may relate to some of these areas e.g. population.
Water consumption in Hong Kong
Water supply in Hong Kong
Energy
Crime (click on the links on the destination page, which bring up simple graphs of crime)
Population
Air pollution
Solid waste and recycling, and the lack of recycling
And the source of lots more information, the homepage for Hong Kong Goverment Factsheets.
There is also the work done by students at RCHK on urban stress in Hong Kong, which may relate to some of these areas e.g. population.
Sources: Waugh, D. (2002) Geography: An Integrated Approach 3rd ed., Nelson Thornes & Oxford Course Companion by Nagle and Cooke.