Urban Climate
The amount of radiation received on urban
ground surface is (greater / less) than in
rural area.
Albedo is greater because of greater
reflection from metallic screen wall and
concrete surface
Greater scattering for more cloud cover
and dust particles
Urban Climate
The annual mean temperature in urban area
is (higher / lower) than rural area.
Artificial heat sources e.g. air conditioner
Concrete surface can be heated up nore
quickly
Less heat loss through latent heat in
evapotranspiration
Greenhouse effect from the concentration
of CO2 and dust particles
Urban Climate
The relative humidity in urban area is
(higher / lower) than rural area.
The higher temperature lower the relative
humidity
Concrete surface and artificial drainage
system drain out most water. Less amount
of is moisture available.
Urban Climate
The occurrence of fog is (more / less)
frequent in urban area.
More dust particles as condensation nuclei
Temperature inversion due to pollution
Lower wind speed
Urban Climate
Amount of precipitation received in urban
area is (more / less).
More dust particles as condensation nuclei
Temperature inversion due to pollution
The high temperature in urban will form a
low pressure centre which brings convection
current.
Urban Climate
The mean wind speed is (higher / lower) in
urban area.
The tall buildings form barriers.
Buildings and streets create rugged relief
which will lead to turbulence
Urban Climate
The visibility in urban area is (higher /
lower) than rural area.
The presence of fog.
Concentration of dust particles
Urban Heat Island
22℃
24℃
28℃
26℃
B
A
Impact cause by an urban
heat island and urban climate
the greenhouse effect and artificial heating
will lead to the formation of an urban heat
island which means that the urban area,
especially the C.B.D. and industrial centres,
will have higher temperature than the
surrounding rural areas.
The heat island at the same time makes
the urban area a low pressure centre where
all winds are blowing to the city centre.
The relatively high air pressure in rural
area forces air to move back into the city.
These will lead to a closed circulation in
the city which means pollutants cannot be
diffused.
Concentration of pollutants will lead to smog,
acid rain
Lower wind speed will prevent the diffusion
of pollution.
Lower relative humidity and pollutants affect
human health, especially respiration system
Conflicting interest of different
parties
.'Pedestrianise" the heart of
shopping area;
.Introduction of LPG taxi and norail tram;
.Using unleaded oil and fuel with
low sulphur content;
.Fine on excess heat emission
Support
More strict control is needed
Wider scope should be
covered
The government and large
companies should do more.
Green
Group
We have to face keen competition
Those measures will increase the
cost of production.
The government should provide
assistance such as lower tax and
financial support
Businessman
•more widespread green area
•separate land use zones
•heat emission plants on downwind
location
•control spacing between buildings
and height
Hydrograph
Discharge
Peak flow
Lag time
Time
Impact of urbanization on
hydrograph
Before
After
Urbanization Urbanization
Peak Flow
Lag Time
Changes brought by urbanization
• Deforestation, vegetation replaced by
concrete surface
• Which is smooth and impermeable
• There is less retention and infiltration
• With the aid of artificial drainage
system
• Surface runoff reaches river channel
much faster
Problems brought by urbanization
• High peak flow means high regime of the
river
• There is greater danger of flood after
rain storm
• However, the discharge becomes small
at other time
• It will lead to accumulation of sediment
and pollutants along the river courses
Efficient Transport System
• Sufficient and stable supply of
transportation facilities for workers and
other commuters, as well as for freight
• Commuters, industrial goods producers and
buyers are able to make use of facilities
without unnecessary difficulties, at a
reasonable cost, and with a high degree of
safety and reliability
Efficient Transport System
• A land use layout of the whole city and
within each section of the city that
• Minimizes the distance of traffic flow
between activity centres
• Discourages unnecessary traffic flows
without affecting industrial output
• A well maintained transportation system
that ensures the above-mentioned
conditions
Major causes
• Improper and insufficient land use and
transport planning
• Mismanagement of transport facilities
• Improper and insufficient land use control
• Sudden surge of traffic demand due to inmigration
• Lack of an inductive business environment
to promote transport improvement
• Poverty and lack of fiscal ability for
transport improvement
Suggested Solution
• build more roads to accommodate the
growing number of cars
• increase the flow capacity of existing
roads by better management (e.g. 'tidal
flow' scheme that was once used by Lion
Rock Tunnel, or build flyovers that
separate pedestrians and cars);
• improve public transport or give priority
to public transport(bus lane) so that
fewer people feel the need to drive
Suggested Solution
• restrict the inefficient road users (e.g.
Singapore's policy to charge private cars
with less than 4 people inside when they
entre the C.B. D. during the rush hour);
• control the number of private cars by
imposing high tax on owning a car;
• reduce the number of parking space so as
to discourage people from driving into
some area (e.g. the beaches of Hong Kong
Island in summer);
Suggested Solution
• encourage major employers to modify
their working hours;
• land use control in newly developed area,
so that people need not travel long
distance to work or to school.
Ranking
A
1
2
3
4
5
B
C
D
E
Your group's choice? Why?
Hong Kong Case
• Hong Kong Moving Ahead : A transport
strategy for the future
http://www.info.gov.hk/tb/highlight/index.htm
• Railway Development Strategy 2000
http://www.info.gov.hk/tb/highlight/index.htm
How transport problems affect
the growth of a city
• increase in congestion leads to an
increase in transport cost and a decrease
in economic productivity
• congestion leads to a distorted land use
pattern in the long run, causing more
serious transport problems in the future
• transport problems discourage
decentralization and re-distribution of
economic activities and population.
• increase in traffic demand caused by the
influx of 'migrants' hinders the smooth
implementation
of
urban
transport
development plans
• insufficient 'space' available within the
built up areas to allow large scale urban
transport improvement programmes, thus
hindering future growth
• the lack of proper inter-modal coordination
leads to increase in transport cost as well
as reduction in overall urban productivity
Criteria for the assessment of
housing quality
•
•
•
•
•
•
•
•
Scenic beauty / view
Relative position
Accessibility
Access to shopping facilities
Social and public facilities
Neighbourhood environment
Open space and green area
Free from pollution
Criteria for the assessment of
housing quality
• Internal structure
• Ventilation, brightness, spacious
• Basic services such as electricity, water,
sewerage
• Social environment / socio-economic
status
• School net
• Reasonable / affordable cost
Common housing problems
•
•
•
•
•
•
•
Housing shortage
Overcrowding conditions
Poor sanitation
Environmental pollution
Fire hazard
Unaffordable rent / value
Social problems (family conflicts, mental
distresses, theft, crime, etc.)
Common housing problem
features
• Urban slums
• Urban ghetto
• squatters
Causes of housing problems
• Rapid population growth because of large
natural increase
• High birth rate and relatively low death
rate resulted from improved sanitation,
upgrading medical facilities, control of
diseases, better nutrition and absence of
war
• Large rural-urban migration
Causes of housing problems
Slums are found in transition zones next to
CBD where houses are deteriorating and
without adequate amenities and the
tenants are too poor to improve the living
conditions
Over-crowdedness results when a tenant
rent part of a dwelling from the owner
and then sub-let parts of this rented
accommodation to others
Environmental pollution results because
workshops and retail units intermingle
with residential units
Housing is scare because of poor financial
support from government and feeble
capital investment from private
developers
Even when public housing schemes are
provided, they are frequently
inappropriate to the urban poor in that
most of them are located at urban fringe
which means high costs to work and fewer
employment opportunities
Squatters are found on roof tops, hillslopes
fringing the urban areas and on silts ot
boats in sheltered coastal areas near the
city
They are usually the result of large influx
of new-comers to the city
These squatter huts are built of wood and
cardboard, there is no surfaced road, no
electricity, no water nor sewage facilities
creating fire and health risks
Poor financial situation and administration
of local government
Kinship and clanship persist here and there
resulting in ethnic and social segregation
Lack of town planning in the early stage of
development
Urban decay
Social segregation
Solutions
Developed Countries
Slum clearance
Developing Countries
Squatter clearance
Renewal/redevelopment Self-help schemes
Provision of better
public utilities
Encourage private
investment
Renewal/redevelopment
Birth control and family
planning
New town development
New town development
Rehabilitation
More balanced economic
development
Need for Urban renewal
• At present, there are about 9 300 private
buildings in the Metro Area (i.e. Hong Kong
Island, Kowloon, Tsuen Wan and Kwai Tsing)
which are 30 years' old and above. In ten
years' time, the number of buildings over
30 years' old will increase by 50%. The
problem of ageing buildings is most serious
in older urban areas
Urban renewal can help alleviate
urban problems by
• thinner the population density of the inner
urban – decentralization of population can
solve the over-crowding problem
• improve the living environment – more open
space, green area, and community facilities
are provided
• get rid of the worn-out buildings which
impose danger of collapse to the residents
• refresh the poor looking of the old
developed areas so to improve the
impression of the city as a whole
• increase accessibility and improve traffic
problems by road-widening, redesign of
street pattern and more parking space
• provide more land for developers, then
more economic activities can be found
• Land use planning – land use zoning policy
can be adopted in the process of renewal.
Offensive land use can be relocated or
isolated. Different land uses will be
separated.
• redistribution of population – low income
class may be resettled and better new
buildings and better living environment will
attract higher social classes to live in the
area. The socio-economic status of the area
becomes higher and a balanced community
can be attained.
Interests and needs of different social
groups
• The landlords demand for higher
compensation and acquire land ownership
after redevelopment.
• The old residents of the area want to
preserve the social bonds and
neighborhood relationships. The small
business owners do have fear of loss
small business. They want to have
resettlement in the same district. They
are reluctant to leave.
• The lower income class has fear of loss of
existing employment opportunities. They
are unwilling to pay for higher rents after
redevelopment and they are unable to
afford the higher living expenses after
redevelopment. Higher compensation is
demanded.
• Land developers want to raise the economic
potential of the area. Therefore,
improvement of accessibility, land and
facilities for economic activities are
important. They also emphasis on the
balance on cost and benefit on
redevelopment.
• Town planners emphasis on a balanced
community and land use zoning. The lowering
of population density is also important.
Adequate open space and green area should
be kept.
• Environmentalists emphasis on the
maintenance of urban ecological balance.
The preservation of historical landmarks
and buildings is important. The social life
and tradition of the community should also
be considered.
• The government officers concern the time
and cost of land acquisition. The problems
involved in the process of redevelopment
such as traffic congestion and pollution
should be settled.