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.