上海大学毕业设计(论文)
Each city, metropolis, megalopolis and country will need to develop its own, localized strategy for sustainable urban development that responds to existing environmentalconditions,socio-economic systems, and structures of governance. However, there are some key elements that are likely to be generic. The emphasis that countries need to place on these elements, and the measures adopted for their implementation, will vary according to the level of urbanization and form of settlement being planned for.
Conservation of non-renewable resources: There is a plethora of actions that could be undertaken to conserve non-renewable resources in and around the world’s cities including: setting land use policies that increase densities to conserve land; setting policies and establishing comprehensive mass transit programs to reduce the use of automobiles in nearly urbanized and rapidly urbanizing nations;regulating the volume of automobile traffic to minimize the consumption of fossil fuels;
conserving wetlands and coastal zones;defining or creating wildlife protection areas.
Resource substitution: Non-renewable - and some man-made - resources need to be replaced with those that are renewable (fig.12). The most obvious is replacement of fossil-based fuels with other resources in the creation of energy - e.g. aside from solar and windpowered energy, biogas energy as pioneered in India.”Others include replacement of building products created from non-renewable resources by man-made materials manufactured with zero discharge or by other natural resources - such as in Peru where traditional adobe technology is slowly beginning to replace cementintensive,masonry construction15 - and replacing chlorofluorocarbons.Comprehensive directories of locally available, substitutable resources for use at all scales of the urban environment, ranging from the megalopolis to the workplace and the home, need to be formulated.
Resource rehabilitation: The rehabilitation of coastal zones, wetlands, aquifers, forests and wildlife habitats are all actions that can occur in urban areas and benefit them. Even the creation of urban parks can play a major role: ten deciduous trees absorb about four tonnes of carbon a year, as much as is created by the average Canadian. Reforestation of urban peripheries in Third World countries can, under proper practices ensuring sustainable yield, provide badly needed fuel. It can also drastically reduce erosion and subsequent silting of urban infrastructure(fig.13). Restocking of fish and wildlife can benefit local and
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上海大学毕业设计(论文)
regional ecosystems and economies,provide an important source of food in Third World countries,and contribute to export earnings, for example,shrimp farming.
Recycling: Urban recycling must go far beyond the scavenging of garbage dumps if it is to contribute fully to sustainable urban development. Materials long believed to be useless waste are now being found to have a wide range of possible applications. Examples are: use of waste from bauxite mines in brick manufacturing, as in the case of Jamaical
substituting energy-intensive cement with ash from combustion of rice husks and blast furnace slag, as applied in Brazil[17];replacement of cement in concrete with fly-ash a byproduct of pulverized coal combustion in thermal power plants, as in Argentlna18; and use of natural pozzolans to replace cement, as in Recycling implies efficiency and innovation, prerequisites to sustainable urban development.
Control and treatment of waste emissions: Technological advances over the last few decades have provided many cost-effective ways of controlling and treating a wide range of gaseous and aqueous emissions in the urban environment. Aside from automobile emission controls and smokestack technologies, domestlc and industrial sewage treatment systems are fast becoming essential elements of urban infrastructures, at least in many urbanized countries. However, most cities in urbanizing countries lag seriously behind in the introduction of systems and technologies to control and treat waste.For example, Shanghai’s Huangpu River is so polluted that, in some stretches, it is anaerobic for 150 days of the year; 80 percent wastewater pollution is of industrial origin and consists of high concentrations of arsenic,mercury, phenol, chromium, lead and zinc.2° Even though Shanghai’s Environmental Protection Bureau attempts to regulate industrial waste emissions and many factories have installed source treatment technologies, these systems are routinely turned off after EPB inspections in order to reduce energy costs.21 Waste control and treatment is more than simply a technological task. It is a function of economic, political and institutional factors as well.
Management of non-recyclable waste: Some wastes are clearly non-recyclable. Special management regimes are required for many toxics and radioactive materials.
Most of these wastes have urban origins. Technologies are becoming available to safely contain these non-recylable wastes but serious problems remain concerning affordability, the location of dump sites in urban regions and
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上海大学毕业设计(论文)
in their management. Even if environment/economic regimes are put into place that drastically reduce the creation of non-recyclable wastes,there will always be a continuing need to provide for the containment of some toxic and radioactlve materials.
Resource distrlbution: There are two aspects of resource distribution that require careful attentlon in any strategy for sustainable urban development:
?The first aspect relates to the belief in many quarters that the distribution of resources should be focused on rural areas in the Third World. This contentlon is based on the perception that “cities are bad” and “drain the countryside,” i.e. if more attentlon was paid to distributing needed resources to rural areas, urban growth would not occur. However, people move to cities not only to
seek economic gain but also for social, cultural and political reasons. In many Third World cities up to 60 percent of urban population growth is generated internally.[22 ]The debate over rural/urban resource dlstributlon is quickly becoming superfluous.*The second important aspect that must be addressed is resource distribution within urban areas: the spread between the rich and the poor in all Third World cities.Reforms of socio-economic regimes that constrain the poor from gaining access to resources need to be the cornerstones of a sustainable urban development strategy.
Clearly, equitable distribution of resources is a fundamental element of the sustainable development equation both globally and within cities, be they in urbanized or urbanizing nations.
Institutional change
No matter how strong a commitment to sustainable urban development, or how effectively a technology can potentially deal with pollution, without institutional changes in the development and management of cities and the natural environment, sustainable urban development will not occur. There are a broad range of institutional mechanisms that need to be addressed,including policies and operations. 5..
Policies
Policies and practices in the urbanized North that encourage resource depletion and pollution in Third World countries through unequal trade practices and capricious consumption of commodities and low-cost manufactured goods; ? Fiscal and monetary measures, such as taxation policies,that provide economic incentives to deplete nonrenewable resources and to
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上海大学毕业设计(论文)
pollute;Socio-economic policies that preclude equitable distribution of resources, particularly to the urban poor;Urban development policies promulgated since the 1950s - and transposed to many Third World countries -that are based on principles of maximum consumption of unlimited resources of land, water and fossil-based fuels;Investment strategies based on minimizing initial capital costs as opposed to optimizing long-term,life-cycle costs; and,Policies that preclude urban governments from generating sufficient revenue, or recovering their costs,in the provision of urban services and ongoing management of municipal infrastructures.
Operations
Regulatory measures, that are insufficient in scope,are not easily enforceable and do not provide forsufficient public scrutiny;
? Organizational mandates and designs in government and industry that preclude consultation, vertical and horizontal integration, and public accountability;
Governing structures that centralize economic and,where it formally exists, environmental decision making away from local communities: and,
? Insufficient and/or inadequately trained technical,professional and managerial personnel to manage urban to be made to provide for the implementation of a sustainable urban development strategy will clearly be infiuenced by the form of settlement and the level of urbanization that a country has reached. Effective institutional changes in ail countries, urbanized and urbanizing alike, will be the cornerstones of sustainable urban development. Without them, prociamations on sustainable development will be empty. rhetoric that do little to improve the quality of life for future, largely urban, generations.
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