توسعه پایدار محیط زیست : ریشه ها، اجرا و چالش ها

The concept of sustainability has received much attention since the publication of Our Common Future by the World Commission on Environment and Development in 1987. Despite the institutionalisation of sustainability principles through legislation and policy around the world, progress in implementing sustainable development actions has been slow. The very open-ended definition of sustainable development provided in these documents, and the “language” used has made interpretation of what is required for implementation controversial. “Principles” of sustainable development have been developed to provide further guidance for implementation, but sustainability remains a contested and value-laden concept. Yet there is increasing recognition that the present development paths around the world are clearly not sustainable into the future and that we need urgently to address this unsustainability. Water use has become a prominent issue through broad acceptance that its use in many situations, including southeast Australia and cities such as Sydney, is unsustainable. This paper provides a broad introduction to the development of the concept of sustainability, barriers to implementation of sustainable development, and the application of sustainable development principles to water provision for a city such as Sydney, with emphasis on the use of recycled water.

The concept of “sustainability” has been much discussed over the past 17 years. Despite millions of articles, thousands of proposed definitions and the attention of a very large number of government and non-government bodies around the world, sustainability remains a contested concept. We seem unable to agree on exactly what sustainability means and how the concept should be interpreted in particular situations. What is clear, however, is that the way in which we use resources and deal with waste products requires urgent attention. This is evident due to the declining state of many natural resources and the potential for continuing, and most likely increasing, human pressure on these resources. This pressure comes from population growth, the need to provide for development in poorer nations, and continuing growth in consumption. Hence, at this time, it is best to urgently address the unsustainable nature of natural resource use, rather than putting this on hold while we argue endlessly about exactly what sustainability means! A current example of the need for such urgent attention is the looming water supply “crisis” in Sydney. A page 1 item in the Sydney Morning Herald on 13-1-05 was a report on research by the Water Services Association of Australia which showed that Sydney needed to cut water consumption by 54% to prevent a “dire water shortage in 25 years”. The looming deficit was seen as particularly alarming because of the assumptions in the analysis — including a very high level of water conservation by households, 25% of all new developments using recycled water, and water-efficient washing machines and appliances as standard. Changing the way people think about water including implementation of large-scale schemes for use of storm-water and grey water was seen as critical.

Applying sustainability principles to the role of water recycling in an urban area such as Sydney shows that a complex holistic and integrated analysis is required that considers the inputs and outputs to the urban system as well as the dynamics of that system. Tools such as LCA need to be employed covering a broad context spatially, and in terms of issues considered. At all times the principles of ESD need to be kept at the centre of the analysis. However, it is also important to recognise that decisions relating to ESD, while informed by science, are also values-based and hence ideology plays an important role. In this regard it is important to note that sustainability decisions may be addressed at a range of levels — from a superficial through to a deep interpretation of sustainability. Three levels may be identified: 1. ”End-of-pipe” approach to sustainability — This approach with respect to water management for Sydney would emphasise maintenance of supply — a high input, high output approach — but with attention to ensuring that outputs of, say, sewage to the ocean, are appropriately treated so as not to cause environmental harm. This is a superficial approach to sustainability of water use for a city. 2. Cleaner production approach — This approach places emphasis on the workings of the system and minimisation of inputs to and outputs from the system. Efficient (and sustainable) ways of harvesting and re-using or recycling water are explored. 3. Assessing products and services — This is the deepest of approaches and would involve all considerations from (1) and (2), but in addition would give strong consideration to detailed analysis of the life-cycle aspects of various alternatives for meeting urban water needs and to the wider water use footprint of urban dwellers. For example, emphasis is placed on demand-side education, and this may include the water use intensity of various foods and other products with the aim of encouraging consumption which minimises water use.