Human Settlements Theme Report
Australia State of the Environment Report 2001 (Theme Report)
Lead Author: Professor Peter W. Newton, CSIRO Building, Construction and Engineering, Authors
Published by CSIRO on behalf of the Department of the Environment and Heritage, 2001
ISBN 0 643 06747 7
Emerging issues (continued)
Opinion is divided on water as a limiting resource factor on the future growth of Australia's population and settlement. Some, such as Withers (1999), argue that water (or the lack of it) is not a barrier to increased population, due to the comparatively high level of renewable water resources in Australia (Walker 2000). Population increase is considered to be more problematic in relation to waste assimilation, environmental systems and greenhouse gas emissions.
The amount of water available per person appears to rank Australia among the most favourable in the world at the national scale; our average annual divertible resource is 7.7 ML per capita (Smith 1998). But Australia does suffer from large temporal and spatial variations in the distribution of rainfall, which is likely to be exacerbated by greenhouse climate change. While there is plenty of water on a gross, time-averaged, national scale, in some catchments water is fully committed. Fundamentally human settlements are not limited by the overall water volume - just the way we use it (Harris 2000).
In the Water and the Australian Economy Study (AATSE and IEAust 1999), the suggestion that water is a prime constraint on Australia's economic growth and population was rejected. The study concluded that there are many ways in which the economy (and population) can grow, despite water resource limitations. The authors felt this could be achieved through maintaining flexibility in water allocation and increases in efficiency of use.
Irrigation within the rural sector is the main consumer of water in Australia; its expansion has been the major factor in the overall growth of water use and the consequent pressures on the resource base and the environment (Crabb 1997). This situation is not expected to change, and the dominant driver of future water demand will continue be the irrigated agriculture sector (AATSE and IEAust 1999). The challenge facing that sector is to ensure that water is used efficiently and allocated to the highest-value uses.
During the 1990s, water use declined absolutely in Sydney and Melbourne and remained static in Hobart and Adelaide (AATSE and IEAust 1999). In comparison, urban water use is still increasing in the Northern Territory, south-eastern Queensland, and the south-west of Western Australia. The latter two regions currently use 38% and 46% of divertible fresh water resources respectively, and are likely to experience pressure for new water resource development (AATSE and IEAust 1999). This pressure for new water resource development may be responded to with traditional approaches such as diverting surface water resources, or with emerging approaches such as stormwater and wastewater reuse and demand management.
Land and groundwater salinity and rising water tables are not just a rural issue; they also cause problems in many urban areas throughout Australia. More than 80 regional towns and cities as well as suburbs of Sydney have problems related to salinity (AWWA 1999; New South Wales Salinity Summit 2000).
The causes of urban salinity include clearing of native vegetation, roof and paved area runoff draining to the soil profile, disruption of natural drainage line, watering of domestic gardens and public areas, overflows from septic tanks and sullage pits, and water leakage from water supply, sewer and stormwater drainage pipes.
The impacts of urban salinity include the loss of trees, grass and other vegetation; corrosion of gas, water and sewer pipes; damage to roads; and decay of building foundations, local streets and highways (MDBMC 1999). The cost of these impacts to the community is great. For example, the reconstruction of major highways costs up to $1 million per kilometre (AWWA 1999), while the reconstruction of just one street in a town block costs an estimated $300 000 (Department of Land and Water Conservation 2000).
Pharmaceutical substances are used for human and veterinary medicine. Most medical substances are metabolised before being excreted from the body, although, for example, 30-90% of an administrated dose of most antibiotics to human and animals is excreted with the urine as active substances (Halling-Sorensen et al. 1998). Such pharmaceutical substances enter the sewer system and, in most cases, drain to wastewater treatment plants.
Some preliminary research in Britain, Switzerland and Germany found that treatment systems remove as little as 20% and, at best, approximately 95% of the pharmaceutical substances, depending on the substance and the level of treatment (Ternes 1998, Buser et al. 1999, Fisher 2000). These substances (including antibiotics and human hormones such as oestrogen) can reach detectable concentrations in rivers and lakes, and there is growing concern about the occurrence, fate and possible effects of such substances in the environment (Ternes 1998, Buser et al. 1999). Industrial wastewater may also be another source for the contamination of surface water bodies such as rivers and lakes (Ternes 1998).
Past experience with biologically active compounds such as pesticides, antifouling agents and endocrine disrupters has shown that, despite low concentrations, potential effects of biologically active compounds on the environment cannot be discounted (Stuer-Lauridsen et al. 2000). In the case of antibiotics, the selection and dissemination of resistant bacteria in nature should be avoided in order to ensure effective treatment against infectious diseases and maintenance of an ecological balance (Guardabassi et al. 1998). However, there is still not enough information about the behaviour of pharmaceutical substances and their metabolites during wastewater treatment, the contamination of the aquatic environment and the toxicity of such substances (Ternes 1998, Stuer-Lauridsen et al. 2000).
Since the 1996 State of Environment Report, the urban water industry has undergone considerable change. There has been a shift from development (engineering) to management. This shift in focus has been accompanied by greater involvement of the community, the introduction of pay-for-use price systems, further organisational restructuring and reform (which started in New South Wales and Victoria in the late 1980s), corporatisation of water utilities and, in the case of the Adelaide system, franchising to an international consortium (ASTEC 1995; Crabb 1997; AATSE and IEAust 1999).
Organisational restructuring and reform sought to clarify accountabilities by separating the policy, regulatory and commercial (operator) functions, and providing urban water businesses with clear commercial goals of customer service, environmental compliance and sound business operation free of other conflicting objectives (WSAA 1997). Regulatory roles were transferred to regulatory authorities. According to Smith (1998), the COAG Water Reform Agenda assumed that the public sector model was inefficient and that private sector business practices would lead to better management and financial savings. Referring to both urban and rural reform, Smith (1998) went on to state:
the hope is that the new institutional arrangements, particularly those linked to tariff changes and other pricing mechanisms, will lead to improvements to all forms of environmental quality. It is recognised, by proponents and critics alike, that attainment of these goals requires strong regulatory bodies.
Again, referring to the water industry as a whole, AATSE and IEAust (1999) considered that the natural resources and environmental aspirations of the COAG Water Reform Agenda are far from being realised.
In the 1996 SoE Report, the State of the Environment Advisory Council (1996, pp. 3-35) hypothesised that, as settlement size increases, resource use efficiency also increases, due to economies of scale (recycling), higher densities (space), accessibility (transport, energy) etc. The universality of this relationship has been questioned by Yencken and Wilkinson (2000, p.143) who have called for a research focus in this area. A report of CSIRO's Urban Water Program (Speers et al. 2000) assessed how scale effects costs for an urban greywater recovery, treatment and reuse system. Five scales of greywater recycling systems were analysed, ranging from 12 through to 120 000 household connections, with results suggesting an optimum size falling between 1200 and 12 000 connections. Similar studies are required for electricity generation in the context of photovoltaic systems in residential subdivisions, local stormwater retention and reuse, and local district public transit ('dial-a-bus') systems.