Professor Graham Harris, ESE Systems
prepared for the 2006 Australian State of the Environment Committee, 2006
Overall, the state of the inland waters environment in the southern and eastern part of Australia is not very healthy. Significant areas of major inland and coastal catchments are degraded (including vegetation, aquatic habitats and water quality), the pressure on water resources continues to be high, and many indicators show that aquatic ecosystems and biodiversity are degraded across large areas of the continent. Water use and infrastructure development continues to grow and there is little indication that key indicators have improved in the last decade. The indicators that do exist are bedevilled by climate variability and periods of low rainfall, population growth, and changing land use patterns. There is much ignorance and uncertainty over the condition of aquatic biota and we lack key data from many areas, particularly data on trends over time for major groups. In some cases, such as frogs, there are data that clearly indicate that species are declining. Other cases, as for aquatic plants, the situation is less clear. While there are many excellent examples emerging of small-scale habitat and species restoration, many of these are under threat from possible climate change and human-induced, large-scale land and water use patterns.
Introduced species continue to flourish and ecological changes ensue. Species such as Carp not only compete with native species but also alter habitats in undesirable ways. Introduced species appear to be favoured by the large-scale, landscape and waterscape management practices found across large areas of the continent. Exotic species such as Carp and Gambusia continue to expand their range, with little evidence of effective control.
Evidence does point to important changes in climate over southern parts of Australia in the last 30 years (the declining runoff into Perth’s dams is but one example) and this shorter-term trend seems to be a part of a much longer trend that has been going on since the early days of European settlement (Thresher et al. 2004). Rainfall and runoff have declined significantly in many areas of the south and east, and hydrological benchmarks and planning frameworks are being constantly revised. Although there are reasonable models that relate climate to hydrology and runoff, knowledge about potential climate change and its impacts is very uncertain. The situation is urgent and we lack key predictive tools. Attempts are made to manage and set water and environmental policy with far less data and resourcing than would be deemed prudent in the case of economic policy. The trend in subsidiarity to engage communities in natural resource management has not been accompanied by sufficient technical and scientific capacity building at the local, regional or state level.
The reduced availability of surface water has resulted in much greater groundwater use in recent years over much of Australia. This has resulted in declining groundwater levels in many areas. As in most of Australia, groundwater discharge to streams maintains the dry season baseflow; the switch to groundwater use will simply have the effect of reducing river flow in the long term wherever connected groundwater and surface water systems occur. The reduced availability of surface water both reduces the security of supply to surface water users and degrades the river ecosystems.
Australian water resources are characterised by great variability in space and time. Climate variability is a fact of life and climate change has the potential to fundamentally alter the patterns of variability that Australians have grown used to. Through a requirement for security, people have greatly altered the natural patterns of variability and connectivity; this has had a significant impact on habitats and biodiversity. There is evidence from recent climate changes in south-western Australia, which occurred abruptly and without warning, that the past may not be the best guide to the future. Certainly, planning timeframes have shortened greatly in the last 30 years and, as long as predictions of future climates are for warmer and drier conditions, it would be prudent to put in place policies and practices that reduce the human demand for water (for example, the permanent Level 1 water restrictions now in place in some jurisdictions). To do so would relieve the dependence on rainfall and runoff and reduce the potential risks, as well as make more water available for vital environmental values.
Australia’s appreciation of groundwater dependent ecosystems has increased from almost zero only 10 years ago. Nonetheless, understanding is still at a rudimentary level and significant scientific research is required. The translation of the science into practical management presents an even greater challenge to water resource managers.
Water use efficiency and reuse are slowly increasing (Radcliffe 2004). The recent southern dry period has caused an increased focus on supply and demand management and a revision of water management plans in major cities. Water restrictions continue. The Council of Australian Governments’ water reform process that started in 1994 was given momentum by the severe lack of rainfall; more protection of the environment and restoration of environmental flows should ensue. Other Commonwealth, state and territory programmes continue to address many of the issues, but in a piecemeal manner, although there are some signs that this is changing. The Basin Salinity Management Strategy , for instance, provides a framework for communities and governments to control salinity and protect natural resources within the Murray-Darling Basin. It establishes end-of-valley salinity targets for each tributary catchment and a basin target at Morgan in South Australia. Implementation is a shared responsibility between valley communities and governments and there is a commitment to the principles of the Integrated Catchment Management Policy Statement. Subsidiarity and the establishment of regional natural resource management committees is to be applauded, but the policy raises key questions about capacity and the ability of regional communities to understand and manage in a much more complex environment. We must be careful, for example, to ensure that the drought does not deflect us from the important task of returning environmental flows to rivers and streams. Subsidiarity in governance must be supported by institutional reform and the strategic provision of key knowledge needs.
Significant progress on environmental restoration will require policy and management initiatives that tackle the large-scale land and water use issues. New mosaics of land and water use that are profitable, equitable, socially acceptable and environmentally sustainable must be found.
The overall themes of this report are the ways in which variability and connectivity—which are both crucial for the ecology and health of Australia’s inland surface water and groundwater systems—have been changed by human actions over the last two hundred years. The demand for security of supply has led to a large change in the ways Australia’s inland surface waters and groundwaters are managed; it has also changed their health. Overall the indicators show that demand for water use is increasing, although use is capped in some regions and, in recent years, supply has decreased in many regions. There is now good evidence that, as demand increases in the coming years, there will be a growing gap between supply and demand. New technologies, such as desalination, aquifer storage and recovery and other approaches—such as demand reductions, and increased reuse and recycling—will be required to close the gap. Water quality and health-related issues will become a greater issue, as water ‘fit for purpose’ will be required for many agricultural, industrial and domestic purposes, especially with increased pressure to recycle and reuse water. While water of poorer quality may be used for many industrial purposes (for example, cooling water), higher quality water is needed for other uses such as environmental flows and drinking water. Salinity can have a significant impact on water quality. Dissolved salt concentrations vary and determine the suitability of water use; for example, a salinity level above 1500 milligrams per litre is not suitable for irrigation.
Water quality remains poor across large areas of the continent and biodiversity is degraded and declining. Land and water are intimately connected; large, catchment-scale landscape and waterscape management initiatives will be required to restore the health of Australia’s inland waters. The trend towards this scale of intervention is now being contemplated and new policy initiatives are being put in place. Nevertheless, the scale and scope of the interventions required are challenging. Climate variability, a fact of life on the Australian continent, makes the task more difficult because it drives change at scales of decades, and this is superimposed on top of human-induced changes, both positive and negative.
By international standards, Australia is not short of water; but regional variation in intensity of water use is great. In many regions, the aquatic environment is showing the strains of present and past policies and management practices. Australians must make more and better use of what they have. Integrated management of surface water and groundwater is urgently needed in many catchments. If the trend towards warmer and drier times continues, then determined efforts will have to be made to use less water, to make more efficient and effective use of scarce resources, to reuse and recycle more water of varying qualities, and to do significantly more to preserve and protect important natural, cultural and aesthetic values. These are complex and difficult issues, which will require effective partnerships between all members of the Australian community.