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(2, 2001)

THE MURRAY-DARLING RIVER BASIN – AUSTRALIA.  Understanding the long-term effects of development of a major river system.

P. B. Bridgewater¹, I. D. Cresswell² and K. Olsson³

1 Environment Australia, GPO Box 787, CANBERRA, ACT 2601, AUSTRALIA, currently  Man and the Biosphere Programme, UNESCO, 1 rue Miollis, Paris 75015.

2 National Land and Water Resources Audit, GPO Box 2182 CANBERRA ACT 2601, currently Programme Officer, CBD Secretariat, World Trade Center Building, 383 rue St Jacques, Office 300, Montréal, Canada, H2Y 1N9.

3 Environment Australia, GPO Box 787, CANBERRA, ACT 2601, AUSTRALIA.

INTRODUCTION

Including the Island Sate of Tasmania, Australia has 12 drainage basins or undrained plateaux (Fig. 1).  The Murray–Darling river system is Australia’s largest, draining about one-seventh of the continent. It ranks with the world’s big rivers in terms of length and catchment area, but has much lower annual discharge. Across all the other drainage divisions, 16 per cent of divertible water has been developed, but the Murray–Darling Basin has a high of 81 per cent.   The Murray-Darling System is set in the driest of all the world’s inhabited continents. Australia has the lowest percentage of rainfall as run-off, the lowest amount of run-off, the least amount of water in rivers and the smallest area of permanent wetlands – apart, of course, from Antarctica.

  The Murray-Darling Basin, defined by its surface water drainage system, covers most of inland south-eastern Australia.  It includes much of the country’s best farm land.  Nearly two million people live within the Basin, and another million living outside are heavily dependant on its water.  Utilisation of the Basin’s water resources has made possible the expansion of agricultural development over inland areas away from the upland regions and coastal fringe.

  The mean annual discharge from the Murray-Darling System is approximately 13 750 GL in the absence of diversions.  Between 1988/89 – 1992/93 the diversion was 10 680 GL/year.  About 95% of the water was for irrigation.  Land and water resources in the Basin have experienced a steady decline in quality since the 1960’s, although this has been arrested somewhat in the last three years, due the recognition of the need for “environmental flows“, discussed in a later section. 

  In terms of governance, the Murray–Darling Basin has an over-arching Commission, which  is responsible for coordinating the efforts of the governments and communities involved in the management of the Basin. The Commission receives its direction from decisions of the Murray–Darling Basin Ministerial Council, which consists of Natural Resources Ministers representing the various governments in the Basin.  The Commission has primary natural resource management policy responsibility in the Basin, although each State, the Australian Capital Territory and the Australian Government have their own environmental legislation which pertains to their part of the Basin

  The Murray-Darling Basin is typical of Australia’s inland riverine systems – which include anastomosing anabranches and chains of ephemeral lakes and waterbodies. The chemistry of Australia’s surface inland waters differs from most waters elsewhere, often being dominated by sodium chloride, rather than calcium and magnesium bicarbonates (Williams, 1982).  Australia has the most variable rainfall and streamflow in the world and its inland streams have high natural turbidity and salinity (McMahon et al., 1992; Williams, 1982).

  The biology of Australian inland waters has many special features (Williams, 1982). Although the invertebrate animal groups resemble those of other continents with a similar environment, many species, and some genera and families, are unique to Australia.  Several groups that are widespread on other continents are lacking in Australia, and a number of families have adapted to a wider range of environments than is the case elsewhere. The fish of Australian inland waters are represented by few species, many of which have evolved from marine forms and are endemic.  The large aquatic plants are also unique, as are some terrestrial forms of the distinctive riparian vegetation.

  The distinctive physical, chemical and biological characteristics means Australia’s inland waters require management using criteria that are appropriate to Australian systems and conditions. Rivers and lakes in other parts of the world vary less, are generally less turbid and have fauna with different water-quality requirements, and so do not necessarily provide appropriate models for Australia to follow . The management of Australian inland waters generally, and in the Murray-Darling Basin in particular, is now being carried out on a catchment basis, to cover land, water and coasts. The condition (or state) of our waters in the Basin encompasses both natural characteristics, such as river flow variability, and the effects of human pressures exerted on the environment, such as impoundment and irrigation.  COAST

THE IRRIGATION INDUSTRY 

  Of all the developed water in Australia, 70 per cent (15 000 GL/year) is used in irrigation. This compares with 21 per cent for urban and industrial use, and nine per cent for rural water supply. Expansion in irrigation has been the major factor contributing to the growth in water use in Australia, with consequent pressures on the resource and environment. This growth was particularly evident prior to the early 1970s, with development of rice and horticulture industries along the Murray and Murrumbidgee (its major rivers in the south of the Basin), and during the 1980s and 1990s with major expansion of the cotton industry in the Darling River system.

  Two other industries that use a substantial amount of land and water are irrigated cereal crops (including rice) and cotton. Water use per hectare and profit margin per ML of water vary significantly between commodities. These factors, coupled with total water use, value of produce and export earnings provide a different perspective on the relative importance of various irrigation commodities. Overall, irrigated agriculture from the Basin makes a large contribution to the Australian economy, with crops such as cotton, rice, wine, sugar and dairy/livestock contributing to a multibillion-dollar export industry.

  Irrigation in the Murray–Darling Basin is nearly at the limit of the water resource , indicating that future expansion of irrigated agriculture will have to be delivered largely through productivity increases, more efficient delivery networks, and industry restructuring. While water for new developments has generally become scarce in Australia, this is particularly true for the Murray–Darling Basin.  At the same time, the irrigation industry is undergoing structural reform associated with changes in water marketing and pricing within a national framework for water resource policy and regulatory reform. This has resulted in a shift away from low-value activities such as mixed farming towards high-value crops such as cotton and horticulture. The development of the cotton industry in the Darling River system has been particularly spectacular, and can be compared with earlier developments in the rice and horticulture industries.

RATE OF WATERTABLE RISE 

In Australia, the most comprehensive information on regional rates of watertable rise exists for the irrigation areas of the Murray–Darling Basin. Watertables are rising at the greatest rate (about 100 to 500 mm per year) in the developments of the south-eastern parts of the Basin. The rise in salt transport rate in the Murray River at Morgan is slowing (see Fig. 2).

It is not yet clear whether the rate has slowed as a consequence of improved irrigation efficiency or because of are cent trend to a climate.   What is clear is that  the salt levels in the system rise sharply towards the mouth of the River Murray (Fig 3).

Although data on rates of watertable rise in dryland catchments are very limited, long-term observations indicate rises of many tens of metres in some regions since clearing began. Observation indicates that groundwater levels have increased by up to 30 m since the 1880s in some parts of south-eastern Australia. 

Unfortunately very few reliable data quantifying the rate of change of stream salt loads exist for any part of the Murray-Darling Basin.  Broad estimates of the rate of increase in salinity of the Murray River at Morgan, made in 1985, suggested a figure of about 1 mg/L/year, compared with an annual fluctuation of about 200 mg/L in river salinity. Preliminary analysis of salt loads in other streams in the Basin shows similar trends. 

SALINISATION 

In the large irrigation areas of the Murray–Darling Basin, which were established at the turn of the century , salinised surface soils, caused by imprudent land use, have been present for a long time.  In other areas, such as the dryland agricultural areas of central and northern New South Wales, salinity is regarded as a more recent phenomenon. However, it is difficult to assess the scope of the problem, as large areas of Australia lack long-term data. Available data sometimes conflict, indicating that standard definitions of relevant parameters are needed. The key indicators of environmental state are rate of rise of groundwater levels, area of land underlain by shallow watertables and rate of change of stream salinity. Generally all irrigation practices add water to underlying groundwater. If more water is being added than can move laterally in the aquifer, groundwater levels will rise. Unless the groundwater is highly saline, most irrigation-induced land degradation begins as waterlogging. After time, and depending on evaporation rates and degree of flushing, salt concentrations increase until they affect crop yield. Waterlogging alone also reduces crop yield.

In 1985, the Murray–Darling Basin Commission estimated that 360000 ha of irrigated land had shallow watertables, and 87 000 ha of land in the Victorian portion of the Basin were visibly salinised (MDBC, 1993).  The Wakool, Deniliquin and Murrumbidgee irrigation areas of New South Wales were estimated to contain 199000 ha of land with shallow watertables and 9000 ha of land that is visibly salinised (1985 figures, MDBC, 1993). By 1991, the area of land overlying high watertables had increased dramatically. For example, the salinised area in Berriquin (part of the larger Deniliquin area) had grown from 22 000 ha in 1985 to 91 300 ha in 1990. 

DRYLAND SALINISATION 

Dryland areas are those that depend solely on rainfall for plant growth. They are susceptible to hydrologic disturbance when deep-rooted native plants are cleared and replaced by introduced shallow-rooted crops that use less water. Under this regime more water then moves below the root zone, raising groundwater levels to a higher point in the soil profile and remobilising salts in the higher, previously unsaturated zone. Salt usually then appears at the surface after evaporation follows periods of waterlogging.

The Murray–Darling Basin Commission estimated that about 200 000 ha of the Basin suffered from dryland salinity in 1992 (although this is now regarded as an underestimate, MDBC, 1993),   and, while the scale of the problem is incompletely documented, in 1992 about 20 000 ha were recognised as salinised in New South Wales (MDBC, 1993).  In Queensland, about 10 000 ha were estimated to be affected in 1990. 

CATCHMENTS AND POLLUTABNTS 

  The natural character, human disturbance and management of catchments in the Basin control the nature and amounts of pollutants. Intensive land uses produce the most pollutants.

 Sources of sediments and phosphorus include land adjacent to streams, channel beds, banks and gullies. The relative magnitude of these sources varies across the country and through time.

  Fine sediments usually transport other pollutants such as phosphorus, pesticides and pathogens.  Nutrients also come from point sources like sewage-treatment plants, feedlots and urban and industrial run-off and discharge.  The relative importance of diffuse and point pollutant sources varies between catchments and with run-off, with point sources being more important in low-flow conditions and in areas of urban development and animal waste disposal.

  Increasing agricultural use of pesticides will result in increasing levels in waters with unknown biological and health consequences.  Other pollutants such as trace metals and synthetic organic chemicals are important in some localities, although their biological and health consequences are largely unknown.  For example, the leaching of nitrate to surface and groundwater from sewage, intensive animal industries, food-processing, fertilisers and natural sources is a potential human health hazard in some areas.  Higher levels of nutrients also contribute to destabilisation and change in riverine and riparian ecosystems.

ECOLOGICAL CHANGE 

  Since the arrival of non-Aboriginal people, reproduction and recruitment of fish in floodplain habitats of the Murray has been reduced and is now limited to small species such as gudgeons. Changes caused by humans in the water regimes of Australian wetlands include changes in water-level fluctuations (size, frequency and seasonality) and changes in water balance (input, output and seasonality), all of which affect their ecological health. Such changes have occurred to the majority of wetlands in the Murray-Darling Basin

Significant environmental degradation commonly occurs when major water inputs are reduced in flow or diverted. However, prolonging wetland flooding well beyond the natural pattern may also have significant impacts. The wetlands of the River Murray have a total area of about 2200 sq km, including the Coorong and Lower Lakes (Pressey, 1990). Some 35 per cent of the area that used to be flooded intermittently now never dries out, and 11 per cent receives irrigation water and now may be virtually permanently wet. Wetland and river habitats rely for their ecological health on their physical environment including temporal changes being maintained. In Australia, physical destruction or degradation of inland water habitats is widespread due to the removal of riparian vegetation, increased bank erosion, river engineering — including realignment, straightening and removal of trees — and construction of barriers to fish migration.

  Riparian zones influence habitat composition, stability and energy inputs, and act as ‘filters’ for the exchange of water, nutrients, sediments and pollutants between terrestrial and aquatic systems (Bunn et al., 1993). The majority of riparian areas in the Basin have been degraded since the arrival of non-Aboriginal people. Clearing of riparian vegetation for agricultural and urban development has been extensive in lowland sections of most of the Basin.

  A recent survey of the Murray and its side-channels found that riparian vegetation was in generally poor condition due to clearing, weed infestation, soil salinisation, grazing and regulation of flow (Margules et al., 1990). At least 30 per cent of the study area was cleared, and introduced weeds constituted 18–63 per cent of plant species. Regeneration of native trees, red gum (Eucalyptus camaldulensis) and black box (Eucalyptus largiflorens), was also affected.

  Bank erosion causes increases in sedimentation and changes in channel form, both of which have negative impacts on river health. The Murray River suffers conspicuous bank erosion, where slumping of banks follows rapid drops in water level. An estimated 1.8 million tonnes of material fell into the lower Murray River over a 153-km section in 1988–89 alone (Walker, 1992) and channel-widening has averaged 16 cm per year since 1977 in the Lake Hume–Lake Mulwala reach (Tilleard et al., 1994).

  Storages trap sediment, increasing river erosion immediately downstream. Impoundments trap up to 73 per cent of sediment in the Murray River (Thoms and Walker, 1992), and at least 50 km of river could be deepened substantially from its sediment supply being trapped in the Hume Reservoir (Tilleard et al., 1994). The 180-km Hume–Lake Mulwala reach conveys all the regulated flow destined for downstream use. Here, channel changes include lateral migration of bends, channel deepening and widening, and side-channel development. Regulation has also slowed development of key side-channels. The river bed between Hume Reservoir and Albury has deepened by up to 24 per cent since 1977. 

River engineering works, designed to provide improvements for human use, have often caused river ecosystems to deteriorate. Along the Goulburn and Upper Murray Rivers some 870 and 400 stream-management works respectively, have been recorded, resulting in serious environmental degradation. Levee-bank construction separates rivers from their floodplains, as it has done for the Murray River downstream of Mannum, and in many other areas of the country. Desnagging — the removal of logs and wood debris from river channels, usually to facilitate the passage of water or boats — results in loss of biological habitat and increased stream erosion. Extensive desnagging was carried out in lowland reaches of the Murray–Darling Rivers until road and rail transport replaced paddle steamers (Pressey and Harris, 1988). Desnagging and willow removal in the Barmah Choke section of the Murray River have reduced overbank flows at the Edward River and Gulpa Creek off-takes for a distance of about 20 km, affecting the health, growth and reproduction of trees in the Millewa Forest (Murphy, 1990).

  The modified temperature regime in the Murray River downstream of Hume Dam does not vary as much as the natural one, and seasonal changes are offset by about one month (Walker, 1985). Such effects are evident for between 40 and 100 km below several dams in the Murray–Darling Basin. Summer oxygen levels reflect the discharge of oxygen-poor bottom water. Such changes have caused major disturbances to the biology of several Australian rivers. Examples include the loss of native fish and invertebrate species and their replacement with exotic species such as carp, trout (Salmo and Oncorhynchus sp.) or redfin perch (Perca fluviatilis).

  Many of the Basins rivers and wetlands are saltier than they were before the arrival of non-Aboriginal people although some are fresher, causing changes in their fauna and flora (Hart et al., 1990, 1991). Salt-affected streams occur throughout Victoria and salinity levels in the Yass River, New South Wales, are increasing by seven per cent per year, while salinity in the River Murray increases downstream( McKay & Eastburn, 1990).

  Many species of inland-water fish migrate over long or short distances to complete their life cycles. Blocking of fish migration by dams, weirs and fords has resulted in population declines in many coastal catchments. Some of these structures have fishways, but many of these are not properly designed or maintained. Twenty fishways are recorded in the Murray–Darling Basin, but none is on high-level (10m or more) dams and only two have been assessed as being effective as fish passages . Golden perch and silver perch were once common as far upstream in the Murray River as Lake Hume, but have now disappeared above Yarrawonga Weir.

  Dams also have the potential to cause genetic isolation of fish populations, with accompanying loss of genetic diversity.  The complex and multiple changes to the quality and extent of Australian inland water habitats have caused fundamental shifts in the structure and function of ecosystems and the composition of biological communities. There is certainly scientific evidence for major changes in Australian inland-water- ecosystem structure and function as a result of changes in habitat. But, as yet no published information is available on the extent to which such changes have occurred at a national or even regional level, other than for wetland and riparian vegetation. 

Indicators of change in the biota of inland waters include changes in the distribution and abundance of native fauna and flora and measures of the impacts of introduced and displaced biota, including aquatic weeds and faunal pests.  Although scientists routinely carry out widespread monitoring of water storages for plankton, there is little information on the composition of algae in other inland waters that can be used to assess the impacts of human activity. However, it is likely that the incidence of algal blooms, particularly of nuisance blue-green algae, has increased, suggesting widespread reduction in the diversity and stability of ecosystems in agricultural and urbanised catchments.

  The composition and abundance of planktonic algal communities varies widely over different places and times, making it difficult to measure trends.  Habitat degradation has reduced the range and diversity of many aquatic plant species, especially in eastern Australia. Of our many different aquatic plants, five species are currently considered endangered (ANZECC, 1993).

  Macroinvertebrates, which include aquatic insects, are both diverse and abundant in inland waters. They are surveyed to assess human impacts on aquatic ecosystems as changes in their communities are often affected by changes in water and habitat quality in Australian wetlands and rivers. The River Murray crayfish (Euastacus armatus) has declined in range and abundance since the 1940s (Walker, 1985) and 13 out of 14 native snails have disappeared from the banks of the River Murray due to artificial changes in water level (Walker, 1994). 

  Native fish species have suffered declines in abundance and diversity since the arrival of non-Aboriginal people. Surveys in Victoria indicate that only two out of 17 segments of river basins still have high-quality native river fish populations. Similar evidence exists for most of the country. Most species of the lowland river fish, including the Murray Cod (Maccullochella peeli), trout cod (Maccullochella macquariensis) and Macquarie perch (Macquaria australasica), have declined in range and abundance.  Three aquatic mammal species are found in the Basin : the platypus (Ornithorynchus anatine), water rat (Hydromys chrysogaster) and false water rat (Xeromys myoides). Of these, only the platypus is restricted to fresh water. Decline in platypus abundance or range indicates severe changes in environmental conditions. Platypuses are still known throughout their original range, but frequently have locally reduced populations — for example, in the lower Murray River and Murrumbidgee rivers .

EXOTIC/DISPLACED FAUNA AND FLORA IN INLAND WATERS 

  The introduction of exotic aquatic fauna into Australia, and the movement by people of native species or stocks to areas outside their natural range, have a profound effect on the ecosystems of the Murray-Darling Basin.

  Fauna have been introduced mainly for recreational fishing and the aquarium and aquaculture industries. Twenty exotic fish species have established or are likely to establish self-sustaining feral populations. Many of them were introduced in the 1800s and early 1900s and their spread has often been helped by active translocation (McKay, 1984). The aquarium industry imports increasing numbers of exotic aquatic species each year — worth some $2.7 million in 1994 alone. Nine species of these aquarium fish have now established feral populations. Some, like the guppy, Poecilia sp., have wide distributions. Accidental or intentional releases of exotic aquarium species are seen as a principal cause of new introductions into Australian inland waters.

  Populations of exotic fish have become established with the most widespread being the brown trout (Salmo trutta), mosquito fish (Gambusia holbrooki) and several species of cyprinids — the goldfish (Carassius auratus), European carp, redfin perch and tench (Tinca tinca). All of these species have aggressively expanded their ranges since first introduction, most with human assistance. Trout and salmon have been stocked intensively since the late 1800s, although climate has largely limited the expansion of their range. European carp has rapidly extended its range and continues to do so. The Boolara carp strain expanded rapidly into the Murray–Darling Basin during the 1970s and 80s.

WATER MARKET REFORM AND IRRIGATION INDUSTRY RESTRUCTURING  

As well as undergoing recent expansion in some sectors, the irrigation industry is being extensively restructured. This is because of changes in water pricing to seek full cost recovery, separation of water property rights from land title and the ability to trade in water allocations, the emergence of major environmental problems — such as rising watertables and salinisation — and continuing reductions in farmers’ terms of trade. Restructuring involves difficult decisions by irrigators and agency managers, and may involve considerable pain for individuals and communities. However, restructuring is necessary to ensure a profitable and sustainable future for the industry, based on the full economic cost of water.

  In areas of mixed farming, such as the western edge of the riverine plains between Kerang in Victoria and Wakool in New South Wales, broad-scale flood irrigation is now only marginally profitable. As a result of proposed economic reforms and environmental constraints imposed by salinisation, many irrigators may decide to sell their water allocation and retire their properties from irrigation. Regions not suited to sustainable irrigation will decline in prosperity, although alternative dryland agricultural industries may develop. By contrast, irrigators in more suitable regions may purchase water from the market, invest in upgraded delivery systems and increase more-profitable activities such as cotton-growing, horticulture or dairying. Expansion of irrigation in areas such as the Sunraysia and Riverland regions of the southern Murray–Darling Basin is likely to increase prosperity in those regions. Additional changes are also occurring, including aggregation of farms into larger units to achieve economies of scale, adoption of improved production technology, particularly in relation to inputs of water and nutrients, and training of irrigators in management and marketing.

  The large-scale restructuring of the industry should lead to greater water-use efficiency, as well as sustainability and improved profitability.   Adoption of best practice methods for all land uses, including urban, industrial and rural, has the potential to bring about substantial improvements in the quality of inland waters. Such methods are being devised through world-wide benchmarking as well as through experimental jointly funded programs like Landcare, a unique Australian program promoting community approaches to land and water management. 

ENVIRONMENTAL FLOWS 

  Australians generally are starting to realise the environmental consequences of the post-war development of Australia’s water resources — among them, disappearing wetlands, and rivers containing too little water at the appropriate times for various fish and bird species to breed. Re-allocating water for environmental purposes, or so-called ‘environmental flows’, now receives serious consideration – and nowhere more seriously than the Murray-Darling basin. Few resolutions have yet been achieved, but balance between economic and environmental needs is central to the discussion.

In 1996 the Prime Minister’s Science and Engineering Council recommended that provision of water for the environment should be a major component of the strategic framework for the reform of the water industry Australia wide

The most useful indicator of the impact of water resource use on the non-human environment is the amount of water abstracted from the river systems each year. Unfortunately, data are not consistent enough to show such an indicator through time. Australia has the highest per capita storage capacity of all countries in the world, as a result of dryness and variability of climate. In parts of both the Murray–Darling Basin and eastern seaboard,  water is grossly over-allocated and demand continues to increase. Over-allocation is placing aquatic environments under severe stress in these regions.  A key response to this problem has been the imposition of a limit or cap on water allocations.  

  The cap limits the amount that can be taken from the rivers of the Murray-Darling Basin to what could have been diverted under the 19993/94 levels of development – the last full year of irrigation before its introduction.  This is the amount of water that could be used with the management rules and level of infrastructure, the capacity of the pumps and channels, the size of form dams, the areas developed for irrigation –that prevailed at that time.  Although set at 1993/94 levels of development, the Cap has the flexibility to take into account different usage in wet and dry years.

Simply halting further diversions will not suddenly eliminate carp or enhance native fisheries; neither will it eliminate blue-green algal blooms or restore wetlands.  However, it is a critical step towards slowing the rivers decline.  The damage we are now seeing is the likely result of the levels of exploitation a number of years ago, when diversions were lower.  The effects of today’s diversion levels may not be fully appreciated for decades to come.  There is still argument that setting the Cap at the current level of diversions will not stop the river deteriorating.  Further research on the levels needed for environmental activity is being urgently undertaken by many academic institutions.

  The Cap was introduced with the intention of limiting diversions, not future development.  However, water needs for new developments have to be met from within the Cap.  Across the Basin at least 14% of gross water consumption is lost during transmission – through leaky channels and evaporation.  Projects that create a more efficient water delivery network will free up water for the environment or future developments. 

Unused water allocations can be traded annually or permanently.  The potential environmental benefits from water trading are considerable.  Trading encourages more efficient use of water – allocations that are not used can be sold.  Trading allows the movement of irrigation to properties that have the most suitable drainage and soils, reducing existing environmental problems such as rising water tables and river salinity.  Water trading will have an impact on the environment.  The impact of diversions can be exacerbated or lessened, depending on where along the river they are taken.

As well as aiming to produce economic efficiencies, water trading should have an environmental goal; namely an attempt to restore natural flow patters to the river.  In unregulated and perhaps summer rainfall rivers, diversions will have less impact the further downstream they are taken.  Conversely, rivers that run at unnaturally high levels during he irrigation season will be impacted less by diversions that are taken as close as possible to the reservoir so that more natural, lower flows are achieved downstream.

LONG-TERM MONITORING 

Monitoring provides data that can be used to indicate broad and specific changes to background environmental conditions as a result of both natural and man-made pressures.   Appropriate monitoring, using agreed indicators, will be vital to test the effectiveness of environmental flows.

Long-term monitoring is critical for providing data that highlight trends in a system — whether it is improving or degrading further. At times, data may need to be collected over long time periods for the significance of change to be fully apparent. Although people who collect and interpret data know this only too well, governments themselves often need to be convinced of the role of monitoring and the importance of long time-series data. In a period when many government agencies are undergoing severe financial restrictions and perpetual restructuring, and adopting shorter planning perspectives, agencies are reducing monitoring or even ceasing it in some areas.

This is particularly significant for basic hydrographic monitoring — formerly managed by State Government water authorities. Many have cut back only to areas of immediate interest for possible water resource development. However, the data agencies used to collect are often critical for many other areas of research and monitoring, such as flora and fauna and nutrient loads.

  In the Basin, long-term monitoring of critical sites provides the only way of detecting change in the environmental state, and of estimating the rate of change and its significance.

The National Land and Water Resources Audit

  The National Land and Water Resources Audit, a special monitoring effort, will foster more rigorous natural resource management decision making, by collating and presenting data on Australia's land, vegetation and water resources. Additional to developing an Australia wide data framework, seven themes group the key natural resource management issues facing Australia's decision makers and provide the basis for Audit activities.  The key focus for these Audit themes is to place the status and trend in  resource condition in the context of current management response and options for remedial action, development and protection – recognising that natural resource management includes biophysical, social and economic components.

The National Land and Water Resources Audit's Audit terms of reference require a National Water Resource Assessment to be undertaken. This assessment is the fourth water resource assessment undertaken in Australia over the last 40 years. The most recent assessment being the "1985 Review of Australia's Water Resources and Water Use" (Review 85) conducted under the auspices of the Australian Water Resources Council.

The focus of the Audit's water resource assessment is to build on, and significantly extend, Review 85 data and make it available in readily accessible format.  Additionally, it will provide information on the status and trend in water resource use and availability. This assessment is being done in the context of water resource management activities of the States and Territories. Options for management activities, resource development and protection will also be explored. Unlike the water resource assessments of the past the Audit's legacy will be a data management framework for synthesising and reporting water resource data into the future. These activities are being undertaken by the Audit in partnership with Australia's State and Territory agencies.

The Water Availability Theme activities will characterise each of  Australia's surface water and groundwater resource systems in terms of water availability, use, allocation and management regime. On the basis of this characterisation each catchment is to be categorised according to the degree of water resource commitment and management responses, taking account of consumptive and environment water requirements. 

  A broad assessment of future potential for development will also be undertaken. Management actions for Australia's water resources will be identified in the context of the COAG Water Reform and Ecological Sustainable Development objectives. In combination with other Audit activities, particularly the Health (catchment/ river /estuarine ecosystems) Theme, a report card for each of Australia's catchments will be prepared.

MURRAY–DARLING BASIN INITIATIVE 

As a response to many of the management challenges outlined above, the Murray-Darling Basin Commission has developed a  program to promote and coordinate effective planning and management, for the equitable, efficient and sustainable use of the land, water and other environmental resources of the Basin. It relies on the Australian government, the four State governments concerned — New South Wales, Victoria, South Australia and Queensland and the Australian Capital Territory working together with the people of the Murray–Darling Basin community to implement and achieve its goals (MDBC, 1990; 1993; 1995). The Initiative is one of the largest integrated catchment management programs in the world, encompassing more than one million sq km.

The key to the Initiative is the Natural Resources Management Strategy, released in 1988, which provides philosophical and organisational structure for governments and communities to coordinate their work.

The Strategy aims to:

·        maintain or improve water quality through  ongoing research into the problems affecting catchment areas and the run-off entering rivers

·        control and, where appropriate, reverse land degradation

·        protect, and in some cases rehabilitate, the natural environment

·        conserve the cultural heritage

Two funding programs support the Strategy: the first covers investigations and education, and the second integrated catchment management. The former finances the research needed to study the resource management problems facing the Basin and to develop solutions and management tools to treat them. The outcomes are then translated and implemented into practical on-the-ground solutions under the second program, which is based on integrated regional land and water management  

The Murray–Darling Basin faces grave and worsening degradation of its land and water. The development of an appropriate structure for its management has been a long and painful process. The Murray–Darling Basin Commission Natural Resources Management Strategy brings this process to maturity — as perhaps best demonstrated by the Council’s landmark decision to implement the cap and promote environmental flows.  But it doesn’t end there, monitoring and adaptive management are the two key elements to actually achieving a sustainable river basin in the next few decades.

REFERENCES 

ANZECC (1993).  ‘List of Threatened Flora.’ (Australian Nature Conservation Agency: Camberra.)

Bunn, S.E., Pusey, B.J., and Price, P. (eds) (1993). Ecology and management of riparian zones in Australia. Land and Water Resources Research and Development Corporation Occasional Paper Series 05/93. 

Hart, B.T., Bailey, P., Edwards, R., James, K., Swadling, K., Meredith, C., McMahon, A., and Hortle, K. (1990). Effects of saline discharges on aquatic ecosystems. Water Research, 24, 1103–17. 

Hart, B.T., Bailey, P., Edwards, R., Hortle, K., James, K., McMahon, A., Meredith, C., and Swadling, K. (1991). A review of the salt sensitivity of the Australian freshwater biota. Hydrobiologia 210, pp. 105–44.  

Margules and Partners Pty Ltd, Smith, P. and J., and Dept of Conservation, Forests and Lands Victoria (1990).  ‘River Murray Riparian Vegetation Study.’  (DCFL: Melbourne.)

Mackay, N., and Eastburn, D. (eds) (1990).  ‘The Murray.’  (Murray-Darling Basin Commission: Canberra.)

McKay, R.J. (1984). Introduction of exotic fishes in Australia.  In ‘Distribution, Biology, and Management of Exotic Fishes’, eds W.R. Courtenay Jr. and J.R. Stauffer Jr., pp. 177-99.  (Johns Hopkins University Press: Baltimore, Maryland.)

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