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  Proceedings of the Second National Conference of the Native Grasses Association
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Salinity in the Goulburn Broken Dryland

Mark Cotter

Goulburn Broken Dryland Co-ordinator

The Goulburn Broken Catchment

Catchment description

The Goulburn Broken Dryland covers an area of 2.3 million ha. The catchment of the Broken River is about 300,000 ha and the Goulburn about 2 million ha. The lower Goulburn, part of the Shepparton Irrigation Region is around 500,000 ha.

The catchment extends from north of Woods Point and Marysville in the south to Yarrawonga in the north and from east of Mansfield through to the Colbinabbin range in the west.

About 600,000 of the dryland catchment remains forested. Much of the land was cleared in the past 150 years.

The climate varies from hot summer/cool winters in the north, with rainfall of around 600mm, to mild summers/cold winters in the south-east and rainfall greater than 1200mm

With regard to salinity the Goulburn Broken catchment can be divided into five sub regions based on hydrology and geology, the Goulburn Highlands, the South West Goulburn, the Goulburn Plains, the Broken Highlands and the Broken Plain

Cropping and grazing is the dominant land use on the Plains country. Grazing dominates the foothills country and uplands. There is an increasing level of high value land use, including viticulture and horticulture, as well as intensive animal industries, including horse breeding and pig and poultry production. Much of the foothills country is also subject to pressures for land development for recreational and hobby farmers, mostly in the southern areas but extending north of Benalla

The dryland supplies water to the Shepparton Irrigation Region, and, at the same time, exports over 90,000 tonnes of salt annually into the SIR.

Figure 3 Salt distribution from the Goulburn Broken dryland

The river salinity at Morgan, on the Murray River in South Australia, is the benchmark for the condition of the Murray Darling Basin. The salt loads leaving the catchment result in an increase of 24.2 EC at Morgan.

Figure 4 Salinity sub regions in the Goulburn Broken Catchment. Information provided by GIS unit Benalla DNRE

Salt loads in the Goulburn Broken

The salt load from the dryland is currently estimated to be 260,000 tonnes each year, with an annual median flow of 4,500,000 ML annually. The recent Murray Darling Basin Commission salinity audit pointed to the risk of the salt load form the Goulburn and Broken doubling over the next 50 years.




Stream flow

Salt load

Salt load/area







Goulburn highlands






South west Goulburn






Goulburn Plains






Broken Highlands






Broken Plains






Goulburn Broken catchment






Highest total salt loads arise from the Goulburn highlands but the most active area is the SW Goulburn catchment which accounts for about 30% of the total load in the Goulburn Broken catchment but only makes up 17% of the catchment area. The south west Goulburn includes Sunday, Dry, Kurkurac, Mollisons and Majors Ck.

Threat to streams

Despite the high salt loads the Goulburn Broken, as a rule, does not record high stream salinities.because of the high flows in the system. There are some exceptions, notably Hughes and Whiteheads Ck and the lower reaches of Sunday Ck which reach peak salinities of up to 8000 EC in periods of low flow.

The Broken system generally has higher salinity levels but because of the comparatively low flows it poses less of a risk to the River Murray than the Goulburn system.

Threat to land

The area of discharge is difficult to assess because of the strong influence of seasonal conditions, but the current estimates are that around 4,000 ha of land is affected by class one salinity or worse. The area of salt affected land is likely to double to around 7,000 to 8,000 hectares, most of this will occur on the north Goulburn and Broken plains area. High water tables will affect 30,000-40,000 ha of this area in the next 30 years, which means waterlogging is set to become a major problem

Understanding salinity

Our understanding of salinity processes has improved enormously over the 11 years of the Plan's existence.

The processes of upland recharge have been separated from discharge processes on the Plain, the extent of connectivity is now known to be low. This means that the Plains area is a largely a self recharging system. Until recently this area has been treated as a hydrologically homogenous area. Of course this was too simplistic. The area is dissected by prior streams and geologic intrusions (minor) which serve to increase the average recharge rate of the Plains area..

Discharge to land at the foothills of the Strathbogies is the result of a difference in the rates of transmission of groundwater due either to geological formations or changes in soil characteristics from the more permeable soils of the foothills to the heavier, less permeable soils of the Plains. The latter process also affects sub surface flow.

It was also assumed that the Goulburn Highlands and South West Goulburn were reaching equilibrium, ie. the amount of salt leaving was unlikely to get much worse. Recent studies have dispelled this misconception but have also highlighted a deficiency in our understanding of the processes by which salt reaches the streams; particularly whether salt ingress is dominated by baseflow or wash-off processes. Knowledge of this is critical to our understanding of the response time of the groundwater flow systems which is important to identifying equitable cost share arrangements across generations.

Groundwater Flow Systems

The results of a nation wide program, the national Catchment Classification system, have led to the definition of nine groundwater flow systems in the Goulburn Broken Dryland. These groundwater flow systems have been classified on such criteria as landform, type of regolith, groundwater aquifer characteristics, catchment size, groundwater salinity, size of salt store, temporal and spatial distribution of recharge, dominant process for salt entry to the streams, likely equilibrium response time and the most likely spatial distribution of impacts.

The groundwater flow systems vary from highly fractured local groundwater systems with relatively quick reaction times through to deeply weathered intermediate systems to extensive regional systems where response times are measured in hundreds of years.

In terms of developing a response the key considerations are the location and size of salt loads, the risk of them being mobilised, the equilibrium response time, and the likely success of management options.

The aims

Achieving our aims under the Salinity Management Plan is a balance between protecting key assets, ensuring continuity of adequate supply of good quality water to downstream users and living with a changed landscape.

Much has been made of our response being one of large scale landscape change and that will be the case but only for specific areas, where the community agrees and then only if the cost share arrangements are equitable and reflect the true costs to land managers.

Figure 2 provides evidence of the significant shift in recharge rates as a result of land clearing since European settlement. For example the SW Goulburn and Goulburn Highland have similar hydrological characteristics but differ in the extent of clearing. Some 40-50% of the vegetation in the Goulburn Highlands remains intact, in the SW Goulburn this is less than 20% and much of that is associated with Majors Ck sub catchment and the army base at Puckapunyal.

These figures highlight the enormous difficulty of trying to restore any semblance of some prior hydrologic balance. It is not only a question of whether it is technically feasible but also whether the community is prepared to invest the resources the task requires. Whether or not the community can justify the investment depends on defining the trade-offs required.

Figure 5 Mean annual recharge for sub regions of the Goulburn Broken catchment


The future management of salinity will involve identifying trade-offs for a number of issues. Most obviously will be trade-offs for the level of recharge and potential discharge management with the extent of conventional land use practices. Other trade-offs will be between the economic and social viability of their community and the damage to the natural assets they affect. Across the catchment there will also be trade-offs between supply of surface water to the Shepparton Irrigation Region and protection of assets in the dryland.

The mechanisms to negotiate and manage these trade-offs are yet to be developed. The emergence of markets and definition of services provided by our ecosystems are a key part of developing a suitable framework. Just as important is the provision of information and the mechanisms that allow full community participation. In many ways the Goulburn Broken is better placed than other catchments because of the strength and success of the Catchment Management Authority structure.

The tools

There is a range of tools available for us to deal with salinity. Briefly they can be categorised as farming systems, engineering options or living with salinity. Which activities are best suited and in what proportion they are used depends very much on the outcomes sought.

Farming systems

For the most part farming systems that do not include deep-rooted perennial vegetation are ineffective in controlling recharge, especially in areas of above 600 mm of rainfall.

The farming systems of the future will be a combination of using some leaky systems because, for the foreseeable future, they remain profitable. We will, of course, be working to minimise this `leakiness' in clearly defined high risk areas or where it can be clearly demonstrated that wider community needs have to be addressed. We will also be managing the degradation of the landscape using alternative production processes or land retirement.

Our knowledge of where salt is likely to discharge in the landscape is improving quickly. Our biggest technical challenge is getting the knowledge of where to target recharge remediation works at more than 1:25,000 scale.

Role of native grasses

There are four groundwater flow systems where native grasses have the potential to play a major role in recharge management:

  • Local and intermediate weathered fractured sedimentary rock (Sheep Pen Ck, Majors Ck)
  • Local and intermediate flow systems in the fractured basaltic rock (Mt Camel Range, Dookie Hills)
  • Local and intermediate `systems' in Riverine Plain (Tungamah, Devenish)
  • Local flow systems in the weathered granites (Strathbogies)

This classification is based on the characteristics of the regolith and, to a lesser extent, rainfall

Key challenges are promoting the appropriate best management practices for enhancement of native grass pastures and linking together, in higher rainfall areas, the combination of high density tree planting and native pastures.

There is also evidence that there is an increasing trend, in parts of the catchment, to voluntary land retirement, brought on by economic considerations and perhaps an ageing of the farm population. Whether or not this proves advantageous to the spread of native grasses will depend on our ability to develop almost zero input management options for the enhancement of native grass pastures.

Although much of the current debate revolves around the potential impact of dryland salinity we do not want to lose sight of the other values that native grasses have. Salinity is the `big' issue and the one that is currently in the headlines. However we do not have to think too far back to when the Darling River was nearly shut down because of blue-green algae outbreaks. In our own catchment the blooms on Lake Mokoan have almost become an annual event.

Native grasses have an important role for the protection of our water quality, often in areas where they would otherwise provide minimal benefits for salinity control.

One of our most depleted resources in the Goulburn Broken is our Plains Grassy Woodlands. Only 2% of the pre-European coverage remains. We know very little about restoring these grasslands and in fact we are flat out protecting what is left. We need cost effective means to enhance and, hopefully extend on what currently exists.


Engineering options remain, most times, an option of last resort, due largely to their cost and often unacceptable political consequences. The exception is groundwater pumping which is readily adopted where there are supplies of reasonably fresh groundwater with adequate yields and the means to use the water on farm. The success of groundwater pumping is obviously linked to the opportunities for high value production viticulture and the like.

It is likely in the future there will be increased demands for engineering solutions but in order for them to be viable there has to be a strong case for protecting assets of very high value. It is a knotty problem to decrease at what stage assets become worthy of protection, particularly if the value has a strong qualitative component, for example the protection of isolated communities.

Living with salinity

The size of the problem and the slow response times of some groundwater flow systems means that we will be living with a greatly degraded landscape in localised areas of the catchment.

To this end there will be more effort in managing degraded land. We will continue to support research into and landholder efforts in finding alternative land use options. Of course the nature of the problem means there is little else we can do until it manifests itself. We expect that up to 5% of the landscape of the Goulburn Broken will be affected by salinisation.

Most of our efforts will stay focussed on protecting the supply of water to downstream users and protecting key assets within the catchment.


To simply maintain the status quo, to prevent the problem getting any worse would take an investment of seven million dollars annually for fifty years. The problems in the catchment community are repeated many times across the Murray Darling Basin and across Australia. The resource requirements are well beyond the reach of the State and Federal Governments within the current taxation arrangements.

In order for us to go the next step it is critical that markets be developed that allow private investors to trade in natural resource commodities. The development of vegetation banks and credit trading markets will be the single biggest breakthrough in the battle against dryland salinity.

At the same time we have to realise that there are biophysical limits on what is achievable and social and political limits on what is desirable. The community, from the Basin down, needs to be able to negotiate acceptable outcomes.

We have to disavow ourselves of the notion that there is the potential for a win-win outcome. There will be losers in any negotiated outcome. Our responsibility is to ensure that the outcomes are equitable and that the transfer of benefits reflects this.

As for native grasses, they have the potential to play a role in the fight against salinity, moreso when used in conjunction with other remediation techniques. And although salinity is the current issue, the role of native grasses in the key areas of maintenance of water quality and particularly in the enhancement of biodiversity should remain a significant focus of future work.

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