Kamarooka Project.htm

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An innovative approach to salinity management at Kamarooka
in North Central Victoria

During 2003 the Northern United Forestry Group (NUFG) decided it was time to tackle the salinity issues at Kamarooka in North Central Victoria. The group put a proposal to the Federal Government outlining their willingness to undertake a program of works that would see barren saline land transformed into an attractive environment supporting saline agricultural production and salt tolerant ecosystems.

The NUFG was successful in gaining funding for the project and in 2004 and 2005 has been involved in analysing soils, preparing strategies, understanding options, and re-vegetating the land.

The Kamarooka project aims to establish and manage halophytic vegetation (largely saltbush) on the most degraded salt affected land, along with salt tolerant native trees, shrubs and grasses in adjacent land moderately affected by salinity.

The Northern United Forestry Group acknowledges the wonderful opportunity to attempt to recover the saline wastelands at Kamarooka for the purposes of both ecological function and agricultural production. NUFG gratefully acknowledge assistance from the National Landcare Innovation Fund in helping make this dream a reality.

The Kamarooka region is approximately 20 kilometres north of Bendigo in Central Victoria. It straddles the junction of the northern foothills of the Great Dividing Ranges with the vast alluvial Riverine Plains of the south-eastern sector of the Murray-Darling Basin.

Undulating hills in the central and southern parts of the region represent the northern extremities of outcropping fractured and folded sedimentary rocks of Palaeozoic age that form most of the Great Dividing Ranges in Victoria. At Kamarooka these rocks are deeply weathered and decayed. Water circulating through the upper most 50 to 60 metres of this landscape over long periods of time has reduced sandstones and shales to much softer kaolin rich clays. The landscape, thus, has a 'soft' gently undulating appearance with little rock outcrop.

The sedimentary rocks are part of a much larger saucer-shaped group that form a giant depression extending from the upper-most regions of the Great Dividing Ranges out into areas of northern Victoria, southern NSW and much of the eastern sector of South Australia. This depression, the Murray Basin, in it's lower extremities is filled with layers of gravel, sand, silt and clay derived largely from erosion of the uplands to the south.

The low north-south ridge at Kamarooka, broadening to undulating hills in the south comprises the weathered bedrock system. The much flatter lands to the north and west comprise the overlying much younger alluvial sediments of the Riverine Plain. It is along the interface between these two systems that salinity occurs. Slow moving groundwater, migrating down-slope through the bedrock system, is progressively inhibited by the presence of clay associated with both decayed bedrock and the alluvial plains. Beyond the junction with the flat lands of plains there is little hydraulic capacity to sustain groundwater flow and the consequent reduction in hydraulic efficiency realises high groundwater pressures along the break of slope. This reduction in transmissive capacity is accompanied by saline groundwater discharge to the land surface along the interface between the two systems.

Saline land occurring at the juncture of weathered bedrock and the alluvial plains at Kamarooka

Dryland salinity first became evident at Kamarooka in the mid 1950s. Prior to that time the watertable along the interface between the weathered bedrock systems and the plains had been rising in response the clearing of native vegetation and the development of agriculture. The change in land use realised an increase in runoff and increase in the volume of rainfall reaching the groundwater system. The increase in the volume of groundwater flow out of the bedrock system was beyond that which could be accommodated by the hydraulic barrier at the break of slope coinciding with the juncture with the Riverine Plains. A build up of hydraulic pressures at this point saw groundwater pressures rise and this ultimately realised saline groundwater discharge at the land surface.

Changes in hydraulic conditions that realised salinity at Kamarooka were fuelled by a remarkably small change in the water balance. Indeed the current area of groundwater discharge is easily accounted for by an increase in groundwater recharge (rainfall reaching the groundwater system) of just 20 millimetres (mm) per year throughout the catchment. This is only about 5% of the average annual rainfall.

This small increment in the water balance causing salinity was seen, several years ago, as good news because it seemed at the time that the aberration in the water balance could easily be redressed through alternative farming systems that made greater use of the rainfall. Unfortunately, however, further research revealed that the groundwater system was so sluggish that even if the original water balance under native vegetation was restored several decades would be required before the existing hydraulic conditions would be overturned to the point where any tangible salinity benefits would be realised. Sustained salinity and groundwater discharge after eight years of low rainfall and little or no recharge to groundwater provides very strong supporting evidence of this condition.

The hydraulic conditions that drive the groundwater system and the salinity issue are a little more complex than described above. Erosion over time has stripped the ancient deeply weathered land surface from the upper catchment, and the fractured rock aquifer is now either exposed at the land surface or has only a minimal soil cover separating the fractured rock from land surface. In this region it is much easier for rainfall to enter the aquifer, particularly where the land is lacking deep rooted vegetation.

Water entering the groundwater system migrates down the catchment through the fractured rock aquifer. It moves very slowly down the slopes where it encounters the remnant deeply weathered landscape comprising salt laden bleached kaolin rich clays. This material thickens toward the plain and reduces the transmissive capacity of the aquifer progressively increasing groundwater pressures. Groundwater pressures are further increased at the junction with the plains in response to a substantial reduction in hydraulic gradient at the break of slope. This increase in groundwater pressures forces saline groundwater in the fractured rock some sixty metres below the saline area to rise to the land surface producing a zone of saline land some 200 to 500 metres (m) wide.

The fractured bedrock under the catchment provides the conduit that connects higher groundwater heads in the catchment to the saline groundwater discharge area at the junction with the Riverine Plains. Elevated groundwater in the catchment drive groundwater discharge in the saline zone. In understanding this condition it is apparent salinity mitigation through re-vegetation of the discharge area is an unlikely outcome since high groundwater pressures will be sustained irrespective of intervention in the saline lands.

The wisest course of action is, thus, one of adapting to saline conditions through the adoption of salt tolerant agriculture and re-vegetation in an effort to produce more salt tolerant native ecosystems.

Saline groundwater rises close to the land surface along the break of slope that marks the boundary between the subdued bedrock hills to the south and east of the region and the Riverine Plain to the north and west. Driven by hydraulic pressure in the fractured rock that lies buried some sixty metres below the saline area, groundwater rises to within 1 - 2 metres of the soil surface. Where it reaches within 1.5 metres of the land surface clay soils draw it up by capillary action and evaporation further concentrates salt in the topsoil. This phenomena is apparent in the following graph that plots soil salinity with depth.

Below a depth of about 20 centimetres (cm) soil salinity is very high but relatively constant at
about 4.0 dS/m (1:5 soil water extract). Here the soil is saturated by saline groundwater being drawn up from the watertable by capillary action. In the upper 20 cm salt is seen to further accumulate through evaporation at the soil surface raising salinity to between 12 - 20 dS/m.

The graph also illustrates alkaline conditions occurring below a depth of about 20 cm. This is a reflection of the presence of calcium carbonate nodules (lime). These nodules most probably originated as wind-blown dust introduced under the very arid conditions that prevailed throughout south-east Australia during the last ice age (about 18,000 years ago).

Given that the salinity problem at Kamarooka cannot be fixed in a timeframe acceptable to most people, there is a need to consider other options. Engineering options involving pumping to remove saline groundwater are sometimes an option where there is an aquifer (gravel/sand/fractured rock) that permits reasonable rates of groundwater extraction. Unfortunately, however geological and geomorphic conditions beneath saline land at Kamarooka are not suitable for groundwater pumping. The most promising option is likely to be the development of saline agricultural and ecological systems adapted to saline conditions. Whilst this strategy is unlikely to realise benefits in reducing salt loads to streams of the region, it does affords great potential for gaining production from barren land, as well as affording greatly enhanced ecological function through restoration of biodiversity.

In April 2004 plans for revegetation were drawn up and works commenced. The group identified the areas to be re-vegetated with native trees, shrubs and grasses and soils were deep ripped to support sowing and establishment.

The group also investigated varieties and sources of saltbush and native vegetation, and determined the most appropriate forms of establishment and agronomy.

Extensive soil tests were conducted by a member of the group, and these revealed that sub-soil salinity varies from about 2-4 dS/m, in soils that most often have an alkaline pH of around 8-9.

Native vegetation was established in the less saline lands adjacent to the severely saline groundwater discharge zone, and halophytic vegetation, principally Old Man Saltbush, was established on the most salt affected soils.

Early preparation for sowing of native vegetation and halophytes

In April 2004 students from the East Loddon P12 College at Dingee visited Kamarooka and became actively involved in the project. The students spoke to local farmers and members of the NUFG about the problem and saw first hand the impact that dryland salinity can have on both agricultural production and the environment. Students learnt about the range of treatments being applied throughout the project area, and observed some of the early site preparation works.

The students will be further involved in the project as it develops, providing support in monitoring the groundwater beneath each of the treatments, and recording the rates of establishment and growth of the new vegetation.

Students from the East Loddon P12 College visit the Project Site

In May 2004 the NUFG contracted the Department of Primary Industries (DPI) to construct groundwater monitoring bores throughout the project site. Seven bores were established along a traverse extending from the south-east to north-west extremities of the area. Each bore was strategically located to monitor the watertable beneath each proposed treatment (saltbush, grasses, trees etc.).

Dryland salinity was first noticed at Kamarooka in the mid 1950s. In the late 1950s the (then) Soil Conservation Authority of Victoria (SCAV) was approached by local landholders interested in understanding what was happening in the landscape and what could be done about it. The SCAV files of that time provide some of the earliest and most informative views of the developing dryland salinity issue in Victoria. Excerpts from these files are reproduced below.

The North Central Catchment Management Authority (NCCMA) is working with the NUFG in support of the Kamarooka Project. The CMA is particularly interested in securing the region's existing native vegetation and improving biodiversity. These are goals that are defined within a bioregional plan that has been developed for the Victorian sector of the Riverine Plains. The plan identifies the activities required to achieve broad-scale conservation of biodiversity through integration of works supported by private landholders, community groups and all levels of government (www.nccma.vic.gov.au).

Implementation of the bioregional plan at Kamarooka will involve improved management of existing remnants through fencing and reduction of grazing pressure, and supplementary planting via tube-stock and direct seeding into areas of depleted vegetation.

For more information on this aspect of the Kamarooka Project contact the North Central Catchment Management Authority.

In July 2004 Dr Sharman Stone MP, Federal Member for Murray, and Parliamentary Secretary to the Minister for Environment and Heritage launched the Kamarooka project. The ceremony was conducted at the Kamarooka Recreation Reserve and was attended by members of local landcare groups, local landholders, students from the East Loddon P12 school, representatives from the North Central Catchment Management Authority, and members of the Northern United Forestry Group.

Dr Stone inspected the project site and jointed with students planting trees to mark the occasion. Participants in the launch also inspected the bores established to monitor the impact of revegetation on local watertables.

Direct seeding of native grasses commenced in mid-July 2004. The following photos show the seeding unit comprising six hoppers calibrated to deliver seed of a specified size at a specified rate. The tynes scarify the land, seed is dropped into the furrow, and a press wheel pushes it firmly into contact with the soil.

During July 2004 final preparation of the site occurred in readiness for both farm forestry and saltbush plantings. Each of the lines that had been deep ripped earlier in the year along the southern and northern extremities was cultivated and rotary hoed to produce a suitable tilth for planting both tube-stock (trees) and plugs (saltbush).

Farm forestry plantings were earmarked for the northern sector of the project area, and within the south- east corner adjacent existing areas of remnant vegetation. Saltbush was targeted on the more saline areas central to the project area, and along the south-west boundary.

Saltbush planting occurred in August 2004, and farm forestry planting occurred in early spring.

Final preparation of the site for farm forestry and saltbush

In August 2004 the NUFG hosted a visit to the project site by three of Australia's most noted scientists working on dryland salinity. The visitors were Dr. Richard George, a Senior Research Scientist (hydrogeologist) with the Department of Agriculture in Western Australia, Dr. Ed Barret-Lennard, Principal Research Officer (saltland pasture specialist) also with the Department of Agriculture in Western Australia, and Dr. Nico Marcar (saltland tree specialist), Principal Research Scientist with CSIRO's Division of Forestry and Forest Products.

The scientists were in Bendigo for a national salinity conference being organised by the Cooperative Research Centre for Plant Based Management of Dryland Salinity. At the site NUFG members explained how and when salinity had developed in the region, the history of various attempts to manage it, the hydrological and hydrogeological processes causing the problem, and the aims and objectives of the current work.

After the site inspection, and in the face of a rather aggressive storm (see below), both scientists and NUFG members retreated to Raywood where considerable discussion took place over the range of species and treatments suitable for saline land in southern Australia. The opportunity for both the scientists and members of the group to share their collective experiences and knowledge proved most welcome.

Photos of the visiting scientist meeting with members of the NUFG are presented below.

Visiting scientists inspect the Kamarooka site with members of the NUFG

An unusual storm appeared over the trial site on the afternoon of 2 August 2004 whilst members of the NUFG were hosting visiting scientists from Canberra and Western Australia. The dark storm cell came from the west and passed to the east. It seemed quite low in the sky and was a rather odd circular shape suggestive of some form of rotation. As it passed across the landscape lightning appeared from the centre of the circular cell, followed by intense rainfall (see photos below):

In August 2004 the NUFG hosted a visit by 20 members representing Mid Macquarie landcare groups and the newly formed CMA for the Central West region of New South Wales to the Kamarooka project site. The group was taking part in a rapid tour of dryland catchments in northern Victoria organised for key community players to gain insight into various models used to implement salinity and other natural resource management projects/programs in the Murray-Darling Basin in Victoria.

The visiting group was led by Alan Nicholson, Salinity Coordinator for the Central West Region of NSW, and included Mr. Tom Gavel, Chair of the newly formed Central West CMA. NUFG members explained the history of salinity in the region, the biophysical processes that cause the problem, and the strategies and actions being implemented by the NUFG to combat the problem.

The NSW visitors compared notes on salinity with the members of the NUFG, including options and approaches for management, species selection and establishment techniques. The discussion extended to a shared appreciation of the principal factors that contribute to successful groups including both the social and economic aspects of various landcare activities.

In September 2004 the Northern United Forestry Group won the prestigious 2004 Telstra Country Wide National Landcare Research Award. The honour was revealed at the National Landcare Awards ceremony held at Parliament House, Canberra.

The award recognised NUFG 's expertise in low-rainfall farm forestry. It also acknowledged the work of the group in promoting the benefits of trees and shrubs in improving farm productivity and biodiversity in the southern Riverine Plains and adjacent foothills of northern Victoria.

The judges were equally impressed by the Group's innovative farming project at Kamarooka, and the opportunities it affords in demonstrating options for the future viability of salt affected land in the region.

Ian and Leanne Rankin with the 2004 Telstra Country Wide Landcare Research Award

On 14 December 2004 the catchment immediately above Kamarooka received between 75 and 100 mm of rain in a few hours. The spectacular flash flood resulting from the downpour pushed an enormous volume of water down the Myers Creek immediately west of the trial site, and the previously dry creek bed and surrounding floodplain turned into a vast lake that persisted for several days.

Soon after the appearance of the large water body local farmers reported an amazing congregation of water birds. Water reached within a few metres of the trial site, but stopped short of flooding it.

Despite all of the water coming down the catchment and flooding over the plains to the immediate west groundwater levels beneath the saline lands remained the same as before the inundation. This provides strong evidence supporting the understanding that salinity and groundwater issues are driven by processes within the immediate sub-catchment above the saline area, as opposed to those in the floodplain below. (see images below of flood waters below).

For more than forty years the trial site has experienced the terrible harshness of dryland salinity. Now the barren saline land of the region is once again becoming productive both from an agricultural and an ecological perspective.

The 'renewal' is immediately apparent and truly amazing to those familiar with the site. Thousands of saltbush seedlings, trees and shrubs are now springing from the ground, and the true potential of the previously degraded land is becoming readily apparent.

In January 2005 the NUFG contracted DPI to return to Kamarooka to drill an additional three groundwater observation wells (bores).

The additional bores were drilled to the north and northeast of the previous seven. The earlier transect established through the centre of the trial was extended to provide watertable monitoring under
(a) emerging young trees planted along the northern end of the trial site. (b) areas of remnant native vegetation along the northern perimeter, and (c) areas of newly established native vegetation in the northeast corner.

Additional monitoring bores at Kamarooka

Students from the East Loddon College visited the Kamarooka Project in March 2005. They assisted the NUFG by reading the depth to groundwater in bores under each of the vegetation types established to combat salinity.

The students witnessed the DPI undertaking a geophysical survey of the project area. The students had the opportunity to inspect the equipment mounted on the four wheel motorcycle and the instruments being towed behind the cycle. They also had the opportunity to talk to the DPI operator and gain some insight into the how the instruments worked.

East Loddon College students inspect geophysical survey equipment at Kamarooka

Young native trees are rising from the less saline land. Sugar gum (Eucalyptus cladocalyx) and flat-top yate (Eucalyptus occidentalis) grow alongside willow wattle (Acacia salicina) and Eumong (Acacia stenophylla). In the next paddock various saltbush varieties are growing rapidly and in some areas direct-drilled acacias and native grasses are establishing.

Flooding at Kamarooka 14th of December 2004

The Desert Begins to Bloom