GRAEME WORBOYS. About Snowy water, catchment restoration, Snowy 2.0 and jobs

The Snowy 2.0 project, if it is to realise its contribution to lowering carbon emissions, should proceed hand in hand with a program of environmental restoration of alpine ecosystems which have not recovered from past and present alpine grazing and which, as a result of global warming, will have less water yield for downstream users, including Snowy 2.0.

Australians are familiar with the high quality waters that flow from the Australian Alps catchments, their contribution to hydro-power generation and the delivery of irrigation water for the Murray-Darling Basin. The Alps provide a staggering 29 per cent of the annual average water flows of the Basin Rivers. This water is used for domestic consumption, agriculture and the environmental flow of the Murray River and is forecast to benefit the Snowy 2 Scheme. Climate change futures however, project that precipitation in the mountains will decline by up to 24 per cent by 2050 and will impact water availability. The current degradation of mountain catchments will also exacerbate this problem. Urgent work is needed in the mountains to stabilise the water catchments, to facilitate improved water yield and to benefit downstream users including Snowy 2.0.

Climate change projections for the Snowy Mountains for the year 2050 identify the mountain catchments as areas that will be hotter and drier, with precipitation reduced by as much as 24 per cent. It is projected there will be more days above 35oC, droughts will be more frequent, severe storms will be more common and there will be increased risk of more intense and more frequent bushfires (Worboys et al, 2011 p31). In the Kosciuszko National Park, a source of the Murray, Murrumbidgee and the Snowy Rivers, much of the water is from alpine, subalpine and montane bogs and fens of the Park’s elevated tablelands. These shrub and sphagnum rich bogs follow drainage lines and seepage areas on slopes and saddles. They are commonly underlain by peat, they only occupy about 2.5 per cent of the Park and they are the most extensive expression of peatlands in mainland south-eastern Australia and a significant carbon store (Hope et al, 2012 piii).

These mountain bogs play a vital role as animal habitat and as regulators of water quality and water flow regimes. They intercept snow melt and rainfall, trap sediment, remove nutrients, store water and gradually release this high quality water to rivers (Hope et al, 2012 p1). Their hummock moss shrublands and sedgelands help maintain a raised water table and water ponds that are habitat for many Australian frogs, skinks, birds and rodents and species not found anywhere else on Earth such as the endangered Northern Corroboree Frog and Freshwater Spiny Crayfish.

The mountain bogs so essential for water delivery have been badly impacted by domestic and wild stock grazing and fire since European settlement in 1823. There has been some recovery since grazing was removed from all of the Park in 1969, but many deeply eroded stream sites have never been restored. The extensive 2003 fires burnt many dried and exposed peatlands and recent rapid rises in wild horse and feral deer populations have re-impacted a large proportion of the remaining wetlands (Worboys et al, 2015). Impacts of introduced stock animals such as wild horses include the trampling of vegetation, overgrazing, stream bank destruction, stream incision and erosion, lowering of the water tables and drying of the wetland habitat and the subsequent conversion of wetlands to grassland. Consequently the role of the bog as a buffer to extreme rainfall events, as a filter and as a slow water release habitat, is lost. For water users downstream including Snowy 2.0 it could mean less water availability at critical times such as droughts, greater susceptibility of catchments to severe storm erosion, more eroded soil charged water, spiked flow regimes and the threat of permanent streams changing to ephemeral streams. The status of the bog as a home for many Australian species could be lost. Importantly, it is possible for management to intervene to reverse such trends through catchment restoration.

In 2011, a Technical Report titled Caring for our Australian Alps Catchments was prepared for the Australian Alps national parks Liaison Committee. It outlined a major 15 year restoration response for these critical bog communities (Worboys et al, 2011). Many of the wetlands to be restored could include important engineering impoundment works given the depth of the stream incision.

The Technical Report also identified an opportunity to enhance water yield for Kosciuszko’s catchments. Researchers identified that snow gums provide a wind fence and enhanced snow deposition benefit during winter snow storms and interaction with passing rain fronts generated additional water. This was estimated to enhance water yield in the catchments by about 10 per cent (Worboys et al, 2011). Large areas of snowgums had been systematically removed from high mountain catchments during 120 years of grazing, and the Report identified a restoration-replanting programme for these impacted areas. The replanting project was long term, with benefits increasing as the snowgums matured. This climate change response would improve water yield benefits for any future precipitation event in the mountains.

The Snowy 2.0 pumped hydro project linking Tantangara and Talbingo requires water for its operation. Any improvements to water yield, water quality and water flow regimes from the Kosciuszko catchments are an investment by helping to underpin and service this energy generation project. In addition, the restoration project would enhance the condition of the catchments and water yield at a time of climate change, a time at which all of the Snowy Scheme will need to be operating at peak efficiency to maintain water delivery to the Murray Darling Basin.

There is a grand and historic opportunity for investing in Australia’s environment in the Snowy Mountains. It would be a combination of Snowy 2.0’s clean energy generation project and a catchment restoration project that provides essential, clean and reliable water generation for Snowy 2 and the larger Snowy Mountains Scheme. In addition, the investment helps make both projects climate change ready. The dual project would enhance 1) Earth’s environment through less carbon emission; 2) Kosciuszko National Park’s National Heritage listed catchments through restoration; 3) the protection and conservation of endangered alpine species through restored habitats and 4) the improved water yield of the Park’s catchments at a time of climate change. Both special projects would offer important enhanced and long-term employment for locals and other Australians.

 

Dr Graeme L. Worboys is an Honorary Associate Professor of the Fenner School of Environment and Society, Australian National University.

 

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One Response to GRAEME WORBOYS. About Snowy water, catchment restoration, Snowy 2.0 and jobs

  1. Tim Shepherd says:

    Graeme’s proposal to link Snowy 2.0 with a major restoration program for the alpine catchments is well considered.
    The proponents of the proposal will also need to consider the potential environmental impacts of the construction phase, which are potentially highly significant. They include; issues with the disposal of very large volumes of tunnel spoil, sediment loads generated during tunnelling (particularly when tunnel boring machines are used) and the generation of highly alkaline waste water from concreting operations.
    These issues can and must be managed to avoid serious impacts to the park.

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