Dealing with salinity in Wheatbelt Valleys - Department of Water

Hatton and Ruprecht
There is a lot of groundwater drainage being
constructed in Western Australia’s Wheatbelt, mainly
on private land with private funds. The on-farm
effectiveness of these engineering works varies, but
to date has been subject only to modest research and
development efforts to improve effectiveness and
efficiency. There are serious concerns expressed by
some downstream stakeholders regarding the
negative impacts of disposal waters. There has been
some evaluation of the flood mitigation options
(Davies et al. 1988), but these studies have not
looked at the impacts on biodiversity or nutrient
flows. In the absence of the evaluation of these
broader aspects, it is difficult to advance a serious
debate on the winners and losers, and who pays,
associated with engineering. It is worth noting that
none of these catchments are water supply
catchments, with the kinds of downstream
constraints on water quality that complicate and
inhibit drainage in catchments such as the Murray-
Darling Basin.
There have been more recent initiatives that have
started to address some of these issues. The
development of water management strategies in the
Lake Dumbleyung and Beacon River catchments, the
implementation of a broad-scale trial pumping
scheme in the east Collie, and research and
investigations into deep drainage in the Narrembeen
area are all examples of recent studies into
engineering applications.
Given these recent initiatives, it is clear that we have
an opportunity to design and optimise catchmentscale
engineering that might bring the greatest
collective benefit to those that have a share in the
health of wheatbelt catchments. Landholders and
government need to look at developing a framework
that can work toward bringing about multiple
benefits in terms of agriculture, flood mitigation and
ecological values. A comprehensive vision for the
management of flows and loads in these rivers,
should we choose to further engineer them, is
essential to deliver the best outcomes.
It is a cruel irony that we have salinity problems in
these catchments precisely because they are in the
process (in the most global sense) of freshening.
More salt is coming out of the landscapes than is now
going into them from the atmosphere, and if we take
the longest possible view, at least the salinity and
associated flooding will eventually (in thousands of
years perhaps) self correct. But in the process, we
will be leaving behind much of the natural and human
heritage we value.
– 14 –
ACKNOWLEDGEMENTS
The authors would like to thank Neil Viney, Don
McFarlane and Peter Muirden for their valuable
comments on this paper. There are also many
people who have contributed to the knowledge and
understanding of salinity and hydrology of the southwest
of Western Australia that has made this paper
possible.
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