Dealing with salinity in Wheatbelt Valleys - Department of Water

• We are uncertain what discharge capacity exists
in playas and new saline landforms.
• We cannot accurately predict the extent of
salinity at a paddock scale.
• We require accurate hydraulic properties
(especially specific yield) for aquifers.
• We have too few commercially attractive
options for its management.
• We are unsure what impacts recharge
reductions will have on the timing and extent of
salinity.
• We do not have enough simple tools to use to
guide assessment and adoption of options.
• We do not know the best designs and impacts of
engineering options in sufficient detail.
• We have between 10 and perhaps 200 years
before hydrologic equilibrium!
Given our knowledge of the groundwater hydrology
and of the response of management systems, then
the impetus should be on the development of
engineering systems to protect assets and potentially,
parallel investment in commercial options for saline
land and water. In the medium to longer term,
revegetation and related commercial opportunities
will also arise that help sustain production in the
uplands and potentially reduce the rate of spread of
salinity. Determining the balance of investment will
be difficult. The following summary may assist in
developing criteria for assessing uses of saline
groundwaters.
Opportunities from saline groundwater
resources
The opportunities for the use of saline groundwater
are varied in their application, economics,
practicality, environmental impact and ability to
remove salt from the environment. Table 7
summarises the relevant facts about each generic
opportunity. A note of caution is that the success or
failure of a venture will hinge mainly on the ability of
the producer to market their product, and this
parameter cannot be tabulated.
It is unlikely in the short term that a sole venture will
be profitable and provide a method of removing salt
from the environment. For example the SAL-PROC
process is a combination of halite and non-halite
– 17 –
George and Coleman
mineral extraction and could operate more
effectively if combined with desalinisation and/or
energy production. There is a good opportunity for
combination of ventures but it is likely that some
cross subsidy will be required for them to be
developed together. Most of these opportunities are
represented by commercial ventures in Australia but
rarely do they co-develop. The reason for this is that
the best geographical, commercial and social location
for one venture may not coincide with a compatible
venture. Dunaliella farming is a good example.
Cognis Pty Ltd has operated a Dunaliella farm in a
limited relationship with Pacific Salt Pty Ltd in
Whyalla for several decades. On the other side of
the spectrum, a north-western salt producer has
actively opposed the development of a new
Dunaliella farm near it for a number of years.
Corporate attitudes vary, as do the reasons for
commercial decisions. It is thought that for a
synergistic development to occur in the Western
Australian Wheatbelt, common facilities such as a
bore field must be developed and a large area of land
be available or acquired using common (public)
funds. The salt removal process must be
constructed first. Once this structure is in place it
would then be possible to solicit interest in
compatible and perhaps more profitable ventures as
adjuncts to the main halite extraction plant.
Wheatbelt valleys are unique landscapes with unique
challenges. However despite the title of menace
under which salinity is portrayed, and can be for
landholders in many valleys, there are opportunities
for its management, and potentially, the longer-term
development of natural resources within new
business and market frameworks. Unlike toxic
pollutants that threaten to destroy agriculture
elsewhere, saline water and land is not in itself
unmanageable, especially in an environment that has
seen climate induced salinity come and go and to a
community which is beginning to see new
opportunities. We need to challenge ourselves to
seek a combination of approaches that maximises
agricultural and environmental benefits, while
minimising the risks. We also need to note that at
worst, salinity will only impact a maximum of about
30% of wheatbelt catchments. We therefore need
to focus on maintaining the productivity of the
remaining 70% as well as the key assets at risk.
Salinity management of our wheatbelt valleys
represents an opportunity to catalyse political,
community and scientific endeavour, by developing a
shared goal and delivering outcomes by
implementing realistic salinity management options
and protecting the resource base for agriculture.