Land and Water Link
16 - May 2004
Towards a Healthy Wheatbelt
 The
Western Australian Wheatbelt, a region of some 20 million hectares, is
far from healthy country. Past management practices have subjected the
land to a series of environmental pressures, and today’s farmers
are left with a legacy of salinity, erosion and acidification.
But rather than watching salt slowly encroach on their properties, many
farmers in the west have taken drastic action – cutting deep open
drains or channels along creeklines and valley floors, to send the salty
water elsewhere.
Dr Tom Hatton explains: ‘Large sections of the community were a
long way ahead of us in their thinking and began to do what they thought
was necessary to protect their assets – in particular, their farmland.’
Using the most basic drainage technology, farmers have been able to restore
formerly salt-affected areas to productive arable land. There are now
thousands of kilometres of drains in existence and some areas have drainage
systems that span up to 80 km at a stretch, but the legal implications
and downstream impacts remain unclear.
As Dr Hatton says, the vast networks of drains were constructed without
any regional planning. Little thought went into the potential downstream
impacts and how these impacts might be mitigated. ‘We recognise
that farmers see a way forward with drainage,’ he explains, ‘but
there are serious concerns – concerns about metals, acids, flooding,
sediment, and nutrients.’
CSIRO research confirms the potential effectiveness of drainage schemes
in shifting between 300 and 1000 tonnes of salt a day, with groundwater
discharging at a rate of up to 15 megalitres per day – depending
on the season. But the problem doesn’t disappear; it is just exported
from one place to another.
Along with a high salt load, acidic drain water can contain elevated
levels of aluminium, iron and magnesium that can damage the environment.
‘As you might expect, the drains are a very divisive feature in
these farming communities’, says Dr Hatton.
These hydrological and social issues are the focus of a new project in
CSIRO’s Water for a Healthy Country Flagship – the Wheatbelt
Futures project, managed out of the WA Department of the Environment by
John Ruprecht.
The project provides a framework for considered debate on the future
of the wheatbelt valleys. With regional arterial drainage systems proposed
for the whole of the wheatbelt, it comes not a moment too soon.
Dr Hatton is the regional coordinator. ‘We propose to forecast
the downstream impacts of landscape engineering on the river environment,
on infrastructure, and on other farmland. ‘
The hard work done by previous generations to clear the land for farming
dramatically increased water runoff and groundwater recharge, and forever
changed the West Australian environment, creating a unique system of sporadically
flowing, salty rivers.
‘It has become clear, based on work done by CSIRO and repeated
by others, that we cannot “turn back time” – that the
rivers and catchments will never be the same as they were when the settlers
first arrived, not with any combination of revegetation or better farming
or drainage schemes,’ says Dr Hatton.‘
However, all of these strategies have a definite place in the future
of the wheatbelt and the community needs to be able to make informed management
decisions, which are based on sound evidence.’
The challenges faced by the project team are fascinating, and the assets
at risk enormous.
CSIRO Contact:
Dr Tom Hatton
Ph: +61-8-9333 6208
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