Thursday 12 March 2020
Topsoil loss during 2020 flooding in the Clarence Valley
The Daily Examiner, 9 March 2020:
Anyone
travelling around the recent flood-affected areas of the Valley,
including along the Clarence River itself, couldn’t fail to notice
the chocolate brown colour of those floodwaters.
The
Orara River was particularly bad, and after the floodwaters had
receded, council needed to use a front end loader to scrape thick
layers of deposited mud off some roadways and bridges. The paddocks
alongside creeks were likewise buried beneath a thick layer of mud.
This
was always to be expected if torrential rain occurred soon after the
bushfires, especially with ash washing off the bare ground into
waterways.
But
these floods brought more than ash. This was topsoil, something that
is in short supply across much of the Australian continent. We are
told that globally, some 24 billion tonnes of topsoil are lost
annually through erosion, and Australia’s contribution is shameful,
given we are a supposedly developed country with sufficient resources
to protect this precious commodity.
Wind
and water are the two main forms of erosion.
Both
can be significantly mitigated simply by maintaining a good
vegetation ground cover. Without that cover there is nothing to hold
the soil, and this past season has highlighted that fact.
Firstly
there was drought, and overgrazing to the point where only bare soil
remained, resulting in one huge dust storm after another for months
on end.
Then
the bushfires destroyed what vegetation the livestock had left. Then
came the floods, ripping apart fragile unprotected stream banks, and
washing them downstream to the ocean.
Even
without bushfires we lose far too much soil to erosion, and again,
poor livestock management is largely to blame.
Many
Australian rivers and creeks have no adequate vegetation to buffer
against erosion and fewer still are fenced to exclude cattle.
As
a result, these animals congregate along waterways, trampling banks,
and browsing any available vegetation, so their impact is even
greater than fire.
Landowners
have a responsibility to manage erosion on their properties and to
consider what they are leaving for future generations. If we are to
solve the erosion problem, livestock management must be a focus
point.
JOHN
EDWARDS, Clarence Valley Conservation Coalition
Labels:
Clarence River,
Clarence Valley,
environment,
erosion,
floods
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