WE鈥橵E ALL seen painful TV footage of tragic villagers drowned or dispossessed
by seasonal floods in Bangladesh or Assam. And even of English townsfolk, shaken
out of their Northern European complacency this autumn by the cruel rain gods.
So how do I dare argue that flooding can be a good thing?
Well, only if I add a serious adjective鈥攃ontrolled. The uncontrolled
variety we normally witness are, after all, a mixture of unacknowledged human
activity and unfortunate geography that we lazily label 鈥渘atural鈥�. Controlled
flooding, as a by-product of proper management, is a very different animal with
much to teach us.
Take one small鈥攁nd rare鈥攊nitiative. The Murray River at Paringa
in South Australia is heavily used, both as a water source for fruit orchards
and vineyards and as a tourist amenity. But uncontrolled irrigation has made its
waters and the surrounding land salty. Overexploitation has gone hand in hand
with riverine plumbing and regulation. Any upsurge in water volume is usually
allowed to slip downriver through opened weir gates and perhaps flush some of
the sand clogging up the river mouth out to sea.
Advertisement
At the end of September, there was an unusual amount of rain and large
volumes of water were swelling the Murray. During the four weeks the upsurge
took to reach Paringa at Weir 5, the new local river manager, Sue Lefebvre,
decided the time was right to put people鈥檚 environmental awareness to the
test.
In the early 1900s, the river鈥檚 waters ebbed and flowed regularly over its
flood plain. Murray cod prospered, laying their eggs in the flood waters where
there was more food. The huge trees, black boxes and red gums, that used to
tower over the river also germinated and were watered by successive overflows.
Now the river is straitjacketed, the cod, black boxes and red gums have
declined, replaced by carp and willow.
By the time the floods arrived, Lefebvre had gathered the support she needed
to keep the sluices shut and allow the water to cover the flood plain. Some 14
square kilometres went under. Why isn鈥檛 this kind of flooding done routinely?
The answer is power. The drive for economic development has not just curbed the
river and caused big salination problems, but has cluttered the banks of the
Murray with caravan parks, tourist reconstructions of pioneer settlements,
houseboat holidays and the like. The river is also home to the holiday shacks of
South Australians鈥攊ncluding state premier, John Olsen. Not surprisingly,
river managers worried that if they caused a flood, they might be sued.
Though it鈥檚 too soon to tell how the ecosystem fared, amazingly the flood
went down well locally. The water lapped at caravan parks but didn鈥檛 cause
commercial damage. Lefebvre reckons the exercise is likely to be repeated. The
Murray Darling Basin Commission, which controls the river, is very keen to close
three weirs at once next time. And Lefebvre hopes guidelines will help prepare
local people for the next flood.
Unlike those local people who have next-to-no warning about the 鈥渘atural鈥�
floods.