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Microflood
Micro flood wins SPE Environmental
Stewardship Award
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Micro flood, a process which transforms flood
irrigation into a highly efficient irrigation system has received international
recognition with the prestigious SPE Environmental Stewardship Award which
will be presented to Colin Austin at the forthcoming SPE Environmental
Conference in Detroit in February 2002.
The technology was initially developed to provide a cheap and effective
method of irrigation to provide sustenance food in the periodic drought in
Ethiopia. As flood is by far the largest user of water it has applications
throughout the world.
This is how it works;-
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This shows why flood irrigation is intrinsically
inefficient. It starts well with water flowing into the irrigation
bay and starting to soak into the ground.
However the next section is irrigated by water flowing
over the first section soaking deeper into the soil.
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By the time the water has reached the end
of the paddock the water at the top has soaked deep into the ground saturating
the soil and with water being lost past the root zone, possibly mobilizing
salt.
It is not just the loss of water, plants do not grew
well when their roots are saturated, so production is lost while the water
soaks or evaporates away.
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It is essential to apply the water rapidly,
this requires large channels which are a major source of waste. Large
volumes of water e.g. 50 mm are applied at each irrigation giving a wet
and dry cycle which is not productive.
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The concept behind micro flood is very
simple. Water is supplied from a pipe running down the irrigation bay with
tap off points along the length.
Laterals, pipes with holes, may be used to spread the water across the
bay. Initially it works just like regular flood with water being delivered
from the first tap off point.
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However when the flow front has reached
the end of each section the flow is diverted to the next tap off point so
the water runs through the pipe rather than over the soil.
Only small amounts of water e.g. 5 mm need be applied at
each irrigation. The soil is not saturated, so there is no loss of water
and the soil is maintained moist which gives optimum production.
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As flows are small water can be delivered
economically through small pipes avoiding seepage and evaporation
losses.
Up to 40% extra production can be obtained from the same volume of water,
without causing environmental damage. Pipes can be manufactured from
recycled plastics bags turning a source of litter into a valuable product.
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last revised 14 jan 2003
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