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DRAINAGE OF IRRIGATED
LANDSCHAPTER 5
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INTRODUCTION
One factor of paramount important in any
irrigation scheme is proper drainage.
Drainage is essential whenever salinity isinvolved in order to
hold the salt concentration
in the root zone at a reasonable level, that is
leaching is compulsory.
Drainage is normally required in different methods
according to local conditions and to the quality
of groundwater.
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INTRODUCTION
If it is not saline and consequently usable
by the crops, the aim of the drainage
network is to get rid of excess water in
the root zone quickly, keeping the watertable at a rather high
level in order to
benefit from capillary movement.
y avoiding over drainage, the water tablecan be drawn to an
optimum level.
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INTRODUCTION
! better choice of drainage system is
between open and closed drains.
Open deep drainage requires wide ditchesresulting in loss of
land, difficulties
for traffic, and maintenance problem.
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1. SURFACE DRAINAGE
"urface drainage is needed for#
the removal of storm rain fall where
sub$ surface drainage is not
economically feasible% andthe collection and disposal of
surface irrigation run$ off.
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SURFACE DRAINAGE
Surface drainage using shallow trenches
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2. SUBSURFACE DRAINAGE
"ubsurface drainage is used#
a& to control water tables which would
otherwise rise to or near to the ground
surface for extended periods% and
b& to improve the internal drainage of soil
of low permeability and thus to permit the
free movement of air and water.
"ubsurface water is collected by deep ditches,
permeable buried pipes, or wells, from which
it passes into a disposal system of channels
or pipes.
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2. SUBSURFACE DRAINAGE
Subsurface drainage using deep wells
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2. SUBSURFACE DRAINAGE
Subsurface drainage using drains
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2. SUBSURFACE DRAINAGE
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2. SUBSURFACE DRAINAGE
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2. SUBSURFACE DRAINAGE
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2. SUBSURFACE DRAINAGE
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2. SUBSURFACE DRAINAGE
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2. SUBSURFACE DRAINAGE
Example (embankment)
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2. SUBSURFACE DRAINAGE
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2. SUBSURFACE DRAINAGE
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2. SUBSURFACE DRAINAGE
