3. Drainage means the removal of excess water from a
given place.
The excess water is
due to heavy rainfall
or over irrigation.
The excess water
causes waterlogging.
DRAINAGE
5. WATERLOGGING ?
Waterlogging refers to the saturation of soil
with water.
In agriculture, most of the crops need air (specifically,
oxygen) for their growth in the root zone of soil.
Waterlogging of the soil stops air getting in.
waterlogging is often accompanied by soil salinity as
waterlogged soils prevent leaching of the salts imported
by the irrigation water.
6. CAUSES OF WATERLOGGING
1. Excessive use of water when the water is
available in abundance or cheaply due to the
belief that more water contributes better yield.
2. Improper selection of irrigation methods.
3. Percolation and seepage from lands canals and
reservoir located at nearby elevated places.
7. Cont..
4. Improper lay out and lack of outlets.
5. Presence of impervious layer with profile
impeding percolation.
6. Upward rise of water from shallow ground
water table or aquifer.
8. EFFECTS OF WATER LOGGING
• Nutrients are made un-available due to leaching.
• Toxic elements will be formed under anaerobic
condition.
• Composition of organic matter under anaerobic
condition results in production of organic acids like
butyric acid which is toxic to plants.
• Reduces the availability of N, Mn, Fe, Cu, Zn, Mo.
9. EFFECTS OF WATER LOGGING
• Reduces soil temperature.
• Reduces the activity of beneficial microbes.
• Destroy soil structure.
• Difficult for cultural operations.
• Incidence of pest, disease and weeds.
10. TWO TYPES OF DRAINAGE
I) Land Drainage:
• Such schemes are necessary carried out in low
lying areas.
• Are mainly Civil Engineering work.
II) Field Drainage:
• This is the drainage that concerns us in agriculture.
• It is the removal of excess water from the root zone of
crops.
11. MAIN AIMS OF FIELD DRAINAGE
1. Drainage to Control Ponding
2. Drainage to Control Waterlogging
3. Drainage to Control Salinization
12. 1. Drainage to control Ponding
Removing excess water from the surface of the
land.
surface drainage is used.
Normally, this consists of digging shallow open
drains (mostly) or pipe drain.
When there is irregular land surface, shaping and
grading is done to remove excess water or avoid
ponding.
13. 2. Drainage to control waterlogging
Removing excess water from the root zone.
To bring down soil moisture from saturation to
field capacity.
subsurface drainage is used.
This is done by digging open drains or installing
pipes, at depths varying from 1 to 3 m.
14. 3. Drainage to Control Salinization
To remove salts from the soil, more irrigation
water is applied to the field than the crops require
(leaching requirement).
This extra water infiltrates into the soil and
percolates through the root zone.
While the water is percolating, it dissolves the
salts in the soil and removes them through the
subsurface drains.
16. Characteristics of good drainage system
1. It should be permanent.
2. It must have adequate capacity to drain the area
completely.
3. There should be minimum interference with cultural
operated.
4. There should be minimum loss of cultivable area.
5. It should intercept or collect water and remove it
quickly within shorter period.
17. TYPES OF FIELD DRAINAGE SYSTEM
1.Surface drainage
2.Sub-surface drainage.
18. 1.SURFACE DRAINAGE
This is designed primarily to remove excess
water from the surface of soil profile.
This can be done by developing slope in the
land so that excess water drains by gravity.
19. SUITABILITY
Slowly permeable clay and shallow soil.
Regions of high intensity rainfall.
Fields where adequate out lets are not
available.
The land with less than 1.5-2% slope.
20. DIFFERENT METHODS OF SURFACE
DRAINAGE
1. Random field ditch method.
2. Land smoothing / Levelling.
3. Bedding .
4. Parallel field ditch system.
5. Broad bed and furrow method.
21. 1.Random Field Ditch Method
Standing water may be present in the field at several
places distributed randomly. These depressions or
micro ponds are connected by mean of shallow
channels or ditches and these are led into an outlet.
22. 2. Land smoothing /Grading
• The elevated area is cut off and excess soil is
spread over low areas so that the surface is even
with uniform slope.
• Excess surface run off is collected and conveyed
into the field ditches provided at the lower end of
the field.
23. 3.Bedding
Small furrows known as dead
furrows are formed at known
intervals parallel to the slope
for draining out water.
land between these furrows is
known as beds.
Small ridges or bunds are
made at the centre of the bed
with gradual slope to drain
water into the dead furrows.
24. 4. Parallel Field Ditch system
It is almost similar
to bedding system
except for deep
drains and uneven
interval between
drains.
25. 5.Broad Bed and Furrow Method
The field is laid out with beds and wide
furrows across the slope. About 0.5 per cent
slope is provided for the furrows for free
drainage. Crops are sown on the beds and
furrows help in drainage of water when there
is excess rain.
26. ADVANTAGES OF SURFACE DRAINAGE
• Provision of surface drainage is cheap.
• The defects in the open drainage can be seen
easily and rectified.
• Effective in low permeability area.
27. DISADVANTAGES IN SURFACE DRAINAGE SYSTEM
• Considerable amount of land is wasted for open drains.
• These drains cause hindrance to field preparation and
intercultivation.
• The drains get silted and periodical desilting is
necessary.
• Weed growth in the drains is heavy and this has to be
removed.
• Open drains are damaged by rodents and farm animals.
28. 2.SUBSURFACE DRAINAGE
Sub surface drains are under ground artificial
channels through which excess water is made to
flow through a suitable outlet.
The purpose is to lower
the ground water level
below the root zone
of the crop.
29. The movement of water into sub surface drains
is influenced by
1.The hydraulic conductivity of soil.
2. Depth of drain below ground surface.
3.The horizontal distance between individual
drains.
30. Underground drainage is mostly needed
• Medium textured soil.
• High value crop.
• High soil productivity.
• High water table.
32. 1.TILE DRAINAGE
• Tile drainage was first introduced to the United
States in 1838.
• Father of tile drainage John Johnston.
• Tile drainage got its name from tiles made from
fired clay (ceramic), similar to pipes but not
necessarily in a pipe shape.
• Today, however the tile drainage can be any
system operating on the same principle, often
with plastic tubing called "tile line".
33. Cont..
• Water enters the tile line either via the gaps
between tile sections, in the case of older tile
designs, or through small perforations in
modern plastic tile.
• In clay soils tile lines are spaced closer together
compared to sandy soils as water is held tightly
in clay soils than in sandy soil .
37. 2. MOLE DRAINAGE
• Mole drains are unlined circular earthen channels
formed within the soil by a mole plough.
• The mole plough has a long blade like shank to
which a cylindical bullet nosed plug (Expander) is
attached known as mole. As the plough is drawn
through the soil the mole forms the cavity to a set
depth.
• Mole drains are used in heavy soils where a clay
subsoil near moling depth (400 to 600 mm)
prevents downward movement of ground water.
38. Cont..
• Mole drainage is not effective in the loose soil
since the channels produced by the mole will
collapse.
• This is also not suitable for heavy plastic soil
where mole seals the soil to the movement of
water.
• Mole drains are a more sophisticated drainage
system than open drains. Mole drains do not drain
groundwater but removes water as it enters from
the ground surface.
41. 3. VERTICAL DRAINAGE
• Vertical drainage is the disposal of drainage
water through well into porous layers of
earth or to outer source.
• Such a layer must be capable of taking large
volume of water rapidly.
• Such layers are found in river bed.
42. Drainage through porous layers of earth.
It depends on the depth of aquifers.
46. 4. WELL DRAINAGE
• The wells are used for the drainage of
agricultural lands especially in irrigated areas.
• One well is sufficient to solve groundwater and
soil salinity problems in a few hectares but one
usually needs a number of wells, because the
problems may be widely spread.
• The wells may be arranged in a triangular,
square or rectangular pattern.
47. • The design of the well field concerns depth, capacity,
discharge, and spacing of the wells.
• The depth is selected in accordance to aquifer properties.
The well filter must be placed in a permeable soil layer.
• Both systems serve the same purposes, namely water
table control and soil salinity control .
• Both systems can facilitate the reuse of drainage
water (e.g. for irrigation), but wells offer more
flexibility.
WELL DRAINAGE
49. Controlled drainage
• This practice involves placing simple water control
structures at various locations in the system to raise
the water elevation.
• This elevated water causes the water table in the soil
to rise, which, in effect, decreases the drained depth
of the field.
• Controlled drainage decreases the volume of water
drained (15-35 percent), slightly increases surface
runoff (because soils have less space to store water),
and significantly decreases (up to 50 percent) nitrate
losses seen in conventionally drained fields.
50. Cont..
• Decreases in nitrate losses have been attributed
primarily to reductions in the volume of water
drained and, to a somewhat lesser extent, by
increased Denitrification in the soil.
• If managed properly, controlled drainage has the
potential to improve crop yields by making more
water available to plants.
• Controlled drainage is called SCIEN is an acronym
for Sustainable, Controlled, Intelligent,
Environmental friendly and Nutrient loss mitigating.
52. Impacts from controlled drainage
• Less drainage water is let out to streams and
lakes .
• More ground water is formed.
• Less nutrients are lost from agricultural soils.
• Outlets of nutrients with drainage water are
reduced.
54. Advantages of sub surface drainage
1.There is no loss of cultivable land.
2.No interference for field operation.
3.Maintenance cost is less.
4.Effectively drains sub soil and creates better
soil environments.
55. Disadvantages of sub surface drainage
1. Initial cost is high.
2. It requires constant attention.
3. It is effective for soils having low permeability.
56. BIO-DRAINAGE
Bio-drainage is defined as
“pumping of excess soil water
using bio energy through deep
rooted vegetation with high rate
of transpiration.”
The bio-drainage system consists
of fast growing tree species,
which absorb water from the
capillary space located above the
ground water table.
57. The absorbed water is translocated to different
parts of plants and finally more than 98% of the
absorbed water is transpired into atmosphere
mainly through stomata.
This combined process of absorption,
translocation and transpiration of excess
ground water into the atmosphere by the deep
rooted vegetation is bio-drainage.
58. Best known example for bio drainage is
Eucalyptus species.
Transpiration rates differ among eucalyptus
species, varying apparently between 20
litres/tree/day to 40 litres/tree/day.
Other suitable species include
1.Casurina sp ( Beach oak, Beefwood )
2.Pongemia pinnata ( Honge )
3.Syzigium cuminii ( Jamun )
59. Merits of bio-drainage over conventional
drainage
Relatively less costly to raise bio-drainage
plantations.
No maintenance and operational cost.
Increase in worth with age instead of depreciation.
No need of disposal of drainage effluents.
60. Cont…
No environmental problem, as the plants drain out
filtered fresh water into the atmosphere.
Insitu solution for the problem of waterloging and
salinity.
Preventive as well as curative system for waterlogging
and salinity.
Mitigates the problem of climate change and
contributes to increased forest cover.
61. Cont…
Purifies the atmosphere by absorbing carbon
dioxide and releasing oxygen.
Acts as wind break and shelterbelts in
agroforestry ecosystem.
Provides higher income to the farmer due to
the production of food, fodder, fuel wood and
small timber.
62. Limitations of bio-drainage
• The transpiring capacity of the trees reduces
progressively as the groundwater salinity increases.
i.e when EC of groundwater is about 8 dS/m,
Eucalyptus trees transpire only half of what they
transpire under non-saline conditions.
• Release of toxic chemicals from leaf, stem and roots
extracts of Eucalyptus may inhibit the germination
and seedling growth of some crops.
• Bio-drainage occupies potentially valuable land
thereby decreasing the availability of area for
commercial/ food crops.
63. BENEFITS OF DRAINAGE
The loss of seeds and fertilizers to flooding can be
eliminated.
The local ponded areas, swamps etc. can be brought
under farming, thereby increasing the area of
cultivation and tillage becomes easy.
The land is dried early after rains and such drying aids
prompt planting and cultivation.
64. BENEFITS OF DRAINAGE
The important improvement is soil moisture ratio which
promotes vigorous root growth and the plants become
healthier resulting in earlier and increased yield .
As the free and excess surface water is removed thus
preserving good granular structure and maintain good
tilth and to resist splash erosion.
Evaporation is retarded and the baking and cracking of
the soil is reduced.
65. By tile drainage the alkali and acid are easily
removed so that the growth of plant will be
effective.
As sufficient aeration zone is created, the
activity of aerobic organisms which influence
the availability of nitrogen and sulphur.
BENEFITS OF DRAINAGE
66. Drainage Coefficient
For subsurface drainage
The coefficient is usually expressed as a depth of
water to be removed over a safe period of time,
usually 24 hours.
For surface drainage
The coefficient may be expressed as a flow rate
per unit area.
67. RESEARCH PAPER
KISHORE BABU G., RAMESH CHANDRA S.,
REDDY K.Y, SUBBARAO G. and RADHA Y.,
2008, Impact of open sub surface drainage on
reclamation of waterlogged and salt affected
soils, A.P. Water Management Project, Bapatla.
68. Table1. Effect of Sub-Surface Drainage System on soil salinity,
grain yield and cropping intensity of rice during 2005-2008
Bapatla , AP Kishore babu et al.(2005-2008)
