Drainage water management

INDIRA GANDHI KRISHI VISHWAVIDYAAYA , RAIPUR
(C.G.)
ASSIGNMENT ON – Drainage, effect of poor
drainage , types of drainage system, depth and
spacing .
Submitted to –
Dr. R. B. Tiwari
Submitted by –
Dhanendra dhanuka
M.Sc. Final plant breeding
Session – 2018-19
Barrister Thakur Chhedilal College Of Agriculture And Research Station
Bilaspur (C.G.)

DRAINAGE
The word drainage has multiple meanings . It is used
in general sense to denote water outflow from a
section of land . More specially , it can serve to
describe the artificial movement of excess water from
cropped fields . drainage aims at maintenance of soil
moisture within the range required for optimum crop
growth . In humid areas drainage is needed for the
removal of excess rain water . In arid and semi-arid
areas , drainage is a necessary complement of
irrigation . Drainage removes excess water to ensure a
favorable salt balance in the soil and a water table
elevation optimum for crop growth and development.

EFFECT OF POOR DRAINAGE
 Poor soil aeration inhibiting normal aerobic
respiration and microorganisms activity.
 High water table curtail root penetration and inhibit
crop growth and production.
 Soluble salt , harmful to crops , tend to concentrate in
the root zone.
 Plant nutrient in soluble form are lost through
leaching and water flow.
 Soil structure is destroyed , besides encouraging
certain disease and delaying crop maturity.
 Wet spots in the field delay timely field operation.

Broadly drainage systems are of two
types-
TYPES OF DRAINAGE
SURFACE DRAINAGE SYSTEN
Safe removal and disposal of excess water primarily
from land surface or cropped area by a net work of
surface drains or constructed channels and through
proper land shaping is known as surface drainage.
There are four general types of surface drainage
systems used in flat areas having a slope of <2% viz.,
(a) Random drain system (b) Parallel field drain
system (c) Parallel open ditch system and (d) Bedding
system

(i). Random drain system:
This system is usually adopted in areas where the
ground surface is characterized by a series and
depression (undulating land surface) and where small
depressions are to be drained off. Depending upon
the possibility the field drains are designed in such a
way to connect one depression to another and water
is safely conveyed to lateral drains. These lateral
drains ultimately guide the water to main outlet drain.
The field drains besides occupying the land area are
likely to interfere with farm operations.

(B). Parallel field drain system:
The parallel field ditch system is used in places where
the surface is uniform and has few noticeable ridges
or depressions. In this system the surface of individual
fields is graded in such a way so that the runoff water
drains into field drains, which in turn discharge water
into field laterals bordering the field and finally the
laterals in turn lead water into the main outlet ditch
through protected over falls. Laterals and mains
should be deeper than field drains to provide free out-
fall. Maximum spacing of parallel field drains is about
200 m for sandy soils and about 100 m for clay soils. It
is the most desirable surface drainage method and is
well suited both for irrigated and rainfed areas.

(C). Parallel open ditch system:
The parallel open ditch system is similar to parallel field
drain system in all respects except that the drains are
replaced by open ditches which are comparatively
deeper and have steeper side slopes than the field
drains. Maximum length of grade draining to ditch
should not be > 180 m. The spacing of the ditches
depends upon the soil and water table conditions and
may vary from 60 – 200m. This system is applicable in
soils, which require both surface and sub-surface
drainage.

(D). Bedding system:
This system is usually adopted in fields with very
little slope, usually 0.5% or less and slowly
permeable soils. It is essentially a tillage operation
wherein the land is ploughed into a series of
parallel beds separated by dead furrows, which
run in the direction of greatest slope lateral drains
are located perpendicular to slope. The ploughing
operations are to be carried out parallel to the
furrows. The bed width and length varies between
8 to 30 m and 10 to 300m respectively depending
upon field conditions i.e., land use, slope, soil
permeability and farming operations. While bed
height should not exceed 40 cm.

Sub-surface drainage systems
The removal and safe disposal of excess water that
has already entered the soil profile is considered
sub-surface drainage. Though several sub-surface
systems are available, the most commonly used
and effective ones are Tile drainage and Mole
drainage system.
A Tile drainage systems
Tile drains removes excess water from the soil
through a continuous line of tiles (pipes) laid at
specified depth and grade. The pipes are made of
either concrete or burnt clay. Free water enters
through the tile joints and flows out by gravity, so
that the water table is lowered below the root zone
of the plants. The common tile drainage system
layout followed is: Random or natural system,

a)Random system: The random system is used in areas that
have scattered wet areas somewhat isolated from each other. Tile
lines are laid more or less at random to drain the wet patches.
b) Herringbone system: The system is applicable in places
where the main or sub-main is located in a narrow depression i.e.,
in areas that have a concave surface or a narrow
depression with the land sloping to it from both directions .The
parallel laterals enter the sub-main from both sides. It is less
economical, because considerable double drainage occurs where
the laterals and mains join.
c) Gridiron and parallel systems: The gridiron and parallel
systems are similar to that of herringbone system except that the
laterals enter the main or sub-main from only one side. It is the
most economical arrangement than herringbone system because
one main or sub-main serves as many laterals as possible.

d) Double main system: The double main system is a
modification of the gridiron system. It may be used where
the sub-main is in a broad, flat depression, which frequently
is a
natural watercourse and sometimes may be wet because
of small amounts of seepage water from nearby slopes.
e) Intercepting system: This system involves the
interception of seepage water that flows over the surface of
an impervious sub-soil. The tile line is placed approximately
at the impervious layer along which the seepage water
travels, so that water will be intercepted and wet condition
is relieved. The tile line should be located in such a way
that there is at least 60 cm of soil cover over the top of the
tile.

Random tile drain system
Herringbone and Gridiron tile drain systems

B Mole drainage system
Mole drainage is a semi-permanent method of sub-
surface drainage, similar to tile drain in layout and
operation. Instead of permanent tiles a continuous
circular mole drain (channel) is prepared below the
ground surface in the soil profile at desired depth and
spacing using a special implement known as mole
plough. The depth of the mole
drain varies from 4.5 cm to 120 cm depending on the
moling equipment and water table. Diameter of the mole
varies from 7.5 to 15 cm. The life the mole drain is 10-15
years. It is adapted to a particular type of soil because
the soil stability is more important in this type of sub-

DRAINAGE DEPTH AND SPACING
Two types of soil profile are considered to illustrate the
influence of drain depth, spacing and other factor on
the quantity of flow of ground water towards and into
drains . In highly permeable sandy soils , underlain by
compact clay of low permeability of 1.7 to 8 m below
the land surface , the ground water flow is essentially
horizontal towards the drains . The water surface is
maintained in the reservoir and adjoining soil at a
distance of H m above the clay . Flow from drain is
steady , it being assumed that the reservoir is the only
source of water.
Ground water actually flows to the
drain from both sided with conditions existing on both
sides of the drain . Let 2q represent the flow into a

in length L . Then the ground water flow from one side to
the drain is –
q = A x V
Where
A = cross section area
V = velocity of flow

Drainage water management

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