Drainage

Drainage:

      Agricultural drainage is the removal of excess water known as free water or gravitational water from the surface or below the surface of the farm land so as to create favourable soil conditions for plant growth.

Causes of Water Logging:

a) Natural

   1) Poor natural drainage of subsoil 

   2) Submergence under floods.

b) Artificial

   1) High intensity of irrigated agriculture irrespective of the soil and subsoil 

2) Heavy seepage of losses from unlined canals , distribution and farm wate courses.

3) Enclosing Irrigated fields with embankments and chocking up natural drainage

4) Hyadraulic pressures from upper saturated areas at higher elevations.

5) Non maintenance of natural drainage or blocking of natural drainage.

Methods:

1) Surface drainage

2) Sub - Surface drainage 

SURFACE DRAINAGE:

     Simplest and most common in India by digging open drains at suitable intervals and depth

MERITS: 

1) Cheap

2) Defects in the open drainage can be seen easily and rectified

3) Requires less available fall or grade for adequate outlet 

DEMERITS:

1) Some land is wasted for open drains

2) Causes hinderance to field Preparation and Intercultivation.

3)Periodical desilting is necessary

4) Heavy weed growth

5) It may be damaged by rodents and farm animals

THERE ARE METHODS AND SYSTEMS FOR SURFACE DRAINAGE, having three functional parts 

Colletion , Disposal and Outlet Systems 

a) Drainage of flat areas ( Slope less than 2%)

For flat areas , two processes are adopted -

1) SMOOTHING / GRADING/ FORMING:

         Means land with continuous slope 

i.e. elevated areas are cut off and excess soil is spread over lower areas so that surface becomes even with uniform slope.

Excess run off is collected and conveyed into the field ditches.

2) FIELD DITCHES SYSTEM:

a) Bedding system:

    Small furrows are formed at known intervals parallel to the slope for draining out water . Those furrows are called dead furrows and land between these furrows are called beds.

b) Parallel field ditch:

Similar to bedding system except for deep drains and uneven interval between drains. 

Most effective and suited for both irrigated & rainfed.

C) Parallel open field ditch:

Deeper in depth and steeper side slopes than parallel field ditch hence is the name 'OPEN' also called diversion ditch system 

It is used in both surface and sub-Surface drainage

d) Broad Bed And furrow System( BBF):

Field is laid out into 120-150 cm width beds and 45 cm wide furrows across the slope. About 0.5% slope is provided for free drainage. Crops are sown on beds having two or more than two rows each . Beds are 15 cm raised. BBFmethod is widely practiced in groundnut in clay soil .

Drainage of Ponded Areas:

Micro ponds or depressions are connected by means of shallow channels or ditches

Drainage of water is made by random field ditch system.

Drainage of sloping areas (Slope greater than 2% ) by interception system or cross slope ditch system:

B) Sub- Surface drainage:

  Purpose is to lower down the ground water level below root zone .

These are following methods:

1)Tile Drains including perforated pipes : It has following types of arrangements of tiles or pipes:

a) Natural or Random

b)Herring bone type: 

   Here there is no submain.

c) Gridiron type:

    Tiles arrangements from one side only

d) Cut off or Interceptor:

    It intercepts seepage moving down a slope .

2.Mole drainage:

      A mole is the egg shaped drain which is made in the clay soil with the help of Mole plough .Once made mole drain remains functional for 3-5 years and especially suitable for clay soils.

3 Vertical Drainage:

Drainage by wells is called Vertical Drainage.

Wells  are digged out to collect water from the nearby areas though seepage and collected water is pumped out.

4) Deep Open Drainage:

Deep open drains are made in which water is collected by seepage which drained out from the field.

5) Burried Drainage: Draining channel is made below the ground surface . After making it drains are filled with tiles , fibres or plastics.

6) Combination of tile and open drains.

✍️Agricoss Vaishnavi Nimkar

(Gunji, Dhamangaon Railway District Amravati)

Contact No: 7666441799