Techniques of water distribution in the farms (or Method of Irrigation)
Their are mainly 7 method of Irrigation:
1. Free Flooding (or Wild Flooding or Ordinary Flooding):
In this method of Irrigation there is no controlled on water. Used on
Rolling land.
Free Flooding:-
→Free flooding also called Ordinary flooding or Wild Flooding or
Uncontrolled flooding.
→In this method, ditches are excavated in the field, and they may be either
on the contour or up and down the slope.
→Low water efficiency because there is no controlled on the water.
→The initial cost of land preparation is low but labour requirements are
usually high.
→Suitable for close growing crops, pastures(grasslands), etc.
→Best - when land is Steep.
→Used on Rolling land ( Topography Irregular ) because borders, checks,
basins, and furrows are not feasible.
→This method is cheap and can be successfully used where water supply is
plenty.
→Main supply Ditch divided into - Subsidiary ditch - and from the Outlet of
subsidiary ditch the water is provided to the fields( farms ) as shown in
Diagram.
2. Border Flooding (or Border strip flooding or simply Strip Flooding):
Land is divided into a number of strips, separated by low levees called borders.
Border Flooding :
→Border flooding also called Border strip flooding or simply strip flooding.
→In this method, the land(or farm) is divided into number of strips,
separated by low levees called borders.
→The length and width of each strip should not exceed 100 to 400m and 10 to
20m respectively.
→Most popular method.
→Water is supplied into strips from the main ditch and it flows slowly over
the whole area. A gate is placed in the main ditch at the head of each strip
for controlling the entry of water.
→When the water reaches the lower end of strip, the supply of water to the
strip is turned off.
→Controlled type technique.
→The size of the supply ditch depends upon the infiltration rate of the
soil, and the width of the border strip.
→Coarse textured soils with high infiltration rates will require high
discharge rate and therefore larger supply ditch, in order to spread water
over the entire strip rapidly, and to avoid excessive losses due to deep
percolation at the upper reaches whereas fine textured soils with low
infiltration rates, require smaller ditches to avoid excessive losses due to
run off at the lower reaches.
→The infiltration rate governs the maximum surface area that can be
irrigated.
Relationship to obtain the maximum area irrigated with a supply ditch.
→A relationship between the discharge through the supply ditch (Q), the
average depth of water flowing over the strip (y), the rate of infiltration
of the soil (f), the area of the land irrigated (A), and the approximate
time required to cover the given area with water (t), is given by the
equation:
3. Check Flooding :
Similar to Ordinary Flooding expect that the water is controlled by
surrounding the check area with low and flat levees. Best for cereal crops.
This method is suitable for both more permeable and less permeable soils.
4. Basin Flooding :
This method is a special type of check flooding and adopted for orchard
trees ( fruits trees )
5. Furrow Method (or Furrow Irrigation):
In this method of Irrigation, water is applied to the land to be irrigated
by a series of furrows. Furrows are small, parallel channels, made to carry
water for irrigation the crops. Small shallow furrow called
Corrugations.
6. Sprinkler Irrigation Method (or Over Head Irrigation):
Water is applied to the land in the form of spray, somewhat as in ordinary
rain through a network of pipes and pumps.
7. Drip Irrigation (Trickle Irrigation or Sub-surface Drip Irrigation):
Highly efficient irrigation method because evaporation and infiltration
losses are very less. Water and fertilizer is slowly and directly applied to
the root zone of the plants.