Types of Irrigation | System of Irrigation - VIVEK DHAKAL

Types of Irrigation | System of Irrigation

types and methods of irrigation

Types of irrigation can be broadly divided into following categories:
a) Surface Irrigation
b) Subsurface Irrigation
c) Micro Irrigation

a) Surface Irrigation

It is further divided into two parts:
i) Flow Irrigation
ii) Lift Irrigation

I) Flow Irrigation

When irrigation water is supplied to the agricultural land by flow of water solely under gravity is called flow irrigation. Flow irrigation is further divided into two parts as:
1) Inundation Irrigation
2) Perennial Irrigation

1) Inundation Irrigation
When water is diverted by excavating a canal at the bank of inundation river (i.e. the river which overflows in rainy season and nearly dries up in summer and winter) without regulator at the head of canal is called inundation irrigation. The bed level of canal is fixed in such a way that water flows through the canal when water level rises above the canal bed and stops automatically when it falls below the canal bed level. As there is no head regulator, over irrigation may occur resulting in damage of crops.

2) Perennial Irrigation
If water is diverted into the canal by constructing headworks at a perennial river (i.e. the river which flows throughout the years in its full capacity) is called perennial irrigation. It consists of regulator at the head of canal to control the flow into the canal. It is of following types:
  • Direct Irrigation
In this system, headworks consist of a weir or a barrage across the river in order to raise water level upstream of the weir or barrage so that water can be diverted into the canal.
  • Storage Irrigation
In this method, a dam is constructed across the river so as to form a storage reservoir at upstream of the dam and flow of water into the canal is controlled by a head regulator. The storage reservoir may be utilized for other purposes as well in addition to irrigation such as water supply, hydroelectricity, fishery, etc.

II) Lift Irrigation

If water is lifted from surface or subsurface sources by means of manpower, mechanical power or electrical power and directly supplied to the agricultural land then it is called lift irrigation. For example, water from a well may be lifted manually in bucket and supplied to the field via same bucket, a water boring may be installed inside the field that operates by electrical power, etc. It is mostly suitable for irrigating small isolated area. The method of lift irrigation has following advantages:
  • Water is supplied to the field as per requirements and there is no possibility of over irrigation.
  • Water is supplied directly to the field and there is no conveyance loss as in canals.
  • There is no loss of valuable land because construction of distribution canals inside agricultural land is not necessary.
  • Installation and maintenance cost is low.
Lift irrigation has following disadvantages:
  • It may not be feasible for irrigating large areas.
  • Pumping from deep wells may not feasible in the areas where water tables decreases below the suction head.

b) Subsurface Irrigation

In this method, water is supplied to the plants by maintaining an artificial water table at some depth below the ground surface. Moisture then moves upward till the root zones by capillary action.

c) Micro Irrigation

The sprinkler and drip irrigation system falls under this category. In sprinkler irrigation, water is sprayed from the nozzle of sprinkler uniformly over the field. In case of drip irrigation, water is supplied to row crops through a small tube and released from the drippers provided at regular spacing along the tube.

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