What type of irrigation system needs mechanical support to supply water for irrigation?

Explanation:

Irrigation is the process of applying water to the crops artificially to fulfil their water requirements. Nutrients may also be provided to the crops through irrigation.

Types of irrigation: Irrigation may broadly be classified into : (1) Surface Irrigation  (2) Sub-surface irrigation

(1) Surface Irrigation: In this type of irrigation water wets the soil surface. It can be further classified into:

• Flow Irrigation: When water is supplied from higher level to lower level by the action of gravity then it is called flow irrigation. The irrigation from canal water or river water is the example of flow irrigation.
• Lift Irrigation: When water is lifted up by any manual or mechanical means such as Persian wheel, pumps, etc. and then supplied for irrigation then it is called lift irrigation.

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Flow irrigation can be further subdivided into : (a) Perennial Irrigation  (b) Flood Irrigation

(a) Perennial Irrigation: In this type of irrigation system, the water requirement for irrigation is supplied constantly and continuously in accordance with crop requirements throughout the crop period.

Perennial canal system may be further sub-divided as follows : 

• Direct Irrigation: When irrigation is done from direct run off of a river, or by diverting the river run off water into some canal by constructing a diversion weir or barrage across the river. For example, Ganga Irrigation canal system.

• Storage Irrigation: When a dam is constructed across a river to store water during the monsoon and the stored water is supplied in the off taking channels during periods of low flow, it is called storage irrigation.

​(b) Flood Irrigation: This kind of irrigation is some times called as Inundation irrigation. In this method of irrigation soil is kept submerged and flooded with water, so as to cause thorough saturation of the land.

(2) Sub-surface Irrigation:

• In this type of irrigation, water does not wet the soil surface.
• In this system of irrigation the supplied water comes directly in touch with root zone of the crops.
• Sub surface irrigation may be classified into two types:
  • ​Natural Sub-irrigation: When underground irrigation can be achieved simply by natural processes without any extra efforts it is called natural sub-Irrigation.
  • Artificial Sub-irrigation: The open jointed system of drain is artificially laid below the soil so as to supply the water to the crop by capillary action, then it is known as artificial sub-irrigation. This process is not adopted in India because it is very costly.