Chapter: Civil - Water Resources and Irrigation Engineering - Canal Irrigation

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Canals

Conveyance subsystem for irrigation includes open channels through earth or rock formation, ones constructed in partially excavated sections or above ground, pipe lines installed either below or above the ground surface, and tunnels drilled through high topographic obstructions.

CANAL IRRIGATION

 

CANALS

 

Conveyance subsystem for irrigation includes open channels through earth or rock formation, ones constructed in partially excavated sections or above ground, pipe lines installed either below or above the ground surface, and tunnels drilled through high topographic obstructions. Formation conduits of a typical gravity project are usually open channels through earth or rock federations. These are called canals.

 

 

The canal is defined as an artificial channel constructed on the ground to carry water from outer or another canal or a reservoir to the fields. Usually, canals have a trapezoidal cross-section. Canals can be classified in many ways.

 

 

Based on the nature of source of supply, a canal can be either a permanent or an gradation canal. A permanent canal has a continuous source of water supply. Such canals are called perennial canals. An inundation canal draws its supplies from a river only during high stages of the river. Such canals do not have any head works for diversion of river to the canal, but are provided with a canal head regulator.

 

 

Depending on their function, canals can also be classified as: (i) irrigation, (ii) navigation, (iii) power, and (iv) feeder canals. An irrigation canal carries water from its source to agricultural fields. Canals used for transport of goods are known as navigation canals. Power canals are field to carry water for generation of hydroelectricity. A feeder canal feeds two or more canals.

 

 

A canal can serve more than one function. The slope of an irrigation canal is generally than the ground slope in the head reaches of the canal and, hence, vertical falls have often we constructed. Power houses may be constructed at these falls to generate power and, thus, irrigation canal can be used for power generation also.


CANAL IRRIGATION

 

CANALS

 

Conveyance subsystem for irrigation includes open channels through earth or rock formation, ones constructed in partially excavated sections or above ground, pipe lines installed either below or above the ground surface, and tunnels drilled through high topographic obstructions. Formation conduits of a typical gravity project are usually open channels through earth or rock federations. These are called canals.

 

 

The canal is defined as an artificial channel constructed on the ground to carry water from outer or another canal or a reservoir to the fields. Usually, canals have a trapezoidal cross-section. Canals can be classified in many ways.

 

 

Based on the nature of source of supply, a canal can be either a permanent or an gradation canal. A permanent canal has a continuous source of water supply. Such canals are called perennial canals. An inundation canal draws its supplies from a river only during high stages of the river. Such canals do not have any head works for diversion of river to the canal, but are provided with a canal head regulator.

 

 

Depending on their function, canals can also be classified as: (i) irrigation, (ii) navigation, (iii) power, and (iv) feeder canals. An irrigation canal carries water from its source to agricultural fields. Canals used for transport of goods are known as navigation canals. Power canals are field to carry water for generation of hydroelectricity. A feeder canal feeds two or more canals.

 

 

A canal can serve more than one function. The slope of an irrigation canal is generally than the ground slope in the head reaches of the canal and, hence, vertical falls have often we constructed. Power houses may be constructed at these falls to generate power and, thus, irrigation canal can be used for power generation also.

 

Similarly, irrigation canals can also be utilized for the transportation of goods and serve navigation canals. Inland navigation forms a cheap means of transportation of goods and, hence, must be developed. However, in India, inland navigation has developed only to a limited sufficient. This is mainly due to the fact that irrigation canals generally take their supplies from Ruvial Rivers and, as such, must flow with sufficient velocity to prevent siltation of the canal. Each velocity makes upstream navigation very difficult. Besides, the canals are generally aligned on the water shed is the dividing line between the catchment areas of two drains so that water may reach the fields on both sides by flow. This alignment may not be suitable for navigation which requires the canal to pass through the whereas in the vicinity of industries.

 

An irrigation canal system consists of canals of different sizes and capacities. Accordingly, the canals are classified as: (i) main canal, (ii) branch canal, (iii) major distributary, (iv) minor distributary, and (v) water course.


Figure: Layout of an irrigation canal network

 

 

The main canal takes its supplies directly from the river through the head regulator and acts as a feeder canal supplying water to branch canals and major distributaries. Usually, direct irrigation is not carried out from the main canal.

 

 

Branch canals (also called ‘branches’) take canals generally carry a discharge higher than 5m3/s and act as a feeder canals for major and minor distributaries. Large branches are rarely used for direct irrigation. However, outlets are provided

 

on smaller branches for direct irrigation.

 

Major         distributaries(aries’lsocalledorrajbaha)3/s‘disofdischarge. car

 

These distributaries take their supplies generally from the branch canal and sometimes from the main canal. The distributaries feed either Watercourse through outlets minor distributaries.

 

Minor distributaries   (also   called   ‘minors’)adischargelessthan are

 

0.25 m3/s and feed the watercourses for irrigation. They generally take their supplies from major distributaries or branch canals and rarely from the main canals.

 

A watercourse is a small channel which takes its supplies from an irrigation channel generally distributaries) through an outlet and carries water to the various parts of the area be irrigated through the outlet.

 

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