A canal is an artificial channel constructed to carry water from a stream, tank or artificial reservoir, the construction of any canal has different purposes such as irrigation or hydel power generation.
Canals are constructed on the basis of objective construction i.e. canals for irrigation, canals for power generation, etc.
Among them, irrigation canals are constructed to carry water from their fields to agricultural fields.
Types of Canals:
Classification based on alignment:
When the canals are to be aligned in mountainous areas, it is not possible to align with the areas that are at the top of the hill.
In such cases, the canals typically align with the contours, the canal originating from the reservoir follows the contour alignment, which aligns parallel to the canal known as the contour canals.
Contour canals have a large number of cross drainage work but no falls, a contour canal can only irrigate one side because the other side is much larger.
Contour canals are not required to follow the same contour along their length, also the longitudinal slope is given to enable the water to flow by gravity.
Ridge canal or Ridge alignment:
This type of canals are usually laid along a ridge or natural watershed line because the canal runs on a watershed that can irrigate both sides and thus irrigate the area on both sides, also known as a watershed canal.
These canals are very economical and do not require any kind of drainage work.
Side slope canals:
In this type of alignment, the canal does not align with either the ridge or the contour, but is aligned to the contour.
These canals run parallel to the natural drain similar to the contour canal, it also irrigates areas on one side only.
These types of canals are not intercepted by cross drainage work.
Classification based on the Nature of water source:
It is a canal, a perennial supply of water is coming from its source.
It is a well graded canal has permanent regulation and distribution functions.
These canals can be further divided into two parts:
They get a constant supply of water throughout the year.
Non – perennial canals:
These canals are constructed on the river which are non-perennial, so during the cropping season only, they are used for irrigation purpose.
It is a canal that receives water only during floods when the water level in the river rises above the average.
There is no head work for diversion of river water in these canals.
Classification based on the function:
Feeders or feeder canal:
This type of canals are constructed with the sole purpose of supplying water to another canal.
These canals serve both purposes, i.e. they supply water directly for irrigation purpose and also supply water from another canal.
Classification based on discharge:
It is a large capacity canal to supplies water directly from the river or from the reservoir and to supply water to major distributors and branch canals.
They are not commonly used to make direct supplies of water to agricultural areas.
They are constructed on both sides of the main canals, also called branches.
They are generally used to collect water from the main canals and supply to major or minor distributors.
In the case of small branch canals, they are also used to provide water directly to agricultural areas.
These distributors receive water from the main canals or from the branch canals.
They are used to supply water from outlets to people in the agricultural sector.
They get water supply either from major distributors or from the branch canals.
They supply water to agricultural areas.
They collect water from an outlet of a major, a minor or a branch canal and it carry water to the agricultural fields also called as watercourses.
Classification based on financial output:
In the case of canals getting full yields to cover up not only the running cost but also about 6% of the capital investment as the saving, so it is called productive canals.
In this type of canals, there is no profit-making, it does not even cover running costs and there is no chance to repay the initial capital expenditure.
These canals are built on alluvial soils, which are very productive and very efficient for farming, so these canals are naturally more profitable.
Classification based on lining provided or not provided to canals:
These are canals made of natural soil and it has no lining of impermeable material is provided.
The flow velocity is always kept low to provide protection to the bed and banks.
As these canals have high seepages and water losses are high, if the length of such canals is more, then the water shortage increases.
These canals have been provided with impervious material lining on its banks and beds, helps prevent water leakage.
Since the flow velocity can be kept higher, the cross-section area can be reduced.
A canal is a passage for the flow of water, mainly under the force of gravity.