Irrigation Report

8/13/2019 Irrigation Report

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A hydraulic structure constructed across a river, not for creatingstorage, but for the purpose of raising water level in the river sothat it can be diverted into the offtaking canals situated at oneor either of its banks.

What is a diversion work ???


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Diversion works are generally constructed on the

perennial rivers which have adequate flow throughout the year

and, therefore, there is no necessity of creating a storage

reservoir.A diversion work differs from a storage work or a dam.

A dam is constructed on the river for the purpose of creating a

large storage reservoir. The storage works are required for the

storage of water on a non-perennial river or on a river with

inadequate flow throughout the year.

On the other hand, in a diversion works, there is verylittle storage, if any.


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LOCATION OF DIVERSION WORKS

rocky

boulder

trough (alluvial)

delta

Four River Stages


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rocky- the beginning of the river, where water flows quickly with lots of energy

- the river here is smaller and usually has a rapid, tumbling flow that cuts a narrow

channel through rocky hills or mountains.

Rocky Stage of a river


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boulder

The bed and sides of a boulder river consist of a mixture of boulder, gravel,

shingle, and sand. The river cross-section is usually well-defined.

Boulder Stage of a river


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trough alluvial)After the boulder stage, a river enters the alluvial plains. The bed and banks are

now made up of sand and silt. The bed slope and the velocity of flow in the river

are much smaller than those of boulder rivers.

Alluvial Stage of a river


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delta

- An extensive platform commonly found at the rivers mouth formed by the

accumulation of layers of sediments build up over a period of time.

- In the delta stage, the irrigation requirements are generally less and also the

nature of the river at this stage poses other problems.

Delta Stage of a river


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1. The river section at the site should be narrow and well defined.

2. The river should have high, well-defined, in erodible and non

submersible banks so that the cost of river training works is

minimum.

3. The canals taking off from the diversion head works should be

quite economical and should have a large commanded area.

4. The site should be such that the weir (or barrage) can be aligned at

right angles to the direction of flow in the river. This is for uniform flow

to occur and for the length of the weir to be minimum.

Considerations:


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5. There should be suitable locations for the undersluices, head

regulator and other components of the diversion works.

6. The diversion works should not submerge costly land and

property on its upstream.

7. Good foundation should be available at the site.

8. The site should be easily accessible by road or rail.

9. The overall cost of the project should be a minimum.

Considerations:


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Documents

Irrigation Report