Cannal Design Essay

3263 WordsMar 10, 201214 Pages
CHAPTER THREE 3. Design of Channels 3.1. General The success of the irrigation system depends on the design of the network of canals. The canals may be excavated through the difference types of soils such as alluvial soil, non-alluvial soil etc. the design consideration naturally vary according to the type of soil. Again, the velocity of flow in the canal should be critical. That means, the velocity should be non-silting and non-scouring. If the velocity becomes less than the critical velocity, then silting will take place and the capacity of the canal will be reduced. If the velocity becomes more than the critical velocity then the scouring will take place and the channel will be damaged. So, determination of critical velocity is very important in canal design. Based on the water requirements of the crops on the area to be irrigated the entire system of main canal, secondary canal, tertiary canal and field distributaries should be designed properly for a certain realistic value of peak discharge that must pass through them, so as to provide sufficient irrigation to the commands. Again, the design of unlined and lined canals involves different practical and economical consideration. 3.2. Definition of some terms 1. Alluvial soil: The soil which is formed by continuous deposition of silt is known as alluvial soil. The river carries heavy charge of silt in rainy season. When the river overflows its banks during the flood, the silt particles get deposited on the adjoining areas. This deposition of silt continues year after year. This type of soil is found in deltaic region of a river. This soil is permeable and soft and very fertile. 2. Non-alluvial soil The soil which is formed by the disintegration of rock formation is known as non-alluvial soil. It is found in the mountains regions of a river. The soil is hard an impermeable in nature. This is not

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