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A lined alluvial canal is best designed on the basis of
Lining of irrigation channels
A lined canal can be designed smaller in cross- section and also in length. The steeper gradients can be provided because higher velocities are permissible. It can, therefore, help to bring high areas under command.
Safety ladders are provided in large irrigation canals, to
In large canals, safety ladders are generally provided on side slopes, at suitable intervals along the canal length. These ladders can be used by persons or cattle, that may be swept away with the flowing water in the canal. Such a person, who may otherwise get drowned, may catch hold of one such ladder and can climb it to get out of the canal easily.
The main advantage offered by Bentonite layer lining in an irrigation canal is that:
Under-drainage arrangements in canals are- necessarily required in
In the alignment of an - irrigation channel wherefrom offtakes have to be provided at regular intervals, changes in the given channel parameters are made use of. The correct sequence of the decreasing order of preference of these parameters is
The best alignment of off-taking channel is that in which the off-taking channel makes zero angle with the parent channel initially and then separates out in transition. The depth of water should always be such that off take channel runs full. The transitions should be properly designed, so as to avoid accumulation of silt. The transition can also be used as metering flume. Thus depth, slope and width will be the correct order of preference of parameters.
Theoretically the best cross section for a lined canal is