Under Sluices are gates controlled openings in the weir with crest at low level. They are located on the same side as off-take canal. If two canal take off on either side of the river, it would be necessary to provide undersluices on either side.
Functions of under-sluices
■ To preserve a clear and defined river channel approaching the canal regulator.
■ To scour silt deposited in front of canal regulator and control silt entry in the canal.
■ To facilitate working of weir crest shutters or gates. The flood can easily pass.
■ To lower the highest flood level.