1. Diversion Head Works
The works, which are constructed at the head of the canal, in order to divert the river water towards the canal, so as
to ensure a regulated continuous supply of silt-free water with a certain minimum head into the canal, are known as
diversion heads works.
2. Objective of Diversion Head Works
(a) To rise the water level at the head of the canal.
(b) To form a storage by constructing dykes (embankments) on both the banks of the river so that water is available
throughout the year
(c) To control the entry of silt into the canal and to control the deposition of silt at the head of the canal
(d) To control the fluctuation of water level in the river during different seasons
3. Selection of Site for Diversion Head Works
At the site, the river should be straight and narrow
The valuable land should not be submerged when the weir or barrage is constructed.
The elevation of the site should be much higher than the area to be irrigated.
The site should be easily accessible by roads or railways.
The materials of construction should be available in vicinity of the site.
The site should not be far away from the command area of the project, to avoid transmission loss.
The river banks should be well defined.
4. Weir and Barrage
It is a barrier constructed across the river to raise the water level on the upstream side of the obstruction in order
to feed the main canal.
The ponding of water can be achieved either only by a raised crest across the river or by a raised crest
supplemented by gates or shutters, working over the crest.
BY RAISED CREST
P1 = P
P2 = 0
CREST LEVEL = POND LEVEL
P1 >>>> P2
(a) Fig: Weir without shutters
(b) Fig: Weir with shutters