the material of this PPt according to the RTU syllabus

1. Assi Prof. Brijlata sharma
JECRC, Jaipur

2. 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 regulated continuous supply
of silt free water with certain minimum head into
that canal is called as diversion head works.
• These are constructed on a river where adequate
flow of river water is available throughout the year.
• If the storage on upstream of diversion head works
is significant, it is called storage weir
• If it is constructed on downstream of dam for
purpose of diverting water from upstream side of
dam into canal, it is called pick up weir.

3. .
LOCATION OF DIVERSION HEAD WORK:-
It should be near the command area. The site which gives economical arrangement
is usually selected.
SITE SELECTION :-
1) Good foundation should be available.
2) The site should be such that weir can be aligned at right angle to the
diversion of water in the river.
3) The site should be such that there should be sufficient space for location of
head regulator and other component of the diversion headwork.
4) The overall cost should be less.
5) Proper approach way should be nearby site.
6) On the upstream side where water is retained, should not include costly
land.
7) While construction of weir or barrages river should be available near the
site.
8) The material and labours should be available nearby site.
9) The river should be perennial.
10)The river should have non erodible as well as non submersible banks.
11)The site should be narrow and well defined.

4. COMPONENT PARTS OF A DIVERRSION HEADWORK
1. Weir or barrage 2. Undersluices 3. Divide wall
4. Fish ladder 5. Canal head regulator
6. pocket or approach channel 7. Silt excluders/ Silt prevention
devices 8. River training works (Marginal bunds and guide banks)

5. Weir & Barrage:-
• Weir: It is an impervious .barrier constructedacross
a river to raise its water level on its upstream side
and divert the water into the canal taking off from
its upstream side.
Weir afflux chances are more in floods.
• Barrage: If storage of water is done by gates and
very small portion or nil portion of water is stored
by raised crest then the barrier is called as barrage.
Barrage is a gate controlled weir. The heading up of
water is effected by the gates alone.
Barrage afflux chances are reduced by gates.

6. .
TYPES OF WEIR:-
• 1) gravity weir 2) non gravity weir
• 1) gravity weir
• Depending on material and design features, gravity weirs are subdivided
into following types-
• (i)Vertical drop weir.
• (ii) Sloping weir
• a. Rock fill weirs.
• b. Concrete weirs
• Weirs are also classified as follows :
• (1) According to use and function.
• (a) Storage weir. (b) Pick up weir.
• (c) Diversion weir. (d)Waste weir.
• (2) According to control of surface flow.
• (3) According to the design of floors.
• (4) According to constructional material
• a) Masonry weir
• b) Rockfill weir
• c) Concrete weir

7. • Gravity weir:- when the weight of weir balances uplift pressure
caused by the head of water seep
.ingbelow weir it is called asgravity
weir.
• Non gravity weir:- in non gravity weir the uplift pressure is
largely resisted by weight of concrete slab with the weight of divide
piers.
i) Vertical Drop Weir:

8. This type of weir consists of horizontal floor and masonry crest with
vertical or nearby vertical downstream face and the shutters are
provided at the crest. Most of the.storage is done by raised crest and
some storage by shutters provided over the crest.
ii) Rock Fill Weir
It is also called as dry stone slope weir. It is suitable for fine sandy
foundation. stone are mainly used for construction of such type of
weir and hence requires large quantities of stone

9. iii) Concrete Weir:
These are suitable for permeable.foundations. In such weirs sheet
piles are provided on both upstream and downstream floors in order
to destroy the energy of water

10. .
According to use and function
a) Storage Weir :
It is high weir constructed for storing water. It is also called as
diversion weir. In such weirs shutters may or may not be provided.
b) Pick Up Weir :
These are constructed when command area is far away from reservoir
either due to rolling topography or because the land is not cultivable
and if there is broken or rolling topography on one or both banks of
parent river in which construction of canal may be costly.

11. • A solid weir usually with crest gates constructed in concrete or stone
masonry located at some distance downstream of dam forming a
large reservoir to raise the water .levelup to FSL of canal is known
as pickup weir .
Situations: It is proposed in the following situations-
i) In case of broken or rolling topography on one or both banks of the
parent river where canal construction is costly.
ii)In case of command area is too far away from the reservoir may be
due to rolling topography.
iii) In case of land nearby the reservoir is not cultivable.
iv) The command area not near the reservoir.
v) Canal has to run idle.
Vi) Geographically difficult terrain so that the canal alignment is
very costly or impossible.

12. c) Diversion Weir:
A weir which is constructed for di.vertingthe river water into the canal
is called as diversion weir. Generally it is constructed at 900 to the
flow of river.
D) Waste weir:- it is constructed in continuation of dam . It is
also known as escape channel or a spillway. It allows flood water to
escape and thus ensure safety of the dam.

13. UNDER SLUICE
Under sluice are opening providedin the body of weir at low level.
These are located at same side from which canal is taking off. The
crest of under sluice is kept lower than crest of weir due to which
water is attracted towards it and thus ensure easy diversion into
canal.

15. FUNCTIONS OF UNDERSLUICE:-
1) it control entry of silt i.nto canal.
2) it lowers the HFL.
3) it helps in passing low river flood without lifting
shutters.
4) it helps to pass silt on downstream side of weir.
whenever silt is remover the gates of head regulator
are closed and of sluice are opened through these
sluice the silt which is deposited is removed and it
goes on downstream side when all silt is removed
silt gates are closed and regulator gates are opened.

16. DIVIDE WALL:-
is wall constructed bet.weenunder sluices and the
weir at right angle to the axis of the weir to
divide the river channel.
Function of divide wall:-
1) it separates the under sluices from weir.
2) it also helps in reducing velocity of flow near the
head regulator due to which silt is deposited and
clear water passes in to canal.
3) it prevents vortices means flow in circular
motion.

18. FISH LADDER
• It is passage provided adjacent to divide wall for the
movement of fish from upstream to downstream
and vice versa.
• It allows free access to fish so that they can travel
from colder water to hot water
• It has been observed that fish moves from old
water to warm water and in monsoon they again
move towards upstream or downstream of the
work.
• These are provided with various fashion like sluice
type in which the baffle wall is in zig zag way over
flow type in which V notches are provided in
staggered arrangement etc.

25. Silt excluder:-
The device which are constructed at the head of main
canal which prevents entry of silt particles into
canal are called as silt exclusion devices.
Silt ejectors:-
• The structure which is constructed across the canal
to eject silt accumulated in canal section is called
silt ejector.
• Silt ejector consist of tunnel which is connected
parallel to the flow of the canal and then turns 90
degree to eject silt.
• The length of tunnel provided may be different.
These are provided with sufficient slope. So that silt
should not be deposited in its bed.

30. GUIDE BANK:-
• Guide banks are provided on either side of diversion head work. In alluvial
soil to prevent river from out flankin.gthe work.
The main object of guide banks are:-
1) it prevent oblique approach to the head regulator .
2) it protect regulator from river attack.
3) it increases maximum discharge at all point.
4) it prevent out flanking of structure.
5) it create reasonable water way for a weir.
6) Toseparate flow from the scouring weir which is at lower level than proper
weir.
7) Toseparate the silting packet from scouring sluices
8) Toprevent formation of cross currents to avoid domain effects
9) Tocut off the main portion of the river and provide a comparatively quite
packet in front of the canal head regulator resulting in deposition of silt in
the pocket and enter clear water in canal

32. Marginal embankment:-
Marginal embankment are provided on either bank
of river upstream of diversion head work to protect
the land and property which is likely to be
submerged during flood.
It helps in :-
1) reduce the intensity of flood.
2) it prevents bed level of the river by silting.
3) it protect land and property which is likely to be
submerged.
SCOURING SLUICE:-
It helps in scour out the deposited bed silt.

33. HEAD REGULATOR:-
1) It regulates the supply.of water entering in canal.
2) It controls the entry of silt into canal
3) It prevents the river flood entering the canal
Stilling Pond:
In still can be taken outing pond water made stil
where deposition of silt takes place due to
sedimentation and from which silt can be taken out.
1) Toreduce velocity of water.
2) Tosettle down the silt and allow clear water to
the canal.