This document provides an overview of hydraulic structures and their components. It defines a hydraulic structure as anything partially or fully submerged in water that disrupts natural flow. Weirs raise water levels while barrages can adjust levels using gates. Dams form deep reservoirs. Diversion structures include temporary barriers and permanent weirs/barrages. Key components are the weir/barrage, divide wall, fish ladder, approach channel, sluices, silt prevention, head regulator, and river training works like guide banks and spurs. The document describes the purpose and design of each component.

1. CE-413 Hydraulic structures
Lecture# 01
(8th semester Civil)
By: Engr. Hayat Hussain
Lecturer Saidu polytechnic institute saidu sharif Swat

2. Content
• Hydraulic structure
• Difference between weir, barrage and dam
• Layout of diversion headwork
• Types of diversion weir
• Components of diversion weir

3. Hydraulic structure
A hydraulic structure is a structure submerged or partially submerged in
any body of water, which disrupts the natural flow of water.

4. Difference between weir, barrage and dam
• Weir : An impervious barrier which is constructed across a river to
rise the water level on the upstream side is known as weir. Here the
water level is raised up to the required height & the surplus water is
allowed to flow over the weir. Generally it is constructed in the
inundation river.

5. • Barrage: when adjustable gates are installed over the weir to maintain
the water surface at different level at different time, then it is known as
barrage. The water level is adjusted by operating the adjustable gates
or shutters. The gates are placed at different tiers and these are
operated by cable from cabin the gates are supported on the piers at
both ends. the distance between pier to pier is known as bay.

6. • Dam: the high impervious barrier constructed across a river valley to form
a deep storage reservoir is known as dam. The surplus water is not allowed
to flow over the dam. The surplus water is not allowed to flow over the
dam but it flows through the spillway provided at some design level.

8. Types of diversion weir
• Storage Headwork : A Storage headwork comprises the construction
of a dam on the river. It stores water during the period of excess
supplies and releases it when demand overtakes available supplies.
• Diversion Headwork: to divert required supply to canal from the
river
a) Temporary Spurs or bunds which are temporary and constructed
every year after floods
b) Permanent Weirs and Barrages

9. Components of diversion weir
1.Weir or Barrage
2. Divide wall or Divide Groyne
3. Fish Ladder
4. Pocket or Approach Channel
5. Scouring Sluices
6. Silt Prevention Devices
7. Canal Head Regulator
8. River Training Works (Marginal Bunds and Guide Banks)

10. 1. Weir & barrage
weir :The weir is a hydraulic structure constructed across the river to raise
its water level and divert the water into the canal If a weir also stores water
for tiding over small periods of short supplies, it is called as storage weir. The
main difference between a storage weir and dam is only in height and
duration for which supply is stored.
Barrage: when adjustable gates are installed over the weir to maintain the
water surface at different level at different time, then it is known as barrage.
The water level is adjusted by operating the adjustable gates or shutters. The
gates are placed at different tiers and these are operated by cable from cabin
the gates are supported on the piers at both ends. the distance between pier
to pier is known as bay.

11. 2. Divide Wall or Divide Groyne
The divide wall is a masonry or concrete wall constructed at right angle
to the axis of the weir. The divide wall extends on the upstream side
beyond the beginning of the canal head regulator; and on the
downstream side, it extends up to the end of the loose protection of the
under-sluices.
Functions :
• It separates the ‘under-sluices’ with lower crest level from the ‘weir
proper’ with higher crest level.
• It helps in providing a comparatively less turbulent pocket near the
canal head regulator, resulting in deposition of silt in this pocket and,
thus, to help in the entry of silt-free water into the canal.

12. 3. Fish Ladder
In big rivers, fish will always move up and down respectively in search of clear and
warm water. It is, therefore, essential for the provision of some space in the
construction of weir.
• It is usually located between the weir and divide wall.
• It is suited near the divide wall as there is always some water in the river section
below the scour sluices
• It consists of an inclined trough with baffles with holes provided in them.
• The baffles reduce the velocity and provide compartments for the fish to rest.
• To have effective control, grooved gates are provided at the extreme upstream
and downstream end walls.
• The fish ladder should be designed to have a velocity of 3 m/s or less in the
trough.

13. 4. Scouring Sluices
They maintain a deep channel in front of head sluice and dispose off heavy
silt and a part of flood discharge on the downstream side of the barrage or
weir.
Functions:
• To preserve a clear and defined river channel approaching the regulator.
• To control the silt entry in to the canal.
• To scour the silt deposited in the river bed above the approach channel.
• To help in passing low floods without dropping the shutters of main weir.
• To provide additional waterway for floods, thus lowering the flood levels.

14. 5. Silt Prevention Devices
The entry of silt into a canal, which takes off from a head works, can be reduced by
constructed certain special works, called silt control works.
Types:
1. Silt Excluders:
Silt excluders are constructed on the bed of the river upstream of the head regulator.
The clearer water enters the head regulator and silted water enters the silt excluder.
In this type of works, the silt is removed from the water before in enters the canal
2. Silt Ejectors
Silt ejectors, also called silt extractors, are those devices which extract the silt from
the canal water after the silted water has traveled a certain distance in the off-take
canal. These works are, therefore, constructed on the bed of the canal, and little
distance downstream from the head regulator

15. 6. Head Sluice or Canal Head Regulator
A head regulator is structures constructed at the head of a canal off
take from a reservoir behind a weir or a dam. It may consist of a
number of spans separated by piers and operated by gates.
Functions:
• To make the regulation of supply in the canal easy.
• To control the silt entry in to the canal.
• To shut out river floods.
• To provide full supply required for irrigation at moderate velocities
with sufficient allowance.

16. 7.0 River Training Works
River training works are required near the weir or barrage in order to
ensure a smooth and an axial flow of water when the length of a weir or
barrage is smaller than the width of a river
Types:
 Guide banks
Marginal bunds
Spurs or Groynes

17.  Guide banks
When a barrage is constructed across a river which flows through the
alluvial soil, the guide banks must be constructed on both the
approaches to protect the structure from erosion.
Guide bank serves the following purposes:
1. It protects the barrage from the effect of scouring and erosion.
2. It provides a straight approach towards the barrage.
3. It controls the tendency of changing the course of the river.
4. It controls the velocity of flow near the structure.

18. Marginal bunds
The marginal bunds are earthen embankments which are constructed parallel
to the river bank on one or both the banks according to the condition. The top
width is generally 3 m to 4 m. The side slope on the river side is generally
1.5: 1 and that on the country side is 2:1
. The marginal bunds serve the following purposes:
1. It prevents the flood water or storage water from entering the
surrounding area which may be submerged or may be water logged.
2. It retains the flood water or storage water within a specified section.
3. It protects towns and villages from devastation during the heavy flood.
4. It protects valuable agricultural lands

19. Spurs or Groynes
These are temporary structures permeable in nature provided on the
curve of a river to protect the river bank from erosion.
• These are projected from the river bank towards the bed making
angles
60oto 75o with the bank of the river.
• The length of the spurs depends on the width of the river and the
sharpness of the curve.
• The function of the spurs is to break the velocity of flow and to form a
water pocket on the upstream side where the sediments get deposited.
Thus the reclamation of land on the river bank can be achieved.

20. Questions & Answers

21. Thanks