This presentation gives information about regulating Structure.

1. 1
Regulating Structure for
Canal Flow
Prepared By
KEVADIYA RONAK

2.  Introduction
 Mechanism of Regulation Works
 Canal Falls
 Cross regulator
 Distributary Head Regulator
 Canal escapes
 Canal Outlets
 Case Study of KLBMC
 Conclusive Remarks
 References
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3.  The structure constructed on a canal to regulate the discharge, full
supply level or velocity of flow are known as Canal Regulation Works.
 A canal obtains its share of water from the pool behind a barrage
through a structure called the Canal Head Regulator. Through this is
also a regulation structure for controlling the amount of water passing
into the canal.
 Classification of Regulation Works:
I. Canal Falls
II. Cross Regulators
III. Distributary Head regulator
IV. Canal Escapes
V. Canal Outlet
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4.  Advantages of Regulation Works:
I. Canal fall is used to reduce energy of water due to velocity of u/s water.
II. Cross Regulator is use for maintain supply of water to off-taking channel
during low discharge period.
III. With combination of canal fall, it is possible to control water surface slope.
IV. Distributary Head Regulator is use as a silt control device and prevents the
deposition of silt in canal.
V. Canal Escape enables to maintain proper head in canal during heavy rainfall
period or low demand time.
VI. Canal outlet act as water measuring device and it is helpful to make water
charge bills according to field utilization.
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5.  Disadvantages of Regulation Works:
I. High construction and maintenance cost of the structures.
II. Difficult to construct the regulating devices on the flowing canals.
III. While repairing of any part of the structure of whole structure cause many
problems related to coming water from the u/s and its distribution.
IV. Failure of any of these structure cause the flooding condition in the
surrounding area.
V. Very skilled labors and continuous supervision is required while construction
of the regulating structures.
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6. 1. Canal Falls:
 A canal fall is an irrigation structure constructed across a canal to
lower down its water level and destroy the surplus energy liberated
from the falling water which my otherwise scour the bed and banks of
canal.
 Necessity of Canal Falls:
 The canal falls are required when the natural slope of the ground along
the canal alignment is steeper than the bed slope of the canal. The
canal bed slope my vary from 1 in 4000 for a discharge of bout 1.5
cumecs to about 1 in 8000 for a discharge of 3000 cumecs. The
average ground slope is about 1 in 200 to 1 in 50. The difference in the
slops is adjusted by providing vertical falls in the bed of the canal at
suitable intervals.
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7.  Location of Canal Falls:
I. For the canal which does not irrigate the area directly, the falls should be
located from the consideration of economy of earthwork.
II. For the canal irrigating the area directly, a fall may be provided at a location
where the F.S.L. of the canal outstrips the ground level but before the bed of
the canal comes into filling.
III. The location of a falls may also be decided from the consideration of the
possibility of combining it with a cross regulator or a rod bridge to effect
economy.
IV. A relative economy is achieved by providing either a large number of small
falls or small number of large falls, whichever is less is worked out.
V. Sometimes it is necessary to provide fewer falls of large drops to enable
hydropower generation at these falls.
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8.  Type of Falls:
I. Ogee Fall:
 The ogee falls was first constructed by Sir Proby Cantley on the Gang canal.
This type of fall has gradual convex and concave curves with an aim to
provide a smooth transition and to reduce disturbance and impact and
reduce dissipation of energy.
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9. II. Rapid Fall:
 The rapid falls was fist evolved by R.F. Croften and first constructed on the
Western Yamuna Canals. Such falls consists of a glacis sloping at 1 vertical
to 10 to 20 horizontal. The long glacis assured the formation of hydraulic
jump for the dissipation of energy. However, due to high construction cost,
this falls are not more popular.
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10. III. Notch Fall:
 A trapezoidal notch fall consists of a number of trapezoidal notches in high
breast wall, called Notch Pier, constructed across the channel. There is a
smooth entrance to the notches. A flat, circular lip projecting down stream
from each notch disperse the water.
 This type of fall was evolved by Reid in 1894. The notches of the fall were
designed to maintain the normal depth of flow in the channel upstream of the
flow at any two discharge values.
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11. IV. Vertical Drop Fall:
 In this, a crest wall is constructed to create a vertical drop. Cistern is provided
to dissipate the surplus energy of water leaving crest. In cistern a grid of banks
of timber placed a few centimeters apart to intercept the falling nappe. This
fall is not become popular due to getting clogged with floating debris.
 The Sharda type fall developed on the Sharda canal project in U.P. is a vertical
fall.
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12. V. Glacis Fall:
 The glacis fall utilizes hydraulic jump for the dissipation of energy.
 Following are the type of Glacis fall:
i. Straight Glacis:
 In Punjab, the flumed fall with straight glacis was developed. There was
some problem with some of these falls. Like one cause of trouble was that
even after the formation of hydraulic jump, there was considerable amount of
surplus energy in water.
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13. ii. Montague Falls:
 It is a modified type of straight glacis fall. In this type, a parabolic glacis,
called as the Montague profile is provided. This gives the maximum horizontal
acceleration to the jet of water in given length of glacis.
 In this type of fall it is not possible to dissipate the entire energy and
considerable surplus energy is still left even after the formation of the
hydraulic jump.
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14. iii. Inglis Fall:
 This fall also a modified form of the straight glacis fall. In this type fall, a
baffle wall of certain height is provided at some distance d/s of the toe of
the straight glacis. The baffle wall ensures the formation of the hydraulic
jump on the baffle platform and effective dissipation of energy.
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15. 2. Cross Regulators:
 It is a structure constructed across a canal to regulate the water level in the
canal upstream itself and the discharge passing downstream of it for one or
more following purposes:-
I. It enables effective regulation of the entire canal system.
II. It helps in closing the supply to the d/s of the parent channel, for the purpose
of repairs.
III. There can be provided a bridge which can be means of communication.
IV. It helps to absorb fluctuation in the various sections to the canal system, and
thus prevents breaches in the tail reaches.
V. It can be use to control the drawdown when the subsoil water level re high to
ensure safety of canal lining.
VI. In conjunction with escapes they help water to escape from the channels.
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16.  A cross regulator is generally provided downstream of n off taking channel so
that the water level upstream of the regulator can be raised.
 Cross regulators may be combined with bridges n falls for economic and other
special considerations.
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17. 3. Distributary Head Regulator:
 A distributary head regulator is provided at the head of the off-taking canal to
control the supplies entering the off-taking canal.
 The Distributary Head Regulator serves to:-
I. Divert and regulate the supply into the distributary from the parent channel,
II. Control the silt entering the distributary from the parent channel,
III. Measure the discharge entering the distributary.
IV. It help in shutting off the supplies when not needed in the off-taking channel
or when off-taking channel is required to be closed for repairing works.
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18.  For regulating the supplies entering the off-taking channel from the parent
channel, abutments on either side of the regulator crest are provided. Piers are
placed long the regulator crest at regular interval.
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19. 4. Canal Escape:
 Canal escape is a structure to dispose of surplus or excess water from a canal.
It is a sort of safety valve. It provides protection of the canal against possible
damage due to excess supply which may be because of either mistake in
releasing water or a heavy rainfall which cause decrease in demand of water
for irrigation in the fields.
 The excess supply makes the canal banks vulnerable to breaches or dangerous
leaks and hence, provision for disposing of excess supply in the form of canal
escapes at suitable intervals along the canal.
 Types of Escapes:
A. Based on the purpose:
I. Surplus Water Escape:
 It is a structure constructed on n irrigation channel to dispose of surplus
water from the channel. It also known as Canal Surplus Escape.
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20.  These escapes are provided in the banks of the channel at interval depending
on importance on the channel and the vicinity of a suitable natural drain for
disposal of surplus water. The channel leading surplus water from escape to
natural drain is called Escape Channel.
 Length of it should be as minimum s possible and its capacity should be 0.67
to 0.50 times capacity of channel.
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21. II. Tail Escapes:
 An irrigation canal generally ends in a natural drain or river. An escape is
provided cross the channel at its tail end to maintain the required F.S.L. at the
tail end, called Tail Escape.
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22. B. Based on the Structural Design:
I. Rectangular Type or Sluice Type Escapes:
 It is also use s surplus escapes. These sluices can empty the canal for repair
and maintenance and, is some cases, act as scouring sluice to facilitate
removal of sediment. Location of escapes depends on the availability of
suitable drains, depressions or river bed level.
II. Weir Type Escape:
 These are flush or weir escapes constructed either in masonry or concrete
with or without crest shutter which re capable of disposing of surplus water
from the canal.
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23. 5. Canal Outlet:
 When the canal water reached near the fields to be irrigated, it has to be
transferred to the watercourse.at the junction of watercourse and distributary,
an outlet is provided. It is a masonry structure through which water is admitted
from the distributray into watercourse.
 It also act as water- measuring device. The discharge through an outlet is less
than 0.085 cumecs. Thus, an outlet is like a head regulator for field channel.
 Requirements of a good Outlet:
i. It should be simple in design with no moving parts, in construction and
maintenance.
ii. It should be strong and durable.
iii. It should not be easily tampered with by the cultivators, but if tampered with
it should be easily detected.
iv. It should be worked efficiently with a small working head.
v. For proper distribution of water the outlet should draw proportionately
more or less discharge with the varying supply I the distributing
channel.
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24.  Types of Outlets:
I. Non-modular Outlet:
 It is the outlet whose discharge depends upon the difference in water level of
both the distributing channel and water course. Therefore discharge through
it varies with the variation of water level in both the distributing and water
course. For example:
i. Submerged Pipe Outlet,
ii. Masonry Sluice and Orifice,
iii. Wooden Shoots.
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25. II. Semi-modular outlets or Flexible Outlets:
 It is the outlet whose discharge depends only upon the water level in the
distributary and is independent of the water level in the water course. Thus
the discharge in a semi-modular outlet does not depend upon the
fluctuations in the water course, provided a minimum working head
required for its working is available. For example:
i. Pipe Outlet,
ii. Kennedy’s Gauge ,
iii. Crump’s Open Flume,
iv. Pipe cum Open Flume.
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26. iii. Modular Outlets or Rigid Modules:
 It is the outlet whose discharge is independent of the water levels of both
the distributary and the water course. Thus, a modular outlet maintains a
constant discharge irrespective of variation of water levels in the distibutary
and the water course. For example, Gibb’s Rigid Module.
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27.  At Kakrapar Left Bank Main Canal following regulating structures are
provided:
Fig.1-KLBMC Layout 27

28.  At Ratania junction, from where Main Left Bank Canal is originates, Head
Regulator is provided with 3 numbers of regulating gates with dimension of
20ft.*10ft, which maintains the head of water level in the canal after
maintaining 153.20ft.level in the Ratania Lake which is use for cooling of
Kakrapar Nuclear Plant.
Fig.2- Ratania lake 28

29.  Near Jarimora junction, 5.665 km from Ratania Head Regulator, canal Escape
is provided to take-off surplus water discharging into Surat Branch Canal.
Fig.-3 Jarimora Junction Fig.-4 Ratania to Jarimora canal line Diagram
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30.  At Jarimora junction Cross Regulator is provided at downstream of the main
canal and Head Regulator is provided for the entry of water into Surat branch
canal with 4 number of regulating gates with dimension of 12ft.*8ft.
 At Bhamaiya junction canal is divided in to two parts that are, Surat
Branch and Bardoli Branch, where Cross Regulator is provided for Surat
branch and Head Regulator is provided for Bardoli branch with 3
numbers of gates with dimension of 8ft.*6ft.
Fig.5- Bhamaiya Junction Fig.6- Surat to Bardoli Canal Line Diagram
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31.  Further near Kantali junction canal is again divided into two parts that are,
Bardoli Branch and Chalthan Branch, where Cross Regulator is provided for
Bardoli Branch and Head Regulator is provided for Chalthan branch with 3
numbers of gates with dimension of 8ft.*6ft.
Fig.7- Kantali Junction
 Near Bardoli branch Canal Escape is also provided before Head
Regulator.
 Tails are provided as Canal outlets at the end of each canals.
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32.  At place where energy in the flowing water is high and can damage canal
banks, canal falls re provide to dissipate its energy.
 Cross Regulator is constructed to regulate water level in the upstream side of
the canal.
 Distributary Head regulator is constructed on the u/s end of canal and regulate
the flow of water to the distributary canals.
 Canal escapes are provided for the removal of the surplus water from the
flowing canal.
 Canal Outlet is the structure through which water is released to the field
channel from distributary canal and it also act as a water measuring device.
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