12. Canal Head Regulators.2.pdf

Canal Head Regulators-2

1. Canal Escapes, Outlets, Head and
Cross Regulators
Dr. Muhammad Ajmal
Lecturer Agri. Engg. UET Peshawar

2. Canal Escape
•Itisasidechannelconstructedtoremove
surpluswaterfromanirrigationchannel
(maincanal,branchcanal,ordistributary
etc.)intoanaturaldrain.
•Thewaterintheirrigationchannelmay
becomesurplusdueto-
•Mistake
•Difficultyinregulationatthehead
•Excessiverainfallintheupperreaches
•Outletsbeingclosedbycultivatorsasthey
findthedemandofwaterisover

3. Canal Escape
•Itisthestructurerequiredtodisposeofsurplusor
excesswaterfromcanalfromtimetotime.Thus,a
canalescapeservesassafetyvalveforcanal
system.Itprovidesprotectiontothecanalfrom
possibledamageduetoexcesssupplywhichmay
beduetomistakeinreleasingwaterathead
regulatororheavyrainfallthatmakessudden
regulardemandofwater.Theexcesssupply
makesthecanalbanksvulnerabletofailuredueto
overtoppingordangerousleaks.Therefore,
provisionfordisposingthissurpluswaterinformof
canalescapesatsuitableintervalsalongthecanal
isessential.Moreoveremptyingcanalforrepair
andmaintenanceandremovalofsediment
depositedinthecanalcanalsobeachievedwith
thehelpofcanalescapes.

4. Escapes are usually of the
following three types.
SurplusEscape
•Itisalsocalledregulatortype.Inthistype
silloftheescapeiskeptatcanalbedlevel
andtheflowiscontrolledbyagate.This
typeofescapesarepreferrednow-a-days
astheygivebettercontrolandcanbe
usedforemployingthecanalfor
maintenance.

5. Surplus Escape

6. Surplus Escape

7. Escapes are usually of the
following three types.
TailEscape
•Atailescapeisprovidedatthetailendof
thecanalandisusefulinmaintainingthe
requiredFSLinthetailreachesofthe
canalandhence,theyarecalledtail
escape.

8. Tail Escape

9. Escapes are usually of the
following three types.
ScouringEscape
•Thisescapeisconstructedforthepurposeof
scouringofexcesssiltdepositedinthehead
reachesfromtimetotime.Hence,itiscalled
scouringescape.Herethesilloftheregulatoris
keptatabout0.3mbelowthecanalbedlevelat
escapesite.Whendepositedsilttobescoured,a
higherdischargethantheFSLisallowedtoenter
thecanalfromtheheadworks.Thegateofthe
escapeisraisedsoastoproducescouring
velocitywhichremovethedepositedsilt.Thistype
ofEscapehasbecomeobsoleteassiltejector
providedinthecanalcanproducebetter
efficiency.

10. Scouring Escape

11. Head Regulator
•RegulatorsConstructedattheofftakingpointarecalled
headregulators.Whenitisconstructedattheheadof
maincanalitisknownascanalheadregulator.And
whenitisconstructedattheheadofdistributary,itis
calleddistributaryheadregulator.
•Function:
•Tocontroltheentryofwatereitherfromthereservoiror
fromthemaincanal.
•Tocontroltheentryofsiltintoofftakingormaincanal.
•Toserveasameterformeasuringdischargeofwater.

12. Head Regulator
•Construction:Thecomponentsofhead
regulatordependsuponthesizeofcanaland
locationofheadregulator.Itconsistsofoneor
moregatedresearchopeningswithbarrels
runningthroughthebank.Forlargecanalshead
regulatorsareflumedtofacilitatethe
measurementofdischarge.

13. Head Regulator

14. Cross Regulator
•CrossRegulator
•ARegulatorConstructedinthemaincanalor
parentcanaldownstreamofanofftakecanalis
calledcross-regulator.
•Itisgenerallyconstructedatadistanceof9to12
kmalongthemaincanaland6to10kmalong
branchcanal.
•Functions:
•(i)ToControltheflowofwaterincanalsystem
•(ii)TofeedtheofftakingCanals
•(iii)Toenableclosingofthecanalbreachesonthe
d/s
•(iv)Toprovideroadwayforvehiculartraffic

15. Cross Regulator

16. Cross Regulator
Construction:ForCrossRegulators
abutmentswithgroovesandpiersare
constructedparalleltotheparentcanal.The
sillofregulationiskeptlittlehigherthanthe
u/sbedlevelofcanalacrosswhichitis
constructed.Verticalliftgatesarefittedin
thegrooves.Thegatescanbeoperatefrom
theroad.

17. Canal regulators

18. Canal regulators

19. Cross Regulator

20. Head Regulator

21. Canal Outlet/modules
•Acanaloutletoramoduleisasmall
structurebuiltattheheadofthewater
coursesoastoconnectitwithaminoror
adistributarychannel.
•Itactsasaconnectinglinkbetweenthe
systemmanagerandthefarmers.

22. Canal Outlet/modules

23. Non-Modular Modules
•Non-modularmodulesarethosethroughwhich
thedischargedependsupontheheaddifference
betweenthedistributaryandthewatercourse.
Commonexamplesare:
(i)Opensluice
(ii)Drownedpipeoutlet

24. Types of Outlet/modules
•Non-modular modules

25. Semi-Modules or Flexible
modules
•Duetoconstruction,asuper-criticalvelocityis
ensuredinthethroatandtherebyallowingthe
formationofajumpintheexpandingflume.
•Theformationofhydraulicjumpmakestheoutlet
dischargeindependentofthewaterlevelinwater
course,thusmakingitasemimodule.Semi-
modulesorflexiblemodulesarethosethrough
whichthedischargeisindependentofthewater
levelofthewatercoursebutdependsonlyupon
thewaterlevelofthedistributarysolongasa
minimumworkingheadisavailable.
•Examplesarepipeoutlet,openflumetypeetc.

26. Semi-Modules or Flexible
modules

27. Rigid Modules or Modular
Outlets
•Rigidmodulesormodularoutletsarethose
throughwhichdischargeisconstantandfixed
withinlimits,irrespectiveofthefluctuationsof
thewaterlevelsofeitherthedistributaryorofthe
watercourseorboth.
•AnexampleisGibb’smodule:

28. Gibb’s Module

29. Exam Questions
•Whatdoyouunderstandbyafallin
canal?Whyitisnecessary?
•Whatarethefunctionsofacanalhead
regulator?
•Explainfunctionsofcrossregulatorand
distributoryheadregulator.
•WriteanoteonTypesofCanalFalls