2-Methods of Irrigation (1).pdf also defines as modern methods of orrigation

Irrigation methods.. Mofern methods of irrigation..

1. Instructor: Prof. Dr. Ashfaque A. Memon
Subject: IRRIGATION ENGINEERING
Presentation #: 02 (3 hours)
METHODS OF IRRIGATION:
Classification of Irrigation methods and factors affecting their choice
Information collected from proposed irrigation site
Surface Irrigation Methods: Uncontrolled/Wild/Free flooding, Check
flooding, Border flooding/Border Strip Method, Basin flooding, Contour
laterals, Furrow irrigation method and Raised bed method
Pressurized/High Efficiency Irrigation Methods: Drip irrigation and
Sprinkler Irrigation
MUET
DEPARTMENT OF CIVIL ENGINEERING
References:
Irrigation and Water Power Engineering by B. C. Punmiaand PandeB. B. Lal
Irrigation Engineering and Hydraulic Structures by S. K. Garg

2. IRRIGATIONMETHODSor
ModesofApplicationofWatertoCrops
Therearevariouswaysinwhichtheirrigationwatercan
beappliedtothefields.
a)SurfaceIrrigationMethods:
Justfloodingwater.About90%oftheirrigatedareasintheworld
arebythismethod.
b)Sub-SurfaceIrrigation:
Floodingwaterundergroundandallowingittocomeupbycapillarity
tocroproots.
c)Pressurised/HighEfficiencyIrrigationMethods:
Applyingwaterunderpressure.
(i)Dripirrigationand(ii)SprinklerIrrigation
2Modes of Application-1

3. The selection of the irrigation method is based on
the following factors:
1. Soil characteristics of the land to be irrigated
2. Topography of the area
3. Available water supply
4. Type of crop and its requirements
5. Size of the stream supplying irrigation water
6. Amount of water required in each irrigation
Factors affecting choice of irrigation method
October 30, 2018 DR. ASHFAQUE A. MEMON 3

4. Information to be Collected on Visit to A Proposed Irrigation
Site.
a)SoilProperties:Textureandstructure,moistureequilibriumpoints,
waterholdingcapacity,agriculturalpotential,landclassification,kindsof
cropsthatthesoilcansupport.
b)WaterSource:Watersourceavailability(surfacewater/boreholes),
hydrologicdata,waterquantity,waterquality,possibleengineering
worksnecessarytoobtainwater.
c)Weatherdata:Temperature,relativehumidity,sunshinehoursand
rainfall.
d)Topographye.g.slope:Fordeterminingthelayoutoftheirrigation
systemandmethodofirrigationwaterapplication
e)HistoryofPeopleandIrrigationinthearea:Pastexposureof
peopletoirrigationandlandtenureandlevelofpossiblere-settlementor
otherwise.
f)Informationaboutcropsgrowninthearea:Preferencebypeople,
marketpotential,waterdemand,growthschedulesandplantingperiods.
4Modes of Application-1

5. Surface Irrigation Methods
Their main classification of surface methods is as follows:
(1)Uncontrolled/Wild/Free flooding
(2)Check flooding
(3)Border flooding / Border Strip Method
(4) Basin flooding
(5)Contour laterals
(6)Furrow irrigation method
(7)Raised bed method
5Modes of Application-1

6. (1) Uncontrolled/Wild/Free Flooding
Wild flooding method is the earliest and
the primitive method of application of
water to the land
In this method the water is applied by
spreading it over the land.
Prior to the application of water, no land
preparations are done in the form of
border or field ditches
The water is allowed to flow the natural
slope of the land
Most suitable for close growing crops,
pastures, etc., particularly where the
land is steep.
October 30, 2018 DR. ASHFAQUE A. MEMON 6
Depending upon the slope, texture of soil, crops to be grown, etc. spacing
between contour ditches / laterals / subsidiary ditches is kept 20 to 50 m

7. (2)CheckFlooding
Check flooding is similar to
ordinary flooding except that
the water is controlled by
surrounding the irrigated area
with low and flat levees
Levees are generally
constructed along the
contours, having vertical
interval of about 5 to 10 cm
7Modes of Application-1
These levees are connected with cross-levees at convenient places
The confined plot area varies from 0.2 to 0.8 hectare
In check flooding, the check may be filled with water quickly/slowly
depending upon the infiltration of soil

8. (3) Border Flooding or Border Strip Method
Landisdividedintoanumberofstrips,separatedbylowleveescalled
borders.
Stripsize:10to20mwide,and100to400mlong.
Topreventwaterfromconcentratingoneithersideoftheborder,the
landshouldbeleveledperpendiculartotheflow.
8Modes of Application-1

9. Thesupplyditch/irrigationstreammayeitherbeintheform
ofanchannel(earthen/lined)orundergroundconcretepipe
havingrisersatintervals.
Thesizeofthesupplyditchdependsupontheinfiltration
rateofthesoil,andthewidthoftheborderstrip.

10. If
Q =Discharge through the supply ditch; A =Area of land strip to be
irrigated;
y =Depth of water flowing over the border strip;f =Rate of infiltration of soil;
Then
Time required to cover the given area is given by the equation
And, maximum area that can be irrigated in a border strip, is given by the
equation
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??????????????????=
??????
??????









fAQ
Q
f
y
t
10
log3.2
10Modes of Application-1

11. Example:
Determinethetimerequiredtoirrigateastripoflandof0.04hectaresinareafroma
tube-wellwithadischargeof0.02cumec.Theinfiltrationcapacityofthesoilmaybe
takenas5cm/hr,andtheaveragedepthofflowonthefieldas10cm.Alsodetermine
themaximumareathatcanbeirrigatedfromthistubewell.
Solution:
A = 0.04 hectares = 0.04 x 10
4
m
2
= 400 m
2
.
Q = 0.02 cumecs= 0.02 m
3
/sec = 0.02 x 60 x 60 m
3
/hr= 72 m
3
/hr.
f = 5 cm/hr= 5/100 m/hr= 0.05 m/hr.
y = 10 cm = 0.1 m.
Using the equation,
Putting the values,
i.e. Ans-1
Maximum area that can be irrigated is computed as
Ans-2
11Modes of Application-1

12. (4)BasinFlooding
Thismethodisaspecialtypeofcheck
floodingandisadoptedspeciallyfor
orchardtrees.
Oneormoretreesaregenerallyplaced
inthebasin,andthesurfaceisflooded
asincheckmethod,byditchwater
12Modes of Application-1

13. (5)ContourFarming
Contour farming is practiced in hilly areas with slopes
and with falling contour.
The land is divided into series of horizontal strips called
terraces.
Small bunds are constructed at the end of each terrace
to hold water up to equal height.
October 30, 2018 DR. ASHFAQUE A. MEMON 13

14. (6)FurrowIrrigationMethod
Furrowirrigationavoidsfloodingtheentirefieldsurfaceby
channelingtheflowalongtheprimarydirectionofthefieldusing
‘furrows,’‘grooves’,‘lines’.
Onlyone-fifthtoone-halfofthelandsurfaceiswettedbywater,
henceresultsinlessevaporationandpercolationlosses
Spacingoffurrowsisdeterminedbytheproperspacingofthe
plants.Furrowsvaryfrom8to30cmdeepandmaybeasmuch
as400mlong.
14Modes of Application-1

15. Siphons/hosepipes:
Itpreventsthenecessityofbreakingthe
ditchbank,andprovidesauniformflow
intothefurrow.
Cuttingtheridge:
Directgravityflowwherebywateris
divertedfromtheheadditchtothe
furrowsbycuttingtheridgeorlevee.
Gatedpipes:
Largeportablepipe(upto450mm)
withgateopeningscanbeusedto
deliverwatertothefurrows.

16. Horizontal movement
due to capillarity
Vertical movement
due largely to gravity
Gravity vs. Capillarity

17. Furrows
Raised bed
(7) Raised Bed Method
Raisedbedmethodofirrigationismodifiedversionoffurrow
method
Inthismethodridgeiswidenedtoprovidemorespaceunder
cultivationandconsequentlylessareaissubmergedwithwater

18. The conventional irrigation methods like flooding, furrows, etc. are
inefficient, resulting:
loss of valuable irrigation water (particularly the loss of costly
pumped water)
loss of applied nutrients
getting poor crop yield
Whereas, in raised-bed planting method, plantation is prepared on
raised-bed/ridges:
To save the valuable water and increase the crop-production
To do inter-cropping pattern such as wheat with sugarcane
Why Raised-bed /Ridge Planting is preferred
over Furrows and Flooding Methods?
Januray 22, 2015
Dr. Shafi M. Kori 18

19. Benefits of Raised Bed Method
Improves crop yields up
to 25%
Saves water up to 40%
Less weeds and less
lodging of the standing
crop
Easy to drain rain water
Low effect of standing
rain water
Saves up to 40% energy
used for pumping water
Easy for sugarcane inter
cropping with wheat
Additional benefits of
Sugarcane inter cropping with
wheat :
Increase in crop intensity
Less fertilizer requirement
Water saving for both
crops
Less cost for crop growth
Less weed infestation in
sugarcane crop

20. Pressurized/HighEfficiencyIrrigationMethods:
(1)DripIrrigationMethod
20Modes of Application-1
Dripirrigation,alsocalled
trickleirrigation,isthelatest
fieldirrigationtechnique,and
ismeantforadoptionatplaces
wherethereexistsacute
scarcityofirrigationwaterand
othersaltproblems.
Inthismethod,waterisslowly
anddirectlyappliedtotheroot
zoneoftheplants,thereby
minimizingthelossesby
evaporationandpercolation.

21. •Slow, frequent, precise application of water
•Most efficient –highest yield
•Water used –10% of Flooding/Border strip method
•Irrigation efficiency –80%
•Popular in Arid or Semi-arid areas where water is scarce
21Modes of Application-1

22. Main components Basic Parts
pumps
filters
meters
valves
automatic timers
mainlines
submainlines
laterals
emitters, etc.
Components of a drip irrigation
system

23. Head Unit

24. Thissysteminvolveslayingofasystemofhead,mains,sub-mains,
laterals,anddropnozzles.
24Modes of Application-1

25. 25Modes of Application-1

26. 26Modes of Application-1

27. Wateroozesoutofthesesmalldripnozzlesuniformlyandataverysmall
rate,directlyintotheplantrootsarea.
Theheadconsistsofapumptoliftwater,soastoproducethedesired
pressureofabout2.5atmosphere,forensuringproperflowofwater
throughthesystem.
Theliftedirrigationwaterispassedthroughafertilizertank,soastomix
thefertilizerdirectlyintheirrigationwater,andthenthroughafilter,so
astoremovethesuspendedparticlesfromthewater,toavoidcloggingof
dripnozzles.
Themainsandsub-mainsarethespeciallydesignedsmallsizedpipes,
madeofflexiblemateriallikeblackPVC.
Thesearegenerallyburiedorlaidontheground,asshowninFig.
Theirsizesshouldbesufficienttocarrythedesigndischargeofthe
system. 27Modes of Application-1

28. Thelateralsareverysmallsized(usually1to1.25cmdia.),specially
designed,blackPVCpipes,takingofffromthemainsorsub-mains.
Lateralscanusuallybeupto50mlong,andonelaterallineislaidfor
eachrowofcrop.Thedripnozzles,alsocalledemitters,orvalves,are
fixedonlaterals,atregularintervalsofabout0.5to1morso,
dischargingwateratverysmallratesoftheorderof2to10litersper
hour.
Thesepressurizedmethodsinvolvesspecializedknowledge,andarenot
beingadoptedbyourordinaryfarmers.
28Modes of Application-1

29. 29Modes of Application-1

30. 30Modes of Application-1

31. Where we can apply?
Onion
Cotton
Cucumber
Banana

32. (2)SprinklerIrrigationMethod
Inthisfarm-waterapplicationmethod,waterisappliedtothesoilinthe
formofaspraythroughanetworkofpipesandpumps.
Itisakindofanartificialrainand,therefore,givesverygoodresults.
Waterunderpressureissuppliedtothelateralsthroughmainsandsub-
mains.
ThewaterjetcomesoutthroughRevolvingsprinklerheadsusually
mountedonrisingpipesattachedtothelaterals.
32Modes of Application-1

33. ItisacostlyprocessandwidelyusedinU.S.A.
Itcanbeusedforalltypesofsoils,differenttopographiesandslopes.
Itcanadvantageouslybeusedformanycrops,becauseitfulfilsthe
normalrequirementofuniformdistributionofwater.
Thismethodpossessesgreatpotentialitiesforirrigatingtheareas,where
othertypesofsurfaceorsub-surfaceirrigationareverydifficult.
ThismethodhasnotbecomepopularinPakistanforthesimplereasonof
costandalotoftechnicalrequirements.
Thecorrectdesignandefficientoperationareveryimportantforthe
successofthismethod.
33Modes of Application-1

34. Specialstepshavetobetakenforpreventingentryofsiltanddebris,
whichareveryharmfulforthesprinklerequipment.
Debrischokethenozzles,interferewiththeapplicationofwateronthe
land,whiletheabrasiveactionofsiltcausesexcessivewearonpump
impellers,sprinklernozzlesandbearings.
Thesystemistobedesignedinsuchawaythattheentiresprayedwater
seepsintothesoil,andthereisnorunofffromtheirrigatedarea.
34Modes of Application-1

35. ConditionsFavoringtheAdoptionofSprinklerMethod
(i)Irregulartopography
(ii)Gradientissteeper,andsoiliseasilyerodible.
(iii)Excessivelypermeablesoil
(iv)Whenthewatertableishigh.
(v)Nearthecoastswhereseasonalwaterrequirementislow
(vi) When the crops:
(a) require humidity control, as in tobacco;
(b) having shallow roots; or
(c) require high and frequent irrigation.
(vii) Water scarcity
35Modes of Application-1

36. TypesofSprinklerSystems.
A)ConventionalSystems;
B)MobileSystems
Conventionally,sprinklersystemcanbeclassifiedunderthree
heads,as:
1.Permanentsystem;
2.Semi-permanentsystem;and
3.Portablesystem.
36Modes of Application-1

37. Inpermanentsystem,allcomponentsarefixedinfield,whichare:
1.Electricmotorofrequiredhp
2.Pumpofrequiredcapacityandhead
3.Suctionlinefromthesump
4.Mainline
5.Checkvalvesandmaingatevalves
6.Lateralswithrisersandsprinklers
37Modes of Application-1
Inthesemi-permanentsystem,sump,pumpandmainlinearefixed,
lateralswithsprinklersaremoveable.
Intheportablesystem:
Allcomponentsaretransportedfromonetoanotherposition
TherearehighestlaborrequirementandlowestInitialcost
Suitableforlowgrowingcorpsbut
Impracticalfortallcornorsugarcane

38. B)MobileSprinklerTypes
Theseinclude:
1.RaingunIrrigationSystem
2.LinearMove
3.CenterPivotSystem
38Modes of Application-1

39. Raingunisamobilemachinewithabigsprinkler.
Thespeedofthemachinedeterminestheapplicationrate.
Thesprinklerhasapowerfuljetsystem.
39Modes of Application-1

40. Raingun Irrigation System

41. Raingun Irrigation System

42. Raingun Irrigation System

43. RaingunSprinkler Irrigating from Lagoon
11/27/2013 43Dr. S. M. Kori

44. LateralMoveSystemisalongmobileboominwhichmany
sprinklersareattached.
Asthemachinemoves,itcollectswaterfromacanalintothe
sprinklersconnectedtothelongboom.
44Modes of Application-1

45. 11/27/2013 45Dr. S. M. Kori

46. InCentrePivotsystemthesourceofwaterisstationarye.g.a
borehole.
Theboomwithmanysprinklersrotatesaboutthewatersource.
46Modes of Application-1

47. Pivot of a Centre Pivot System

48. Center Pivot System with Spray Pad
Sprinklers
11/27/2013 48Dr. S. M. Kori

49. Centre Pivot

50. Side-Roll Sprinkler Lateral in Peanuts
11/27/2013 50Dr. S. M. Kori

51. Water Infiltration Rates and Soil Texture
Surface sealis defined as the orientation and packing of dispersed soil particles which
have disintegrated from the soil aggregates due to the impact of rain drops. OR
Surface seals are formed at the very surface of the soil, rendering it relatively
impermeable to water. (Courtesy: http://www.fao.org/docrep/t1696e/t1696e06.htm)

52. Soil Infiltration Rate vs. Constant Irrigation
Application Rate

53. Soil Infiltration Rate vs. Variable Irrigation
Application Rate

54. AdvantagesofSprinklerIrrigation
(i)Seepagelosses,whichoccurinearthenchannelsofsurface
irrigationmethods,arecompletelyeliminated.Moreover,only
optimumquantityofwaterisusedinthismethod.
(ii)Landlevelingisnotrequired,andthusavoidingremovaloftop
fertilesoil,ashappensinothersurfaceirrigationmethods.
(iii)Nocultivationareaislostformakingditches,thatresultsin
increasingabout16%ofthecroppedarea.
(iv)Insprinklersystem,thewateristobeappliedataratelesserthan
theinfiltrationcapacityofthesoil,andthusavoidingsurfacerunoff,
anditsbadeffects,suchaslossofwater,washingoftopsoil,etc.
54Modes of Application-1

55. AdvantagesofSprinklerIrrigation(contd.)
(v)Fertilizerscanbeuniformlyapplied,becausetheyaremixed
withirrigationwateritself.
(vi)Thismethodleachesdownsaltsandpreventswater-loggingor
salinity.
(vii)Itislesslabororiented,andhenceusefulwherelaboriscostly
andscarce.
(viii)Upto80%efficiencycanbeachieved,i.e.upto80%of
appliedwatercanbestoredintherootzoneofplants.
55Modes of Application-1

56. LimitationsofSprinklerIrrigation
(i)Highwindsmaydistortsprinklerpattern,causing.non-uniform
spreadingofwateronthecrops.
(ii)Inareasofhightemperatureandhighwindvelocity,considerable
evaporationlossesofwatermaytakeplace.
(iii)Theyarenotsuitedtocropsrequiringfrequent/constantandlarger
depthsofirrigation,suchaspaddy.
(iv)Initialcostofthesystemisveryhigh,andthesystemrequiresahigh
technicalskill.
(v)Onlysandandsiltfreewatercanbeusedtoavoiddamagetopump
impellers.
(vi)Itrequireslargerelectricalpower.
(vii)Heavysoilwithpoorintakecannotbeirrigatedefficiently.
(viii)Aconstantwatersupplyisneededforcommercialuseof
equipment.
56Modes of Application-1

57. Sub-surface IrrigationMethod
Asystembywhichelevationofthegroundwater
tableisregulatedbyartificiallyaddingwatertothe
sub-soilthroughsub-surfacepipeslaidunderground.
Waterflowinginthepipes,infiltrateintothesub-soil
throughthejointsofthesepipes.Inthiswaythe
watertableismaintainedatapre-determineddepth,
mostbeneficialtothecrop.
57Modes of Application-1

58. Sub-surfaceirrigationislimitedtotheareaswhere:
•soilisrelativelypermeableforaconsiderabledepth;
•surfaceslopesaregentle;
•naturaldrainageisrestricted;and
•itispracticaltoholdgroundwatertableata
particulardepth.
58Modes of Application-1

59. 59Modes of Application-1

60. 60Modes of Application-1

61. Modes of Application-1 61

62. 62Modes of Application-1

63. 63Modes of Application-1

64. 64Modes of Application-1