Gully classification and its contol measures

gully classification, gully erosion, gully formation stage, erosion control structures, engineering measures of erosion control, dam, earthen dam, temporary control structure

1. Subject: Soil and Water Conservation Engineering
Topic: Gully Classification & control measures
by
Dr. Sanjay Singh Chouhan
Assistant Professor
College of Agriculture, JNKVV,
Powarkheda, Hoshangabad
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2. Gully

3. Gully
•Agullyisalandformcreatedbyrunningwater,erodingsharplyintosoilorotherrelativelyerodable
material.
•Gulliesinsizecanvariesfrommetertotensofmetersindepthandwidth.
•Gullyerosionistheprocessbywhichgulliesareformed.
•Hillsidesaremorepronetogullyerosionwhentheyareclearedofvegetation,throughdeforestation,over-
grazingorothermeans.
•Gulliesreducetheproductivityoffarmlandwheretheyinciseintotheland,andproducesedimentthat
mayclogdownstreamwaterbodies
•Becauseofthis,mucheffortisinvestedintothepreventionofgullyerosion,andinrestorationofgullied
landscapes,sothattotalsoillossfromgullyformationandsubsequentdownstreamriver
sedimentationcanbesizeable.
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4. JNKVV-College of Agriculture, Powarkheda 4
Physical Factors
•Precipitation
•Monthly distribution of rainfall
•Rainfall intensity and Runoff
•Rapid snowmelts
•Topography
•Shape of catchment
•Size of catchment
•Gradient pf the slope
•Soil properties
•Vegetative cove
Man Made Factors
•Improper land Use
•Forest and grass fires
•Overgrazing
•Mining
•Road Construction
•Livestock and vehicle trails
•Destructive logging
Factors Affecting Gully Formation

5. Gully Development
Gullies are developed by several processes which may be either single or in
combination at the same time.
These processes are:
1.Scouringof the soil particles from the bottom and sides of the gully by
flowing water mixed with abrasive materials such as hard soil particles or
debris.
2.Water fall erosion at gully head which result the cutting of gully banks
and thereby extension of gully into non gullied lands.
3.Sliding or mass movement of the soil from gully banks due to seepage.

6. JNKVV-College of Agriculture, Powarkheda
Generally, the following four stages are involved in the development of gully:
1.Stage1:Formationstage:Channelerosionanddeepeningofgullytakesplacebydownward
scourofthetopsoil.Thisstagenormallyproceedswithslowspeedwherethetopsoilisfairly
resistanttoerosion.
2.Stage2:Developmentstage:Inthisstage,duetorunoffflowfromUpstreamportionofthe
gullyhead,thesizeenlargementofwidthanddepthtakeplace.Thegullydepthreachesupto
the‘C’horizon.
3.Stage3:Healingstage:Vegetationbeginstogrowinthechannelandfurthererosionceases.
4.Stage4:Stabilizationstage:Thegullybedandsidesreachastableslopeandsufficient
vegetationgrowstoanchorthesoilandtotrapsoilflowingfromupstream.Thereisnofurther
changetodevelopthegully,unlesshealingprocessisdisturbed.
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Gully Development Stages

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Gullies can be classified
based on their
Size
Shape (cross section)
State
Dimensions (Tejwani& Narayana
gully classification)
Classification of Gullies

8. •Smallgulliescanbeeasilycrossedbythe
farmimplementsandcanberemovedby
tillagepractices.
•Mediumgulliescannotbecrossedbyfarm
implementsandtheycambecontrolledby
terracingoperation.
•Largegullyhavegonebeyondtheir
reclaimablestage;andforreclamationof
largegullies,vegetativeaswellaserosion
controlstructureareplanned.
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ClassificationDepth(m)Drainagearea(ha)
Small <1 <2
Medium 1to5 2to20
Large >5 >20
Based on Size (depth and drainage area)

9. •BasedonShape
U-Shaped:
•Theseareformedwhereboththetopsoilandsubsoilhavethesameresistanceagainsterosion.Becausethesubsoiliserodedas
easilyasthetopsoil,nearlyverticalwallsaredevelopedoneachsideofthegully.
•Thesetypesofgulliesaregenerallyfoundinthealluvialplains.Catchmentareaislargeandmorelateralspacing.
•Flowvelocityislessbutvolumeislarge.
V-Shaped:
•Thesegulliesdevelopwherethesubsoilhasmoreresistancethantopsoilagainsterosion.
•Thisisthemostcommonformofgullyfoundinhillyarea,catchmentareaislessandithassmalllateralspacing.
•Flowvelocityishighbutflowvolumeisless
Trapezoidal:
•Thesegulliesareformedwherethegullybottomismadeofmoreresistantmaterialthanthetopsoil.Belowthebottomofgully,the
subsoillayerhasmuchmoreresistancetogeterodedandthusthedevelopmentoffurtherdepthofgullyisrestricted.
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10. Based on
State of Gully
Active gully
•Active gully are those where dimensinosare enlarged
with time. The size enlargement is based on the soil
characteristics, land use & volume of runoff passing
through the gully. The gullies found in the plain areas
are active in nature.
Inactive gully
•These types of gully has constant dimensions,
generally found in rocky area.

11. Tejwani& Narayana
Gully Classification
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S.
No.
SymbolDescriptionSpecifications
1G
1 Very Small
Gullies
Depth-upto3m,
Width<18m,
Side slope varies
2G
2 Small GulliesDepth-3m,
Width>18m,
Side slope varies
3G
3 Medium
Gullies
Depth-3 to 9m,
Width>18m,
Side slope 8-15%
4G
4 Deep and
Narrow gullies
Depth >9m,
Bed width and,
Side slope varies

12. Gully Control
Measures

13. PrinciplesofGullyControl
Generally,gulliesareformedbyanincreaseinsurfacerunoff.Therefore,minimizing
surfacerunoffisessentialingullycontrol.Therateofgullyerosiondependsprimarilyon:
1.Therunoffproducingcharacteristicsofthewatershed,
2.Thewatershedarea,
3.Soilcharacteristics,
4.Size-shapeandslopeofgullyetc.
Ingullycontrol,thefollowingthreemethodsshouldbeappliedaccordingtotheordergiven:
i.Improvement of gully catchments to reduce and regulate the runoff rates (peak flows).
ii.Diversion of surface water above the gully area.
iii.Stabilization of gullies by structural measures and accompanying re-vegetation.
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14. Gully Control Measures
•Preventingtheformationofgullyismucheasierthancontrollingitonceithasformed.
•Oneofthemajorstepsinagullycontrolprogrammeistoplanthecontrolofrunofffrom
thedrainagearea.
Thevariousmethodsemployedforcontrollingrunoffmaybeconsideredinthefollowing
order:
1.RetentionofRunoffontheDrainageArea:
•Itispossiblethroughgoodcropmanagementandapplicableconservationpracticessuch
ascontouring,stripcropping,bunding,terracingetc.
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18. 2.DiversionofRunoffAroundtheGulliedArea:
•Themosteffectivecontrolofgulliesisbycompleteeliminationofrunofffromthegullied
area.
•Thiscanbeobtainedbydivertingrunofffromthegully,causingittoflowatanon-
erosivevelocitytoasuitableoutlet.
•Terracesanddiversionditchesaregenerallyusedfordivertingrunofffromitsnatural
outlet.
•Terracesareveryeffectiveinthecontrolofsmallgulliesoncultivatedfieldsoreven
mediumsizeshallowgullies.
•Iftheslopeaboveagullyistoosteepforterracing,diversionditchesmaybeusedtokeep
therunoffoutofthegully.
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19. JNKVV-College of Agriculture, Powarkheda
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20. 3.ConveyanceofRunoffthroughtheGully:
•Ifitisnotpossibletoeitherretainordiverttherunoff,thenrunoffmustbeconveyed
throughthegullyitself.
•Thisispossibleonlyifvegetationcanbeestablishedinthegullies,orifsoilconservation
structuresarebuiltatcriticalpointstogiveprimarycontrol.
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21. Classification of Gully Control Measures or Structures
Basically gully control structures are used to reduce soil erosion, control sedimentation,
and harvesting water. Gully control measures are mainly of two types.
1.Biological or Vegetative Measures
2.Engineering Measures (Temporary and Permanent)
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22. Biological or Vegetative Measures
“Ingullycontrol,abagoffertilizerismoreimportantthanabagofcement.”
Purpose:
1.Itprovidesoilcover.
2.Protectthegullyagainstscouring.
3.Reducetheflowvelocitybyincreasingthehydraulicresistance.
4.Helpsindepositionofsedimentloadscarriedbyrunoffoverthegullybed.
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23. JNKVV-College of Agriculture, Powarkheda
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24. 1Anti-ErosionCrops
Thesecropsstabilizegully.Cropsproducedprovidesupplementaryincome.
2ChangingGullyintoGrassedWaterway
•Smallandmediumsizegulliescanbeconvertedintograssedwaterways.
•Inpractice,gullyisshapedandsuitablespeciesofgrassesaregrown.
•Channelcross-sectionshouldbebroadandflat,tokeepwaterspreaduniformovera
widearea.
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25. 3SodFlumes
•Itmaybesuccessfullyusedtocontroloverfallingullieswithhead<3mandarea<10ha.
•Itservesthepurposeofpreventingfurtherwaterfallerosionbyprovidingaprotected
surfaceoverwhichtherunoffmayflowintothegully.
•Slopevarieswiththesoiltype,sizeofwatershed,heightofoverfallandtypeofsodused.
4:1isthesteepestslopeconsideredforitsdesign.
•Tomaintainanon-erosivevelocity,flumeshouldbe
wideenough.
•Themaximumdepthofflowovertheflumeshould
notexceed30cm.
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4SodStripChecks
•Thesechecksarebestadaptedtosmallgullieswithsmalltomediumsized
watersheds.
•Thesecheckscannotbeusedingullieswithverysteepgrades.
•Stripsarelaidacrossgullychannel.Stripsshouldhaveaminimumwidthof30cm
andshouldextenduptogullysidesatleast15cm.Stripspacingusuallyvaries
from1.5to2.0m.

27. 5LowSoddedEarthfills
•Theseareusedassubstitutesfortemporarygullycontrolledstructuresinsmallandmedium
sizedgullies.
•Alreadygrowingsodsarecutalongwithsoilmassandcombinedtogethertoformearthfill
dams.
•Theyareconstructedwithamaximumheightof45cm,upstream(u/s)sideslopeof3:1and
downstream(d/S)sideslopeof4:1.
6 Trees, Shrubs etc.
•Trees, shrubs etc. are used to stabilize severely eroded gullied area.
•Generally gullied area is fenced and trees are grown.
•A plant spacing of 1 ×1 m, 1.2 ×1.2 m or a maximum of 2 ×2 m should be maintained.
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28. Temporary Gully Control
Structures (TGCS)

29. Engineering Measures
TemporaryGullyControlStructures(TGCS)
•TGCShavealifespanof3to8yearsandtheyareprettyeffectivewheretheamountof
runoffisnottoolarge.
•Thesearemadeoflocallyavailablematerials.
•Basicpurposestheyservearetoretainmorewateraswellassoilforproperplantgrowth
andpreventchannelerosionuntilsufficientvegetationisestablishedontheupstream
sideofthegully.
TGCSareofmanytypes:
1.Wovenwirecheckdams 2.Brushdams
3.Looserockdams 4.Planorslabdams
5.Logcheckdams 6.Bouldercheckdams 7.Gabion
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30. DesignCriteriaofTGCS
•Theoverallheightofatemporarycheckshouldn’tordinarilybemorethan75cm.An
effectiveheightofabout30cmisusuallyconsideredsufficient.Also,sufficientfreeboard
isnecessary.
•Lifeofthecheckdamsunderordinaryconditionsshouldbeinbetween3to8years.
•Spillwaycapacityofcheckdamsisgenerallydesignedtohandlepeakrunoffthatmaybe
expectedoncein5to10yearreturnperiod.
•Sincethepurposeofcheckdamsingullycontrolistoeliminategradeinthechannel,
checkdamstheoreticallyshouldbespacedinsuchawaythatthecrestelevationofone
willbesameasthebottomelevationoftheadjacentdamup-stream.
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31. Woven Wire Check Dams
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32. Woven Wire Check Dams
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33. Woven Wire Check Dams (Cylindrical Rings)
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34. Woven Wire Check Dams
•Woven-wirecheckdamsaresmallbarrierswhichareusuallyconstructedtoholdfine
materialinthegully.
•Usedingulliesofmoderateslopes(notmorethan10percent)andsmalldrainageareas
thatdonothavefloodflowswhichcarryrocksandboulders.
•Helpintheestablishmentofvegetationforpermanentcontroloferosion.
•Damisbuiltinhalf-moonshapewiththeopenendup-stream.
•Toconstructawoven-wiredam,arowofpostsissetalongthecurveoftheproposed
damatabout1.2mintervalsand60-90cmdeep.
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•Heavygaugewovenwireisplacedagainstthepostwiththelowerpartsetinatrench(15-
20cmdeep),and25-30cmprojectedabovethegroundsurfacealongthespillwaywidth.
•Rock,brushorsodmaybeplacedapproximatelyuptoalengthof1.2mtoformtheapron.
•Forsealingthestructure,straw,finebrushorsimilarmaterialshouldbeplacedagainstthe
wireontheupstreamsideuptotheheightofspillway.

36. Brush Dams

37. BrushDams

38. BrushDams

39. BrushDams
•Cheapandeasytobuild,butleaststableofalltypesofcheckdams.
•Bestsuitedforgullieswithsmalldrainagearea.
•Centreofthedamiskeptlowerthantheendstoallowwatertoflowoverthedamrather
thanaroundit.
•Foradistanceof3to4.5malongthesiteofthestructure,sidesandbottomofthegully
arecoveredwiththinlayerofstraworsimilarfinemulch.
•Brushesarethenpackedcloselytogetheroverthemulchtoaboutonehalfofthe
proposedheightofdam.
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40. •Heavygalvanizedwireisusedtofastenthestakesinarow,aswellastofirmlycompress
thebrushesinplaces.
•Sometimeslargestonesarealsoplacedontopofbrushtokeepitcompressedandin
closecontactwiththebottomofthegully.
•Majorweaknessisthedifficultyofpreventingtheleaksandconstantattentionis
requiredtoplugopeningsofappropriatesizewithstrawastheydevelop.
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41. Loose Rock
Dams
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42. Loose Rock Dams
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LooseRockDams

44. LooseRockDams
•Looserockdamsmadeofrelativelysmallrocksareplacedacrossthegully.Themain
objectivesforthesedamsaretocontrolchannelerosionalongthegullybed,andtostop
waterfallerosionbystabilizinggullyheads.
•Loosestonecheckdamsareusedtostabilizethesmallgullies.
•Thelengthofthegullychannelisnotmorethan100mandthegullycatchmentareais2
haorless.
•Thesedamscanbeusedinallregions.
•Usedinareaswherestonesorrocksofappreciablesizeandsuitablequalityareavailable.
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45. •Flatstonesarethebestchoicefordammaking.
•Stonescanbelaidinsuchawaythattheentirestructureiskeyedtogether.
•Atrenchismadeacrossthegullytoadepthofabout30cm.Thisformsthebaseofthe
damonwhichthestonesarelaidinrowsandarebroughttotherequiredheight.
•Thecentreofthedamiskeptlowerthanthesidestoformspillway.
•Toserveasanapron,severallargeflatrocksmaybecountersunkbelowthespillway,
extendingabout1mdown-streamfromthebaseofthedam.
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46. Log Check Dam
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47. Log Check
Dam
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48. Log Check Dam
•They are similar to plank or slab dams. Logs and posts used for the construction are
placed across the gully.
•They can also be built of planks, heavy boards, slabs, poles or old railroad ties.
•The main objectives of log check dams are to hold fine and coarse material carried by
flowing water in the gully, and to stabilize gully heads.
•They are used to stabilize incipient, small and branch gullies generally not longer than
100 m and with catchment areas of less than 2 hectares.
•The maximum height of the dam is 1.5 m from the ground level. Both, its downstream
and upstream face inclination are 25 percent backwards.
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49. Boulder Check Dams
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50. Boulder
Check Dams
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51. BoulderCheckDams
•Bouldercheckdamsplacedacrossthegullyareusedmainlytocontrolchannelerosion
andtostabilizegullyheads.
•Inagullysystemormultiple-gullysystemallthemaingullychannelsofcontinuousgullies
(eachcontinuousgullyhasacatchmentareaof20haorlessanditslengthisabout900
m)canbestabilizedbybouldercheckdams.
•Thesedamscanbeusedinallregions.
•Themaximumtotalheightofthedamis2m.Foundationdepthmustbeatleasthalfof
theeffectiveheight.
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52. •Thethicknessofthedamatspillwaylevelis0.7to1.0m(average0.85m),andthe
inclinationofitsdownstreamfaceis30percent.
•Theupstreamfaceofthedamisusuallyvertical.Iftheabove-mentioneddimensionsare
used,itisnotnecessarytotestthestabilityofthedamagainstoverturning,collapsing
andsliding.
•Thedimensionsofthespillwayshouldbecomputedaccordingtothemaximumdischarge
ofthegullycatchmentarea.
•Theformofthespillwayisgenerallytrapezoidal.
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53. Sandbag Check-Dam
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54. Sandbag Check-
Dam
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55. Sandbag Check-Dam
•Sandbag check-dams are made from used jute or polyethylene bags (50 kg) filled with
soil/sand.
•The bags are piled up to a maximum of 3 –4 layers to form a small check-dam.
•This cheap technique is particularly useful in areas with insufficient supply of stones for
building ordinary check-dams.
•By erecting sandbag dams large rills or small gullies (finger gullies) can be controlled, while
they are not suitable for the treatment of large gullies.
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Gabion Check Dam

57. Gabion Check Dam
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Gabion Check Dam
•Ifthecatchmentareaofagullyis20haorlessandthelengthofthegullyisabout1000
m,channelerosionwillbecontrolledbybouldercheckdams,butthefirstcheckdamand
itscounter-damshouldbeconstructedasgabions.
•Ifthegullycrossesaroad,gabioncheckdamsmaybebuiltaboveandbelowtheroadat
thejunctionpoints.
•Inaddition,gabioncheckdamscombinedwithgabionretainingwallscanbeusedto
stabilizelandslidesintheupperportionsofthegully.
•Generally,itisneithernecessary,noreconomicaltobuildaseriesofgabioncheckdams
tocontrolchannelerosionalongthegullybeds.

59. Permanent Gully
Control Structures
(PGCS)

60. Permanent Gully Control Structures (PGCS)
•Iftheerosioncontrolprogrammerrequiresbiggerstructure,thenPGCSareused.
•PGCS,builtofmasonry,reinforcedconcreteorearthareefficientsupplemental
controlmeasuresinsoilandwaterconservation.
•Theyarehelpfulinsituationwherevegetativemeasuresortemporarystructuresfail
toservethepurposeofcontrollingtheconcentrationofrunofforreclaimagully.
•PGCSaregenerallyusedinmediumtolargegullieswithmediumtolargedrainage
area.
•PGCSaredesignedtohandlerunofffromtheheaviestrainsthatmaybeexpected
oncein25to50yearsormoredependingupontheestimatedlifeofthestructure.
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61. Basic permanent structures, generally employed in stabilizing gullies are:
➢Drop spillway
➢Drop-inlet spillway
➢Chute spillway
➢Permanent earthen check dams
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62. JNKVV-College of Agriculture, Powarkheda
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Basic Components of PGCS
Thesecomponentscanbedividedintothreegroups:
1.Inlet:Waterentersthestructuresthroughtheinlet,whichmaybeintheformofa
boxorweirinawall.
2.Conduit:Theconduitreceivesthewaterfromtheinletandconductsitthrough
thestructure.Itrestrictsthewatertoadefinitechannel.Theconduitmaybeclosed
intheformofaboxchanneloritmaybeopenasinarectangularchannel.
3.Outlet:Itsfunctionistodischargethewaterintothechannelbelowatasafe
velocity.Theoutletshouldprovideforthedissipationofkineticenergyofthe
dischargewithintheconfinesofthestructure.

63. Drop Spillway
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64. JNKVV-College of Agriculture, Powarkheda 64
Drop Spillway

65. Drop Spillway
•It is a weir structure, in which flow passes throughthe weir opening, fall or drops on an
approximatelylevel apron or stilling basic and then passes intothe downstream channel.
•Its use is limited to a maximum drop of 3 m.
•It is mainly used at the gully bed to create a control point.
•Several such drop structures are constructed across the gully width throughout the
length at fixed intervals.
•The series of such structures, develop a continuous break to flow of water, causing
deposition of sediments and thus filling the gully section.
•Sometimes, the drop structures are also used at the gully head to pass the flow safely
and controlling the gully head.
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66. Drop Inlet Spillway
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67. Drop Inlet Spillway
•Adropinletorshaftspillwayisoneinwhichthewaterentersthroughahorizontally
positionedcircularorrectangularboxtyperiserorinletandflowstosometypeofoutlet
protectionthroughacircular(horizontalornearhorizontal)conduit.
•Thedropinletspillwayisideallysuitedtoconditionswhenthereisneedtocontrolthe
downstreamchannelflowbyprovidingatemporarystorageupstreamofthestructure.
•Itconsistsofanearthendamandapipespillway.
•Thedamprovidesthetemporarystorageofrunofffromthecontributingwatershedwhile
thespillwaypermitsthedesigndischargetopassdownstream.
•Itisadaptedwheredropis>3.0m.
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68. JNKVV-College of Agriculture, Powarkheda
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Chute Spillway

69. JNKVV-College of Agriculture, Powarkheda
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Chute Spillway

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Chute Spillway

71. Chute Spillway
•Chute(openchannelortrough)spillwayisaspillwaywhosedischargeisconveyedfromtheupper
reachofthechannelorareservoirtothedownstreamchannellevelthroughanopenchannel
placedalongadam,abutment(supportingwall),orthroughasaddle.
•Chutestructuresareusefulforgullyheadcontrolandtheycouldbeusedfordropsupto5to6m.
•Chutespillwaysareconstructedatthegullyheadtoconveythedischargefromupstreamareaof
gullyintothegullythroughaconcreteormasonryopenchannel,whendropheightexceedsthe
economiclimitofdropstructures.
•Chutespillwayhasmoreadvantagethanadropspillway,whenalargerunoffvolumeisrequired
tobedischargedfromthearea.
•Flowinachutespillwayisatsuper-criticalvelocities.
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72. Earthen
Dam
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73. Earthen Dam
•Anearthenembankmentisaraisedconfiningstructuremadefromcompactedsoil.
•Thepurposeofanearthenembankmentistoconfineanddivertthestormwaterrunoff.
•Itcanalsobeusedforincreasinginfiltration,detentionandretentionfacilities.
•Earthenembankmentsaregenerallytrapezoidalinshapeandmostsimpleandeconomicin
nature.
•Theyaremainlybuiltwithclay,sandandgravel,hencetheyarealsoknownasearthfilldamsor
earthendams.
•Theyareconstructedwherethefoundationortheunderlyingmaterialorrocksareweakto
supportthemasonrydamorwherethesuitablecompetentrocksareatgreaterdepth.
•Theyarerelativelysmallerinheightandbroaderatthebase.
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74. JNKVV-College of Agriculture, Powarkheda
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Earthen Dam

75. JNKVV-College of Agriculture, Powarkheda
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Earthen Dam

76. Thanks for listening…..
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