An Introduction to Erosion Control

Second Edition March 2006

A Joint Publication from Earth Works InstituteThe Quivira Coalition and

Zeedyk Ecological Consulting

by Bill Zeedyk and Jan-Willem Jansens

Thisdocumentdescribeserosioncontroltechniques,suchasthoseusedforseveraldemonstrationsitesintheGalisteowatershedaspartoftheGalisteoWatershedRestorationProject–phase2(2002-2005).ThisprojectwassponsoredbytheNewMexicoEnvironmentDepartmentwithfinancialsupportunderCleanWaterActSection319(h)administeredbytheUSEnvironmentalProtectionAgency.TheprojectprotectedsurfacewaterqualityinNewMexicowatersbyreducingnonpointsourcepollutionofthewatersoftheGalisteoCreek. IntroductiontoErosionControlisanillustratedfieldguideforthegeneralpromotionoferosioncontroltechniques.Itisdesignedtobeusedbyabroadaudiencethatincludesprojectmanagers,governmentof-ficials,participantsofeducationalworkshopsandfieldtours,alongwithcontractorsandvolunteers(duringinstallationofstructures).Thisfieldguideisnottobeusedorinterpretedasadesignmanual. Three-thousandfive-hundredcopieswereprintedinthefirstedi-tion,three-thousandinthesecond.

ContentsI. An Introduction to Erosion Control

WhyThisFieldGuide?Restoringthe“Sponge”

II. Landscape Degradation ProcessesSlopes:Sheet,RillandWindErosionGulliesandBadlands

III. General Soil Healing TechniquesWaterHarvesting

RetentionandDiversionStructuresWaterSlowingStructuresMulchforSoilCover

SoilConservationIV. Healing Techniques for Gullies and Headcuts

GullyTreatmentsGradeControlInducedMeanderingWaterHarvestingStructuresStreambankProtection

HeadcutTreatmentsWormDitch(BypassChannel)Log&FabricStructureStrawBaleStepFallsRockBowl

V. Not Recommended!

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Cover Photos:Front:[left]One-rockdam,RedWindmillDraw,MalpaiRanch;[middle]Thesamedam,alittlewhilelater;[right]Largeone-rockdam,TorreonChapter,2002.(PhotoscourtesyofVanClothierandEarthWorksInstitute.)Back Photo:LogandfabricstepfallsinstalledonSanPabloCreeknearCuba.(PhotocourtesyofMikeChavez.)

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Why this Field Guide? Thesoil,theupperpartoftheearth’s“skin,”isa livingenvironment.Thetopsoillayer,typically4inchesorlessinourdesertclimate,includesbillionsofmicroorganismspercubicfoot.Thetopsoilalsoincludesplantroots,fungi,worms,andinsects.Onepartofthislivingtissuegrowsintolivingorganismssuchasplants,mushrooms,andsmallanimals,whiletheotherparthelpsbreakdowndeadorganicmaterialintocomponentsthatserveasnutrients(mineralsand“vitamins”)fortheregenerationofnewlife.Tofunctionwellasaspawningbedforlife,allsoilneedsissun,air,water,andplantresidue. Thisfieldguideisintendedtoinformthoseofuswhodependonthesoilandits life-givingproperties. Inthisguide,wewilldiscusswaystoregeneratesoilsothatitholdsmorewater,supportsmorevegetation,andreducessoilerosion.Intheend,soilconservationwillreduce“non-pointsourcepollution”inoursurfacewatercourses.Wewillfocusonaffordableandreplicabletechniques based on natural processes and advocate the use oflow-costandlocallyavailable,naturalmaterials.

Restoring the “Sponge” Thesoilplaysacrucialroleintheregenerationoflifeon

earth.Therefore,itisofutmostimportancethatthesoilstructure,composedofmineralparticles,decomposingorganicmatter(hu-mus),andmicroorganisms,isofoptimalqualitytohelpregeneratelife. Oneofthemostimportantfactorsinthesoil’sstructureisitscapacity,likeasponge,toabsorbwaterandholditinitspores.Degradedsoilshavelosttheirspongecapacity.Soilconservationandrestorationinourdesertclimatemustfocusonrestoringthespongeeffect. InmanylandscapesintheWest,soilshavebeenseriouslydegradedbytheimpactofuncontrolledlanduses,suchasunman-agedgrazing,mining,construction,pollution,andexcavation.Inmanycases,theseactivitieshaveledtoahardeningorremovalofthetoplayerofthesoil.Asaresult,itisdifficultforrainorsnowmelttoinfiltratethesoil.Instead,precipitationrunsoverthelandsurfaceinlargequantities.Poorinfiltrationdepletesthesoil’sabil-itytoabsorbwaterandsustainplantgrowth. Ifwewanttobringbacklifetodegradedland,itisimpor-tanttohelpthesoilretainmorewater.Onewaywecandothatistodirectwatertositeswhereinfiltrationoccursorisenhanced.Oncewaterissloweddownorretained,itisgivenmoretimetosoakintothesoil.Inthatprocess,thesoil’scrustystructuresoftens

I. Introduction to Erosion Control

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andallowsmorewatertosoak inandclingtosoilparticles. Inaddition,itenlivensmicroorganisms,suchasmycelium(fungi),thathelptransportwaterfromtheporesinthesoiltoplantroots.Theroots“wakeup”andbecomemoreabletoabsorbthewatertostrengthentheabove-groundplantparts.Insum,waterharvestingreinvigoratesexistingplantlife. Inaddition,ifthemoistureisretainedlongenoughandifitisreplenishedeffectively,dormantseedsinthesoilmayger-minate.Therenewedandreinvigoratedplantlifeinterceptsandslowsdownprecipitationasitrunsoffalongplantleavesandstemstosoakintothesoil.Plantsalsoslowairmovementandcastsome

shadeontheground,reducingevaporation,sothatmorewaterinthesoilisavailabletoplants.Plantstemsandrootsholdtogetherthesoil,deadplantmatteraddstotheorganiccomponentsofthesoilandstimulatestheproliferationofmicroorganisms,andplantrootsagainsupportothermicroorganisms.Inthisway,plantlifehelpsdevelopsoilstructureandbiologicalactivity(Figure�). Thisbiologicalprocessalsohelpsretainandcatchsoilparticles,thusreducingsoillossduetoerosiveforcesandreduc-ingpollutionofwaterwayswithdirt(amajorformofnon-pointsourcepollutionintheSouthwest).Theresultof“sponge”resto-rationistheresurgenceofnativeplantgrowthandthereductionofuncheckedrunoffanderosion.Withthis,thenativeecosystem

Figure 1. Restoring the soil’s “sponge” capacity restores the watershed.

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receivesanindispensableboosttoitscapacitytobeginanewcycleofplantsuccession.Typically,plantdiversitywillincrease,meaningthenumberofperennialplants,thepercentageofgroundcover,andwithallthistheresilienceoftheplantcommunitytosudden,catastrophicimpacts(fire,pests,flooding,drought).Inaddition,plantcommunitieshelpcreatehabitatforanincreasingnumberofinsects,arachnids,reptiles,birds,andmammals.Eventually,thelandscapemaybecomeproductiveagainformanagedhumanuse,suchasagarden,farm,orpasture.

II. Landscape Degradation Processes Howdolandscapeslosetheirwater-storingcapacity?

Slopes: Sheet, Rill, and Wind Erosion Whenthetopsoilisdisturbed,itsplantcoverdestroyed,anditsstructurebroken,microorganismlifedecreases,water isreadilydrained,andacrustformsonthesoilhamperinginfiltrationofwater.Asaresult,seedsandmicroorganismswashorblowaway.Technically,soilerosionoccurswhenthereisinsufficientcovertoprotectthesoil’ssurfacefromraindropimpactortheshearstressofflowingwater. Erosionworsenswith increasingslopeangle,slopelength,andfragilityofthesoil. Theseweakenedsoilconditionsthenincreasetheimpactofraindropsplash,wind,andstormwaterrunoff.Soilloss(ero-

sion) in the form of sheetflow, rills (small erosionalrivulets), and gullies willfollow. Eventual ly, thewatertabledropsasaresultofthedrainingofthesoil.When water rapidly runsthroughclaysoils,mineralcompounds, such as salts,are leached out (defloc-culation).Theclaylosesitsstructure and is blown orwashedaway.Toomuchairin the clay hampers plantgrowth and increases un-derground water drainage,causing tunnel erosion (piping). Eventually the soil collapses,whichisthebeginningofgullyerosion.

Gullies and Badlands Gulliesoccurwhenrillsconvergeinaconcentratedflowofsurfacerunoff.Asthesoilsurfacesteepens,thevelocityofthesurfaceflowincreasesandtheenergyoferosiveforcesincreasesexponentially.

Gully on San Pablo Creek.

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Runoffcausesanabrasiveforceonthesoil.Wherethegradesteepensorwherethesoilhardnesschangesabruptly,runoffwillscourmoreandcreateaheadcut.Headcutstravelupstreamdisturbingmoresoils,and g utting entirehillsidesandpastures.Headcutsincreaserap-id runoff as a resultof increased drainagepatterns. The end iswhat is called “bad-lands”: a landscapewith a multitude ofgullies and headcuts,flatareasconsistingofrockandgravel,anddevoidofvegetation.Theregenerationcapac-ityofsoilsinbadlandsisminimalduetopoorsoilstructure,verylowwaterholdingcapacity,lackofseeds,andabsenceofmicrobiallife.

III. General Soil Healing Techniques Soilscanbehealedthroughwaterharvestingandsoilimprovementtechniques.

A. Water Harvesting Inourdry,Southwesternlandscapes,effectiverainfallforplantgrowthisscarceandoftenfurtherlimitedduetounintendedwaterlosses.Therefore,itisimportanttoharvestasmuchprecipita-tionaspossibleandmakeitinfiltratethesoil.Waterthatisstoredinthesoilevaporatesslowlyandflowsgraduallydownhilltothemainwatercoursesandwetlandsofthearea,providingvaluableflowtospringsandseeps,whichmaintainriparianhabitat.Waterharvestingonslopescanbeachievedbestbyplacingbarriersoncontours,technicallyformingasmallterrace.Regionallyappropri-ate,low-costharvestingtechniquesinclude:

Structuresthatretainordivertstormwaterrunoff,suchasrollingdips,diversiondrains,swalesandberms,andmicro-catch-ments.Thesestructuresaredesignedtoholdthewaterbackandwatershouldnotflowoverthem.Theyare,therefore,highenoughtoretainordivertthewaterflow.

Structuresthatslowtheflowofwatertogiveitmoretimetoinfiltrate,suchasone-rockdams,rocklinesoncontour,strawwattles,andstrawbaledams.Thesestructuresaredesignedtobeovertoppedbywaterflowsandarethereforeratherlow.

Mulching:thespreadingofaprotectivelayerontopofthesoiltoprotectandenrichthesoil.Organicmulchprotectsthesoilagainstwinderosionandevaporation,andaddsorganicmatterwhiledecomposing.Mulchalsoprovidesamorecohesivestructure

Gully near Santa Rosa.

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tothe soil,whichhelpskeep soilparticles together. Mulchingcan be combined with other techniques, such as enriching thesoilwithcompost.

1. Retention and Diversion Structures Rolling dips areshallowdepressionswithgentlyrollinghumpsonthedowngradeside,diagonallyplacedacrossroadsandtrails,todivertrunofffromtheroadsurfacetoasidedrainorslope.Thedipandhumparewideratherthandeepinordertocausetheleasthinderancetotraffic. Dipsandhumpsshouldstretchthelengthoftheaveragecarusingtheroad.Humpsarebestmadeinatriangularshapewiththeapexofthetrianglepointingtowardtheoutslopeoftheroadway. Diversion drains aretrenches(swales)withanearthenwallonthedownhillside(berms)thatarelaidatagradeof0.�to�%ontheslopetodivertflowstoastabledrainagepath(rocksurface, riprap spill path, stabilized gully, or grassed waterway)(Figure �). The mouths of diversion drains are armored withrock to prevent headcut erosion. Diversion drains should notbefilledwithplantingsorlinedwithmulchasthiswill leadtothedepositionofsedimentthatobstructswaterflowandcauseswatertobreachthewallandcreateunwantederosion. Swales and Berms areshallowtrenchesfollowingthecontourofahillside.Theexcavateddirtispiledinalinearmoundonthedownslopesideofthetrench,creatingtheberm.Swales

capture runoff and make it soak in the soil. Swales and bermsworkbestonwell-drained,sandyandloamysoilsinconjunctionwith other soil conservation and water harvesting techniques.Onclayeysoils infiltrationistooslow,whichmaycauseswalestooverflowandbreach,whichexacerbatestheerosionweintendtostem.Swalesandbermsarelaborintensivetoinstallandneed

Figure 2. Diversion drains.

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annual inspection and maintenance, which make them lessdesirableinextensivelyused,largeareas,suchasrangelands. Micro-catchments (also called boomerangs) are half-moon or V-shaped mounds with shallow depressions behindthem. These depressions can make excellent planting areas fortrees,shrubs,orgrasses.

2. Water Slowing Structures One-rock dams are so named because they are only

one rock tall. The damshould be built withseveral rows of rock acrossfrom the upstream to thedownstreamedge.Thedamshould not be taller than�/� bankfull depth of theplanned channel (Figure �andFigure�,page��).

Stones should be se-lected, sized, and placed sothatthecompletedstructureendsuprelativelylevelfrombanktobankandflatfromthe upstream edge to thedownstreamedge.Thiscan

beaccomplishedbyplacinglargerrocksinthedeepestpartofthechannel,smalleronestoeitherside(Figure�,page��).Donotstackrocksontopofoneanothertogettheneededheight.Thestackedrockswillbesweptawaybyfloodflows. Placinggreatlyoversizedrocksinthestructurewillgenerateturbulencethatcouldundermineit.Rocksshouldbesizedproportionatelytothe�/�bankfulldepthofthechannel,�0-40poundrocksforachannelonefootdeep,�0-80poundsforstreamsoneandahalffeetdeep.Floodflowswillpacksmaller-sizedbedloadparticlesbetweentherocks,graduallystrength-eningthestructureovertimeasanewrifflebeginstodevelopatthesite(seephotoonpage��).

Figure 3.

Rock line at Torreon Chapter, 2002.

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Rock lines and/or log lines on contours are simplestructuresthatslowsheetflowonaslope.Byplacingrock,logs,or branches on the contours of the hillside, stormwater runoffis slowed down and sediment trapped behind the structures.Overtime,thebarriersandsedimentwillhelpwatertoinfiltratemoreeasily,whileleavingdirtinplace.Thematerialsblendinthelandscape.Thestructuresareeasytoinstallandeasytomaintain.Theyworkbestongentleslopesof�0%orless. Straw wattles aresausage-likedevicesmadefromstrawheldtogetherinabiodegradablemeshwithadiameterof�-��inches.Placedonthecontourandpeggeddownwithsteelpinsorwoodenpegs,theyslowrunoffandhelpwaterinfiltrate.Overtimetheydisintegrateandaddamulchcovertotheslope.Straw

wattlesbecamepopularinthe�990sinrestorationprojectsonburntforestareas.Theyworkbestonshort,gentleslopesof�0%orless. Straw balescanbeveryeffectiveastemporarysedimentand runoff catchment devices. They are effective in clayey andloamy soils with sheet flow that moves a significant amountof sediment and in shallow gullies with low flows. They areparticularlyusefulinlocationswherethereisanabsenceofrockandbrushandwhereyouneedmoremulchandorganicmatterinthesoil.Strawbaledamsshouldnotbeusedinsandyareaswheresaturatedsandmaywashawaybeneathornexttothestrawbales.They should also not be used in deep gullies with high flowswheretheshearstressofthewaterwilleasilybreakthroughthestrawbale(seepages��-�4). 3. Mulch for Soil Cover Covering the soil with live or dead material reducesevaporation, runoff,anderosion.Asoil coverof inertmaterialsuchaswoodchips,straw,orpebblesiscalled“mulch.” Mulchcanalsobeappliedintheformofpre-fabricatedblanketsormatsoffibrousmaterials,called“erosioncloth.”ForourdrySouthwesternlandscapes,itisadvisabletoselectrelativelylightandthinerosionclothinordertoallowplantstogrowthroughit.Mulchingmaybenefitthesoilby:

Straw wattles at the Lippard property, Galisteo watershed, 2001.

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slowingerosionhelpingjump-starttheregenerationofplantsmoderatingsoiltemperaturescontrollingweedseliminatingsoilcrusting,allowingwater,air,andnutrients

topenetratebetterreducingevaporation

Organicmulcheshaveadditionalbenefits,because:(�)theyprovidenutrientstothesoilwhentheybreakdown,andcandecreasesoilnitrogenlevelsduringdecomposition;(�)theykeepsoiltemperatureslower;and(�)theycanincreasethepopulationofcertainsoilorganismsandinsects.

B. Soil Conservation Besides the techniques described above to captureand conserve storm water and runoff from snow and otherforms of precipitation, we need to conserve and improve thesoil. Soil conservation and improvement techniques includethose that improve soil structure and texture, and soil fertility.Wecan improve soil structureandtexturebyapplyingorganicmatter(manure,compost,ormulch)orclay,sand,orlime,andby breaking the crust and loosening the top layer of the soil.Thelattercanbeaccomplishedbyraking,tilling,orimprintingthesoilorbythehoofimpactofanimals. Overtime,planting

vegetation will also improve soil structure and texture. Wecan improve soil fertility by applying minerals and nutrientsin the form of artificial fertilizer or manure, or by the manureproducedbydirectgrazing.Insomecases,wehavetokick-startbiologicalactivityofthesoilby inoculatingthesoilwithfungispores (mycelium) and trace minerals, such as magnesium andmanganese,andbyspreadingseedorplantingseedlingsofshrubsandtrees.Insomecases,itmaybebeneficialtointroduceanimallife through managed grazing or the introduction of rodents,insects,orbirds.Thefaunawillincreasethebreakdownoforganicmatter,availabilityofmineralsandmicrobesinthesoil,dispersalof seed, and the pollination of plants (see also the companionpublication, Rangeland Health and Planned Grazing Field Guide,July,�004).Lastbutnotleast,wewillconservesoilsbyalteringourlandusepatternsinsuchawaythattheimpactwehaveonthesoilisreduced.Fencingouttrespassers,especiallyoff-roadvehiclesandhorses,redesigningroadsandtrailstospreadrunoff,andmanagingtheimpactofwildlifeanddomesticanimalsarecrucialtotheprotectionofthefragilesoilsintheSouthwest.

IV. Healing Techniques for Gullies and Headcuts In a gully, surface runoff is concentrated and acceler-

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atedandsurfaceprotectionisreduced. Anydisturbancecangenerateamigratingheadcut(Figure4andFigure�,page�0).Disturbanceexposesthelesscohesivesubsurfacesoilstotheerosiveforceofrunningwater,thusincreasingtheheadcutting.

Healing Principles:Dispersesurfaceflow,preventconcentra-

tion,increaseinfiltrationandpercolation.Reduce channel slope to reduce runoff

velocitiestoreduceavailableenergy.Widenchannelbottomtolessenerosion

force.Increasechannelroughness.Retainsoilmoisturetoimproveenviron-

mentforcolonizationandgrowthofplants.

A. Gully Treatments Gullytreatmentscanincludegradecontrolstructures,inducedmeandering,waterharvest-ingandrevegetation. Thismanualwillfeaturehand-madetreat-mentsand,forthemostpart,locallyavailable,

Figure 4.

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naturalmaterialssuchasrocks,logs,trees,brush,andstrawbales. Arti-ficial materials are limited to sandbags,erosionfabrics,andwire.Useof wire baskets, concrete, and steelstructureswillnotbeaddressed.

1. Grade Control The primary purpose of agradecontrolstructureistokeepagully from eroding deeper. Prop-erly used, grade control structuresare the first step in reversing theerosionprocessand initiatingsedi-ment deposition, water harvesting,nutrientretention,revegetation,andbank stabilization. Grade controlstructures are especially importantin harvesting a bit of water fromeachstormflowinordertoirrigateandnurturenewlyestablishedplantgrowth. Vigorous plant growth iscriticaltoincreasingchannelrough-ness,trappingsediments,detainingFigure 5.

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andretainingorganicdebris,andcapturingsoilnutrients.Ulti-mately,it’sthenewvegetationthatstopserosion,notthestructureitself. Gradecontrolstructuresincludeone-rockdams,logmats,felledtrees,brushdams,wickerweirs,andstrawbaledams.Inallcases,emphasisisplacedonkeepingthesestructureslowinprofileandcompactinform.Incontrast,checkdamstendtobetallinprofileanddesignedtotraplargevolumesofsedimentandwater.Checkdamstendtobevulnerabletoundercuttingandendcut-tingwhentoomuchwaterisstoredbehindthedamoroncethestructurehasfilledwithstoredsediments. One-Rock Dams. Aone-rockdamconsistsofmorethanonerock!Thekeytoitssuccessisthatrocksareplacedonlyonetierdeep!Theyarenotstacked.Rocksareplacedinseveral,parallelrowsacrossthegullyfloorandpackedtightlytogether.Arowof

rocksshouldbeofequal height andappear relativelyflator level fromb an k to b an k(Figure �). Theelevation of theupstreamrowcanbeslightlyhigher

thanthedownstreamrowsothatthedamslopesgentlyfromthetopedgetothebottomedge. Dams consisting of � to � parallel rows of rocks haveconsiderablemassbutminimalsurfaceexposuretotheforceofmovingwater(Figure�,page�).Therefore,advancingfloodwatersslideacrossthesurfaceofthedamratherthanpushingagainstit.Becausethedamislowinheight,thewaterdropsonlyafewinchesandhaslittlepowertoerodeascourpoolthatmightundercutthestructure.Successivefloodspacksand,gravel,andorganicmaterialbetweentherocksforminganexcellentseedbedfornewplantstocolonizethesite.Moistureaccumulatesundertherockstonurtureth e y o un gplants.Soonthe roots ofthematuringplants bindt h e r o c k sof the damtogether forgreater resis-tancetosuc-cessive floodforces.

Figure 6.

One-rock dam at Torreon Chapter, 2002, doing what one-rock dams are supposed to do,

hold water and grow grass.

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Log Mats.Logmatsarefashionedfromonetierofsmalllogswiredtogetherandstakedinplace.Logsareorientedparallelwiththecurrenttominimizebedscourratherthanperpendiculartotheflow.Logmatsconservemoisture,detainsedimentsandshelteryoungplants. Wicker-Weirs. Wicker weirs are small dams across acreekorgullybuiltbydrivingsharpenedstakesorpickets intothechannelbedandthenweavingsaplings,treelimbs,orwillowcuttingsbetweenthestakesperpendiculartotheflow(Figure�).Theyaredesignedtocontrolstreambedelevation,channelslope,andpooldepthwhileenablingfreepassageofwater. Brush Dams.Brushdamsarebuiltoflooselypiledbrushortreebranchespiledingullybottom.Thesecanbewiredtogetherforstrengthandincreasedstability.Keepthemlooseandlowinheightinordertostimulateplantgrowth.Tall,thickbrushdamssmothernewplantgrowth. Felled Trees.Felledtrees(canbefulllength)shouldbeplacedonelayerdeepwiththetoppointingdownstream.Theirbranchesbecomeimpaledinthegullybottom,holdingthetreesinplace.Greentreeswilltendtobendandmoldtoirregularitiesinthestreambottomandarepreferredtodeadmaterial. Straw Bale Dams. Strawbalescanbeeffective ifem-bedded at least 80% of their height in a trench and staked inplace. Strawbaledamsareespeciallyvulnerabletoendcutting

andundercuttingiffloodwatersareimpoundedtoodeeply. Akeyadvantageofstrawbalesistheabilitytotrapseedsandplantpropagulesfromthewaterflowandtostorewater,spongelike,forextendedperiodsoftimetonurturenewplantgrowth.

Figure 7.

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Strawbaledamsareconstructedbyplacingstrawbalesacrossthecontourofaslopeoracrossagullychannel.Topreventthebalesfromfloatingaway,itisimportanttodigatrenchaswideasthewidthofastrawbaleandatleast80%ofitsheightordeeper(Figure8).Thetrenchesshouldbedeeperatthecenterofthegully.Seenfromabove,theyshouldformaslightVshapeorhalfmoonshapewiththepointorbottomofthecurvepointingupstream.Thisproperinstallationwillallowthebalestoformalowerpointatthecenterofthedamwherethewatercanovertopthebalesifnecessaryandremainconcentratedinthecenterofthechannel.

Strawbaledamsneedtobeshapedwithaspillwaythatcanaccommodateatleasta�-yearflood.Makesurethatthetrenchesextendintothebanksforseveralfeet(inwidechannels,forthelengthofoneentirestrawbale),andmakesurethatthetopsofstrawbalesplacedinthebanksareastallasthehighestflowyouexpectonceayearinthegully(Figure9).Placethebalesinthetrench,leavingthebailingstringsattachedfacingup.Thisallowsthebalestobegentlycurvedinthetrenchandto absorb moisture faster, while maintaining their integrity.Constructamatofbrush,rock,orpreferablyanotherstrawbale(partlyburiedintheground)atthetoeofthespillwaytoserveasaspillpad.Thespillpadmustbeaswideasastrawbaleand

Figure 8.

Figure 9.

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spanthewidthofthestreambedofthegully.Thedirtremainingfromdiggingthe trenches shouldbeusedtobackfillholes and openings around the strawbales.

2. Induced Meandering Inducedmeanderingisanero-sioncontrolmethodwhichusesinstreamstructuresandvegetationmanipulationto increase channel sinuosity, bed sta-bility, alluvial bank storage, floodplaindevelopment, and channel roughness.

important in sandy or gravelly gullysystems. Sand Bag Dams: Sand bagdamsareusefulinslowingandretain-ingmoistureinsmall,first-stagegulliesincised in former wet meadow andcienegasites.Sandbagsarerelativelylightinweightandeasilydisplacedbyhigh velocity flows and should onlybeusedwherelowtomoderateveloc-ity flows or sheet flows are expected.Placingsandbagsattheupstreamedgeofarockdamorlogmatwillprovidephysicalsupportagainststrongflows.

Sand Bag Burritos:Sandbagsarevulnerabletorapiddecay. Burlap bags rot, while woven plastic sandbags decay inultravioletlight.Wrappingsandbagsinalayeroferosionclothor silt-fencing fabric protects bags from sunlight and extendslongevity.Thedisadvantageisthatthefabricwillsuppressplantgrowth.

4. Streambank Protection Streambanksandgullybankserodeatvariableratesde-pendingontherelativestabilityaffordedbyvegetativeormechani-

Strawbale headcut control on contour, Galisteo watershed, 2001.

For more information, see the companion publication An In-troduction to Induced Meandering: a Method for Restoring Stability to Incised Stream Channels,June�00�.

3. Water Harvesting Structures Waterharvestingstructuresareusedtopondwatertem-porarily,soakgullybanks,increasebankshape,irrigatestreambankvegetation,andextendtheactivegrowthperiodforcolonizingvegetation.Suchstructuresareespeciallyusefulinclayeygullieswhereinfiltrationandpercolationratesareslowandbanksbakehardlikeadobeinthehotsummersun.Suchstructuresareless

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calcover.Bankerosioncanbecausedbystreamflow,overlandflow,masswastingorslumping,frostheave,andsloughingwithrepeatedcyclesofwettinganddrying.Iceflowsanddebrisflowscanexacerbatetheerosiveeffectsofflooding.

Basically, two types of streambank stabilization meth-odsareavailable:revegetationandmechanicalprotection.Thisbookletaddressesonlyrevegetationtechniques.Mechanicalpro-tectionincludesrockmattresses,rockbaskets,rip-rap,concrete,boulder placement, vanes, deflectors, revetments, and groins.Pleaseconsultprofessionaljournalsandbooksfordetailsonthesetechniques. Revegetation Management. Streambankstabilitycanbeaccomplishedbyestablishingavigorousstandofvegetation.Nativespeciesarepreferred.Successfulrevegetationdependsuponeffectivecontrolofherbivory(grazingorbrowsingbywildlifeanddomesticlivestock).Controlcanincludetotalexclusion,seasonalgrazing,orspecies-specificmeasuressuchaselk-prooffencingorbeaverexclusion.HumanusessuchashikingtrailsmayneedtoberestrictedaswellasATVtraffictopreventrepeatedtrampling. Revegetationsuccesscanbeenhancedbysupplementalirrigationespeciallythroughthefirstgrowingseasonafterplanting.Sprinklers,floodirrigation,dripsystems,orevenhandwateringby bucket can be effective until plants become self-sufficient.Sprinklersareespeciallyeffectiveinstimulatinggerminationand

growthofnativeseedsstoredinthenaturalseedbankordispersedbythewind. Herbaceous Species. If soil moisture is favorable,avarietyofwetlandherbaceousgrasslikespeciescanbeplantedassodwads,ormats,simplybyexcavatinghealthyreproductivematerialsfromestablishedpopulationsandreintroducingthemto the new site. Most wet-soil species spread naturally frompropagulessuchasbulbs,tubers,orrhizomesandareadaptedto

Cottonwood pole planting on first terrace, Richardson property, Galisteo watershed, 2002.

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uprooting,dispersingbyfloods.Examplesincludesedges(Carex),bullrushes(Scirpus),rushes( Jun-cus),andcattails(Typha).Careshouldbetakennottospreadexoticplantsandweedssuchassaltcedar, musk thistle, or curly dock incidental totransplantationofdesirablespecies. Woody Trees, Shrubs, and Vines.Willowscanbeplantedascuttings,orasrootedstock,orastransplantedwildlings. Willowcut-tingsarebestplantedduringlatewinterorspringbutcanbesuccessfullytransplantedinanyseasonifthewatertable,oritscapillaryfringe,iswithinreachoftheplantroots,oriftransplantsareirri-gated.Manytechniqueshavebeenused,rangingfrom individual stems to standing bundles andwattles.Insomestudies,successhasbeenachievedwhenfourtosixcuttingsarebundledandplantedtogetherinasinglehole,dugtowatertabledepth.

Afterbackfillingtheholewithsoil,thebundleshouldbethor-oughlywettedandfirmlytampedtoremoveairpocketsthatwouldstiflerootdevelopment.Cuttingsshouldbeprunedtoanaverageabovegroundheightof�-�feetinordertoreducewaterdemandinexcessofthatwhichnewlydevelopingrootscanprovide. Some riparian species cannot easily be reestablished

ascuttingsbutshouldbetransplantedfromrootedstockorastublings.Theseincludealders,wildcherry,currants,hackberry,walnut,sycamoreandboxelder,forexample.Wildroses,however,areeasilyestablishedascuttingsorasdormantstock. Cottonwoodpolesshouldbeplantedduringlatewinterorearly spring inorder togivecuttings timetodevelopa rootsystempriortoleafingout.Polesshouldbeplantedatthelevelofthefirstterrace,notwithinthefloodplain,becausecottonwoodpolesareeasilydamagedduringfloods.

B. Headcut TreatmentsHeadcutsarecharacterizedby:

awaterfallorabruptchangeinslopeofastreambedafragile,cracked,orcrumblinglipofthefallsabowl-shapedpoolatthebaseofthefalls(plungepool)undercuttingrapidheadwarderosionduringfloodflowsdrying,cracking,andsloughingduringthedryseason

Thehigherthefalls,themorepoweravailableforerod-ingsoilsubstratesatthebaseofthecutandthemoredifficultyinrepairingtheheadcut.Turbulenceatthebaseofthefallsundercutstheheadwall,whichleadstocrackingandsloughing.Exposuretosunandairduringno-flowperiodsfurtherdehydratesthesoil.

Sedge (Carex).

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HealingPrinciples:Lowertheheightofthefallsinordertoreducetheforceoffallingwater.Widenthelipofthefallstodisperseconcentratedflow.Harden the base of the falls to protect substrates fromerosion.Conservesoilmoisturetoenhanceplantgrowthandrootdensities.

Successful headcut control depends on the successfulapplicationoftheaboveprinciples. Thesearesometechniquesthathavebeenshowntobeeffective:

WormDitchesLogandFabricStepFallsStrawBaleFallsRockBowls

Worm Ditch (Bypass Channel). One way to stop aheadcut is tostarve it forwater. Accomplishthisbydiggingabypassditcharoundtheheadcut(Figure�0,page�8). Asuccessfulbypasswillrequire:(�)abroadvalleywithsufficientspacebetweenthegullyandthehillslopeforthewormditch;(�)awell-armoredre-entrypointdownstreamofthefalls,and (�)wetlandsoilscapableofsupportingadensegrowthofwetlandplantssuchassedges. Selectastartingpointabovetheheadcutthatwillcollectmostoftheconcentratedrunoff.Apoint�0to�00feetupstreamshouldsuffice.Selectthere-entrypointdownstream.Measurethestraightlinedistance(the“valleylength”)betweenthosetwopoints.Theconstructedwormditchshouldhaveachannellengthabouttwotimesthevalleylengthandaconstantslopeofabout�%.Tip:Usealengthofropetwicethevalleylength.Onatrialanderrorbasis,layouttheropeinaseriesofevenlyspacedmeander

Headcut on the Dry Cimarron, near Folsom, NM.

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loopsconnectingstartingandendingpoints.Thiswillbethecourseofthenewchannel. Using a sharp spade or shovel, dig ameanderingchannelnexttotherope.Makeit��to�8incheswideand�to��inchesdeep.Scatterthesoil. Donotbuilda leveealongthedownstreamedgeoftheditchexcepttoplugany lowspots. Floodflowswill followthechannelbutsomewaterwillspillovertoirrigatethewetlandplantsandhealthecut.

Figure 10 [above]. [Right] Worm ditch near Comanche Creek, Valle Vidal.

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Log and Fabric Step Falls (Headcut Control Structure For Moist Soils).Thisstructureisusedtocontrolheadcutsad-vancingthroughwetsoilareassuchaswetmeadows,springseepsandcienegas.Theerosiveactioncanbestoppedifahealthymatofwetsoilplantscanbecomeestablishedtoholdtheheadwallinplace. �.Preparethesiteby“squaringup”theheadwall,side-walls,andbottomofthechannel.Eliminatethescourpoolandanyirregularities(rocks,roots,orindentations)inthechannelbottom,sidewalls,orheadwall.Useashovel,spade,pick,orcrowbartoshapethesite.Saveandstockpilesodclumpsofwetsoilgrassesandsedgesforuseinthefinalstep. �.Whenpreparationisfinished,cutanddrapegeotextilefabricacrosstheheadwall,sidewalls,andchannelbottom.Threepiecesworkbetter thanone. Thefirst shouldstartabout�feetabovethelipoftheheadwall,ex-tenddowntheheadwall,andcoverthechannelbottomfor�-8feet(thelengthofthebottomtieroflogs).Thesecondshouldbedrapedoveronesidewallandpartwayacrossthechannelbottom.Thethirdshouldbedrapedovertheoppositesidewallinalikemanner.Temporarilyanchorthefabricinplacebyweightingtheends

withrockorsodclumps.Oncelogsareplaced,theextraflapofmaterialwillbefoldedbackoverthelogs. �.Installlogsinthepreparedsiteusingasmanytiersasnecessarytostackthemevenwiththelipoftheheadwall.(SeeFigures��and��).Logswithineachtiershouldbeofthesamediameter;betweentiers,theycanbeofdifferentdiameters.Logsinthebottomtiershouldbethelongest;thetoptier,theshortest.Forexample,ifthreetiersareneeded,makethebottomtier8feetlong,themiddletier�feet,andthetoptier4feetlong.Itisim-portanttowedgelogstightlyagainstthefaceoftheheadwallandsidewalls.Whenalltiersareinplace,foldtheextraflapoffabric

Figure 11.

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backoverthetoplogs.Usingsmoothwireandfencingstaples,wireeachtieroflogstogetherasyougo.(Wiretieronelogsbeforeinstallingtiertwo,etc.)Tampsoilintoanyopenspacesbetweenfabric,headwall,andsidewalls. 4.Workingupstreamfromthelipofheadwall,excavateasmoothplatformlevelwiththetoptierofinstalledlogsandonelog-diameterwideroneithersideofthechannel.Theplatformshouldextendatleast4feetupstreamfromthelipoftheheadwall.Linetheplatformwiththefabricextendingoutovertheinstalledlogsby�-4feetandupstreamfor�-�.�feet. �.Usinglogsofequaldiameter,install the final tier by wedging andtampingeachlogfirmlyinplace(Figure��).Thelogsshouldbelongenoughtoextend about � feet downstream fromthe lipof theheadwall. Wire this tiertogetherandtotherestofthestructure.Tucktheupstreamflapoffabricinplacealongtheleadingedge(upstreamface)ofthelogsinthefinaltier(seeFigure�4forcross-sectionoffinishedstructure). �. Transplant live green sodclumps of aquatic grasses, sedges, orrushestotheleadingedgeandsidesof

thefinaltieroflogs.Completelyfillanycracksorholesbetweenthefabricandchannelwallswithlivesod.This is a key step.Thesuccessofthelogstructuredependsonyoursuccessfullyestablish-ingalivingmatofwetsoilgrassesandgrasslikeplantsalongtheupstreamedgeandsidesofthestructure. �.Afterinstallationiscomplete,returntothesiteperi-odically(every�-�weeksinitially,thenlessfrequently)tofillanydevelopingcracksorholeswithfreshsodclumpsuntilahealthymatofvegetationissuccessfullyestablishedandnonewcracksorholesdevelop.

Figure 12.

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Materials Needed�.GeotextileFabric(siltfencingfabricin�footwidthsworks

wellandisconvenienttouse).�.Logs:Logs�to�0inchesindiameterandvaryinglengths

from4to8feetlong.(Forexample,bottomtier,8feetlong,secondtier,�feet,thirdtier,4feet.)Logsshouldbestraight,trimmedand

green,orseasoned,butnotrotten.Anyprotrudingknots,limbs,orknobsmakestackingverydifficultandshouldbetrimmed..

�.Wire:onerollofsmoothfencingwireorbarbedwire. 4.Fencingstaples:�incheslong,about�lbs. �.Sodclumps:�”X�”X�”.Diglocally.

Figure 13.

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Tools Needed �.Shovel(fordigging) �.Pick(forsquaringsidewalls) �.Crowbar(forwedginglogstogether) 4.Axe(forcuttingroots,trimming) �.Utilityknife(forcuttingfabric)

�.Clawhammer(fordrivingstaples) �.Fencingpliers(forcuttingwire) 8.Wheelbarrow(transportlogs,tools,materials) 9.Logcarrier(optional–forlifting,carryinglogs)

Straw Bale Step Falls.Strawbalescanbeusedtostabi-lizethefaceofaheadcutandconservemoistureuntilnewplantgrowthbecomesestablished.Tightlypackedbalestiedwithwirearepreferabletolooselytiedstringbales.Donotusestrawbalestructuresatsitessubjecttolivestockuseorgrazing(Figure��). Beforeplacingbales,shapetheface,sides,andbaseofthegullywithshovel,spadeormattock.Excavateanotchatthebaseofthefallstoseatthebalessnuglyagainstthefaceandsides.Besuretoallowplentyofspaceforthelargestexpectedstormrunoffevent. Stormflowmustbeable topourover thebales,notbeforcedtogoaroundthebalesforlackofchannelcapacity.Drivestakesorrebarpinsthroughthebalestoholdtheminplace. Strawbalescanbestackedupto�baleshighandarrangedasstepstoreducetheforceoffallingwater.Itisnotnecessarytousesiltfabrictoconservemoisturesincethebalesthemselvesstoremoisture.Largerockscanbeplacedalongthedownstreamedgeofthestructuretohelpanchorthebales. Rock Bowl. Arockbowlcanbeusedtoheallowheadcutsupto�feethigh.Rockbowlshardenthebaseofthecut,stopscour,

Figure 14.

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protectthefaceoftheheadcutfromdrying,sloughingandfrostheave;andconservemoistureforenhancedplantgrowth.Therockscapture sediments,debris, seeds,andplantpropagules,andactasrockmulchthatprotectsyoungplants. Rockbowlsusuallyrequire�to4wheel-barrowloadsofsoccertobasketball-sizedrocks.Linethepool,face,andsidesoftheheadcutwithrocksuptotheoriginalgroundlevel,butnothigher.Next,movedownchannelfromthelipofthecutabout�-4feetandbuildadamaboutone-halftheheightoftheFigure 15.

cut.Makeitbroadandwideandblenditwiththeliningtoformabowlshapeddepressionthatwillcatchwaterpouringoverthelipoftheheadcut.Thefaceofthebowlshouldlayergraduallydownslopetoblendsmoothlywiththebottomofthegully. Liningthebowlwithsiltfabricwillhelpcatchsedimentanddetainmoisture.Ifaliningisused,besuretocoveritwithrocktosecureitinplaceandhideitfromview.Fabricisugly! Finally,godownchannelandbuildaone-rockdam about 8-�0 feet downstream from the rock bowl.Thiswillhelptotrapsedimentandretainsoilmoisturefornewplantgrowth(Figure��).

Figure 16.

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A futile treatment is to pilerockorothermaterialsonthetopoftheheadcutinthebeliefthatdoingsowillprotectthelipfromerosion.Sinceheadcutsadvancewiththeprogressiveundercuttingandcollapseoftheheadwall,thistreatment will not succeed. Infact, raising the lip only servestoincreasetheerosiveenergyofthe water falling from a greaterheight.

Anotherfutiletreatmentistopilelooserockatthebaseoftheheadwallontheassumptionthattherockswillblunttheforceofthe falling water, stopping theheadcut. While this treatmentworksinitially,aspacewillgradu-allyopenalongthefaceofthecutduetodryingandcrumblingof

thesoilduringdryweatherandfrost heaving inwinter. As thespace widens, more and morerocks will be flushed away andthe headcut will continue tomoveupslope.

Pilingbrushatthefaceofthecutissometimeseffective,sometimesnot,dependingontheheightofthecutandthenatureofthesubstrate.Brushmaytrapother debris, thus mulchingthe site, keeping it moist andencouraging revegetation, butmoreoftenthannotthecutwillcontinuetomoveheadward.

Dumping trash in aheadcutisseldomeffectiveandisneverenvironmentallyaccept-ableforobviousreasons.

V. Not Recommended!

AuthorsandEditors:BillZeedykandJan-WillemJansens

Production&Layout:TheQuiviraCoalition

Printing:PaperTiger

Funding:EnvironmentalProtectionAgency

NewMexicoEnvironmentDepartment~SurfaceWaterQualityBureauRioPuercoManagementCommittee

To Contact Us:Earth Works Institute

1413SecondSt.,Suite4SantaFe,NM87505

505-982-9806

The Quivira Coalition1413SecondSt.,Suite1

SantaFe,NM87505505-820-2544•505-955-8922(fax)

Bureau of Land Management/Rio Puerco Management Committee

AlbuquerqueFieldOffice435MontañoN.E.

Albuquerque,NM87107-4936505-761-8900•505-761-8911(fax)

New Mexico Environment Department~Surface Water Quality Bureau~ Watershed Protection Section

1190So.St.FrancisDriveSantaFe,NM87505

505-827-1041•505-827-0160(fax)

PhotoscourtesyofEarthWorksInstituteandTamaraGadzia;graphicscourtesyof

TamaraGadzia.