usace gabions for streambank erosion control

7/27/2019 USACE Gabions for Streambank Erosion Control

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GabionsforStreambankErosionControlby GaryE.Freeman 1andJ .CraigFischenich' May2000

Complexity Low Moderate High

EnvironmentalValue Cost

OVERVIEW Gabionsarecylindersthatare filledwitheartho rstones,whichareusedinbuildingstructuressuchasdamso rdikes.abionshavebeenusedfor severalmillenniainEgyptandChina.Priorto 1879,gabionswereconstructedwith plantmaterials,whichseverelylimitedtheirusefullife.nabout1879afirminItalyisthoughtto havefirstusedwiremeshintheconstruct iono fgabionbaskets.h isispossiblyth efirstuse o fth emodernwiremeshbasketsasusedtoday.abionsareno w usedth roughoutth ewor ldfo rbedprotect ion,bankstabilization,retaining walls,and numerouso therpurposes.Gabionscomeinthreebasic forms,thegabionbasket,gabionmattress,and sackgabion.llthreetypesconsisto fwiremeshbasketsfilledwi thcobbleo rsmallbouldermaterial.hefillnormallyconsistso frockmaterialbu tothermaterialssuchasbrickshavebeenusedto fillthebaskets.hebasketsare usedto maintainstabilityand to protectstreambanksand beds.Thedifferencebetweenagabionbasketandagabionmattressisth ethicknessandth eaerialextento fth ebasket. sackgabionis,asthenameimplies,ameshsackthatisfilledwith rockmaterial.Thebenefito fgabionsisthattheycanbe filledwi throcksthatwou ldindividuallybe to osmallto withstandtheerosiveforcesofth estream.hegabionmattressissha l lower(0.5to 1.5ft)thanth ebasketand isdesignedto protectth ebedo rbanksofastreamagainsterosion.

Gabionbasketsare normallymuchthicker(about1.5to 3ft)and coveramuchsmallerarea.heyareusedto protectbankswheremattressesare no tadequateo rare usedto stabilizeslopes(Figure1),constructdrop,structures,pipeoutletstructures,o rnearlyanyotherapplicationwhe resoilmustbeprotectedfromth eerosiveforcesofwater.eferencesto gabionsinthisarticlerefergenerallyto bothmattressesandbaskets.ackgabionsarerarely

Figure1.abionbasketsinstalledforslopestabilizationalongastream usedinth eUnitedStatesandareno twithinthescopeo fthistechnicalnote.Gabionbasketscanbemadefromeitherweldedo rwovenwiremesh.hewireisnormallygalvanized to reducecorrosionbu tmaybe coatedwithplastico rothermaterialto preventcorros ionand/ordamageto th ewi remeshcontainingtherockfill.ew materials

*P

1RiverResearchandDesign,Inc.,1092N.75 E.,Orem,UT 84057 2USAEWaterwaysExperimentStation,3909HallsFerryRd.,Vicksburg,MS39180ERDCTN-EMRRPSR-22

BffSFBCXED4 DISTRIBUTION STATEMENT A roved forPublic Release2 0 0 0 0 6 1 5 0 1


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suchasTensar,aheavy-dutypolymerplasticmaterial,havebeenusedinsomeapplicationsinplaceo fth ewiremesh.fth e wirebasketsbreak,eitherthroughcorrosion,vandalism,o rdamagefromdebriso rbedload,th erockfillinth ebasketcanbelostandtheprotectivevalueofth emethodendangered.Gabionsareoftenusedwhereavailablerocksizeisto o smallto withstandth eerosiveandtractiveforcespresentataprojectsite.heavailablestonesizemaybeto o smalldu eto th ecostoftransporting largerstonefrom remotesites,o rth edesireto haveaprojectwithasmootherappearancethanobtained fromriprapo ro thermethods.abionsalso requireabouto ne thirdth ethicknesso fmaterialwhencomparedto riprapdesigns.Riprapisoftenpreferred,however,du eto th elo w laborrequirementsfo ritsplacement.Thesciencebehindgabionsisfairly wel lestablished,wi thnumerousmanufacturersprovidingdesignmethodo logyandguidancefo rtheirgabionproducts.r.StephenT.Maynordo fth eU.S.ArmyEngineerResearchandDevelopmentCenterinVicksburg,Mississippi,hasalso conductedresearch to developdesignguidanceforth einstallationo fgabions.w o generalmethodsare typicallyusedto determineth estabilityofgabionbasketsinstreamchannels,th ecriticalshearstresscalculationandth ecriticalvelocitycalculation.Asof twarepackageknownas CHANLPROhasbeendevelopedbyDr.MaynordMaynordetal.1998).Manufacturershavegeneratedextensivedebateregardingth euseanddurabilityo fweldedwirebasketsversuswovenwirebasketsinprojectdesignand construction.Projectresultsseemto indicatethatperformanceissatisfactoryfo rbothtypeso fmesh.Therockscontainedwithinth egabionsprovidesubstratesfo rawidevarietyo faquat icorganisms.rganismsthathaveadaptedto livingonandwithinth erockshaveanexcellenthome,butvegetat ionmaybedifficultto establishunlessth evo idsintherockscontainedwithinth ebasketsarefilledwithsoil.

If largewo o d yvegetat ionisal lowedto grow inthegabions,thereisarisk thathebasketswil lbreakwhenth elarge woodyvegetat ionisuprootedo rasth eroo tand trunksystemsgrow .hus,itisnormallyno tacceptableto allow largewo o d yvegetat ionto grow inth ebaskets.hepossibili tyofdamagemustbe weighedagainstth edesirabili tyo fvegetat ionontheareaprotectedbygabionsand th estabilityo fth elargewo o d yvegetat ion.Iflargewo o d yvegetat ioniskepto uto fth ebaskets,grassesand o therdesirablevegetat iontypesmaybe establishedandprovideamoreaestheticandecologicallydesirableprojectthangabionsalone.PLANNING Thefirststepinth eplanningprocessisto ascertain whethergabionsare th eappropriate t oo lto meetprojectobjectivesandconstraints relatedto stabilityand habitat.eammembersconduct ingthisassessmentshouldincludehydraulicengineers,biologists,geologists,landscapearchitects,and othersthathavean understandingo fstreamrestorat ion,fluvialgeomorpho logy ,and vegetat ionandhabitatrequirements.Numerousquestionsmustbeaddressedby theteamincluding,bu tno tlimitedto ,th efo l lowing interrelateditems:1)re gabionsth eappropriatetoo lsgiventhemagnitudeofth eerosionproblem? 2)re streamvelocitiesandshearstressespermissible? 3)stheredangerto th ewiremeshfrom f loatingdebris,sharpbedload,o rfrom vandalism? 4)illsitecondit ionsduringconstruct ionpermitinstallation?5)ave consequences o ffailurebeenconsideredandwhatare they,e.g.,wha thappensifoneo rseveralbaskets becomesdislodgedandmovedownstream o rbreakopen?6)anandwi l lth esponsorrepairth ebasketsinat imelymannerwhennecessary?7)re thereareasthatmustbe protectedto preventerosiondamagefromth eupperbankareasbehindth egabions?

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8) Are th eprojectcostsacceptable?Costsfor gabionprojectsareamongth ehighestforstreambankerosionandbankstabilizationtechniques.ostsfo rth ebasketsvarybysizeand depthbutare ontheordero f$1.50to $3.20/ft2(allf iguresin1999dollars)fo r3-ft-deepbaskets,$1.25to $2.00/ft*fo r18-in.-deepbaskets,and$1.10to $1.75/ft2fo r12-in.-deep baskets.losureitemsfo rthebasketsarenormallyincludedandpricesalso vary wi th th egaugeofthewire,wi thheavierwirebeingmoreexpensive.asketscanbe orderedincustomsizesfo rahigherprice.Keyso rt iebacks,ifrequired,stone,backfill,andvegetat ionplugs,ifany,addto materialcostsbu tvarywi thdesignandavailability.Tota lprojectcostisestimatedatabout$150.00to $450.00/yd3o fprotect ion.hisincludesthebaskets,assemblyandfillingthebaskets,stonefill(mayvarydependingonlocationandavailability),andbasketclosure.Basketinstallationdoesno talwaysrequireheavyequipmentbu tth efillingandclosureo fth ebasketscanbeverylabor-intensiveandagoodcrew shouldbeplannedto completeinstallationinatimelymanner.

SITE CONSIDERATIONS Gabionsare suitedto avarietyo fsitecondit ions.heycanbeusedinperennialo rephemeralstreams,andinstallationcanoccurindryo rw etcondit ionswiththeproperequipment.hemainconcernisth edeliveryand handlingofthebasketsand rockfill.If w et condit ionsexistfo rlongperiodso ft imeintheareasurroundingth esite,th edeliveryo frock materialsmaybe impossible o rextremely problematic.Themostimportantconsiderat ionfo rth einstallationo fgabionsisthestabilityofth estream.fth estreamisundergoingrapid changesinbaseelevat ion(down-cuttingo rdeposit ion)o rextremelateralmovement,plansshouldbemadeto correctth elargerproblemsthatare contributing to th elocalproblem.fthelargerproblemsareno taddressed,localprotect ionmeasuresmay be overwhelmed o rf lanked.

Foundat ioncondit ionsarealso importantinsiteselectionbecauseth egabionsmusthaveafirmfoundat ion.fth esubstrateisnoncohesivematerial,suchassando rsilt,th ematerialmay be removedthroughth egabionsandcausesettlemento rf lankingto occur.nstallationo fafiltermaterialo rfilterfabricshouldbe consideredineveryproject.iltermaterialshouldonlybeomit tedifitisclearlyno tneeded.omeprojectsmayrequireafilterfabricas wel lasagravelfilter materialto preventeros iono fth eunderlyingbankandbedmaterial.Anaddit ionaland extremelyimportantconsiderat ionisth ecalculationofth eamountoferosionto be expectedinaproject.his shouldbecalculatedto ensurethatth efoundat ion fo rth egabionsisno tundercutdueto scour.DESIGN Primarydesignconsiderat ionsfo rgabionsandmattressesare:1)foundat ionstability;2)sustainedvelocityandshear-stressthresholdsthatth egabionsmustwithstand;and3)to eandf lankprotect ion.hebaselayero fgabionsshouldbeplacedbelow th eexpectedmaximumscourdepth.lternatively,th eto ecanbe protectedwithmattressesthatwil lfallinto anyscouredareaswi thoutcompromisingth estabilityo fth ebanko rbe dprotect ionport iono fth eproject.fbankprotect iondoesno textendaboveth eexpectedwatersurfaceelevat ionfo rth edesignf lood,measuressuchas t iebacksto protectagainstf lankingshouldbe installed.Theuse ofafilterfabricbehindo runderthegabionbasketsto preventth emovement ofsoilmaterialthroughth egabionbasketsisan extremelyimportantpart ofth edesignprocess.Thismigrat ionof soi lthroughth ebasketscancauseunderminingofth esupport ingsoi lstructureandfailureofth egabionbasketsand mattresses.PrimaryDesignConsiderationsThemajorconsiderat ioninth edesigno fgabionstructuresisth eexpectedvelocityatth egabionface.hegabionmustbedesignedto withstandtheforceofth ewaterinth estream.

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Sincegabionmattressesaremuchshal lowerandmoresubjectto movementthangabionbaskets,careshouldbe takento designth emattressessuchthattheycanwithstandtheforcesappliedto thembyth ewater.owever,mattresseshavebeenusedinapplication whereveryhighvelocitiesarepresentandhaveperformedwell.ut ,projectsusinggabionmattresses shouldbe carefullydesigned.Themedianstonesizeforagabionmattresscanbe determinedfromth efo l lowingequation:

Table1.1versusSideSlopeAngle

dm=SfCsCvd\0.5r

- r vV " (1 )Thevariablesinth eaboveequat ionare def inedas :

CsCv

d9

S fV WYs Yw

=stabilitycoefficient(use0.1)=velocitydistributioncoefficient=1.283-0.2lo g(R/W)(minimumof1.0)and equals1.25atendofdikesand concretechannels=averagerockdiameteringabions=localf low depthatV =accelerationdueto gravity=sideslopecorrect ionfactor(Table1)=centerlinebendradiuso fmainchannelflow=safetyfactor(1.1minimum)=depth-averagedvelocity=watersurfacewidtho fmainchannel=unitweightofstone=unit weight ofwater

1V:1V:1V:1V:


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Table2.tone Sizesand AllowableVelocit iesfor Gabions(courtesy ofandadapted from Maccaferr iGabions)

Mattress

Basket

0.5 0.5 0.75 0.75 1 1 1.5 1.5

3-4"3-6"3-4"3-6"3-5"4-6"4-8"5-10"

3.4"4.3" 3.4"4.7"4" 5"6"7.5"

11.513.8 14.8 14.8 13.6 16.41921

13.814.816 2018 21 24.926.2

Whenth edatainTable2arecomparedto Equation1 ,ifV=11.5,C s=0.1,Cv=1.0,K,=0.71,yw=150 andSf=1.1,thelocalf low depthmustbe onth eorderof25ftinorderto arriveatth estonediameterof 3.4in.showninTable2.DesignersshoulduseEquation1 to taketh edeptho ff low into account.able2does,however ,givesomegeneralguidelines fo rfillsizesandisaquickreferencefo rmaximum al lowablevelocit ies.Maccaferrialso givesguidanceonth estabilityofgabionsintermsofshearstresslimits. Thefo l lowingequationgivesth eshearfo rthebedo fth echannel:

* b=rJd (2 )withth ebankshearrm takenas 75percento fth ebedshear,i.e.tm =0.75rb .(Sisth ebe do rwatersurfaceslopethroughthereach.)hesevaluesare thencomparedto th ecriticalstressforth ebedcalculatedby th efo l lowingequat ion:

T e=0.l0{y,-rwK (3 )withcriticalshearstressfo rthebanksgivenas:

T =T si n200.4304 (4 )

where0=theangleo fth ebankrotatedupfrom horizontal.Adesignisacceptableift T S ,thenacheckmustbe madeto seeif theyare lessthan120percentofrbnd rs .fth evaluesarelessthan120 percento fx bndT S ,th egabionswi l lno tbe subjectto morethanwhatMaccaferridefinesas"acceptable"deformation.owever ,itisrecommendedthatstonesizebe increased to limitdeformationifpossible.Researchhasindicatedthatstoneinth egabionmattressshouldbe sizedsuchthatthelargeststonediameterisno tmorethanabouttw o t imesthediametero fth esmalleststonediameterandth emattressshouldbeatleasttwiceth edeptho fth elargeststonesize.hesizerangeshould,however ,varybyaboutafactor of tw o to ensureproperpackingofth estonematerialinto th egabions.inceth emattressesnormallycomeindiscrete sizes,i.e.0.5,1.0,and1.5ftindepth,normalpracticeisto sizeth estoneand thenselectth ebasketdepththatisdeepenough to be atleasttw o t imesth elargeststonediameter.hesmalleststoneshouldalso be sizedsuchthatitcannotpassthroughth ewiremesh.Stability ofUnder ly ingBedandBank Materials.nothercriticalconsiderat ionisthestabilityofth egabionfoundation.hisincludesbothgeotechnicalstabilityand th eresistanceo fthesoi lunder th egabionsto th eerosiveforces

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ofth ewatermovingthroughth egabions.fthereisanyquestionregardingthestabilityo fthefoundation,i.e.possibili tyofrotat ionalfailures,slipfailures,etc.,aqualif iedgeotechnicalengineer shouldbeconsulted prior to and duringth edesignofthebank/channelprotect ion.everalmanufacturersgiveguidanceonhow to check for geotechnicalfailure(seeMaccaferriGabionsbrochure asan example).Stackedgabionbasketsusedforbankstabilityshouldbe tiltedt owardsth esoiltheyareprotectingby aminimumo fabout6degfrom vertical.abionsare stackedusingtw o methods.heseare showninFigure3. hileth egabionscanbe stackedwithno tilt,itisrecommendedthatsometiltinto th esoilbeingprotectedbe provided.

Thelimitforvelocityonth esoi lisdifferentforeachtypeof soil.helimitfor cohesivesoilsisobtainedf romachart,whi lemaximum allowable velocit iesfor o thersoi ltypesare obtainedbycalculatingV e ,th emaximum velocityallowableatth esoilinterface,andcomparingitto V fth eresidualvelocityonth ebed,i.e.underth egabionmattressand underthefilterfabric.V e fo rloosesoilsisequalto 16.1d f/2whi leV f\scalculatedby:

vf= 1.486 v2/3nfamy1/ 2 2z (6 )

whereV a isth eaveragechannelvelocityanddmistheaveragerockdiameter.

Figure3.rontstepandrearstepgabion l a you t(courtesy ofMaccaferr iGabions)One ofth ecriticalfactorsindetermining stabilityisth evelocityo fth ewaterthatpassesthroughth egabionsandreachesthesoilbehindth egabion.he water velocityunderthefilterfabric,i.e.waterthatmovesthrough thegabionsand filterfabric,isestimatedto be one-fourthto one-halfo fth evelocityat themattress/fi lterinterface.(Simons,Chen,and Swenson984)hevelocityatthemattress/fi lterinterface(Vb )isestimatedto be K = 1.4S6(dm}2/3

nt-.1/2 (5)

Jwhe renf=0.02forfilterfabric,0.022for gravelfiltermaterialandSisth e water surfaceslope(o rbedslope)throughth ereach.fth eunderlyingsoi lmaterialisno tstable,additionalfiltermaterialmustbeinstalledunderth egabionsto ensuresoilstability.accaferrialso providesguidanceonth estabilityo fsoilunderth egabionsintermsofvelocitycriteria.

IfV fislarger thantw o to fourt imesV e ,agravelfilterisrequiredto furtherreduceth ewatervelocityatth esoilinterfaceunderth egabionsuntilVf isinan acceptablerange.o checkfo rtheacceptability ofth efilteruse th eaveragegravelsizefordm inEquation6.fth evelocity V fsstillto o high,th egravelsizeshouldbe reducedto obtainanacceptablevaluefo rV f .OtherDesignConsiderat ionsItmaybepossibleto combinegabionswith lessharshmethodso fbankprotect iononth eupperbankandstillachieveth edesiredresulto fastablechannel.rovisionsforlargewo o d yvegetat ionandamoreaestheticallypleasing projectmayalso beusedo nth eupperbankso rwithinthegabions(Figure 4) .owever ,th estabilityo fvegetat iono ro therupperbankprotect ionshouldbecarefullyanalyzed to ensurestabilityofth eupperbankarea.failureinth eupperbankregioncanadverselyaffectgabionstabilityandleadto projectfailure.CONSTRUCTION Agabionprojectisinstalledbyfirstsmooth ingth eareato be protectedto th edesiredfinalslope.hefilterfabric andanyrequiredgravelfilterare theninstalledaccordingto th edesignplans.

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feofif>

/it. .S :,-/.%/ ,* "ZKitXff&vxe8js

lip!

Figure4 .Woody vegetat ionusedwithinth egabionarchitecture (Coppinand Richards 1990)

Thegabionsarenextassembledandtiedtogether,foldedflat,stacked,andbundled by thesupplier.heyare bentintoth edesignform,andal lendsand diaphragms arelacedintoplace.Theassembledgabionsarethenplacedintheirproperlocationandlaced(tied)to al lsurroundinggabions.tisimportantthatalladjacentgabionsbelacedtogether.hispreventsmovementandth efailureo faprojectdueto th elossofo nebasketo utof aprotectedarea.acingshouldoccurinaccordance withth emanufacturer'srecommendations.Afterasufficientnumbero fgabionsareassembled,filling canstart.hefillshouldbe placedcarefullyinth egabionsto preventdamageto th ediaphragmsand edges.illingshouldbe doneinliftsofno morethan12in.andsomehandadjustmentmayberequiredto obtainasmooth attractiveface.o rgabion basketswithheightsgreaterthan12in.,tie wireso rstiffenersarerecommendedaftereachlift to preventexposedfacesfrombulging(seeFigure5).

.1/3EPTH///TYPICAL. INSTALL 4 STIFFENERS/fPER EXPOSED FACE.// AND PER BACKACE 9 GATIFFENERHOOKEDTHEINTERSECTION OFTWO WIRESDEPTH-~AL44^'f ^1/3 HEIGHTTYPCiAL

/3 HEIGHTTYPCIAL >-1/3 Wj- TYPtCAi.

ENDELLSSTIFFENED DERAILS

-WIDTH "WE XPOSEDA C E S WHEREEIGHTFABIONISerRESS,NSTALL 2 STiFFENERSERACE.WHEREOGHT IS S 2*.NOTIFFENERSEQUIRED

Figure5.t iffenerinstallationto preventbulging faces(courtesy HilfikerRetainingWalls)Afterfilling,th ecoversareplacedonth egabionsand securedwithtiewires(laced).Thegabionscanbe seededwithgrasso rothercover vegetat ionif th esoi lisintermixed with ERDC TN-EMRRPSR-22

theliftsofstoneand if th ehydro logyisno tlimiting.gain,largewo o d yvegetat ionshouldbe avoidedinth eareaprotected by gabions.


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Careshouldbe takento determinesoilpropertiesif th egabionsareto be covered.fth esoi lissalineo racidic,deteriorat ionofthegabionwirecanoccurrapidly,leadingto projectfailure.If th esoilhasal owe rpermeabilitythanth eunderlyingbankmaterial,watermayno tbe ableto movereadilythroughthegabions,result inginhydrostat icpressurebehindthegabions.hiscancauseaslidingo rrotat ionalfailureofth egabions.fth esoilthatisplacedonth egabionsisporousenough to allow easypassageofwaterthroughth egabion,itmayno tretainenoughwaterto supportth edesiredvegetat ion.If agrasscover canbeestablishedovergabions,itispossiblethatth egrasswil lremainstableduringhighf l owssincetheroo tsystem wi l lbe firmlyattachedto th egabionmeshandunderlyingrockfill.heproblemsofadequatemoistureand sufficientpermeabilityo fthesoilneedto be carefullyinvestigated.Whilegabionsmaybeableto suppor tsometypesofvegetat ion,careshouldbe usedwhenrecommending coveringand fillingth egabionswithintermixedsoi landrockto suppor tvegetat ion.OPERATIONAND MAINTENANCE Gabionsneedto be checkedfo rbrokenwiresand repairedifnecessaryto protectstonecontainedinth egabionsfrombeingremovedby th eforceofwaterpassingth ecage.Anylargew o o d yvegetat ionthathasstartedto grow inth egabionsshouldberemovedandany damageto th egabionsrepaired.hismayincludereplacingloststoneand repairingany damagedwirewi thwiresimilar to thatusedinth econstruct iono fth ecages.Theprojectareashouldbemonitoredfo rsignso feros ion.f eros ionisoccurringattheto eo fthegabionstructures,measuresshouldbe takento protectth egabionsf romundercutting andsubsequent failure.fwateriserodingsoilf rombehindagabionwall,eitherthewaterneedsto bedivertedo rmeasuresneedto be takento eliminatetheeros iono fsoilfrom behindth egabions.hisoftenoccurswhere8

surfacerunoffentersth estreamatalocat ionthatisprotectedbygabions.Theprojectshouldbe moni toredfor anysignso fgeotechnicalfailure.fany ofth egabionshaveshiftedo rappearto bebulgingawayfrom thebank,measuresshouldbe takento evaluateth eseriousnessofth eproblem.fpropergeotechnicalevaluationsandmeasuresaretakenduringth edesignand construct ionstages,thereshouldbe littlechanceo famajorproblemdueto geotechnicalfailures.APPLICABIL ITYAND LIMITATIONS Theaestheticso fgabionsareno tasdesirableassomeothertypesof protectivemeasuressuchasre-vegetat ion,bu twhe reth edamagesanddangersassociatedwi thfailuresishigh,o rwhereseriouserosionproblemsexistthatcannotbe controlled withothermethods,gabionsareaviablealternative.Cautionshouldbeexercisedinusinggabionsinareaswherethereisahighl ikel ihoodo fvandalism o rdamagefromin-streamdebrisincludingmovingcobble,etc.,thatcanharm thewirebyimpactand scour.nderthesecondit ions,th ewirecontaining th erock fillcanbe damagedandth eprotect ionlost.abionsmustalso be protectedagainstimpactf rom large wo o d ydebrisand sharpobjects.hesematerialstendto distortandbreakth egabions.Iflargewo o d yvegetat ionisdesiredinan areato beprotectedbygabions,itmaybepossibleto use gabionso ro thermethodssuchas peakedstonetoesto protectth el owe rbankandavegetativetreatmentonth eupperbanks.Thiscanprovideforlargew o o d yvegetat ionontheupperbankandyetprovidehighlyeffective protect ionoftheto eo fth ebank.ACKNOWLEDGEMENTResearchpresentedinthistechnicalnotew asdevelopedunderth eU.S.ArmyCorpso fEngineersEcosystemManagementand Restorat ionResearchProgram.echnicalreviewswereprovidedbyMessrs.JerryL.MillerandHollisH.Allen,bothofth eEnvironmentalLaboratory.

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POINTSOFCONTACT Foradditionalinformation,contactDr.J.CraigFischenich,601-634-3449,f ischecf).wes. armv. mil),orthemanageroftheEcosystemManagementandRestorationResearchProgram, r.RussellF.Theriot(601-634-2733,therior@>wes.army.mil).histechnicalnoteshouldbecitedasfollows:

Freeman,G .E.,andFischenich,J.C.(2000).Gabionsfo rs treambankerosioncontrol,"MRRP TechnicalNotesCollection (ERDC TN-EMRRP-SR-22) ,U.S.ArmyEngineer Researchan dDevelopmentCenter,Vicksburg,MS.www.wes.army.mil /el /emrrpREFERENCES Coppin,,nd Richards,(1990).se ofvegetation in c iv i lengineering.utterworths,London .

ABOUT THE AUTHORS GaryE.FreemanisPresidento fRiverResearchandDesign,Inc.eho ldsbachelor'sandmaster'sdegreesinAgriculturalandIrrigationEngineeringfromUtahStateUniversityandaPh.D.inCivilEngineeringfrom TexasA&MUniversity.isresearchhas focusedonhydraulics,sedimentat ion,andhydraulicuncertainty.J.CraigFischenichisaResearchCivilEngineeratth eU.S.ArmyEngineerResearch andDevelopmentCenter.eholdsbachelor's andMastero fSciencedegrees,respectively,inCiviland EnvironmentalEngineering f rom SouthDakotaSchoo lof MinesandTechnology,andaPh.D.inHydraulicsfrom Colorado StateUniversity.isresearchhas focusedonstreamandriparianrestoration,erosioncontrol,andf looddamagereduction.

Maynord,S.,Hebler,M.,and Knight,S.(1998)."User'smanualfor CHANLPRO,PC programfo rchannelprotect iondesign,"TechnicalReportCHL-98-20,U.S.ArmyEngineerWaterwaysExperimentStation,Vicksburg,MS.Simons,D.B.,Chen,Y.H.,andSwenson,LJ.(1984).Hydraulictestto developdesigncriteria fo rth euse of renomattresses,"ReportpreparedforMaccaferriSteelWireProducts,Ltd.,Ontario,Canada.ivilEng.Dept,Colorado StateUniv.,FortCollins,CO.U.S.ArmyCorpso fEngineers.1994)."Hydraulicdesignoff loodcontrolchannels,"EngineerManual1110-2-1601,Change1 ,30June,1994,Washington,DC.

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usace gabions for streambank erosion control

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