城市规划相关外文翻译.docx

城市规划相关外文翻译.docx

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城市规划相关外文翻译

RiverfrontLandscapeDesignforLondon2012OlympicPark

Client:

OlympicDeliveryAuthority

Location:

London,UK

ProjectCredit:

Atkins

Text:

MikeMcNicholas,ProjectDirector,Atkins

Howdoyouplantalongariver'sedge,knowingthatmillionsofpeoplecouldbepassingthroughthesiteinthenearfuture?

Howdoyoudesign,createandmaintainthesurroundingwetlands,knowingthatman-madewetwoodlandisveryrareandtransitionalbynature?

Howdoyouensurethatthehabitatbeingcreatedremainsviableandsustainableinthelong-term?

Atkins’engineersofthewetlandsandriveredgesontheLondon2012OlympicParkweretaskedwithfindinganswerstoallofthesequestions.

Coveringmorethan246hectaresofformerlyderelictindustrialland,London’snewOlympicParkfortheLondon2012OlympicandParalympicGamesisoneofEurope’sbiggest-everurbangreeningprojects.Riversandwetlandsareattheheartofthevisionforthenewpark,whichliesineastLondon’sLowerLeeValley.Thelandscapethat’snowemergingwillprovideabackdropforthemainactionoftheLondon2012Games.

Asriveredgeandwetlandengineersfortheproject,Atkinshasplayedacriticalroleinturningthevisionintoreality.Atkins’remitincludesdesignofthesoftriveredgesandwetlands,includingriverbankrestorationandbioengineering.

Thetransformationisunprecedented.Morethan8kmofriverbankshavebeenrestoredaspartoftheproject;intandemwiththis,2hectaresofreedbedsandpondshavebeencreated,alongwith9,000squaremetersofrarewetwoodland（Fig.01）.

Thechallengewasaboutgettingpeoplebothvisualandphysicalaccessdowntotheriver-toactuallymaketheriversmoreaccessibleandmoreopen,andthereforethecenterpieceofthePark.

MikeVaughanheadsupAtkins'multidisciplinarydesignteam,whichincludesriverengineers,geomorphologistsandecologists.“Theideawastoopenuptherivercorridorbymakingthesteepslopesthatlinetheriverflatter,”explainsMike.“Bydroppingtheslopes,we’vebroughttheriverintotheparkandmadeitmuchmoreaccessible-peoplecangetclosetotheriverandseewhat’sgoingonthere.”

Gettingtheriverbankgeometryjustrightwasadelicatebalancingact.Toosteep,andthebankswouldneedcostlyartificialreinforcement;tooshallow,andtheywouldstarttoeatintovaluablespaceonthesite.Anoptimumslopeof1in2.5-about22degrees-waschosen.Thespaceoccupiedbyriverbankwasrestrictedbytheneedtoconveyfloodwaterandthelocationofterrestriallandscapeandinfrastructure.Assuch,thebankswereover-steepenedusingtwoapproaches.Firstly,wherepossible,theriverbankswereterracedusingcoirrollsandtimberstakes.Inotherlocations,whereonlya70degreebankwaspossible,areinforceddetailwasused,providinglayersofgeo-gridandsteelmeshcages,facedwithariversideturf.

Today,withthenewlandscaperapidlytakingshape,it’seasytoforgethowtheLeeValleyusedtolook.UntiltheOlympicDeliveryAuthority（ODA）tookpossessionofthesitein2006,manyoftheriverchannelsthatcriss-crossthesitewerecloggedwithinvasiveweeds,alongwiththepredictabledetritusofurbandecay:

abandonedshoppingtrolleysandcartires.

TheLeeValley’sneglectedrivernetworkwasn’tonlyaneyesore,butalsoanobstacle-agulfseparatingHackneyandTowerHamletsinthewestfromWalthamForestandNewhamintheeast.

Now,therevitalizedwaterways-andthenewcrossingsspanningthem-willbevitalnotonlyduringtheGames,butalsoafter2012.Theyareanintegralpartofthelegacysolution,stitchingthenewParkanditswaterwaysintothewiderfabricofeastLondon.

1BringingHabitatsbacktoLife

Makingthemostofthesite’sriversandnaturalfeaturestocreatesustainablehabitatsisakeypartoftheOlympicDeliveryAuthority’svisionfortheOlympicPark.Buttheprocessoftransformingthepark’sriversfromweedandrubbish-infestedgulchesintopristinewatercourseshasbeenlongandtough.

ForAtkins,thatprocessstartedwithdevelopinganintimateunderstandingofthelabyrinthofwaterwaysandchannelsthatwindtheirwaythroughthesite.Flowsandvelocitiesweremeasuredatdifferentpointsoveraperiodoftime,withdatausedtoconstructadetailedhydraulicmodeltopredictfloodrisk.That’sofcriticalimportance,becauseAtkinshadresponsibilityforeverythinguptoacontourof4metersaboveordnancedatum（sealevel）onthesite.

Afullfloodriskassessmentwasundertakenatenvironmentalimpactassessmentstage.Atkinsundertookanalysesoftheriskoffloodingcausedbyfrequentrainfall,takingintoaccounttheautomatedregulationofwaterlevelsintheimpoundedreachesandtheimpactoftidallockout.Themodelingexercisewasmadeconsiderablymorecomplicatedbytheimpoundmentoftheriversystemduringthecourseof2008;ineffect,thiseliminatedthedirecttidalinfluenceoftheThames.Butitsindirectinfluenceisstillfelt.“WhenthetidecomesinontheThames,itstopswaterflowingoutoftheRiverLee,”explainsMikeVaughan.“Sotheriverlevelsfluctuatebyanaverageof400mmaday.”

Atkins’modelingcalculationscorrectlypredictedthisphenomenon,andalsotheincreasedriskofflooding.“Thesediscoveriesledtosomechangesinthelandscapingprofile,”saysMike.“Theriversidepathshavebeenraisedbyuptoameterandtheprofileofthewetlandswasalsoraised,asmaintainingcorrectwaterlevelsiscriticaltotheirsurvival.”

SustainabledrainagetechniqueshavealsobeenusedacrossthePark.Inthelandscapeareas,porousstripshavebeenusedintheconcourse,feedingintobioswaleswhichdraindownintotheriversideponds.Surfaceconveyance,undergroundpipesandstoragefeatureshavealsobeenutilized（Fig.02）.

Thefirststepintheriverrestorationprocesswasto“layback”thebanks,manyofwhichwereprecipitouslysteep.Thisre-profilingwasnecessarybecausemuchofthesurroundinglandwas“made”ground,theresultofcenturiesoftippingthathadraisedthegroundlevelbyasmuchas10metersinplaces.Thecocktailofmaterialsonthebanksincludedrubble,glass,animalbonesand,morerecently,wartimedemolitionmaterialsfromLondon’seastend.

AnotherchallengefacingtheAtkinsteamwastheprevalenceofinvasiveweeds.TheseincludedHimalayanbalsam,Japaneseknotweedandgianthogweed.Allarefast-growingnon-nativeplantsintroducedtoBritaininthe19thcenturyasgardencuriosities;allhaveprosperedonthewrongsideofthegardenwall.

Invasivespeciesarebadnewsforriverbanks.Theyreproduceandgrowwithprodigiousspeed,drivingoutnativeplantspecies.Andthey’rehighlyresilient.Knotweedcanforceitswaythroughsolidconcrete,whilegianthogweedcontainsfurocoumarins,sun-activatedtoxinsthatcancauseskinulceration.Eliminationwasapriority–soilwastreatedthroughoutthesiteandthebanksstrippedofallremainingvegetation.

Inaddition,Atkinswasresponsibleforensuringtheprotectionoftheexistingfloraandfaunaonthesite.Phaseonehabitatsurveyswereundertakenaspartoftheenvironmentalimpactassessmentin2006,includingbirdandfishsurveys.Amajortranslocationofspecieswasundertakentosuitablereceptorsitesincludingaspecially-created1hectaresitejustoutsidethePark.Atkinstranslocated330commonlizards,100toadsand4,000smoothnewts.Inordertoprotectthefloraonthesite,Atkinsmaintaineda‘permittoclear’systemforcontractors,andspecifiedsafeguardedhabitatareasthatwerenottobetouchedincludingareasofsycamoretrees.

2ChoosingPlantstoPlant

Atkinsisresponsibleforthefinallookoftheriverbanksandwetlands-anddecidingwhattore-plantpresentedachallenge.Withbanksnowbare,newplantingwouldhavetofulfillnotonlyecologicalandaestheticdemands-they’dbeexpectedtobeinbloomfortheOlympicGames-butengineeringimperativestoo.

TheAtkinsdesignteamchosebioengineeringtechniques,ratherthanculvertingandhardengineering,fortheproject.Thatmeansprotectingandconsolidatingriverbanksbyusingvegetationandnaturalproductsinsteadofconcrete.Choosingtherightspecieswiththerightrootsystemswouldbecriticaltoprotectthebanksfromerosion.

Anaddedchallengewasthattherivernetworkissemi-tidal.Thetwice-dailyriseandfallofaround400mmhadthepotentialtoplayhavocwithnewplanting,andtheriver’shighsedimentloadsthreatenedtosmotheranythingplantedfromseedorplugs.“Wedon’tactuallyhaveanaturalriversystem,”notesMike.“Plantsdon’tcopwellinthoseconditions.”

Tofindoutwhichplantswouldfarebest-andtoestablishthemosteffectiveplantingmethods-Atkinsconductedauniqueriverbankplantingtrialalonga50-metrestretchoftheLeeintheOlympicPark.

“Wetrialledplantsofdifferentelevationsanddifferentinstallationtechniques.Theseweremonitoredoverayear,”saysIanMorrissey,seniorenvironmentalscientistwithAtkins.“That’sreallyhelpedtoinformexactlywhatspeciesweshouldplantandwhere.”

Thetrialrevealedthatplugplantswouldbejusttoovulnerable.Butplantspre-grownincoir-coconutfibrematting-resistedbeingwashedawayorswamped.Coirhasotherbenefitstoo-it’seasyandquicktoinstallinrollsandpalletstwometerslongandameterwide（Fig.03）.

“Thematitselfactslikeamulch,soyoupreventanyweedsgrowingupthroughitthatmightalreadybewithinthebankmaterial.Butmoreimportantly,whenthebanksbecomeinundated,yougetfinesedimenttrappedwithinthecoir.Thathelpstobindtherootsandfeedtheplants,”saysIan.

3BankingonTomorrow’sSeedlings

Creatingasustainableriverbankecosystemmeansusingnativespe