Restoration design for Three Gorges Reservoir shorelands_转转大师.doc

Contentslists available at Science DirectEcological Engineeringjournal homepage: /locate/ecolengRestoration design forThree Gorges Reservoir shorelands,combiningChinese traditional agro-ecological knowledge with landscapeEcological analysisChundiChen,ColinMeurk,JilongChen,MingquanLv,ZhaofeiWen,YiJiang,ShengjunWuKeyLaboratoryofReservoirAquaticEnvironment,ChongqingInstituteofGreenandIntelligentTechnology,ChineseAcademyofSciences,No.266FangzhengAvenue,ShuituTown,BeiBei,Chongqing,Chinaa r t i c l e i n f oa b s t r a c tArticlehistory:OneofthegreatestchallengesassociatedwiththeThreeGorgesDamandReservoiristhemassiveextentofthedrawdownzone,causingsoilerosion,lossofhabitats,andlandscapeaestheticdegradation.Throughtworoundsofeldandinterviewsurveys,wehavere-engagedwithtraditionalagro-ecologicalknowledgeasasourceofsolutionstothesechallenges.Amodiedpond-landterrace(MPLT)land/waterusesystemisproposedtomaximiseshorelandconservationandassociatedecosystemservicesbasedonlocalpracticesof paddy terrace and dike-sh pond farming. The MPLT system has a functional structure comprisingwater retention ponds atthe top, vegetation elds inthe middle, and the reservoir lake atthe bottom.Thedesignofthesystemisdescribed indetailinthisarticlebyreference totheWuyangBayinanurbanwetlandpark.Face-to-facequestionnairesurveyrevealedthatthecommunityholdsapositivewillingnessto participate in the MPLT project. Given signicant environmental uncertainties in this region, post-construction monitoring isrecommended foranextended periodinordertodetermine howitsbenetsmeetthepredictionsandfurtherinformadaptivemanagement andrenementofthesystem.Theresultsillustrate the value ofcombining modern ecological design with traditional land-based knowledge andcommunity engagement whenseekinginnovative, site-specic, andmultifunctional landscapesolutionstochanging environments.Received27October2013Receivedinrevisedform30May2014Accepted12July2014Availableonline23August2014Keywords:AdaptivemanagementThreeGorgesReservoirDrawdownzoneTraditionalecologicalknowledgeWetland2014ElsevierB.V.Allrightsreserved.1. IntroductionGreatopportunitiesexisttoimprovedrawdownzoneecosys-temperformance by application of ecological design andWaterlevelsoftheThreeGorgesReservoir(TGR)areoperatedbetween145mduringsummerand175mabovesealevelduringwinter.ThisisoppositetonaturalriveroodingrhythmsinChina.Ithascreatedacomplexandcompletelynewecosystemdrawdownzone surrounding the TGR, with a total area of 348.9km2 . Thelong, erratic water impoundments have brought environmentaland social challenges to local people, such as soil erosion, bio-diversity reduction, bio-invasion, loss of capacity for ltration ofnon-pointsourcepollutionfromtheuplands(Huang,2001;NewandXie,2008;Yuanetal.,2013),aswellaslossofculturalheritageandriverscapeaestheticssignicantforthetouristindustry.management (Mitsch et al., 2008; Yuan et al., 2013). Ecologicalapproaches embrace the notion of mediating human destructiveimpacts on the environment through working with natural pro-cesses (Van der Ryn and Cowan, 2007). They incorporate widerconsideration of physiography, climate, vegetation, wildlife, andtherebyencouragethedevelopmentofmultifunctionallandscapesthatdeliverecosystemservicesandpovertyalleviation(McHarg,1969;McNeelyandScherr,2003;NassauerandOpdam,2008).Human interactions with nature are often neglected in eco-logicalengineering.However,improvedhuman-ecologicaldesignmodelshavebeendevelopedtorecognisehuman-naturedepend-ency and “cultural cohesiveness” (Forman, 1995). The ways ofintegratingculturalconsiderationsarediverseandmanyprojectsareconductedlargelyonacasebycasebasis(Moshiaetal.,2008;Yahneretal.,1995).Theoverallprincipleisthatdesignneedstobeculturally sensitive: respect local values and knowledge through Correspondingauthor.Tel.:+8615922655809.E-mailaddress:(C.Chen)./10.1016/j.ecoleng.2014.07.0080925-8574/2014ElsevierB.V.Allrightsreserved.Ecological Engineering71(2014)584597C.Chenetal./EcologicalEngineering71(2014)584597585Fig.1. Conceptdiagramoftraditionaldike-shpondmodelfromsoutheastCegratingbio-physicalandsocio-culturalinventoryofthelocalenvironmentalhistoryandhistoricallandscapeuse(Ndubisi,2002;Steinitz,1990).hydrologicalconditions.Itisanticipatedthatitwillbeavaluablereferenceforcomparableareaswhichhavetheintentionofpro-motinglocalculture,ecologicalintegrityandlandscapeaestheticsagainstthebackgroundofrapidurbanisationandincreasinglycom-plex,dynamicenvironments.Traditional agro-ecological knowledge is a pivotal source ofinspirationformoresustainablesolutionstotodaysenvironmen-talproblems(Martinetal.,2010).Incorporatingsuchknowledgeintoeco-friendlylandmanagementhasrecentlybeenpractisedintheTGRregion(Willisonetal.,2012;Yuanetal.,2013).Forexam-ple,dike-pondengineeringbasedontraditionalmulberrydike-shpond,wasexperimentedwithinLaotudiBay,PengxiRiver,Kaixian(Lietal.,2011).Traditionally,themulberrytreesfeedsilkwormsforsericulture,andwastefromthesilkwormsandpoultryprovidesextrafoodforthesh,whiletheaccumulatedshwasteatthebot-tomofthepondisdredgedandusedasfertiliserforthemulberrytreesalongthedikes(Fig.1).Thisintegratedsystemmaximisestheuseoflandandwaterresources,recyclesnutrientsandcapturesenergywithinanoverallbalancedecosystem(RuddleandZhong,1988;Zhong,1982).Arecentvariantisemployedincoastallow-landstoovercomeseasonalinundationandsalinisation.Therethedikesareusuallycultivatedinarice-sugarcanerotationwithinter-polatedvegetables(RuddleandZhong,1988).Thisbringseconomicbenetstolocalpeopleinotherwiseunproductivecoastalland.Ourproposalforrehabilitatingthedrawdownzoneisamodiedpond-land terrace (MPLT) system based on hybridising long-established farming practices from southern China and modernecological restoration design analysis. It was applied to HanfengLake, which became the second largest urban lake in China as aresultofTGRformationwithinKaixian.Withitsuniquelandscapeandrichruralculture,ithasbeendesignatedanationalurbanwet-land park. One of the goals of the park is to use the drawdownlandwiselyandcombineenvironmentalprotectionandlandscapeaestheticstocreateamultifunctionallanduseexemplarforothersimilarlocations(ChongqingUniversity,2010).SomesectionsofthedrawdownzonearoundtheHanfengLake2. Methodology2.1. SitedescriptionKaixianofChongqingMunicipalityisanewtownrelocatedtohighergroundtomakewayfortheTGR.PengxiRiver,oneofthemost important primary tributaries and recharge sources of theYangtzeRiver,meandersthroughKaixianurbanareas(Fig.2).Tominimisetheadverseeffectsofdramaticseasonaloodingonthecity, a dam has been constructed on the Pengxi River and formsHanfengLake.Whenthedamisinuse,theHanfengLakeisoperatedaboveaminimumof170.28mduringsummer,bycontrasttheTGRfallsto145m.Duringwinter,bothTGRandHanfengLakeareheldat175m.Nevertheless,Kaixianhasadrawdownzoneof58km2 ,thelargestofanytown/countywithintheTGRcatchment.Theaffectedland is generally 220800m wide on each side (Zhang and Zhu,2005),ofwhich72%waspreviouslyusedforagriculture.HanfengLakeUrbanWetlandParkwasestablishedwithatotalarea of 13.03km2 and drawdown zone area of 3.74km2 , mainlysurrounded by urban and suburban land. The demonstrationproject (311055N, 1082745E) is being carried out betweenthe170.28mto179melevationsonWuyangBayofHanfengLake.The total project area is 1.6ha. Previous land uses were paddyfarming, cropping on the ats, and scattered forest which stillremainsonsteepslopes(Fig.2).Theregionhasanorthernsubtropicalhumidmonsoonalclimatewithanaverageannualprecipitationof1200mm,6080%concen-tratedbetweenAprilandSeptember.Themeanairtemperatureisarealreadyhardenedwithconcretetoprotecttheshorelinefromerosion1. Compared with such conventional riverscape practicesin China, our design is intended to demonstrate an optimised,ecologicallysoundshorelandmanagementthatisvisuallyandcul-turally desirable. From 2011 our interdisciplinary team began acomprehensiveinvestigationoflocallandmanagementpracticesand environmental variables such as topography, soil types and18.2C, and there are less than 20 frost days per year. The mainsoiltypesattheprojectsitearepaddysoil(below173m)andpur-plesoil.Subtropicalbroad-leavedevergreenforestistheregionalclimaxvegetation.2.2. Methods2.2.1. Data1 From Kaixian 2012 satellite aerial photography, we calculated that currentlyThisstudyused2002SPOTimagery(10mresolution)and2012high resolution (0.5m) satellite aerial photography to produceforsomeurbansectionsofHanfengLake,manicuredshorelinegreening(treesandowerbeds)accountsfor30%oftheshorelineplaza.586C.Chenetal./EcologicalEngineering71(2014)584597Fig.2. Location and illustrations ofdemonstrationsiteinWuyangBayonHanfengLakeofKaixian.digitallanduse/covermapsbeforeandafterreservoiroperation.Theimageswererectiedandgeo-referencedagainsta2010topo-graphicmap(1:2000).Landuse/covercategorieswerecreatedbythe object-based classication method in Envi 5.0 (Exelis VisualInformationSolutions,Boulder,CO,USA)andArcGIS10(ESRI,Red-lands,CA,USA)combinedwitheldsurveyandground-truthing.TheoverallanalysisframeworkisshowninFig.3.to Hanfeng park were randomly chosen for face-to-face inter-views.Wepresentedthemwith5digitalphotosshowingdifferentviews of the current status of the site and 5 showing the effectsofMPLTdevelopment,andaskedaboutacceptabilityofthedesignLocal agricultural/ecological treatmentfor sustainable landmanagementIdentify ecologicallysound and culturallydesirable land use modelField survey, face-toface interview2.2.2. SurveysontraditionalknowledgeandpeoplesattitudestowardsthedesignTraditionalfarmingknowledgeandpracticesrelatedtonaturalresourcemanagementwererevealedthrougheldobservationandhousehold-basedstructuredinterviewswithlocalpeople(BalramandDragicevic,2005;Farizoetal.,2014;JimandChen,2006).Therespondentslivingaroundthesitewereselectedandaskedabouttheir general economic status and agricultural practices, includ-ingtypesofcrops,poultryandhowtheyplant/rearthem(detailsseeSupplement).Fieldmeasurementclariedhowthetraditionalsystemswork.Forinstance,wemeasuredlessrunoffandsoilero-sion under a land preservation treatment (terraced slopes withstrawmulching)thanforslopeswithoutsuchtreatment.Wealsoworkedalongsidefarmersintheireldstodeepenourunderstand-ingofindigenousvaluesandpractices(Butler,2006;Pinto-CorreiaandKristensen,2013).Throughthisclosecollaborationwecouldtestourdesignideasandlearnwhatthefarmersconsideredtobepracticalanddesirable.Landscape ecologyprinciplesProvide overall spatialstructure guidelinesBio-physical analysisIdentify suitable sites fororganising various landuse demandsSurvey and GISanalysis: topography,hydrology, soil andvegetationAdaptive landscapemanagement strategiesAccommodateenvironmental uncertaintiesEstablish resilient, self-sustaining ecosystem evolving with changing environmentsAftercompletionofthedesigndraft,asecondsurveywascon-ducted. Aside from those farmers who were resurveyed, visitorsFig.3. Theframewor k used to developaresilient,self-sustainingecosystemfortheTGRshorelands.C.Chenetal./EcologicalEngineering71(2014)584597587(attitudes towards the MPLT system), and if they would be will-Table1Datausedforcalculationofrunofffromtheupland.ingtoparticipateinbuilding,managementandmaintenancethesystem(willingnesstohelp).Responseswererecordedonave-stepLikertscalefromhighlyapproveorwillingtodisagreementorunwilling(JimandChen,2006).DataSourceExplanation/analysisLanduse/cover2012Highresolution(0.5m)satelliteaerialphotographyofKaixianfromChongqingPublicServicePlatformforGeographicTheclassicationincludes:1.Ruralresidentialareas;2.Roads(urbanandrural);3.Exuberantforestland;4.Sparseforestland;5.Cropland;6.Vegetableland;7.Paddyelds;8.Ponds;9.OrchardsDerivedfrom2.2.3. LandscapeecologyprinciplesLandscape ecology provides spatially explicit models thatconnect conguration with ecological functions and processeson a range of scales (Forman, 1995; Turner et al., 2001). Thepatchcorridormatrix model proposed by Forman (1995) is thewidelyacceptedspatialnormforcreatingnetworksthatmaintainecosystemstabilityandintegrity(Opdametal.,2006;Tayloretal.,1993).Patchesarethebasicunitofthelandscapethatregulateuxesofmatterandenergyinanecosystem,aprocesscalledpatchdynam-ics(Forman,1995).Thecharacteristicsofnaturalpatches(e.g.size,shape,locationandspeciescomposition)arecriticaltonaturecon-servation as they may preserve endemic or unique habitats, andprovide“steppingstones”thatfacilitatespeciesdispersal(SauraandRubio,2010;Shafer,1990).Inthisexercise,wefocusonthepreservingpatchesofremnantnativevegetationtoforma“nativebushpatchroadcorridorrestoredterracevegetationmatrix”networktostrengthentherestorationefforts.InformationDEMChongqingKaixianCountyLandandResourcesAuthorityChongqingKaixianCountyLandandResourcesAuthorityKaixianHualinHydro-meteorologicalStationtopographicmaponthescale1:2000Thescaleis1:2000SoiltypeanddistributionPrecipitation19992011monthlyprecipitation(mm)thancumulativeaverageannualrunoff.Si ispotentialmaximumretentionorinltration(mm)foraparticularlandusetypei.ItiscaculatedbytheformofadimensionlessrunoffCurveNumber(CN).CNisthekeyparameterdeterminedbysoilantecedentmoisturecondition (AMC), soil type, land use/cover, rainfall duration andintensity(seeSupplement).EachlandusetypeihasitsownCNiandvaluesrangefrom0to100(USDA,SCS,1972).2.2.4. Bio-physicalanalysisFourmainbio-physicalfactors(topography,soil,hydrologyandvegetation)wereinvestigated.Basedonadigitalelevationmodel(DEM),thesitetopographywasanalysedbySpatialAnalystToolsinArcGIS10(seeSupplement).Fivetosixsoilsamplesfromeachmetreelevationwerecollectedinsummer2012atadepthof30cm.ThepHwasmeasuredina1:2soilwaterslurrywithaglasselec-trodepHmeter.SeveraltransectsurveysoforisticcompositionandstructurewerecarriedoutaroundHanfengLakeandPengxiRiver(Chenetal.,2014).Itwasexpectedthatthesurvivingplants,afterseveralfullcyclesofwateructuation,wouldformcomparativelystablecom-munitiesasaresultofnaturalselection(seeSupplement).Runoff and soil erosion from the upland inuent catchmentwere calculated to determine required pond dimensions for theMPLTsystem.. Soilerosioncalculation. WeestimatedtheannualaveragesedimentyieldusingtheworldwideappliedRUSLEmodel(RevisedUniversalSoilLossEquation)describedinEq.(2)(WischmeierandSmith,1978).A=RKLSCP(2)S=AArsdrwhereSisthetotalsoillossofthewholeareaAroftheinuentcatchment. sdr is the sediment delivery ratio. A is the spatialaverage soil loss per unit area over a selected period, usuallyon a yearly basis (tha1yr1); R is the rainfall erosivity factor. Runoff calculation. The widely used Soil ConservationService model (SCS) was applied to estimate runoff from theinuentcatchment(USDA,SCS,1972;Zhengetal.,2008).Thedataused,itssourceandtypeofanalysisarelistedinTable1.TheSCSmodelisdenedinEq.(1).in units (MJmmha1h1yr1); K is the soil erodability factor(thMJ1mm1); L is the slope length factor (dimensionless), Sis the steepness factor (dimensionless); C is the cover and man-agementfactor(dimensionless,rangingbetween0and1.5);andP is the erosion control (conservation support) practices factor(dimensionless, ranging between 0 and 1). All required data arelisted in Table 1. Each factor was extracted and calculated inArcGIS10.Q = (P0.2Si)2(P0.2Si)(1)iP+0.8SiQi=0 (P0.2Si)25,400. Water level uctuation analysis. Since the Hanfeng LakeDam is not yet fully operational, the current water level uctu-ation is different from the future regime. Many relevant studieson this particular area have generally adopted the water lev-els recorded from the TGR Hydro-meteorological Station whichdirectly observes the water levels at the TGR Dam (Johnson andRainey, 2012; Li et al., 2011; Wang et al., 2012a). We used the1D hydrodynamic model to estimate Pengxi River water levelsand calculated the inundation duration (the model applicationreferstoLietal.,2012b).Themodelusesthe1:2000topographicmap of Pengxi River, daily water levels and volume of the TGR(HoY, 2012) and Wanzhou stations (CQWRB 2012) from 2011 to2012.Si=254CNinR=QiLii=1whereRistherunoffyield(m3).Qiisrunoffdepth(mm)forlandusetypei.Liistheareaoflandusetypei.Pistheprecipitation,assumingauniformdepthofprecipitationacrosstheinuentcatchment.Wecalculatedthestoragecapacityofwater-harvestingpondsfora10-yearstormevent(1999to2011)withoutoverbankoodingrather588C.Chenetal./EcologicalEngineering71(2014)5845973. ResultsanddesignstrategiesPlanning/design phase3.1. Localagro-ecologicalknowledgeInterdisciplinary teamEvaluate water quality baselineAlternative plantsAmong62households,atotalof156localpeoplewereinter-viewed,mainlycomprisingeldersandwomenremainingathome.15%areilliterate;69%havehadaprimaryeducationonlyandtheremaining have received secondary education. 82.7% have smallfarmswhile17.3%havenon-intensiveeldcropsforself-supply.Femalerespondents(59%)exceededmales.Theseniorgroup(60years old) with 42.3% outnumbered the 4059 (34%) and 2039group (23.7%). The majority of respondents (86.5%) have beenresident in Kaixian for several generations, while some are emi-grants from surrounding towns/villages through marriage. WesummarisedtheirfarmingpracticesinTable2.Becausehillsarepronetorapidsurfacerunoffduringthesum-mermonsoo