Assessingthecosteffectivenessofthewaterpurificatio

Assessingthecost-effectivenessofthewaterpurificationfunctionofwetlandsforenvironmentalplanningMichaelTrepel*Schleswig-HolsteinStateAgencyforAgriculture,EnvironmentandRuralAreas,DepartmentofWaterManagement,HamburgerChaussee25,D-24220Flintbek,Germany1.IntroductionProvidingsocietywithcleanandhealthywaterbelongstothechallengesforthenextdecadestomeetthedemandsbothofhumansandecosystems(MillenniumEcosystemAssessment,2005).Actionstoimprovewaterqualitycanbetakenduringallstagesofwaterflowthroughthelandscape.Cost-efficientstrategiesforwaterqualitymanagementaimonareductionofquantitativelyimportantinputsofharmfulsubstancesaswellasonenhancingthetransformationandretentioncapacityinthelandscape(Kronvangetal.,2005;TrepelandPalmeri,2002).Fornutrients,quantitativelyimportantinflowstothewatersystemoriginatefromdiffusesourcesandpointsources.Ontheothersidelakes,riversandwetlandsarelandscapeelementswithahighnutrienttransformationandretentionpotential(VerhoevenandMeuleman,1999;FisherandAcreman,2004).Quantifyingtheservicestheseecosystemsprovideforsocietyisgainingmoreattentioninenvironmentaldecisionmaking(Turneretal.,2008).ThepressuretoimprovewaterqualityofgroundwaterandsurfacewaterbodieshasincreasedinEuropesincetheEuropeWaterFrameworkDirective(WFD)cameintoforceinDecember2000.TheecologicalaimsoftheWFDcanonlybeachievedifthenutrientloadstosurfaceandcoastalwaterbodiesarereducedsignificantly.Toachievethisenvironmentalgoalpolicyhastodevelopmanagementstrategiesfornutrientloadreductionfordifferentsectors(Turneretal.,1999).Foreachsectormeasureshavetobedeveloped,theireffecteitheronreductionofnutrientinputsoronimprovedretentionassessedandtheircostscalculated.Thesedataandinformationareneededbypolicyanddecisionmakerstoimplementdifferentcost-effectivewatermanagementstrategiesfornutrientloadreduction.Forthispurposeinthispaper,theeffectsofimprovedwastewatertreatmentonnutrientloadreductionarecomparedwitheffectsofwetlandrestorationonimprovednitrogenretention.Thecost-effectivenessisusedasanecological–economicalindicatortocompareandevaluatebothstrategies.Itiscalculatedforbothstrategiesindependentlyduetodifferentdataavailabilitywithtwodifferentapproaches.Theseecological–economicaldataareneededtoapplyandimprovetheconceptofecosystemservicesEcologicalComplexity7(2010)320–326ARTICLEINFOArticlehistory:Received6January2009Receivedinrevisedform25November2009Accepted8February2010Availableonline6March2010Keywords:Cost-effectivenessEcosystemservicesWastewateractionplanWaterframeworkdirectiveWetlandrestorationABSTRACTAreductionofnutrientinputintofreshwaterandmarinewaterbodiesisaprerequisitefortherestorationofhealthyaquaticecosystemsandfortheachievementoftheambitiousgoalsoftheEuropeanWaterFrameworkDirectiveandtheHELCOMandOSPARconvention.InNorthernGermany,phosphorusinputsfrompointsourceswerereducedbynearlytwo-thirdscomparedtothephosphorusloadintheperiod1980–1985.Thissuccesswasmadepossiblebytheinvestmentof2.1billionssince1985inthedevelopmentandenhancementofwastewatertreatmentplants.However,theseinvestmentshadonlylittleeffectonnitrogeninputs,whichenterwaterbodiesmainlyfromnon-pointsources.In2002,thefederalstateSchleswig-Holsteinimplementedapeatlandrehabilitationprogramaimingtorestorethewaterpurificationfunctionofthiswetlandtype.Therationaleofthisplanisbasedonaneconomicalanalysisoftheeffectsoftheinvestmentsinthewastewateractionplan.AreductionofthePloadby1kghasmeancostsbetween70and100s.Basedonmodelcalculation,restoringwetlandsforwaterqualitypurificationwillcostbetween1and50sperretainedkgofnitrogenwhenconsideringa10-yeartimespan.Comparedtothewastewateractionplan,wetlandrestorationisalsoacost-efficientstrategyfornutrientloadreduction.For10%oftheinvestmentsofthewastewateractionplan,thenitrogenloadfromSchleswig-Holsteincanbereducedby10%;thiswillrequirerewettingof20,000haofwetlands.TheimplementationofthisstrategyaswellastheapplicationoftheconceptofecosystemservicesinenvironmentalmanagementiscurrentlylimitedbyalackofpoliticalsupportandfundingforsuchprojectsfromhigherpoliticalbodiessuchastheEuropeanUnion.2010ElsevierB.V.Allrightsreserved.*Tel.:[phone];fax:[phone].E-mailaddresses:[e-mail],[e-mail]ScienceDirectEcologicalComplexityjournalhomepage:–seefrontmatter2010ElsevierB.V.Allrightsreserved.doi:10.1016/j.ecocom.2010.02.006inenvironmentalplanningandtomakeitausefultoolforresponsiblemanagementofnaturalresources.Thispaperespeciallyintroducesanewmethodforthemodel-basedquantificationofecosystemservicesprovidedbywetlandsforwaterpurificationandimprovesunderstandinghowhumanactivitiescancontroltheseservices.Furthermoreitoffersexampleshowscientificknowledgeonwaterandnutrientexchangeinwetlandscanbetransformedforcommunicationtodecisionmakersinenvironmentalplanning.2.MethodsThispaperevaluatesthecost-effectivenessoftwowatermanagementstrategiesfornutrientloadreductioninthestateofSchleswig-Holstein,Germany.Cost-effectiveness(CE:skg1t1)isdefinedasthecosts(C:s)requiredachievingaloadred