1 ResidentialAccess toPublicGreenSpacein Denver-Aurora-Lakewood GeographicDataScience(A:SpatialAnalysis) ZacharyElliott BAGeographyFHS2022
2 Map1 SatelliteImageryofDenver, Colorado[21]
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1.Introduction
PublicGreenSpaceisanincreasinglypopularupstreamhealthpromotioninterventionthatis beingimplementedincitiesacrosstheglobe(Malleretal.,2006;Hartigetal.,2014; Markevychetal.,2017).Thisisbecauseaccesstopublicgreenspacehasbeenlinkedto improvedphysicalhealth(Hartigetal.,2014),lessstressindeprivedcommunities(Ward Thompsonetal.,2012),increasedmentalwellbeing(Fulleretal.,2007),coolerclimates (Bowleretal.,2010),andgreaterbiodiversity(BolundandHunhammar,1999).
1.1.StructureoftheReport
However,greenspaceisnotevenlydistributedincitiesacrosstheglobe,andonlybenefitsthose whocanandwanttoaccessitwithinashortwalkfromtheirhomes(Burgessetal.,1988;Wang etal.,2015).Futuregreenspaceinvestmentsshouldbetargetedsothattheybenefitthemost deprivedandunderservedcommunitiesfirst,especiallycommunitiesthathavebeen systematicallydisinvestedinanddeprivedofpublicgreenspace(Malleretal.,2006;Wolchet al.,2014).Accesstogreenspaceisasocialjusticeissuebecauseitisavitaldeterminantof goodhealth(Malleretal.,2006).Anditisvitaltoinvestininfrastructurewhereitsupportsthe mostdisadvantagedcommunitiesthemost,astrickle-downdevelopmentfrominvestmentin 'favoured'neighbourhoodsdoesnotworkinpractice(Mahmoudietal.,2020).Theemphasis onpublicgreenspaceisvitalhere,asnoteveryonehasaccesstohigh-qualityprivategreen space,suchasingardens,andprivategardensarenotsubstitutesfornearbypublicgreen spaces(Farahanietal.,2018).
Section2surveystheliteratureonthebenefitsofgreenspaceandtheimportanceofhaving accessiblegreenspaceclosetopeople’shomesforurbanhealthandwellbeing.Section3then exploresgreenspaceinthecontextofDenver-Aurora-Lakewood.Section4outlinesthe methodsemployed,whileresultsarepresentedanddiscussedinSection5.Section6concludes.
ImagebyRobertKash-https://www.flickr.com/photos/mkoneeye/8438474948,CCBY2.0,https://commons.wikimedia.org/w/index.php?curid=47924803
Residentialgreenspacecanalsobuildcapacitiesthroughtwomechanisms.Firstly,greenspace canencouragephysicalactivity,asasafe,accessible,andattractivesettingtodoexercise(Lee
4 2.LiteratureReview 2.1.Thebenefitsofgreenspace
Residentialgreenspacedirectlyreducesharmtohealththroughthreemechanisms.Firstly,trees, shrubsandvegetationaffectambientairqualityandreduceexposuretoairpollutionthrough gaseousuptakebyleafstomata,depositionofPMonleaves/plantsurfaces,andthephysical blockingofthedispersaloftrafficpollutionfromnearbyroadcorridors(WardThompsonetal., 2012;Markevychetal.,2017).However,treesandplantscanalsoaggravateallergiesby releasingpollen(WardThompsonetal.,2012).Secondly,greenspacescooltheenvironment aroundthemthroughprocessesofevapotranspirationandasplantingsprovideshadecover, helpingtomitigatetheurbanheatislandeffect,andreducenearbyresidents’exposuretoheat (Bowleretal.,2010;Ngetal.,2012;Markevychetal.,2017).Thiseffectcanbesubstantial,as Bowleretal.’s(2012)meta-analysisofurbangreeninginterventionsfoundthatparksare,on average,0.94Ccoolerthannon-greensitesduringtheday.And,thirdly,thesetting-backof greenspacesfromroadsandthepresenceofdenseplantingsreduceexposuretonoiseand bufferstressresponsestotrafficnoise(Markevychetal.,2017).Theseeffectsallvarywith differenttypesofgreenspace,vegetation,andspatialconfigurations(Markevychetal.,2017). Greenspacealsorestorescapacities,asviewinggreenspacecanevokepositiveemotionsthat blocknegativethoughts.Theycanalsoholdaperson’sattentionwithouteffort,enablingtherest ofneurocognitivemechanisms,andrestoringcapacitiestoexercisedirectedattention(Kaplanet al.,1998;Markevychetal.,2017).Contactwithnaturethroughviewingandbeinginnatural environmentsisanaffordablewaytotackleagrowingmentalhealthepidemic,ascontactwith greeneryandwildlifehasbeenlinkedtoreducedbloodpressure,improvedmood,andlower levelsofperceivedstress(Chiesura,2004;Malleretal.,2006;WardThompsonetal.,2012).
‘Contactwithnature’andaccesstogreenspacehavebeenidentifiedaseffectiveupstream healthpromotioninterventionsforurbanpopulations(Malleretal.,2006).Althoughaccessto greenspaceandcontactwithnaturehavesmalleffectsonindividualhealthandwellbeing comparedtostructuralfactors(e.g.income,employment,education),theeffectof‘contactwith nature’iscumulative(Hartigetal.,2014).Asmalleffectonalargenumberofpeoplecreates largeimpactsonpopulationhealth(Hartigetal.,2014).Beneficiallinksbetweengreenspace andhealtharealsostrongestinmoredeprivedneighbourhoodsandforthosewithlowsocioeconomicstatus(Wangetal.,2015;Markevychetal.,2017).Greenspacenearresidential propertiesbenefitshealththroughthreeinteractingpathwaysidentifiedbyMarkevychetal. (2017):reducingharm,restoringcapacities,andbuildingcapacities.
Andincreasedlevelsofgreenspaceisassociatedwithlowerlevelsofstressanddiurnalcortisol levels(WardThompsonetal.,2012).Naturalareasandgreenspacescanreduceexposureto stressorsbycreatingdistancefrom,andreducingperceptionof,stressorsbycreatingasenseof privacyandtranquillitywithinthecity(Fulleretal.,2007;Hartigetal.,2014).Therestorative propertiesofurbangreenerymeanthatvisitingurbangreenspacecanreducetheriskof chronicstressandattentionalfatigue(Hartigetal.,2014).
2.2.Theimportanceofaccessiblegreenspace Itisimportanttoaccommodatenearbygreenspacewhendesigningnewresidential developmentsandredevelopingurbanareasbecausestresscanbereducedthroughmany minorepisodesofcontactwithnatureandurbangreenspaceneednotnecessarilybe spectacularorexpensivetobebeneficial(WardThompsonetal.,2012;Hartigetal.,2014).
3.StudyAreaandContext
TheDenver–Aurora–LakewoodConurbation(Maps1&2)inColorado,USA,wasselectedas thestudyareaforthisextendedprojectbecauseoftworeasons.Firstly,theconurbationhasa legacyofenvironmentalracismandredlining,whereinvestmentinstreettreesandcityparksin theurbanareahasbeendisproportionatelyconcentratedinwealthy,whiteneighbourhoods (Penney,2020).Analysisofspatialinequalitiesinaccesstogreenspace,andwhichareasof Denver-Aurora-Lakewoodaremostunderservedbymacro-scalepublicgreenspacefacilities, canhelptoinformfuturegreenspaceinvestmentsintheconurbation.And,secondly,DenverAurora-Lakewoodisanareawithhighquality,highlyavailable,andpubliclyaccessible datasetsthatcanbereadilymobilisedforgeospatialanalysis.
5 andMaheswaran,2011;Markevychetal.,2017).Exercisedoneinurbangreenspacesmay alsohavegreaterpsychologicalandphysiologicalbenefitsthaninothersettings(Hartigetal., 2014;Markevychetal.,2017).Greenspacecanalsocreateasettingforcontactwith neighbours,improvingneighbourhoodsocialcohesion(asensethatpeopleknowandtrust eachother),withhealthandwell-beingbenefits(Markevychetal.,2017).However,these benefitsonlyimprovethehealthofurbanresidentsiftheywantto,can,anddoaccess,visit,and usegreenspaces(Kaplanetal.,1998;Jamesetal.,2015;Markevychetal.,2017).
Weavinggreenspacethroughoutthecityinthiswayalsoreducestheriskofurbangreening resultingin‘greengentrification’,asaccesstonaturebecomesdistributedinmoresociallyjust ways,ratherthanconcentratedasfocalpointsforgentrification,landspeculation,andproperty development(Wolchetal.,2014;Mahmoudietal.,2020).
Peoplebenefitmorefromgreenspaceswhentheyvisitthemmoreregularly,andpeoplevisit greenspacesmoreregularlywhentheyareperceivedasbeingclosetowheretheyliveandas offeringenjoyableexperiences(BradleyandMillward,1986;Burgessetal.,1988;Kaplanet al.,1998;Wolchetal.,2014).
Denver-Aurora-Lakewood’surbanplannersandpolicymakersarecurrentlyengagedina large-scalepushtocorrectalonghistoryofdiscriminatoryurbanplanningpracticeanduneven distributionofaccessibleurbangreenspace(NCRC,2018;Penney,2020).However,despite therhetoric,urbanplanningofficialsintheconurbationarestillinvestingmoremoneyinstreet treesandurbanparksin‘favoured’downtownbusinessdistrictsandwealthyneighbourhoods thaninpoorerneighbourhoods(Penney,2020).Thisextendedprojectactsasavitalcheckpoint toestablishwhichpartsofDenver-Aurora-Lakewoodaremostinneedofnewgreenspaces withinashortwalkingdistanceofresidentialaddressesandwhichpartsofDenver-AuroraLakewoodarecurrentlywellservedbypublicmacro-scalegreenspaceservices.
6 Map2 MapoftheDenver-AuroraLakewoodMetropolitanArea[19]
4.Methods
Toanswertheseresearchquestions,thisextendedprojectperformsGISspatialanalysis techniquesinESRI’sArcGISProsoftwarepackage.Theoverallapproachisexplainedand interrogatedinthissectionandtechnicaldetailsareelaboratedinanAppendix. ToidentifywhichareasofDenver-Aurora-Lakewoodhavethebestandworstprovisionof greenspaceswithina10-minutewalkofresidentialaddresses,anetworkmodelwasbuiltusing OpenStreetMap(OSM)RoadandPathlinedatatocomputeserviceareasforallentrancesto urbangreenspaces(parksandnaturereserves)inDenver-Aurora-Lakewood.Theseservice areawalking-shedswerethenusedtoassignthetimetakentowalktoanurbanparkentrance toeachresidentialaddressinDenver-Aurora-Lakewood.Thisdatawasgeneralisedtothe CensusBlockGrouplevel,asaproportionofresidentialaddressesineachblockgroupthatcan accessaparkwithina10-minutewalkingdistance.Thiswascomparedwithsocio-economic andenvironmentaldatatomakesubjectivejudgementsonwhereinDenver-Aurora-Lakewood ismostinneedofmacro-scalegreenspaceinterventions.A10-minutewalkingdistance(halfa mile)isgenerallyconsideredtobethefurthestpeoplearewillingtoregularlywalktoaccessa greenspace(Wolchetal.,2005;Booneetal.,2009;Rigolon,2017).
Itiswiththiscriticalmotivationandcommitmenttosocialjusticethatthisextendedprojectasks: “whichareasofDenver-Aurora-Lakewoodhavethebestandworstprovisionof greenspaceswithina10-minutewalkofresidentialaddresses?” and,relatedly, “whereinDenver-Aurora-Lakewoodisinmostneedofmacro-scalegreenspace interventions”?Greenspacesaredefinedasformalparksandnaturereserves,macro-scale greenspaceinterventionsthatactasdestinationsforurbanitestohavecontactwithnature.
4.1.OverallApproach
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Thisisacountermappingpracticethatmobilisesgeospatialtechniquestoraisequestionsabout andpromptdiscussionovervitalissuesofurbanjustice(Wolchetal.,2005;Booneetal., 2009;MaharawalandMcElroy,2018).Thisisespeciallysalientgiventhelong-standingand continuedenvironmentaldiscriminationagainstpeopleofcolourandworkingclass communitiesbyurbanplannersandpolicymakersintheUnitedStates(Wolchetal.,2005; Booneetal.,2009),especiallyincitieswithahistoryofredlining,suchasDenver(NCRC, 2018;Penney,2020).Asfarastheauthorisaware,analysingaccesstogreenspaceforall residentialaddressesintheDenver-Aurora-Lakewoodconurbationusingatopological proximitymodelratherthanametricproximitymodelhasnotbeenundertakenbefore.Theonly similarstudiesofgreenspaceaccessintheDenverMetropolitanAreathattheauthorisaware ofuseametricproximityapproach(Baldwin,2020)ordonotincludeAuroraandLakewood, excludingmanylower-incomesuburbanareasintheDenver-Aurora-Lakewoodconurbation (Rigolon,2017).
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Figure1 Usingastraight-lineradiusapproach,the walkingdistancebetweenHouseBandthe parkistreatedasshorterthanthedistance betweenHouseAandthepark.Thenetwork modelapproachmorecloselyemulatesthe realityofsuburbanareas,whereittakes muchlongertowalkfromHouseBtothe parkthanfromHouseAtotheparkbecause theparkuserlivinginHouseBmustexittheir housingestate,walkalongthesidewalk alongamajorroad,andthenwalkalong HouseA’sroadinordertoaccessthepark.
Thenetworkapproachtocalculatingtheserviceareasofurbangreenspaceswasselectedover astraight-lineradiusapproach.Astraight-lineradius,orbuffer,approachtocalculatingthe serviceareasofurbanparksdoesnotconsiderthepositionsofapark’spoint(s)ofaccessand doesnotrealisticallyaccountfortherealdistancetakenbyparkuserstoaccessapark,asit assumesthatmovementisfreeandpossibleinalldirections(Figure1).Anetworkapproach morecloselyemulatestheactualroutesthatusersarelikelytofollowbetweenresidential addressesandpointsofaccesstourbanparksbymeasuringdistancealongroadsandpublic rightsofwaytoparksratherthaninastraightline(Nicholls,2001).Figure1makesthisclear. RatherthanundertakingsuitabilityanalysistoidentifywhichareasinDenver-AuroraLakewoodaremostinneedofmacro-scalegreenspaceinterventions,individualmapsforeach socio-economicandenvironmentalindicatorwerevisuallycomparedwithvisualisationsof residentialpropertyaccesstourbangreenspacewithina10-minutewalkingdistance.This approachwasselectedbecausejudgementsofsuitabilityareintrinsicallysubjectiveandthe placesinDenver-Aurora-Lakewooddeemedtobemostinneedofgreenspacesvary dependingonthesocio-economicandenvironmentalindicesusedtomakeajudgement.
5.1.Currentgreenspaceprovision
However,despitetheselimitations,theresultspresentedbythisreportstillindicatethebroad contoursofunevenaccesstoandprovisionofgreenspacesintheDenver-Aurora-Lakewood conurbation.Thisiswhatthisreportnowturnstoconsider. 5.ResultsandDiscussion
Thisanalyticalapproachhasatleastthreemainlimitations.
Secondly,thisanalysisdoesnotaccountforinformalgreenspaces,anddependsonparks beingidentifiedonOSM.BecauseOSMisacommunity-made,open-sourcerepositoryof geospatialinformation,itdoes,however,containmoreinformalgreenspacesthanmunicipal datasetsavailablefortheDenver-Aurora-Lakewoodarea.
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4.2.Limitations
Firstly,thenetworkmodel,duetoinconsistentlevelsofdetailintheOSMDataset[15],assumes thatsomeresidentialstreetsandquieterroadshavesidewalks,whenthisisnotalwaysthecase. Italsoassumesthatpeopleareequallywillingtowalkthroughallenvironmentstoaccessan urbanpark,ignoringperceptionsofsafetyandcomfort.Itisalsoassumedthatpeopleonly walkonmappedpaths,whenthisisnotthecaseinreality,asnotallpathsaremappedon OSM,andpeopledonotalwaysfollowformalpathways.
And,thirdly,parkaccessalonemaynotcapturegreenspace’simpactsonphysicalactivity, healthorobesity,asrealisedusageofaparkdependsonthepark'scharacteristicsandthe activitiesavailable(Wolch etal.,2014).Notallparksarethesame,andjustbecausepeople livenearnaturalspaces,viewnature,orvisitthemdoesn'tmeanthattheyhavecontactwith naturethatimprovestheirhealth (Hartig etal.,2014).Asremotesensingapproachesdonotfully captureperceivedgreenspace,theuseofeye-levelpanoramicimageryispreferredtoevaluate howmuchgreenspaceisineachurbanpark.Machinelearninganalysisofeye-level panoramicimagerywasdeemedbeyondthefeasiblescopeofthisextendedproject (Jiang etal., 2017).
Maps4to6demonstratehowurbanparksareconcentratedincertain,‘favoured’ neighbourhoodsforgreenspaceinvestmentintheDenver-Aurora-Lakewoodconurbation. DowntownDenver,neighbourhoodsintheSouthoftheconurbation(HighlandsRanch,Acres Green,LoneTree,Parker,DoveValley,Sheridan,andDakotaRidge),andcitiesintheNorthof theconurbation(Thornton,Northglenn,Broomfield,Arvada)havemoreresidentialproperties within10-minutewalkingdistancesofgreenspaceaccesspoints.Intheseneighbourhoods, oftenover30%ofresidentialpropertiesinblockgroupshaveaparkwithina10minutewalkingdistance(Maps5&6).
10 Map3 MapofNDVI[22]
11 Map4 MapofParkAreaasproportion ofBlockGrouparea
12 Map5 Walk-shedsforgreenspacepoints ofaccess
13 Map6 Theproportionofresidential propertiesineachBlockGroup thatcanreachagreenspace accesspointwithina10-minute walkingdistance
14 Map7 HouseholdincomebyBlock Group[18]
15 Map8 TheproportionofBlockGroup populationsmadeupbyWhite populations
Furthermore,theparkqualityinNorthDenverandAuroraislikelymuchlowerthaninother partsofthecity,asNDVIintheseneighbourhoodsislow(Map3)andparklandformsavery smallproportionoftotalblockgrouparea(Map4).
However,thelevelofgreenspaceprovisionisnotnecessarilycommensuratewithincome. Predominantlywhiteneighbourhoodswithveryhighlevelsofhouseholdincome(morethan $160,000/year),likeCherryPinesVillageandCastlePinesVillageintheSouthofthe conurbation(Maps7&8),haveverypoorpublicgreenspaceprovisionwithina10-minute walkingdistanceofresidentialaddresses(Maps5&6).Yet,theseareashavehighNDVIvalues (Map3),indicativeofhighlevelsofvegetationcover.Thisparadoxisbecauseareaslike CherryPinesVillageandCastlePinesVillageareorganisedaroundprivate,ratherthanpublic, greenspaces,suchaslargeprivategardensandgolfcourses(Map1).
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Thisanalysistellsusatleastthreethings.Firstly,greenspaceprovisionintheDenver-AuroraLakewoodconurbationcontinuestobehighlystratifiedalongaxesofraceandincome,with lower-incomeandpredominantlyBlackandLatinoneighbourhoodsinAuroraandNorth Denverparticularlypoorlyservedbypublicgreenspaces,withlessthan10%ofresidential propertiesbeingabletoaccessaparkwithina10-minutewalkofhomeinmanycases(Maps 5-8).Thisisalegacyofsystematicdisinvestmentintheseneighbourhoods.And,secondly,when theseparks do exist,theyarelikelypoorqualityandsmallinsize(Maps3&4).Finally,itis importanttocontextualisemetricsofgreenspaceaccessibilitywithsocioeconomicdata,as predominantlywhiteandwealthyneighbourhoodsinDenver-Aurora-Lakewoodhavepoor accesstopublicgreenspace,substitutedbyhighlevelsofaccesstoprivategreenspaces(Maps 1,3,5&6). 5.2.Recommendationsforfuturegreenspaceinvestment Contrastingmetricsofparkaccessibilityandparkquality(Maps1,3-6)withsocio-economic andenvironmentaldata(Map7-12)allowsustobegintoconsiderwhichareasofDenverAurora-Lakewoodshouldbeprioritisedforfuturegreenspaceinvestmentsandpublicpark programmes.
GreenspaceprovisionisespeciallystratifiedalonglinesofincomeinAurora,towardstheEast oftheconurbation,andtowardstheNorthofDenverCity,whereBlackandLatino neighbourhoodsareconcentrated(Map8),andwheretherearelowlevelsofmedian householdincome(lessthan$48,000/year)inmanyblockgroups(Map7).Blockgroupsin Aurora,particularlytowardstheNorthandSouth,aresopoorlyservedbypublicgreenspaces thatlessthan10%ofresidentialpropertiescanaccessaparkwithina10-minutewalk(Map6).
17 Map9 Heatseverityin2021.Darkred areasexperiencethehighest levelsofsevereheat[16]
18 Map10 Roadandaviationtransportation noise.Yellowandorangeareas havehigherlevelsofnoise pollution[20]
19 Map11 Averageparticulatematter pollutionlevelsintheDenverAurora-Lakewoodconurbation from1998-2016[13]
20 Map12 PopulationdensitybyBlock GroupfortheDenver-AuroraLakewoodmetropolitanarea[11]
Firstly,NorthDenverexperienceshighlevelsofHeatSeverityinalmostallneighbourhoods, whileotherneighbourhoodshaveonlypatchesofheatseverity,evenifmoreextreme(Map9). Thismeansthatthereisalmostnospacetoseekrespitefromtheheatforresidentsinthese neighbourhoods.Secondly,bothAuroraandNorthDenverexperienceveryhighlevelsof transportationnoise(Map10)relativetotherestoftheconurbation,ashighwaysrunpastand throughmanylower-income,Black,andLatinoneighbourhoodsintheurbanarea.Thesenoise inequalitiesareaproductofsystematicallocationofdisposabilityalonglinesofraceand incomethatcharacterisesmuchofAmerica’spost-warfreewayplanning.And,finally,North DenverandAuroraexperiencehigherlevelsofpollutionthansomeofthewealthiersuburbsin theSouthofthecity(Map11),inpartbecausemorecarsandhighwaysrunthroughthese neighbourhoodsthaninotherpartsoftheconurbation(Map10).
Accesstogreenspaceisasocialjusticeissueasitisavitalingredienttogoodhealth(Malleret al.,2006).
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TheintroductionofnewurbangreenspacesinNorthDenverandAuroracouldworktomitigate andcounteractthediscriminatorygreenspaceplanningandenvironmentalracismthat continuestoaffectthelivesofpeopleintheseneighbourhoodstoday(Holifield,2001;Penney, 2020).Thisisbecausegreenspacesreduceharmstohealthbycoolingtheneighbourhoods aroundthemandbyofferingasanctuaryfromthenoiseandpollutionofthecitytothe urbaniteswhousethem.Theseinterventionswillbeespeciallyimpactfulbecausehighnumbers ofpeopleliveinNorthDenverandAurora(Map12).
6.Conclusion
Throughcounter-mappingpractices,thisextendedprojecthasdemonstratedthataccessto publicgreenspaceandgreenspaceprovisionisstillstratifiedintheDenver-Aurora-Lakewood conurbationinColorado.Areaswiththebestandworstprovisionofgreenspaceswithina10minutewalkofresidentialpropertieshavebeenidentified,andrecommendationsputforward. Thegeospatialanalysisofthisreportsuggeststhatgreenspaceinvestmentsshouldbeurgently consideredinAuroraandNorthDenvertocorrectsystematicandracialiseddisinvestmentin theseneighbourhoods’publicservicesthroughpracticesofredlininganddiscriminatory planning,especiallysinceAuroraandNorthDenveraredisproportionatelyexposedto
Residentialaccesstopublicgreenspacehasbeenlinkedtoimprovedphysicalhealth,lower levelsofstress,increasedmentalwellbeing,coolerurbanclimates,andincreasedurban biodiversitylevels(BolundandHunhammar,1999;Fulleretal.,2007;Bowleretal.,2010; WardThompsonetal.,2012;Hartigetal.,2014;Markevychetal.,2017).However,green spaceisnotevenlydistributedincitieslikeDenver(Burgessetal.,1988;Wangetal.,2015).
ThisextendedprojectrecommendsthatgreenspaceinvestmentsshouldbeconsideredinAurora andNorthDenvertocounteractlong-termandracialisedsystematicdisinvestmentinthese neighbourhoodsthroughpracticesofredlininganddiscriminatoryurbanplanning.People livingintheseneighbourhoodsdonotonlyhavelowlevelsofresidentialparkaccessrelativeto therestoftheconurbation(Maps5-8)butarealsoexposedtohighlevelsofenvironmental hazards,whichgreenspaceinterventionscouldworktoameliorate.
Where greenspaceneedstobecreatedinDenver-Aurora-Lakewoodisclear.Thequestionis now how canmoregreenspacebeprovidedinAuroraandNorthDenverwithoutthe displacementofexistingpopulationsthroughprocessesofgreengentrification(Safransky, 2014;Anguelovskietal.,2019;Penney,2020)?
Imagebyrefractor-Flickr,CCBY2.0,https://commons.wikimedia.org/w/index.php?curid=1102597
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Penney,V.(2020)‘DenverWantstoFixaLegacyofEnvironmentalRacism’,TheNewYorkTimes,30 September.Availableat:https://www.nytimes.com/2020/09/30/climate/city-parks.html (Accessed:24April2022).
Maharawal,M.M.andMcElroy,E.(2018)‘TheAnti-EvictionMappingProject:CounterMappingand OralHistorytowardBayAreaHousingJustice’,AnnalsoftheAmericanAssociationofGeographers, 108(2),pp.380–389.doi:10.1080/24694452.2017.1365583.
Networkserviceareapolygonswerethencreatedusingthisnetworkmodelforeachpark accesspoint.Highprecisionwalk-shedswerecreatedat5,10,15,20,25,and30minute walkingdistances(atassumedspeedof20minutes/mile)forallparkaccesspointsand dissolvedtogethertocreatezonesoftemporalaccessibilitytoanyparkentrance/exit. Residentialaddresseswereisolatedindifferentwaysdependingondataavailabilityindifferent partsoftheDenver-Aurora-Lakewoodconurbation.High-detailaddressdatawasavailablefor CommerceCity[10]andCityofThornton[8],andresidentialaddresspointswereisolated usinganSQLQuery.HighdetailbuildingdatawasavailablefortheCityofAurora[4],which wasfilteredtoresidentialbuildingsusinganSQLQueryandusedtoclipNationalAddress Database(NAD)points[17]toisolateresidentialaddresspoints.ForareasinArapahoe, Denver,Jefferson,andDouglasCounties,LandParcelData[12,14]wasmergedandclippedto theDenver-Aurora-Lakewoodconurbationarea,andresidentialparcelsisolatedusinganSQL Query.NADpoints[17]werethenclippedtoResidentialLandParcelstoisolateresidential addresspoints.Intheabsenceofhigh-detailresidentiallandparceldataforunincorporated AdamsCountythecitiesofFederalHeights,Westminster,Northglenn,Arvada,andBrighton,
25
8.Appendix:Technicalexecutionofdataanalysis
Thefirststageofthedataanalysisinvolvedidentifyingwheregreenspacepointsofaccess were.Firstly,parksandnaturereserveswereisolatedfromtheOpenStreetMap(OSM)Polygon Dataset[15]usingtheExportFeaturestool.Theproportionoftheareaofeachblockgroup[19] thatwasaparkornaturereservewasthencalculatedusingtheCalculateFieldandSummarize Withintools.Pointsofaccessforallparksandnaturereserveswasidentifiedthroughtwo approaches.Whentherewerezeropathswithinapark,entry/accesspointswereadded manuallyusingAerialImageryandGoogleStreetView.Iftherewerepathswithinapark, accesspointsweregeneratedatallplacesthatpathscrosstheboundaryoftheparkpolygon byclippingOSMPathData[15]totheextentoftheseparksandrunningtheintersecttoolto createpointswherepathscrosstheseparks’boundaries.Pointsofaccesswereconsolidated usingthemergetoolforuseinnetworkmodelling.
Thesecondstageofthedataanalysisinvolvedcreatinganetworkmodeltocreateserviceareas andwalk-shedsforeachgreenspacepointofaccess.TheOSMRoadsandPathslinelayer[15] wasfilteredusinganSQLQuerytoexcludemotorwaysandprimaryroutesinaccessibleto pedestrians.Pedestriansandcyclistsareassumedtoonlyusequietroadsordesignated, segregatedpathnetworkstoaccessurbanparks.Geometrywasfixedusingtherepair geometry,multiparttosinglepark,densify,extendline,andremovedangletools,andstreets/ pathssplitatintersectionsusingtheplanarizetool,sothatnetworknodesareproperly connectedinthenetworkmodel.FollowingvalidationusingTopologywithRules,anetwork featuredatasetwascreatedtohousetheNetworkDataset,andtheOSMRoadNetwork appendedtoaschemathatArcGISProrecognisesasastreet/pathnetwork.TheCreate NetworkDatasetFromTemplatetoolwasthenruntocreateanetworkdatasetfortheDenver region,usingthetemplateprovidedbyESRI,andtheBuildNetworktoolruntocreatea routablenetwork.Acustomwalkingtravelmodewasthenaddedwithatimecostsetto20 minutes/mile(assumedwalkingspeedofpedestriansaccessingparkspaces).
[7]CityofNorthglenn –Zoning.Dataavailableat https://services7.arcgis.com/ JeS0Sns8Qnvm0GB9/arcgis/rest/services/NorthglennZoning/FeatureServer
Thespatialjointoolwasusedtoassignthewalkingtimetothenearestparkaccesspoint, generatedthroughnetworkserviceareaanalysisinanearlierstep,toeachresidentialpointin theDenver-Aurora-Lakewoodarea.TheAggregatePointtoolwasthenruntocountthetotal numberofresidentialaddressesineachblockgroupaswellasthenumberofaddresseswithin a10-minutewalkofanurbangreenspace.TheCalculateFieldtoolwasthenusedtocalculate theproportionofresidentialaddressesthatcanaccessaparkwithina10-minutewalk.
26 zoningordinances[1,3,5,6,7,9]werefilteredusinganSQLQuerytoresidentialzonesand usedtoclipNADpoints[17]toisolateresidentialaddresspoints.Residentialaddresspoints werecombinedusingtheAppendtool.
9.DataSources
[2]BroomfieldCounty–Addresses.Dataavailableat https:// opendata.broomfield.org/datasets/2aa832f778224f068b9f271b1d3e5e0f_0/about [3]CityofArvada –Zoning.Dataavailableat https://gis-arvada.opendata.arcgis.com/ datasets/557477077d2b4b728e1f4dbae7e334f8_0/about [4]CityofAurora –Buildings,EsriCommunityMapsContributors;Aurora,CO;CCBY4.0. Dataavailableat https://services6.arcgis.com/Do88DoK2xjTUCXd1/arcgis/rest/ services/Aurora_CO_Buildings/FeatureServer
[14]OIT-GISCoordinationandDevelopmentProgram -StatewideAggregate ParcelsinColorado2021(Public)forArapahoe,Broomfield,Denver,andDouglas Counties.Dataavailableat https://data.colorado.gov/Local-Aggregation/StatewideAggregate-Parcels-in-Colorado-2021-Publi/izys-vycy [15]OpenStreetMapContributors –ParkAreas,NatureReserveAreas,Roads,Paths. DataextractedusingtheHOTOSMExportTool(https://export.hotosm.org/)with Denver-Aurora-LakewoodCOMetropolitanStatisticalAreasetasextentdefinition
[8]CityofThornton –Addresses.Dataavailableat https://datacityofthornton.opendata.arcgis.com/datasets/cityofthornton::addresses-for-download/ about [9]CityofWestminster –ResidentialAreaBoundaries.Dataavailableat https:// services1.arcgis.com/1qGtTVx4f5UwkUd6/arcgis/rest/services/Residential_Boundary/ FeatureServer
[16]TrustforPublicLand -USA2021HeatSeverity.Dataavailableat https:// server6.tplgis.org/arcgis6/services/Heat_Severity_2021/ImageServer
[12]JeffersonCounty –LandParcels.Dataavailableat https://www.jeffco.us/3165/ Maps-Data-Download undera CreativeCommonsAttribution4.0InternationalLicense. [13]NASASocioeconomicDataandApplicationsCenter(SEDAC),KevinButler (Esri) –USAParticulateMatter(PM)2.5between1998-2016.Dataavailableat https:// services.arcgis.com/jIL9msH9OI208GCb/arcgis/rest/services/ USA_PM25_1998_to_2016/FeatureServer
[5]CityofBrighton –Zoning.Dataavailableat https://brighton.maps.arcgis.com/home/ item.html?id=0801681127324cd38b982a65da273dd4
[6]CityofFederalHeights –Zoning.Dataavailableat https://www.fedheights.org/ index.asp?SEC=D1A883BE-0C29-4602-8CC9-5D6A08DA5503
[17]U.S.DepartmentofTransportation(USDOT) –NationalAddressDatabase. Dataavailableat https://www.transportation.gov/gis/national-address-database [18]USCensusBureau,GeographyDivision –AmericanCommunitySurvey5-Year Estimates(GeodatabaseFormat,BlockGroupLevelDataforColorado,2019).Data
[11]ESRILivingAtlas –2021PopulationDensitybyBlockGroup.Accessedthroughthe EnrichGeoprocessingToolfortheUSARegion,usingtheStandardsetofstatistical variables.
[1]AdamsCountyColoradoGovernment –Zoning.Dataavailableat https://dataadcogov.opendata.arcgis.com/datasets/f4060f8fb08742c797a3a2d8d456ca03_0/ about andundera CreativeCommonsAttribution4.0InternationalLicense.Zonedistrict regulationsarelistedat https://www.adcogov.org/sites/default/files/Chapter03ZoneDistrictRegulations_0.pdf
[10]CommerceCity –Addresses.Dataavailableat https://datac3.opendata.arcgis.com/datasets/addresses-1
9.1.OSMDataPullQuery
planet_osm_line: types: -lines select: -bridge -highway -layer -name -oneway -smoothness -surface -tunnel -width where: -highway='footway' -highwayISNOTNULL
27 availableat https://www.census.gov/geographies/mapping-files/time-series/geo/ tiger-data.html anddocumentationat https://www2.census.gov/geo/tiger/TIGER_DP/ 2019ACS/Metadata/BG_METADATA_2019.txt [19]USCensusBureau,GeographyDivision –CoreBasedStatisticalAreas (Metropolitan/MicropolitanStatisticalArea);Counties;CountySubdivisions(Colorado); Blocks(2020,Colorado);BlockGroups(Colorado);UrbanAreas;Places.Dataavailable at https://www.census.gov/geographies/mapping-files/time-series/geo/tiger-linefile.html anddocumentationat https://www2.census.gov/geo/pdfs/maps-data/data/ tiger/tgrshp2021/TGRSHP2021_TechDoc_Ch4.pdf [20]USDepartmentofTransportation -USATransportationNoise(Roadand Aviation,2018).Dataavailableat https://tiledimageservices.arcgis.com/ P3ePLMYs2RVChkJx/arcgis/services/ 211103a_USA_Transportation_Noise_Road_and_Aviation_2018/ImageServer [21]USDAFarmServicesAgency –NationalAgricultureImageryProgram(NAIP): NaturalColor.Dataavailableat https://naip.arcgis.com/arcgis/services/NAIP/ ImageServer [22]USDAFarmServicesAgency /ESRI-NationalAgricultureImageryProgram (NAIP):NDVIProcessed.Dataavailableat https://naip.arcgis.com/arcgis/services/ NAIP/ImageServer
planet_osm_polygon: types: -polygons select: -landuse -leisure -name -natural where: -leisure='park' -landuse='forest' -natural='grassland' -natural='wetland'