b'TECHNOLOGYNature-based solutions on commercial roofsHow they can mitigate urban floodingBy/par Zahra Jandaghian & Bas BaskaranSolutions naturelles sur les toitures commerciales Comment peuvent-elles attnuer les inondations urbainesI ncidents of flooding are rising due to climatic changesdeschangementsclimatiques,lesinondations cause across Canada, causing billions of dollars of damage tosemultiplient,provoquantdesmilliardsdedollarsde buildings and urban infrastructure, as well as loss of lifedommages.Auparavant,lagestiondeseauxpluviales and property. Previously, the focus of stormwater managementmettait laccent sur les infrastructures et le systme dgout. was on urban infrastructure and the urban sewerage system.Toutefois, les municipalits, les propritaires dimmeubles, les However, there is now growing interest from municipalities,assureurs et dautres intervenants sintressent de plus en plus building owners, insurers and other stakeholders to use the lutilisation de la vaste surface inutilise de toits commerciaux vast unused surface of commercial roofs in the dense urbandans la canope urbaine dense pour attnuer les effets nfastes canopy to mitigate the adverse impacts of urban flooding. Indes inondations urbaines.some municipalities, roof cover accounts for approximatelyLestoitsfaiblepentepeuventtredotsdesolutions 30 to 50 per cent of surfaces. naturelles(SN)pourgrerleseauxpluviales.Lessolutions Low-slopedroofscanbeequippedwithinnovativenaturelles sur les toits commerciaux (SNTC) comprennent nature-based solutions (NBS) to manage stormwater. NBSuntoitvertouunensembledertentiondeseauxpluviales on commercial roofs (NBSCR) are a Vegetated Roofing(SREP)aussiappeltoitbleu.Onprtendquelessolutions Assembly (VRA), known as a green roof, and/or a Stormwaternaturellespeuventattnuerlesimpactsdeseauxpluviales Detention Assembly (SDA) known as a blue roof. Claimsde2575%etdunesurchauffeurbainemodrejusqu are being made that NBSCR, when properly designed,1,5C.Cestechnologiespeuventrduireefficacement constructed and maintained, have the potential to mitigatele ruissellement. stormwaterimpactsby25to75percentandmoderateMalgr ces avantages perus, la croissance des SNTC au urban overheating by up to 1.5C. These technologies canCanadaestlimiteparlabsencedevalidationscientifiqueet effectively reduce stormwater runoff by using advanced drainde rglementation. Le Conseil national de recherches Canada technologies and operational strategies to store-and-release(CNRC) est en train de former un consortium avec des parte-stormwater during and after extreme storm events.naires de lindustrie et des dcideurs pour dvelopper une ligne In spite of these perceived benefits, the growth of NBSdirectrice complte sur les meilleures pratiques de gestion pour la CRinCanadaislimitedduetothelackofscience-basedvalidationandregulatoryrequirements.Nationalmise en uvre efficace et pratique de la SNTC. Research Council Canada (NRCC) is forming a consortiumVoici plusieurs questions et rponses issues de ces recherches. withindustrypartnersandpolicymakerstodevelopa comprehensive guideline and best management practices forQue sont les technologies SNTC ?the effective and practical implementation of the NBSCR.Le systme de couverture vgtalise (SCV) et le systme de Here are several questions with their answers outlining thertention des eaux pluviales (SREP) offrent des options pour att-concept of this research activity.nuer les inondations (Figure 1). Le SCV peut retenir leau : elle est capte par le systme o elle svapore partiellement, et son rejet What are the NBSCR technologies? dans lgout est retard, ce qui rduit le volume dcoulement. Le TheVegetatedRoofingAssembly(VRA)andStormwaterSREP peut retenir leau : les eaux pluviales peuvent tre tempo-DetentionAssembly(SDA),inspiredandsupportedbyrairement retenues sur le toit et, par des systmes de drainage nature, offer options for urban environments in mitigatingavancs, elles sont libres de faon contrle dans linfrastruc-storm flooding (Figure 1). The VRA can retain water: theture dvacuation des eaux. La toiture vgtalise retarde natu-stormwater is captured on the assembly where it is reducedrellement et rduit lcoulement des eaux pluviales, alors que le due to vaporization and its release to the sewerage system isSREP assure des conditions contrles pour le dbit dvacuation delayed, lowering the run-off volume. The SDA can detaindu toit, permettant de retenir de grandes quantits deau.24 ROOFING CANADA FALL/WINTER 2022'