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Spatial pressures in many contemporary cities restrict the construction of surface wetlands of the scales necessary to deliver storm water management and ecosystem services. Alternative means are able to deliver some of these services by harvesting storm water at source and storing it in soils beneath road verges where it can irrigate urban trees and other vegetation. By incorporating vegetation into this storm water management infrastructure both water harvesting rates and storage capacities can be increased. If integrated with street infrastructure on a large scale, water sensitive urban design features and associated vegetation have the potential to make major contributions to improved human health, environmental quality and flood risk mitigation. Infrastructure established to support preliminary investigations in the cities of Mitcham and Salisbury has demonstrated problem-free function of storm water harvesting for street tree irrigation at the local level over seven years.
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Acta Hortic. 1108. ISHS 2016. DOI 10.17660/ActaHortic.2016.1108.8
XXIX IHC – Proc. Int. Conf. on Landscape and Urban Horticulture and International
Symposium on Sustainable Management in the Urban Forest
Eds.: G. Groening et al.
63
The Council verge as the next wetland: TREENET and
the cities of Mitcham and Salisbury investigate
T.Johnson1,D.Lawry2andH.Sapdhare3
1CityofMitcham,131BelairRoad,TorrensPark,5064,SouthAustralia,Australia;2TREENETInc.,WaiteCampus,
University of Adelaide, PMB 1 Glen Osmond, 5064, South Australia, Australia; 3University of South Australia,
MawsonLakesBoulevard,MawsonLakes,5095,SouthAustralia,Australia.
Abstract
Spatialpressuresinmanycontemporarycitiesrestricttheconstructionof
surfacewetlandsofthescalesnecessarytodeliverstormwatermanagementand
ecosystemservices.Alternativemeansareabletodeliversomeoftheseservicesby
harvestingstormwateratsourceandstoringitinsoilsbeneathroadvergeswhereit
canirrigateurbantreesandothervegetation.Byincorporatingvegetationintothis
stormwatermanagementinfrastructurebothwaterharvestingratesandstorage
capacitiescanbeincreased.Ifintegratedwithstreetinfrastructureonalargescale,
watersensitiveurbandesignfeaturesandassociatedvegetationhavethepotentialto
makemajorcontributionstoimprovedhumanhealth,environmentalqualityand
floodriskmitigation.Infrastructureestablishedtosupportpreliminaryinvestigations
inthecitiesofMitchamandSalisburyhasdemonstratedproblem-freefunctionof
stormwaterharvestingforstreettreeirrigationatthelocalleveloversevenyears.
Keywords:watersensitiveurban design,sustainableurban drainage system,storm water
management,permeablepavement,streettrees,hydraulicredistribution
INTRODUCTION
The global rate and scale of urbanisation is stressing ecologicalsystemsandthe
infrastructure on which cities depend (Andersson et al., 2014; Childers et al., 2014; Wu
2008),withmost ecosystemson Earthnowbeingaffectedbyurban demandsand outputs
(Elmqvistetal.,2013).Urbandevelopmentislargelyimpervious torainfallsoit canaffect
local hydrological cycles (Ferguson, 2010). Accompanying vegetation loss compounds the
hydrological consequences. These impacts together contribute towatershortagesand
flooding(Sheng and Wilson, 2009; Lee andHeaney,2003), urban heatislands (Australian
Government,2013;Ewenzetal.,2012)andgeneratesignificantnegativeimpactsonhuman
andenvironmentalhealth(Connell,2013;Weinstein,2013;Tarran,2006).
Greeninfrastructureandwatermanagement
LocalgovernmentsinAustraliaarelargelyresponsiblefortheprovision and
maintenanceofcivilinfrastructure.Theyarealsoincreasinglyresponsibleforhumanhealth
mattersthroughpreventivemeanssuchastheprovisionof‘green’urban environmentsfor
passiverecreation,includingsportingandactiverecreationfacilities and vegetated
streetscapes(HealthyEnvironsPtyLtd.,2014).
Green urban designs promise increased delivery of ecosystem services from within
cities as well as reduced impacts on surrounding environments. However, increasing
pressureonspace canresult inconflicts betweenacity’sbuilt andnaturalassets.Current
trendsingreenurbanism(Lehmann,2011)andgreeninfrastructure(ElyandPitman,2012;
Colding,2011)seeaunitingofthehorticulturalandcivilcomponentsofurbanpublicspace
todelivergreaterbenefitmorecosteffectivelyandtoprogresscitiestowardssustainability.
Waterisacriticalresourceofgreeninfrastructure.‘Intermsofsheermass,waterisby
far the largest component of urbanmetabolism(Kennedyetal., 2007). Massive
infrastructureisneededtoprotectcommunitiesfromfloodingandtosupplywatertocities
(Brownetal.,2008).Predictionsofmoreextremeandfrequentdroughtsandfloods(IPCC,
2007)callintoquestionthepracticalityofcontinuingtosupplywaterandmitigateflooding
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solelythroughatraditional,centralised,engineering-basedapproach.
Waterisfundamentaltosustainingvegetationinurbanareas.Thispointiskeytothe
sustainablemanagementofbothurbanstormwaterandvegetation.Wetlands,swalesand
rain gardens have demonstrated the benefits achievable through retaining and detaining
waterintheenvironmentatornearitssource,butthesesolutionsrequireadequatespace.
For functional, financial, human and environmental reasons water storage solutions are
needed which require little space. Technologies such as the TREENET Inlet, permeable
pavements,infiltrationtrenches and‘leakywells’can reduce pressureontraditionalstorm
waterinfrastructureandpotablewatersuppliesbymoreeffectivelyusingroadreserves.
Byintegratingwaterandvegetationmanagementintoroadandfootpathengineering,
thecities of Mitcham and Salisbury have demonstratedthat costsaving,lowmaintenance
solutionsareavailablewithinmanyexistingroadverges.Bysustainingurbanvegetation,an
integrated approach to water management supports other local government initiatives
including climate change adaptation,protectingthehealthandwell-being of citizens and
reducing environmental impacts. Increased evapotranspirational cooling, shading and
thermalmassattributedtoagreaterabundanceofwaterinthelocalenvironmentwill,asan
example,provideamoretemperature-stablecitywhichwillfurther reduce energy
consumption, greenhouse gas emissions and costs to the community (McPherson et al.,
2005). Similarly, benefits will accrue from ecosystem services provided by trees, such as
improvements in social and psychological health resulting in reduced anxiety and fatigue
levelsandlowercrimerates(Tarran,2006).
To investigate and demonstrate the integration of horticulture and storm water
engineering, purpose-built infrastructure has been established in Salisbury Council’s
suburbanstreetstothenorthofAdelaideinSouthAustraliaand inMitcham tothe south.
Designedtoallowobservationandassessmentofsynergiesbetweenurbanhorticultureand
civilengineering(Levettetal.,2014;Johnsonetal.,2011a),thisinfrastructureishelpingto
providedataandquantifysolutionsthatwillincreaselocalgovernment’scapacitytoaddress
compoundingdevelopment,ecologicalandfinancialpressures.Bydeliveringstormwaterto
soilnearstreettrees,theCouncilsaimtoretainandusethisresourceatitssourceand,by
minimisingconflictsbetweentheinfrastructureandtreeroots,toimprovepublicsafetyand
reducemaintenancecosts.
Water harvesting strategies used by the cities of Mitcham and Salisbury include
wetlands,swales,detentionbasinsandstreetscape-scaleinfiltrationdevices,thelatterbeing
the subject of this paper. At the streetscape scale, devices used include permeable
pavements,soakagetrenches,andTREENETinletscoupledtoleakywellsofvariousdesigns.
Allofthesesystemsharvest‘firstflushstormwaterrunoffto mitigate pollution loads
(Beecham,2010;Denmanetal.,2006;Leeetal.,2004)anddelayandreducefloodpeaks.
Permeablepavements
Permeable pavements have been developed over several decades (Ferguson, 2010;
ScholzandGrabowiecki,2007)andarebeingincreasinglyutilizedinternationally,yettheir
application in Australia remains relatively limited in comparison to impermeable
pavements.Reasonsforlowrateofapplicationmayincludemarginallyhigherconstruction
costsandalackofdataregardingeffectsofwaterinfiltrationintoreactivesoilsadjacentto
roadsandotherinfrastructure.
Construction details and aspects of the two different permeablefootpathpavement
designsunder investigationare detailed in Johnsonet al. (2011a). Permeableinterlocking
concrete brick footpath surfaces are supported by a layer of crushed rock (20 mm
screenings)whichisfreefromfinerparticles.The40%air-filledporosityofthescreenings
providesstormwaterdetentionadequatetocontaina42-mmrainfalleventinonedesign
and68mminanother;thewaterthensoaksintounderlyingsoils. The smaller capacity
designhasalevelinterfacebetweenthescreeningsandunderlyingsoil(designated‘perm-
level’); the larger capacity design has the screenings formed into a swale (‘perm-swale’)
beneath the footpath to encourage deeper root growth beneath its center (Johnson et al.,
2011b).Soilmoistureandoxygenlevels,treegrowthandsoilreactivityhavebeenmonitored
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sinceconstructionandplantinginSeptember2009.
TREENETinlets
Developed by not-for-profit tree research organisation TREENET Inc., the TREENET
inlet device harvests storm water from the road for watering tree root zones in adjacent
verges. Severalhundred TREENETinlets have been installedacrosseightlocalgovernment
authoritiesinthreestatesofAustralia.Thiscurrentresearch is providing data to better
inform the application of this technology in future by investigatinglifecyclecosts,
quantifyingtheeconomicbenefitsofrelatedgreeninfrastructureandmeasuringimpactson
soilmoistureandreactivity.
TREENETinletdevices(Figure1)arecastintoconcretekerbstodivertstorm water
fromtheroadtosoilintheverge.Waterexitsthekerbandgutterdrainagesystemthrougha
slottedfaceplatemountedinthekerbandthenflowsviaaPVCstormwaterpipeintoleaky
wells(Figure2)constructedinthevergeuntilthelimitofthe well and the infiltration
capacityofitssurroundingsoil arereached.Theshallowdepressionintheguttercreatesa
small pool which reduces flow velocity marginally, thereby establishinganeddywhich
depositssedimentshighinthegutterandawayfromtheentryslot,thusminimisingclogging
andallowingformaintenancethroughroutinestreetsweeping.Flowvolumeswhichexceed
thedesigncapacitysimplybypassthedeviceandcontinuedownstreamtothenextinletor
beyondviathestormwaternetwork.
Figure1.TREENETInletinstallation.
Leakywells
Several designs have been developed in the search for the optimalleakywellfor
Adelaide’sclimate.Primaryfactorsconsideredintheirdesignaretotalstoragecapacityand
adequacytoaccommodatethepollutantloadedfirstflushofstormwaterrunoff(Leeetal.,
2004).Otherconsiderationsincludehydraulicconductivityandreactivityofthesite’ssoils,
localrainfallpatterns, catchmentarea,vegetationproximityandtype,andaccessibilityfor
maintenancepurposes.
Roadsideleakywellsandinfiltrationtrencheswithcapacitiesranging from 10 L to
7 kL have been constructed. Those connected to TREENET Inlets range between 65 and
150L;thesmallerbeingusedinshallowsoils and the larger at sites wheredrainage isa
primaryconcern.Theleakywelldesignwhichformspartofthecurrentresearch(Figure2)
hasa capacityof 50 L. Optimising design capacity ona cost-benefit basis requiresfurther
research.
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Figure2.Leakywelldesign.
TwentyeightTREENETinletshaverecentlybeeninstalledinthecityofMitchamusing
variousbackfillmaterialstoinvestigatepotentialpollutionmitigationbenefits.Stormwater
sampleswill be collected from thebasesoftheleakywellsduring late2014 and through
2015, to be analysed for pollutants including phosphates, nitrates,heavymetalsand
suspended solids. Soil samples collected from the sites during construction of the leaky
wells, and additional samples to be taken in 2016, will be analysed and compared to
determinethepollutionmitigationcapacityofthethreebackfillmaterials.
RESULTSANDDISCUSSION
Infiltrationtrenchesandleakywells
Streetscape-scalestormwaterharvestingsystemshavebeensuccessfullyfunctioning
inthecitiesofMitchamandSalisbury since 2007withnooperationalfailuresorproblems
observed.Atonesite,soakagetrenches600mmwide,1000mmdeepandtotaling80min
lengthcandetainupto20kLofstormwaterinthevoidsbetweenthecrushedrock
screenings which fill them; the water then percolating into surrounding soil. Percolation
rates after seven years of operation appear consistent with those immediately following
construction.DuringheavyraininJuly2014,flowobservedby-passingthesystemwas
minimal.Increasedsoilmoisturelevelshavenotresultedinanyobservabledeteriorationof
footpath,road,drainageorotherinfrastructure.
Similarly,ataseparatesiteadrainagepitdivertsstormwaterintoasoakagetrench
9minlengthwithadetentioncapacityof2.5kL.Thistrenchfillstocapacityapproximately
40timesperyear.Builtattheendofaseveredrought,waterrecharge wasanticipated to
causesubstantialsoilheave,potentiallydislodgingthe newkerbing.Noimpactshavebeen
observedatthissitesinceconstructionin2008.Inanenvironmentwithcopiousamountsof
leaflitter and fruit producedby a matureavenue ofWhite cedar (Meliaazedarach)street
treesandusingonlyascreenedagriculturaldrainagepipeinthestormwaterpittofilter
waterenteringthetrench,afterthreeyearsofoperationthesystem was measured to be
operatingwithaninflowrateof70Lmin-1.
67
Inbothofthesecasesitislikelythattheestablishedavenuesofriverredgum
(Eucalyptuscamaldulensis)andwhitecedar(Meliaazedarach)havedevelopedopportunistic
root systems which take advantage of the additional water, with hydraulic redistribution
(Prietoetal.,2012;NeumannandCardon,2012;Blebyetal.,2010)reducingwaterpotential
around the trenches and sustaining prolonged storm water harvesting. Several similar
systemshaveremainedfullyoperationaloversimilartimespanswithno maintenanceand
withnoobservedinfrastructureissues.
TREENETinletshavebeenprovidingdrainageandirrigationsolutionsatseveralother
locations for over two years. At one site a large river red gum(Eucalyptuscamaldulensis)
treehadlifted kerbingby approximately 100mm, creatingpoolingalongthestreetwhich
resultedindrivewayaccessdifficulties.Installationof5TREENETinletsatafractionofthe
costofkerbreplacementhasdrainedthesitethroughtwoyearswithnoilleffectsobserved
on surrounding infrastructure. As road-sweeper access is difficult at this site, sediments
regularly build up in the inlets’ pools. This has been observed to only marginally reduce
infiltration rates however. Adequate drainage is possibly sustained by the inlets in the
absence of maintenance due to high hydraulic conductivity of the built-up sediments. At
severalsiteswhereTREENETinletshavebeeninstallednearmaturetrees,rootgrowthhas
been observed to occupy screenings in the leaky wells within the first spring after
construction, suggesting that hydraulic redistribution of waterfromthewellsto
surroundingsoilscanbeexpectedtoestablishrapidly.ThecurrentresearchintoTREENET
inlets,theircostsandbenefits,isscheduledforcompletionin2016.
Permeablefootpathpavements
Datarelatingtopermeablepavementresearchiscurrentlybeinganalysed;anumber
of preliminary observations warrant reporting at this stage however. All of the average
annual rainfall of 546 mm incident upon the permeable research pavements has been
intercepted and managed in situ since September 2009, with no runoff and discharge to
receivingwatersresultingandnonegativeimpactsonthepavements themselves or
problemswithsurroundinginfrastructurebeingobserved.
Between2011and2014surfacelevelmovementduetomoistureinduced soil
reactivityappearedsimilar atpermeable andimpermeable controlpavements.Soil ‘heave’
recordedattheendofwinter2013(30August)rangedfrom+1to+30mmatcontrolsites,
+7 to +31 mm at ‘perm-level’ sites, and +10 to +30 mm at ‘perm-swalesites(relativeto
February2011levels).LevelsrecordedonApril 8,2014of+18to-25mmatcontrolsites,
-4to-20mmat‘perm-levelsitesand+11to-22mmat’perm-swale’ sites (relative to
February2011levels)showedageneraltrendofshrinkageduetodryingcausingasurface
levelreductionofapproximately30mmacrossthedifferentpermeablepavementtypesand
controls.Theserelativelyminorsurface levelfluctuationsobservedonmoderatelyreactive
soilsalongthe320mlong researchsite,andtheabsence ofdiscontinuitiesinlevelsatthe
interchangesbetweenpermeableandimpermeablesurfaces,suggest that permeable
pavementsmaybeabletobesafelyusedinfootpathconstruction,particularlyinsemi-arid
climateswithmoderateorlowsoilreactivity.
ACKNOWLEDGEMENTS
The authors acknowledge the ongoing support of the project partners: city of
Mitcham,Adelaideand MountLoftyRanges Natural ResourcesManagement Board,city of
Salisbury,TREENETInc.,UniversityofMelbourne,UniversityofSouthAustralia.
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70
... The exfiltration rate determines the storage availability before the arrival of a new storm event. This parameter is a function of the native soil type, filter medium properties and hydraulically efficient fissures in adjacent soil attributed to the presence of tree roots (Johnson et al., 2016). The installed kerbside leaky well systems across the catchment exfiltrated 100 L in approximately 10 h. ...
... exfiltration rate of up to 0.005 L/s resulting in a 14% greater annual retention over the present case (Fig. 12). Previous research (Johnson et al., 2016) on the impacts of tree roots as conduits for both uptake and preferential flow pathways has indicated that the hydraulic redistribution phenomenon can occur immediately upon the installation of kerbside leaky well systems. This suggests that the present systems can potentially be expected to retain 14% more runoff annually than expected due to the presence of tree roots. ...
Article
The popularity of subsurface distributed storage-based kerbside stormwater infiltration systems is increasing because they can be integrated within the strict spatial constraints of existing infrastructure. Distributed systems operate based on the concept of spreading a limited amount of storage throughout the catchment area to achieve runoff management objectives. Storage can also limit the performance of urban stormwater systems. This study investigated the role of storage capacity, especially the volumetric capacity and the emptying time, in the performance of kerbside leaky well systems in a residential catchment area with a native clay soil environment. A detailed, process-based deterministic hydrological model was used to analyze hydrologic storage via a continuous simulation approach. The model was calibrated against catchment outflows measured with stormwater infiltration devices. Individual kerbside infiltration systems were also calibrated to monitor the behavior of on-site kerbside infiltration systems. By using approach of continuous simulations during designed scenarios, this study considered the prestorm storage availability in the hydrological analysis. The results demonstrated that hydrologic storage greatly influences the performance of kerbside leaky well systems during higher-intensity storms. In addition, the results show that distributing a stormwater storage volume equal to thirty-five 1-kL rainwater tanks across the catchment area as a kerbside infiltration system could notably reduce the runoff flow rates and volumes. The results further highlight that the addition of more homes within the connected area could diminish the stormwater reduction benefits achieved through the installation of a distributed kerbside infiltration system.
... More recently, a focus on liveability and urban greening has encouraged the increased adoption of infiltration facilities for passive street tree irrigation in urban environments (Payne et The kerb side tree inlet ( Fig. 1) with a leaky well is a relatively new approach to infiltration, specifically designed to harvest stormwater for street tree irrigation. Leaky well infiltration systems are designed to harvest road runoff and to allow subsequent exfiltration to the surrounding soil where the water may be potentially used by street trees (Johnson et al., 2016;Sapdhare et al., 2018). While the infiltration capacity of the system may be expected to decrease over time due to sediment clogging Kandra et al., 2015), previous research has reported that vegetation or tree roots can create micropores which maintain hydraulic conductivity (Bartens et al., 2009). ...
... However, current weaknesses in the MUSIC modelling approach include the inability to model the influence of vegetation on the performance of infiltration based systems in urban areas. Street trees have been shown to increase the overall performance of infiltration systems in urban areas (Johnson et al., 2016) and further research is required to determine how this influence can be included in MUSIC simulations, or in other urban runoff simulation tools such as SWMM. ...
Article
Kerb side inlets with adjacent leaky wells are an emerging tool to harvest stormwater and to reduce runoff volumes and peak flow rates. This is achieved by collecting the first flush runoff into kerb side storages and infiltrating this water into the surrounding soil, thereby also reducing stormwater pollutant loadings. The hydraulic performance of the kerb side inlet, filter media and surrounding soil are key factors in the performance of these systems. However, no field or laboratory data are currently available for the hydraulic performance of a kerb side tree inlet pit. In this study, 12 tree inlet pits were constructed and filled with various media types including gravel, water treatment solids (a recycled waste product), sandy loam and clay to examine (1) leaky well infiltration rates (2) emptying times of the wells and (3) the well capacity (runoff storage volume) before and after runoff filtering through the wells. Using a laboratory model, the water harvesting performance of the kerb side inlet plate was also examined for various road longitudinal slopes. Using the field and laboratory data, simulation of the well performance was undertaken using the Model for Urban Stormwater Improvement Conceptualisation (MUSIC) to assess the capacity of these systems to reduce runoff volumes at the residential street scale. It was hypothesised that the type of filter media used in leaky well systems has a significant impact on the infiltration rate, regardless of the native soil type through which the stormwater eventually infiltrates. The results showed that the infiltration rates of systems filled with gravel were significantly higher than for the other media types, and this was followed by water treatment solids, sandy loam and clay. The results of the MUSIC modelling indicated that 2.8% of the mean annual runoff volume in the catchment could be harvested by the systems at the case study site. It was found that selection of high infiltration rate media and regular maintenance are the key factors for maintaining long-term performance of these systems.
... Curbside stormwater harvesting systems are a form of WSUD that have been developed to intercept runoff from sealed urban surfaces and direct the captured runoff into the root zone of street trees (Grey et al., 2018;Johnson et al., 2016;Szota et al., 2019). Research into curbside infiltration measures is limited, but some studies have reported on the application of these systems in mainstream stormwater management. ...
Article
Distributed infiltration systems can benefit downstream water bodies by reducing the runoff flowrate and volume discharges from the catchment. Investigating their runoff flowrate and volume reduction potential at the catchment scale will inform decision makers regarding their efficacy for managing catchment outflows. To this end, we conducted field investigations at the residential catchment scale for three years. The study monitored the catchment for one year before the installation of leaky well systems (preinstallation) and two years after installation (postinstallation). The hydrological model, calibrated to preinstallation catchment outflows, acted as a virtual control tool. Runoff flow outputs from the control model and two years of monitored runoff flow data from the postinstallation period were analysed using statistical methods. The statistical tests showed a significant 13% reduction in average flowrates in storms with a corresponding runoff flowrate of 50 L/s. The study further reported the ability of infiltration systems to reduce runoff volume in the catchment by 9%. This reduction was not significant, however, as per the results of the statistical analysis. We then fitted the generalized linear model (GLM) to the monitored and simulated runoff volume data. This enabled us to break down the effect of curbside infiltration systems on runoff volume according to corresponding peak flowrates during the storm. The results of the two-way ANOVA performed to detect significant differences in the regression slopes of the GLM indicated that curbside infiltration systems significantly reduced runoff volume for storms when the runoff flowrates remained below 100 L/s. The article can be dowloaded free for next 50 days from this link https://protect-au.mimecast.com/s/IdM2CQnM05U8v0MmTMqZts?domain=authors.elsevier.com
... Reduced flow velocity due to greater cross-sectional area in the gutter established an eddy in the pool which deposited larger sediments away from the capture slot. In this way, clogging of the inlet may be reduced and routine mechanized street sweeping used to remove deposited sediment [23]. ...
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The conveyance of stormwater has become a major concern for urban planners, considering its harmful effects for receiving water bodies, potentially disturbing their ecosystem. Therefore, it is important to characterize the quality of catchment outflows. This information can assist in planning for appropriate mitigation measures to reduce stormwater runoff discharge from the catchment. To achieve this aim, the article reports the field data from a typical urban catchment in Australia. The pollutant concentration from laboratory testing is then compared against national and international reported values. In addition, a stochastic catchment model was prepared using MUSIC. The study in particular reported on the techniques to model distributed curbside leaky wells with appropriate level of aggregation. The model informed regarding the efficacy of distributed curbside leaky well systems to improve the stormwater quality. The results indicated that catchment generated pollutant load, which is typical of Australian residential catchments. The use of distributed storages only marginally improves the quality of catchment outflows. It is because ability of distributed leaky wells depended on the intercepted runoff volume which is dependent on the hydrological storage volume of each device. Therefore, limited storage volume of current systems resulted in higher contributing area to storage ratio. This manifested in marginal intercepted volume, thereby only minimum reduction in pollutant transport from the catchment to outlet. Considering strong correlation between contributing impervious area and runoff pollutant generation, the study raised the concern that in lieu of following the policy of infill development, there can be potential increase in pollutant concentration in runoff outflows from Australian residential catchments. It is recommended to monitor stormwater quality from more residential catchments in their present conditions. This will assist in informed decision-making regarding adopting mitigations measures before considering developments.
... Recent literature further grounds the multiple benefits of verge gardens as NBSs in cities. Verge gardens have great potential to facilitate rain-water run-off capture (Johnson et al., 2016) and enhance biodiversity conservation (Lin et al., 2015). The road verge garden is essentially an extensive green corridor network that increases plant diversity, reduces the impacts of fragmentation and facilitates the dispersal and movement of pollinators and wildlife (Phillips et al., 2020). ...
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Australia is currently grappling with a range of social and environmental challenges, many of which impact the way our public health system, and society more broadly, function. In this short communication paper we explore urban agriculture in Australia as a Nature-Based Solution (NBS) to address some of the ecological, social, economic and health challenges facing the continent. We argue that urban agriculture has the potential to mitigate the effects of climate change extremes while simultaneously providing multiple benefits such as improving wellbeing, people-nature connections, and food security. We present three exemplar case studies diverse in geography, context and governance from Queensland, Tasmania, and New South Wales exploring verge gardening, market gardening, and a community greening program respectively to highlight the benefits of urban agriculture as a NBS. We advocate that various forms of urban agriculture need to be researched and considered for their potential impacts and multiple benefits to be fully supported, governed, and understood in light of the social-ecological challenges Australian cities face.
... In 2002, TREENET Inc. developed the TREENET inlet, a novel kerb side inlet to harvest road runoff for passive irrigation of street trees. This inlet, coupled with a leaky well infiltration pit ( Fig. 1), is an emerging WSUD tool that has been installed in Australia to reduce runoff volume, reduce mains water demand and improve stormwater quality (Johnson et al. 2016). In its most common configuration, one leaky well infiltration pit is installed adjacent to a tree or ideally between two trees in Responsible editor: Philippe Garrigues * Harsha Sapdhare harsha.sapdhare@mymail.unisa.edu.au a street. ...
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The TREENET inlet is an emerging water-sensitive urban design technology that consists of a novel kerb side inlet coupled with a leaky well infiltration system. The inlets have been retrofitted to existing roads since 2006; however, there is currently little information available on the effectiveness of these inlet and leaky well systems. This study investigated the performance of the kerb side inlets and leaky well system for water quality improvement prior to infiltration to native soil. The leaky wells included four filter media types, namely gravel, water treatment solids, sandy loam and clay. To compare the performance of the four filter media types, batch and column studies were performed in the laboratory. The best performance was observed using the sandy loam as a filter media, followed by clay, water treatment solids and then gravel. The selection of effective media for removal of heavy metals is important as each media type has different pollutant removal capacity, infiltration and clogging performance.
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Researchers and water managers have turned to green stormwater infrastructure, such as bioswales, retention basins, wetlands, rain gardens, and urban green spaces to reduce flooding, augment surface water supplies, recharge groundwater, and improve water quality. It is increasingly clear that green stormwater infrastructure not only controls stormwater volume and timing, but also promotes ecosystem services, which are the benefits that ecosystems provide to humans. Yet, there has been little synthesis focused on understanding how green stormwater management affects ecosystem services. The objectives of this paper are to review and synthesize published literature on ecosystem services and green stormwater infrastructure and identify gaps in research and understanding, establishing a foundation for research at the intersection of ecosystems services and green stormwater management.We reviewed 170 publications on stormwater management and ecosystem services, and summarized the state-of-the-science categorized by the four types of ecosystem services. Major findings show that: (1) most research was conducted at the parcel-scale and should expand to larger scales to more closely understand green stormwater infrastructure impacts, (2) nearly a third of papers developed frameworks for implementing green stormwater infrastructure and highlighted barriers, (3) papers discussed ecosystem services, but less than 40% quantified ecosystem services, (4) no geographic trends emerged, indicating interest in applying green stormwater infrastructure across different contexts, (5) studies increasingly integrate engineering, physical science, and social science approaches for holistic understanding, and (6) standardizing green stormwater infrastructure terminology would provide a more cohesive field of study than the diverse and often redundant terminology currently in use. We recommend that future research provide metrics and quantify ecosystem services, integrate disciplines to measure ecosystem services from green stormwater infrastructure, and better incorporate stormwater management into environmental policy. Our conclusions outline promising future research directions at the intersection of stormwater management and ecosystem services.
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