Jump to: navigation, search

Climate change

4,553 bytes removed, 1 year ago
‘No-regrets’ approach
[[File:Lake_Ontario_Drought_2007.png|thumb|Drought conditions at Island Lake in the summer of 2007]]
 Ways in which Green Infrastructure will help mitigate the effects of climate change, particularly in urban centres. :==*Manage flood risk==,==*Help reduce erosion==,==*Stabilize groundwater recharge==,==*Reduce urban heat island==,==*Lower energy use== ==Concerns with projections==*Even if we significantly reduce GHGs, the impacts of climate change will continue.*There is uncertainty in the models, confusing policy makers and practitioners*“The extent of the impact of climate change is not fully known, and there are limitations in understanding the Earth’s climatic variations over long spans of time (CSIRO 2007). Additionally the modelling of climate projections to a local level is still not yet precise. As expressed by the MOE (2011): “Climate change science and modeling currently is not at a level of detail suitable for stormwater management where knowledge of the intensity, duration, frequency of storms and their locations and timing is required. However the economic, health and environmental risks dictate a need to be proactive in the management of stormwater.” These uncertainties require a process for continuously assessing the adapted measures, as well as assessing the physical facilities or infrastructures affected by these adaptations.” Upadhyaya et al 2014*Climate change should be considered in future planning but the uncertainty in estimates makes it harder for those involved*“How to adapt cities to climate change is emerging as one of the greatest challenges that spatial planners will face in the 21st Century (Measham et al., 2011; Perry, 2015).” cited in Matthews et al 2015
==Impact of observed and projected climate change on urban infrastructure==
* “It is common to consider adapting stormwater systems to climate change by adding simple uplifts to rainfall intensities and then assessing whether or not the existing system can cope or not (e.g., Defra, 2010; Semadeni-Davies et al., 2008). This is the Predict-Then-Adapt method which begins by considering the changing climate system (drivers) and the consequent pressures (e.g., increased runoff), state (e.g., system performance) to predict the impacts (e.g., flooding and pollution). Responses then need to be formulated to deal with the pressures and impacts in a way that maintains expected levels of performance. This method has been classified as cause-based after its reasoning (Jones and Preston, 2011). The main problem with it is the reliance on estimated climate change scenarios that are expected to provide some precision as regards forecasts of climate change. However, despite past and current scientific advances in climate modelling, there remain large uncertainties about the direction, rate and magnitude of climate change”  Gersonius et al 2012.
*“It should be noted that although the stormwater management initiatives that are proposed to be integrated into Toronto’s street network will not contribute significantly to mitigating the impacts of extreme precipitation events, they will improve the function and resilience of existing stormwater infrastructure by reducing runoff volumes, thereby freeing up capacity within the downstream stormwater drainage system”  City of Toronto 2016 (green streets technical guidelines)
==‘No-regrets’ approach==
This is an approach referenced in few different studies and seems to fit well with the benefits of LID in light of climate change. Tie back to the fact that climate change projections are uncertain, especially at local scales, so why not implement LIDs – they are practices that work well for stormwater management with and without the effects of climate change.
*Climate change should be considered in future planning but the uncertainty in estimates makes it harder for those involved
*“Acknowledging that there is uncertainty as to how the climate will change and at what rate, the team developed strategies that are built upon three principles which ensure that their recommended actions make sense under any scenario: • Triage: Avoiding efforts that are unlikely to succeed and concentrating on areas where improved management can have the biggest impact; • Precautionary principle: Not waiting for certainty to act where the consequences of potential impacts are high; and • No regrets: Focusing on actions that provide benefits regardless of how the climate changes (Wisconsin Initiative on Climate Change Impacts, 2011).”  Huron River Watershed Council, 2013
*“No-regrets actions are those that provide benefit under both current climate conditions and potential future climate conditions. No-regrets options increase resilience to the potential impacts of climate change while yielding other, more immediate economic, environmental, or social benefits (Heltberg et al, 2008). The no-regrets approach is considered “proactive adaptive management” which is based on the development of a new generation of risk-based design standards that take into account climate uncertainties. There are a wide variety of no- regrets actions that improve the adaptive capacity of the watershed to handle stormwater.” Huron River Watershed Council, 2013
*‘No-regrets’ strategies “Faced with uncertainty about future climate change, and given constraints on available resources, communities may choose to pursue no-regrets strategies – actions that are beneficial in addressing current stormwater management needs regardless of whether or how climate may change in the future (Means, Laugier, Daw, Kaatz, & Waage, 2010)”. -Cited in Pyke et al 2011. “The results of this study also demonstrate the effectiveness of site redevelopment, including increased density and reduced impervious cover as a no-regrets adaptation strategy for reducing pollutant loads associated with stormwater runoff.”  Pyke et al 2011. “management infrastructure, a challenge that many practitioners and decision makers are just beginning to consider (Blanco, Alberti, Forsyth, et al., 2009; Blanco, Alberti, Olshansky, et al., 2009). Responding to climate change will be complicated by the scale, complexity, and inherent uncertainty of the problem, therefore it is unlikely that this challenge can be solved using any single strategy. The scenario analyses conducted in this study illustrate the potential effectiveness of one common element of LID, reducing impervious cover, in the context of climate adaptation.”  Pyke et al 2011
*“Managing green infrastructure for climate adaptation is primarily about managing risks or uncertainties created by anthropogenic activities. The risk-based approach to climate change has three defining aspects: problem framing and role; embedded policy discourse; and planning approaches. First, problems associated with adverse weather conditions, including rainstorms, floods, heat waves and cyclones, tend to be understood in probabilistic terms. The ‘thing’ that matters is not discrete material benefits that can fulfill the needs of the public, but non-linear, irreducible uncertainties associated with changes in the climate. Functioning as a risk buffer, green infrastructure actually helps minimize the impacts of public ‘bads’ (i.e. natural perils) and, by doing this, indirectly provides public ‘goods’. There is limited precision as to where and when these impacts will eventuate and in what manner. The ‘necessity’ for green infrastructure is thus reduced to a matter of probabilities that are influenced by global climatic dynamic and humanity’s collective actions. It is driven by problems that we seek to avoid and are unable to predict with high level of precision.”  Matthews et al 2015
==Water as a valuable resource==
==Infiltration and Filtration==
“In particular, the frequency and magnitude of overflow from the systems substantially increased under the climate change scenarios. As this represents an increase in the amount of uncontrolled, untreated runoff from the contributing watersheds, it is of particular concern. Further modelling showed that between 9.0 and 31.0 cm of additional storage would be required under the climate change scenarios to restrict annual overflow to that of the base scenario. Bioretention surface storage volume and infiltration rate appeared important in determining a system’s ability to cope with increased yearly rainfall and higher rainfall magnitudes.” <ref>Hathaway et al , J. M., R. A. Brown, J. S. Fu, and W. F. Hunt. 2014 – modelling study . “Bioretention Function under Climate Change Scenarios in US to see how bioretention can mitigate climate changeNorth Carolina, USA.” Journal of Hydrology 519 (PA):503–11.</ref>*“This study shows that the current levels of SGI in two major Mid-Atlantic cities and surrounding areas do have small, but significant to marginally significant and positive impacts on hydrology and nitrogen exports. Specifically, this study found that at the watershed scale, when stormwater green infrastructure controls N5> 5% of drainage area, flashy urban hydrology and nitrogen exports are reduced. The magnitude of impacts are small, but will likely increase with more SGI. There were also some promising trends towards reduced CSO levels with higher SGI in watersheds, but the differences between sewersheds create high variability in CSO levels.” <ref>Pennino, Michael J., Rob I. McDonald, and Peter R. Jaffe. 2016. “Watershed-Scale Impacts of Stormwater Green Infrastructure on Hydrology, Nutrient Fluxes, and Combined Sewer Overflows in Penino et al the Mid-Atlantic Region.” Science of the Total Environment 565. The Authors:1044–53. – already evidence of improvement.05.101.</ref>
==Simultaneous benefits for periods of drought and periods of excess water==
“Approaching urban climate adaptation to extreme events in an integrated way, shows that we are dealing with a temporal variation in water surplus (pluvial flooding) and water shortage events (drought and heat stress). Linking water surplus and water shortage events is required in order to buffer temporal variations. To this end storage has to be created [35]. Sufficient storage capacity helps to prevent heavy rainfall events to cause pluvial flooding. In addition, the water stored serves as supply for evaporative cooling to prevent heat stress in times of heat waves and as water source to prevent drought in times of no or little precipitation.” <ref name=Voskamp >Voskamp, I. M., and F. H M Van de Ven . 2015. “Planning Support System for Climate Adaptation: Composing Effective Sets of Blue-Green Measures to Reduce Urban Vulnerability to Extreme Weather Events.” Building and Environment 83. Elsevier Ltd:159–67.</ref>*“For combined scenarios of high climate change and high urban development, there is a projected increase in winter flows of up to 71 percent % and decrease in summer flows of up to 48 percent%.”  cited in <ref>Praskievicz , S, and H Chang 2012  shows . 2011. “Impacts of Climate Change and Urban Development on Water Resources in the Tualatin River Basin, Oregon.” Annals of the extremes Association of climate changeAmerican Geographers 101 (2):249–71. 933400604\rDoi 10.1080/00045608.2010.544934.</ref>*“We find that in situ and modeling methods are complementary, particularly for simulating historical and future recharge scenarios, and the in situ data are critical for accurately estimating recharge under current conditions. Observed (2011–20122011 – 2012) and future (2099–21002099 – 2100) recharge rates beneath the infiltration trench (1750–3710 1750 – 3710 mm/yr) were an order of magnitude greater than beneath the irrigated lawn (130–730 130 – 730 mm/yr). Beneath the infiltration trench, recharge rates ranged from 1390 to 5840 mm/yr and averaged 3410mm3410 mm/yr for El Nino years (1954–20121954 – 2012) and from 1540 to 3330mm3330 mm/yr and averaged 2430 mm/yr for La Nina years. We demonstrate a clear benefit for recharge and local groundwater resources using LID BMPs. (<ref>Michelle E. Newcomer et al , Jason J. Gurdak; Leonard S. Sklar; Leora Nanus; 2014). “Urban Recharge beneath Low Impact Development and Effects of Climate Variability and Change.” Water Resources Research, 1716–34.</ref>
==Flow volume and erosion reduction==
==Retaining pollution from non-point sources==
“Work done to reduce nonpoint sources of contaminants to streams needs to consider the realities of not only groundwater inputs and the role of ambient conditions but also the additional stress caused by climate change and other factors like invasive species which can often counteract initiatives taken to improve stream water quality. These considerations only emphasize emphasise the need for source control where possible and for monitoring programs which when thoughtfully designed will help determine what can be done to achieve tangible improvement in water quality.”  Long et al 2016 (Hamilton study)
#Reduced CSOs - Discussion on CSOs – introduction of Vineyards et al 2015 has a detailed explanation of the issue.
#Reduction of Urban Heat Island Effect
#CO2 SequestrationCO<sub>2</sub> sequestration
#Overall ecological benefits
Conventional stormwater drainage has been identified as a primary driver of the commonly observed, severe degradation of stream ecosystems in urban catchments (Walsh et al 2010; Wenger et al 2009)  cited in Walsh et al 2012
#Case that our infrastructure is degrading, hard to upkeep, so when we are changing to new infrastructure, change to LID
#Old infrastructure using old methods
*“The built environment of an existing city is continuously changing by maintenance, modification and renewal. This inherent dynamics of the urban environment provide opportunities for retrofitting blue-green measures synergistically with other structural changes in the urban form [15,28,40,41]. Opportunities for retrofitting arise for instance when existing paved areas are removed for works on cables or for sewer rehabilitation [15,28,41], when buildings are renovated, when infill development takes place [28], and with urban renewal projects [40,41]. Linking implementation of blue-green climate adaptation measures with such ‘windows of opportunity’ is greatly beneficial for a reduction of implementation costs [15].” <ref name=Voskamp and Van de Ven 2015/>d. ===Watershed-scale approaches to LID===
Single LIDs placed scarcely may not be able to tackle climate change. For this reason, there has to be a (sub)watershed scale effort.
 *“Retrofitting a single blue-green measure is hardly ever a successful strategy to deal with all relevant climate risks. In order to optimally use the potential of blue-green measures in creating urban resilience to flooding, drought and heat stress combinations of blue-green measures, ‘adaptation sets’, have to be implemented. The composition of an effective and cost efficient package of measures depends on the characteristics of the project site.”  in <ref name=Voskamp and Van de Ven 2015/>* “Four vulnerability reduction capacities are required to effectively create resilience: adaptive, threshold, coping, and recovery capacity. An urban area has different levels of these capacities for pluvial and fluvial flooding, heat stress, and drought. Each type of blue-green measure strengthens these capacities in a different way and to a different degree. A combination of measures is required for all-inclusive climate vulnerability reduction. It depends on the current vulnerability of a site which capacities require strengthening most [15] and, accordingly, which combination of measures is most beneficial to increase resilience to extreme events of a particular site.” in <ref name=Voskamp and Van de Ven 2015/>
* LID BMPs are like a toolbox from which engineers can pick and choose depending on site constraints. But this has to come after a larger scale planning strategy to manage water and other ecosystem spaces.
*“Green infrastructure retrofits, which included street- connected bioretention cells, reduced peak and total stormflow and increased lag times from a suburban residential headwater street. On Klusner Ave, a voluntary participation scheme in which 13.5% of households had rain barrels and rain gardens or street-connected bioretention cells added to their parcels resulted in up to 33% reductions in peak flows, 40% reductions in total storm volumes and desynchronization of peak flow timing compared with an adjacent street where no green infrastructure was installed. Connecting” <Ref>Jarden et al , Kimberly M., Anne J. Jefferson, and Jennifer M. Grieser. 2016, . “Assessing the Effects of Catchment-Scale Urban Green Infrastructure Retrofits on Hydrograph Characteristics.” Hydrological Processes 30 (10):1536–50.</ref>also notes: “The results of this study demonstrate promising effectiveness of catchment-scale green infrastructure retrofits in mitigating stormwater run-off from headwater streets. In particular, connection to streets appears to leverage high value out of a limited number of installations. The site of this study is very typical of mid-20th-century American residential development, suggesting that the results achieved here may be possible to replicate in other areas.”
==Within Ontario==
===Climate Ready Adaptation Strategy Action Plan 2012. ==='''Action 10 | ''' = Develop Guidance for Stormwater Management'''  The Ministry of the Environment is currently reviewing best management practices in other jurisdictions in support of proposed Municipal Water Sustainability Planning under the Water Opportunities and Water Conservation Act. The review includes municipal water, wastewater and stormwater systems for additional guidance and information on adapting water systems to deal with impacts caused by climate change. Among system issues and practices being reviewed: *source control (reuse and low impact development) *sewers for conveyance *end-of-pipe treatment works *water conservation *inflow and infiltration *by-passes and combined sewer overflow. .  '''Action 3 | ''' = Promote Water Conservation - • *applying proactive solutions that encourage groundwater infiltration of stormwater, such as increasing permeable surfaces in built-up areas.
===Town of Ajax===
The Official Plan for Ajax has extensive content and calls for the promotion of LIDs to treat Stormwater. they also mention that new infrastructure needs to be sized properly, although they do not specially say if there are new requirements. <ref>OCC, GLISA, Clean Air Partnership. 2016. “Historical and Future Climate Trends in York Region."</ref>
===City of Ottawa===
“Green infrastructure and low impact development (LID) have many common elements with the objectives of stormwater management adaptation; however, like existing measures and no regret actions, techniques and the promotion of green infrastructure/LID was well developed in some jurisdictions when climate change, mitigation and more recently adaptation began to be considered at the municipal level. The City’s Infrastructure Master Plan promotes green infrastructure however the scope of promotion is limited to giving “greater consideration” to green infrastructure in the context of capacity management of urban systems. This level of commitment is very different from other cities including a number of cities in the northeastern United States with similar climate, anticipated climate change impacts and infrastructure profiles as Ottawa. Some cities have adopted and are moving forward aggressively with green infrastructure plans as a cost effective (and some assert cost saving) plan to address infrastructure deficits, combined sewer overflows, water resource improvements and climate risks.” <ref>Boliviar Philips. 2013. “Adaptive Approaches in Stormwater Management for City of Ottawa.” City of Ottawa, no. July:81.</ref>
New York City – “New York City has created a Green Infrastructure Plan and is committed to goals that include the construction of enough green infrastructure throughout the city to manage 10% of the runoff from impervious surfaces by 2030.”  cited in Mellilo et al 2014
Zahmatkhesh et al 2015 – NYC modelling study of LID vs no LID scenarios. Based on the model results, it was observed that future runoff volumes increased in comparison to historical runoff volumes due to expected increase in rainfall. The monthly runoff volumes decreased when looking at the with-LID scenarios. Runoff increases by 44% under a projected scenario without LIDs, while runoff decreases by 17% for with-LIDs scenario. “Although the effect of LID implementation on projected runoff based on the maximum scenario was not considerable, future runoff corresponding to a 25-year return period for the mean P scenario will correspond to a 50-year event, and runoff corresponding to 5-year return period for minimum scenario will correspond to a 25-year event, for the same scenarios after using LIDs. The de- crease in runoff reduction was more for climate scenarios that had less precipitation for the future time period. Among the implemented LID types, porous pavement was noted to have the greatest effect on peak flow reduction. In summary, faced with uncertain future weather conditions considering the adverse impacts of cli- mate change, LIDs can provide mitigation benefits.”
“New York City is adopting this new stormwater rule to reduce the adverse impacts on City sewers from runoff during rainstorms that are more severe than combined sewers are designed to handle and, to the greatest extent possible, maximize the capacity of these systems. Sewer overflows, floods, and sewer backups can occur when excessive stormwater from impervious surfaces enters too quickly into the combined sewer system. The new Stormwater Rule will allow the City to more effectively manage stormwater runoff from new developments and alterations in combined sewer areas by reinforcing, specifying and prescribing the methods and standards for the application, permitting, construction and inspection of sewer connections to the City sewer system. DEP expects the rule to: *slow the flow of stormwater from sites, *mitigate flooding and sewer backups, *protect the sewer system, and, *mitigate combined sewer overflows.” The new rule is: “For a new development, the Stormwater Release Rate will be the greater of 0.25 cubic feet per second (cfs) or 10% of the Allowable Flow, unless the Allowable Flow is less than 0.25 cfs, in which case the Stormwater Release Rate shall be the Allowable Flow. (Allowable Flow means the stormwater flow from a development that can be released into an existing storm or combined sewer based on existing sewer design criteria.)” <ref>The City Record, January 4, 2012, NYC (mode detail on this new rule is found in this document). More info found in</ref>
City of Philadelphia Green Streets Design Manual 2014 – “As we witness the effects of climate change causing storms of greater frequency and severity, the green infrastructure we build on our streets is an added safeguard that can help mitigate flash flooding during such events.”
*US 3rd National Climate Assessment (Melillo et al 2014) – Key Message 11: Adaptation Opportunities and Challenges – green infrastructure listed as on the adaptation strategies. “Increasing resilience and enhancing adaptive capacity provide opportunities to strengthen water resources management and plan for climate change impacts. Many institutional, scientific, economic, and political barriers present challenges to implementing adaptive strategies.”
*City of Moncton – Climate Change: Adaptation and Flood Management Strategy (2013) – an adaptation strategy listed is “Adopt zero-net stormwater policies and regulations in order to reduce the quantity of stormwater run-off”
*Lake Champlain Basin Program (2015) recommends the use of LID as an adaptation strategy “be located outside of established flood hazard zones. As new development occurs, the conservation of functioning ecosystems, widespread adoption of GSI and LID practices, and awareness of the impacts of flooding are fundamental climate-ready tools. Training and funding for implementation of better management practices is necessary to prepare for future changes.”

Navigation menu