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‘No-regrets’ approach
[[File:Lake_Ontario_Drought_2007.png|thumb|Drought conditions at Island Lake in the summer of 2007]]
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 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== ===Climate-related impacts===Since 1995, Ontario has had a weather-related state of emergency almost every single year <ref>Swiss Re (in collaboration with Institute for Catastrophic Loss Reduction) (2010). Making Flood Insurable for Canadian Homeowners. Available at URL: http://www.iclr.org/images/Making_Flood_Insurable_for_Canada.pdf</ref>. The City of Windsor saw extreme events that caused severe flooding in 2007, 2010, 2016 and 2017 <ref>City of Windsor. 2012. Climate Change Adaptation Plan. Available at URL: http://www.citywindsor.ca/residents/environment/environmental-master-plan/documents/windsor%20climate%20change%20adaptation%20plan.pdf</ref>. The Ottawa region experienced one extreme event every year for five years, and in the Greater Toronto Area (GTA), there have been four extreme rainfall events in the past ten years <ref>Environment Canada. 2014. Climate. Available at URL: http://climate.weather.gc.ca/</ref>. Such high intensity events produce heavy rainfall in relatively short periods of time. While it is reasonable to expect runoff to be produced under such conditions – particularly when rain falls which exceeds a soil’s hydraulic conductivity - the production of stormwater is exacerbated in urban areas where the overwhelming majority of surfaces are impervious. The problems associated with managing stormwater volumes are exacerbated when dense storm sewer networks efficiently convey stormwater runoff volumes from a large contributing upland area to a single outlet location, such as a storm-sewer outfall in a river or stream. In July 2013, the GTA experienced its most severe storm event in 60 years. Nearly five inches (126 mm) of rain fell in a two-hour period. In comparison, during Hurricane Hazel (a devastating event in 1954 where 81 lives were lost), the two-hour maximum precipitation was 91 mm and the total amount of rainfall was 285 mm over nearly two days <ref>Toronto Star. 2013. Monday’s storm vs. Hurricane Hazel. Available at URL: http://www.thestar.com/opinion/letters_ to_the_editors/2013/07/14/mondays_storm_vs_hurricane_hazel.html</ref>. Conventional municipal drainage systems could not carry stormwater away fast enough. Roads and highways were overcome with floodwater closing major transportation corridors including Highway 427. GO Train passengers were stranded, and power outages and basement flooding were widespread with property damage of more than $1 billion. <ref>Insurance Bureau of Canada (IBC). 2016. Facts of the property & casualty insurance industry in Canada. 36th edition, ISSN 1197 3404. Available at URL: http://assets.ibc.ca/Documents/Facts%20Book/Facts_Book/2016/Facts-Book-2016.pdf</ref>. While it is nearly impossible to ascribe the cause of a single event to the broader issue of climate change, the trend is clear: an increasing number of high-intensity, short-duration (HISD) events are impacting our urban areas, exacerbating the stresses on overtaxed stormwater infrastructure. The figure highlights a series of seven recent extreme rainfall events which have struck the Greater Toronto and Hamilton Area (GTHA). On August 10, 2012, a large storm tracked across Lake Ontario parallel to the Canadian shoreline. Situated only 15 km southeast of Mississauga, this event lasted 6.5 hours and had estimated sustained intensities of 150 - 200 mm/hr. While the impacts of extreme rainfall events on urban areas cannot be ignored, the increasingly prolonged, dry inter-event periods necessitate that stormwater infiltration and percolation be maximized in order sustain base flows in support of aquatic ecosystems. While urban flooding and extreme rainfall garner the most attention in discussions pertaining to stormwater management, it is crucial that consideration also be given to the management of our water cycle during dry periods as well. Collectively, we need to be able to manage extreme rainfall events such as the July 8, 2013 storm, combined rain and snow events such as that which caused the Bow River flood in Calgary in 2013, and extended periods of drought as occurred in southern Ontario in 2007. Drought preparedness is required if we are to sustain riverine baseflows, ensure the security of drinking water resources and optimize both water and waste water infrastructure.  As municipalities grapple with these new climate realities and their associated costs, they are rethinking how to manage stormwater using a variety of innovative solutions. The figure illustrates what has already happened in Ontario under conditions of prolonged drought. The Island Lake Reservoir, located near the Town of Orangeville, saw significant drawdown during the summer of 2007 after a period of prolonged drought. Reliant on [[groundwater]] for its municipal supply, continued pumping by the Town led to a significant drawdown within the reservoir. This was problematic not just for the ecosystem of the Lake, but for the downstream wastewater treatment plan as well, which relies on discharges from the reservoir in order to ensure that treated effluent can safely be assimilated by the receiving watercourse.</div> ==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  ==Climate Trends in Ontario=====Observed to date===* IDF: Changing rainfall intensities affect stormwater runoff timing, peak rates and volumes; Methods have been relying on static IDF curves* Increased frequency of 12% and increase intensity of 16% of extreme precipitation events for 1958 - 2007 for the US Northeastern region <ref>Larson, L, Nicholas Rajkovich, and Clair Leighton. 2011. “Green Building and Climate Resilience: Understanding Impacts and Preparing for Changing Conditions.” University of Michigan, 260. http://scholar.google.com/scholar?hl=en&btnG=Search&q=intitle:GREEN+BUILDING+AND+CLIMATE+RESILIENCE+Understanding+impacts+and+preparing+for+changing+conditions#0.</ref>* “Percent changes in the amount of precipitation falling in very heavy events (the heaviest 1 %) from 1958 to 2012 for each region. There is a clear national trend toward a greater amount of precipitation being concentrated in very heavy events, particularly in the Northeast US (71 %) and Midwest US (37 %).” <ref>Melillo, Jerry M, T C Richmond, Gary W Yohe, and US National Climate Assessment. 2014. Climate Change Impacts in the United States: The Third National Climate Assessment. US Global Change Research Program. Vol. 841. https://doi.org/10.7930/j0z31WJ2.</ref>* “As for the temporal trends, significant warming trends are detected throughout the province of ON and the overall trend in annual mean temperature varies largely between 0.01 and 0.02 ∘C year–1. Increasing trends in annual rainfall (by 1 – 3 mm/year) and total precipitation (by 1 – 4 mm/year) are detected at the vast majority of gauged stations, but no significant trends in annual snowfall are identified at most of the stations.”<ref>Wang, Xiuquan, Guohe Huang, and Jinliang Liu. 2016. “Observed Regional Climatic Changes over Ontario, Canada, in Response to Global Warming.” Meteorological Applications 23 (1):140–49. https://doi.org/10.1002/met.1541.</ref>* “Extreme downpours are now happening 30 percent more often nationwide than in 1948. In other words, large rain or snowstorms that happened once every 12 months, on average, in the middle of the 20th century now happen every nine months. Moreover, the largest annual storms now produce 10 percent more precipitation, on average.”  Madsen et al 2012 a study in the US* “Extreme weather events including prolonged heat waves, torrential rainstorms, windstorms, and drought have increased throughout Ontario in recent years (Ontario, 2011). The frequency of very hot days (above 32°C) is expected to increase by 2.4-fold in Ontario by the late 21st century (Vavrus and Dorn 2009)”.  cited in Thunder Bay, 2015* “Increases in the frequency and magnitude of extreme rainfall events have been documented in New York State (Fig. 1). These changes are among the largest seen within the United States (DeGaetano 2009). Climate change projections suggest that these increases will continue (Frumhoff et al. 2007).”  in Tryhorn 2010 ===Projected===*Increase in frequency and intensity of extreme precipitation events between now and 2100 (Larson et al 2011)* “The analysis indicates that there is likely to be an obvious warming trend with time over the entire province. The increase in average temperature is likely to be varying within [2.6, 2.7]8C in the 2030s, [4.0, 4.7]8C in the 2050s, and [5.9, 7.4]8C in the 2080s. Likewise, the annual total precipitation is projected to increase by [4.5, 7.1]% in the 2030s, [4.6, 10.2]% in the 2050s, and [3.2, 17.5]% in the 2080s. Furthermore, projections of rainfall intensity–duration–frequency (IDF) curves are developed to help understand the effects of global warming on extreme precipitation events. The results suggest that there is likely to be an overall increase in the intensity of rainfall storms. Finally, a data portal named Ontario Climate Change Data Portal (CCDP) is developed to ensure decision-makers and impact researchers have easy and intuitive access to the refined regional climate change scenarios.”  in Wang et al 2015* “Some researchers, however, have demonstrated that the volume (Kuchenbecker et al. 2010, in Germany; cited in Bendel et al. 2013), frequency (Bendel et al. 2013, in Germany; Fortier and Mailhot 2014, May and October in Canada) or mean annual duration (Fortier and Mailhot 2014,in Canada) of CSOs should increase in the future climate. Logically, these increases will cause water quality to deteriorate in urban rivers – impacts that could be more severe as a result of increased water temperature.”  St-Hilaire et al 2016** For York Region: “• Of all temperature variables, the minima are anticipated to increase the most significantly by the 2050s in all seasons and on an annual basis (i.e. minimum temperature, average minimum temperatures) • Precipitation is expected to increase annually and over most months; however, may in fact remain relatively consistent or decrease compared with the current climate for the summer season • Extreme events are anticipated to become more frequent and more extreme. • Extreme heat indicators demonstrate that the number of days by the 2050s experiencing extreme temperatures will increase significantly. On the other hand extreme cold events are anticipated to decrease correspondingly by the 2050s, where the number of days exhibiting extremely cold temperatures could decrease • Extreme precipitation events are likely to increase in magnitude and in frequency, particularly in the summer time when convective activity is highest in and surrounding York Region. The future trend of extreme precipitation intensity; however, is unclear. It is recommended that a conservative approach should be taken in planning and adapting for extreme precipitation events. • The growing season in York Region is expected to lengthen by over 30 days by the 2050s. With this, the start date will shift earlier and the end date will shift later in the year. It is less certain, but more likely than not, that drier conditions will be present throughout the growing season in the 2050s as a result of no significant increase in precipitation over summer months and significant increases in temperatures.”  OCC et al, 2016* “If [winter] precipitation falls as rain instead of snow, which may actually occur more frequently in temper- ate regions with climate change, phosphorus concentrations in winter have the potential to be equivalent to those observed in other seasons due to the ubiquitous impacts of runoff events.”  Long et al 2014, a study done in Hamilton, ON* “Another potential impact of climate change on summer nutrient conditions that has been discussed in the literature is an increase of summer soluble reactive phosphorus (SRP) concentrations in creeks during low flow conditions due to temperature-dependent release from riverine sediments.”  Long et al 2014* “Dominguez et al. (2012) found increases in the intensity of 20- and 50-year return period winter precip- itation events over the western United States, while over Canada, Mailhot et al. (2012) showed that the intensity of annual maxima precipitation would increase, with the largest increases for Ontario, the Prairies and Southern Quebec.”  from Guinard et al 2015* “The hydrological response to climate change was investigated through stormwater runoff volume and peak flow, while the water quality responses were investigated through the event mean value (EMV) of five parameters: turbidity, conductivity, water temperature, dissolved oxygen (DO) and pH. First flush (FF) effects were also noted. Under future climate scenarios, the EMVs of turbidity increased in all storms except for three events of short duration. The EMVs of conductivity were found to decline in small and frequent storms (return period <5 years); but conductivity EMVs were observed to increase in intensive events (return period ½5 years). In general, an increasing EMV was observed for water temperature, whereas a decreasing trend was found for DO EMV. No clear trend was found in the EMV of pH. In addition, projected future climate scenarios do not produce a stronger FF effect on dissolved solids and suspended solids compared to that produced by the current climate scenario.”  He et al 2011* “The potential consequences of climate change for P cycling in streams include (i) increasing prevalence of droughts and extreme summer low flows causing a reduction in baseflow dilution capacity, increased P retention during summer as residence times increase and a greater frequency of anoxia (Caruso, 2002; Van Vliet and Zwolsman, 2008), (ii) changes in magnitude and frequency of extreme high flows and floods causing reduced river P retention capacity and net in-channel loss of P under eutrophic conditions, greater seasonal variability in runoff volumes, carbon and nutrient inputs from terrestrial sources (e.g. more winter runoff and less summer runoff), scouring of streams and more frequent flushing of storm sewer overflows (Newson and Lewin, 1991; Schindler, 1997; Biggs et al., 2000; Bouraoui et al., 2002; Wilby et al., 2006a), (iii) greater range and higher average air tempera- tures causing warming of water temperatures in shallow streams, increasing the time window of biological activity, higher rates of primary production, increased soil wetting/ drying cycles, greater rates of OM mineralization and greater dissolved organic carbon (DOC) concentrations reaching the stream with impacts on microbial populations and metabolic rates (Wilby et al., 2006b; Durance and Ormerod, 2007; Harrison et al., 2008).”  Withers and Jarvie 2008 – study on phosphorus in rivers, this quote shows how climate change would also negatively impact the phosphorus cycle* Climate change can substantially increase future urban runoff volume and peak flow rate (Zahmatkesh et al 2016).* Zahmatkesh et al 2015 report a potential increase of up to 60% in precipitation in the NYC region by 2030. * Pyke et al 2011 – Boston scenario for with and without LID vs conventional* “Burian (2006) assesses drainage infrastructure performance in response to increased precipitation intensity. The results show that upstream parts of urban drainage catchments in the United States may be resilient to precipitation effects of climate change because most development codes have required a minimum pipe size that has resulted in oversized drainage systems. Results also show downstream parts of urban catchments are more affected by in- creased precipitation intensity and thus more susceptible to the effects of flooding from climate change.”  cited in Zahmatkesh et al 2014* Impacts of weather on buildings, roads, bridges, hydro-transmission lines, stormwater drainage, drinking water and water treatment services, natural gas and communication lines, range from softening of tarmac during summer heat waves and cracking of concrete during freeze-thaw cycles, to catastrophic flooding, road washouts, ice and windstorm damage. The frequency and intensity of all these small- and large-scale effects is changing and infrastructure of all kinds is in danger of becoming subject to conditions for which it was not designed. For example, this means that the environmental performance of some infrastructure, such as wastewater and stormwater infrastructure may become inadequate, which would have impacts on the water quality, water quantity and the ecosystem.  Ontario 2012 (Action Plan)* “Thus, in order to adapt to the increased winter precipitation expected with climate change, greenspace provision will need to be considered alongside increased storage. There is significant potential to utilize sustainable urban drainage (SUDS) techniques, such as creating swales, infiltration, detention and retention ponds in parks”  Gill et al 2007* “CC effects were on average two orders of magnitude greater than LU impacts on mean daily stream T. LU change affected stream T primarily in headwater streams, on average up to 2.1°C over short durations, and projected CC affected stream T, on average 2.1 - 3.3°C by 2060.” <ref> Daraio and Bales 2014 – a modelling study that assesses the effects of land use vs climate change on urban stream temperatures </ref>*Higher temperatures, greater annual precipitation, larger precipitation events, increase in frequency of high flow events. Future climate scenarios predict a 40% increase in future TSS loading. Return periods for critical flows are reduced in future scenarios, while larger storms will be more frequent. Baseflow will decrease with potential impacts on rates of stream aggradation. Increased risk of erosion damages to infrastructure . Stream crossings may need to be larger. Erosion thresholds exceeded more frequently. Greater sediment loading in watercourses. Combines with higher peak flows and lower baseflow, altered sediment transport regimes could change the way our rivers form and adjust. Potential change in vegetation, habitat with increase of invasive species, drying wetlands, stress on fish species in warm and turbid waters.  Karen Hofbauer 2016 NCD 2016 Conference Presentation. Need to contact her in few months to obtain a draft of the study. Based in Hamilton – good local example of potential impacts of climate change to local streams and rivers.
==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. https://doi.org/10.1016/j.jhydrol.2014.07.037.</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. https://doi.org/10.1016/j.scitotenv.2016 – 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. https://doi.org/10.1016/j.buildenv.2014.07.018.</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. https://doi.org/Pii 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. https://doi.org/10.1002/2013WR014282.Received.</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. https://doi.org/10.1002/hyp.10736.</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. ===MOECCMECP===
MOECC 2014 (Ontario’s Climate Change Update) – Glen Murray intro “To keep reducing emissions with a growing population, we need to build for the future. More energy-efficient buildings, smart urban planning, low-carbon transportation options, and green infrastructure are just some of the solutions we need.”
MOECC 2015 – (Ontario Climate Change Strategy): “Build green infrastructure to restore eco- systems, reduce atmospheric carbon and protect and expand carbon sinks. Green infrastructure is inter-connected networks of green open spaces that provide a wide range of ecosystem services. Benefits of green infrastructure include cooling communities, reducing the urban heat island effect which, in turn, improves air quality and reduces the impacts of heat stress on our health, preserving biodiversity and pollinator health, capturing and filtering rainwater to reduce flood risk and improve water quality, and promoting carbon sequestration to reduce emissions.”
===City of Toronto===City of Toronto Green Streets Guidelines Draft 2016 – “Green streets incorporate green infrastructure into the road rights-of-way to complement or replace grey infrastructure, to build a city that is resilient to climate change and that contributes to an improved quality of life. Green infrastructure as defined in Toronto’s Official Plan refers to “natural and human-made elements that provide ecological and hydrological functions and processes” (Toronto, 2016). Examples of green infrastructure integrated into green streets can include: alternate energy sources, high efficiency lighting, street trees, permeable surfaces, Low Impact Development (LID) stormwater infrastructure and more.”…” Finally, in May of 2016, the Ministry of Municipal Affairs and Housing (MMAH) approved an amendment to policies within the City’s Official Plan (OPA 262) that focuses on climate change, energy conservation, green infrastructure and the natural environment. Adoption of this amendment affects several sections of Toronto’s Official Plan policy framework.”….” The City’s vision was amended to include the following: *a healthy natural environment including clean air, soil, energy and water; *infrastructure and socioeconomic systems that are resilient to disruptions and climate change; and,*a connected system of natural features and ecological functions that support biodiversity and contribute to civic life.”…From Climate Change Adaptation Chapter  “According  According to Toronto’s Future Weather & Climate Driver Study: Outcomes Report (Senes<ref>Theobald, K., Z. Radonijc, B. Telenta, S. Music, D. Chambers, 2012)and J.W.S. Young. 2011. “Toronto’s Future Weather and Climate Driver Study.” Toronto.</ref>, over the coming decades, climate change will produce variable weather patterns throughout the City of Toronto. The study projects some positive outcomes, such as shorter, milder winters with less snow and more rain as well as and longer growing seasons, however it also warns of the occurrence of extreme weather events.”….” The GTSG seeks to assist in climate change adaptation efforts by providing a tool that outlines proper design, construction and care of green infrastructure practices within road rights-of-way that will: * Enhance ecology and reduce heat Island effect; * Protect air quality; * Manage stormwater quality, quantity & efficiency; * Reduce greenhouse gases and promote energy efficiency.”….” "Unlike conventional stormwater management systems, some LID practices have the potential to be expanded to provide additional storage capacity. This will be of critical importance for ensuring that Toronto remains a resilient City in spite of potential future changes in precipitation volumes and patterns that may occur as a result of climate change.”…..o Based on these predictions, the City of Toronto should take aggressive action immediately to not only reduce greenhouse gas (GHG) emissions, but also to adapt to changes that will be imminent in the coming decades. The City of Toronto defines climate change adaptation as “initiatives and measures taken to reduce the vulnerability of natural and human systems to actual or expected climate change effects.” Some notable examples of “adaptive actions” already being implemented in the City include: *Increasing the size of storm sewers and culverts to handle greater volumes of runoff; *Increasing the frequency of inspection and maintenance of culverts both as part of a routine inspection program and after storm events; *Changing the slope of the land at the lot level to direct runoff away from property that can be damaged by excess surface water; *Installation of basement backflow preventers and window well guards to reduce flooding risks; *Using cool/reflective materials on the roofs of homes and buildings to reduce urban heat island effect.
===York Region===
The Region is increasing its efforts to combat climate change, including adopting best practices for infrastructure design. Other strategies include: *Improve hydrological data collection *Use of models and monitoring localized effects *More frequent monitoring and maintenance *Improve bridge, road and culvert design to be more climate change resistant <ref>York Region Transportation Master Plan 2016</ref> 
===Town of Ajax===
The Official Plan for Ajax has extensive content and calls for the promotion of LIDs to treat SWStormwater. they also mention that new infrastructure needs to be sized properly, although they do not specially say if there are new requirements.  Town of Ajax <ref>OCC, GLISA, Clean Air Partnership. 2016. “Historical and Future Climate Trends in York Region."</ref> 
===City of Ottawa===
Ottawa (Boliviar Philips 2013): “Green infrastructure and low impact development (LID)10 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 .11 The success ” <ref>Boliviar Philips. 2013. “Adaptive Approaches in Stormwater Management for City of Ottawa.” City of these green infrastructure plans is worth noting as a possible avenue for stormwater management adaptation (and many other Ottawa, no regret benefits) in Ottawa and is discussed further in Section 9 (pg. 44)July:81.</ref>
===Thunder Bay===
Thunder Bay – “Climate-ready city: City of Thunder Bay climate adaptation strategy” 2015. Stormwater management is one of 5 areas of adaptation efforts: The way stormwater is managed will be crucial as extreme weather events increase in frequency and intensity. The City's Stormwater Management Master Plan will consider climate change impacts and focus on resilient Low Impact Development (LID) and Green Infrastructure to reduce and treat stormwater while also delivering many other benefits to the community.  GOAL 4. CONSIDER CLIMATE CHANGE IMPACTS IN THE DESIGN, CONSTRUCTION AND MAINTENANCE OF PHYSICAL INFRASTRUCTURE WHILE CONSIDERING AFFORDABILITY AND CO- BENEFITS: Objective 4.1 Objectives include:#Incorporate new technology and best practices in the design, construction and maintenance of new municipal infrastructure and facilities to minimize service disruption and increase resiliency. Objective 4.2 #Identify retrofit opportunities for municipal infrastructure to minimize service disruptions related to extreme weather events. Objective 4.3 #Investigate areas of priority to incorporate best practices and green infrastructure into community and land- use planning and design. The hectares of catchment areas of LID sites is an indicator of Goal 4. #Develop education and communication materials promoting the use and benefits of green infrastructure. #Prepare a tool kit or resource kit for City administration with information on available best practices and latest innovations in green infrastructure relating to community and land-use planning and design.<ref>Thunder Bay. 2015. “Climate-Ready City: City of Thunder Bay Climate Adaptation Strategy,” no. December:116.</ref>
==Other Jurisdictions==
===IPCC===
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 http://www.sprlaw.com/new-york-city-adopts-new-stormwater-performance-standards-for-development-projects/</ref>
===Philadelphia===
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.”
==Temperature==

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