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Climate change

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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.
 
==Concerns with projections==
*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
 
* “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)
==Impact of observed and projected climate change on urban infrastructure==
* Stormwater is sensitive to 3 main drivers – amount of impervious cover, precipitation volume and event intensity.
* Natural vs built infrastructure
* “Typically, stormwater management practices are designed to meet performance standards based on historical climate conditions. In the coming decades, however, the built environment, including stormwater management systems, may need to meet performance expectations under climatic conditions different from those in recent history (IPCC, 2007; Karl, Melillo, & Peterson, 2009; Milly et al., 2008; USGCRP, 2009)”.  cited in Pyke et al, 2011
===Mitigation, adaptation and resiliency===
*According to The Co-operators (2014), the City of Toronto scored a grade of B- for flood preparedness. Among 16 metrics, the Urban Drainage Maintenance metric scored as one of the lowest, with a grade of D. “Urban drainage maintenance refers to pro-active efforts to ensure that structures such as culverts, sewer grates and storm sewer systems remain clear. Eight cities in the survey have established formalized programs to maintain urban drainage – notably, Vancouver is near completion of an integrated storm water management plan, which will include recommendations for green infrastructure on public and private land.”  The Co-operators 2014
 
*“Some responders noted that installation of backwater valves provides only a secondary line of defense. Improvements to drainage infrastructure, long term investments into redevelopment of sanitary and storm sewer systems, and the introduction of green infrastructure techniques are also required to protect property from loss.”  The Co-operators 2014
 
*Bill 72, the Water Opportunities and Water Conservation Act Section 26(2) 4. “An assessment of risks that may interfere with the future delivery of the municipal service, including, if required by the regulations, the risks posed by climate change and a plan to deal with those risks.”  calls for a plan to deal with risks of climate change
 
* “Characteristics of a resilient urban system are its ability to bounce back from impacts which may include elements of flexibility, diversity, sustainability, adaptability, self- organization, self-sufficiency, and learning.6 However, community resilience and climate adaptation are difficult to assign value, given uncertainties about future climate impacts and the subsequent difficulty in knowing when a community is adequately “adapted.” Multiple goal, no-regrets policies centered on “green-infrastructure” can offer measureable benefits regardless of how climate changes.”  in Foster et al 2011
 
* Resilience: “The ability of a system to absorb and rebound from weather extremes and climate variability and continue to function.”; Adaptation: “Any action or strategy that reduces vulnerability to the impacts of climate change. The main goal of adaptation strategies is to improve local community resilience.”  Roseen 2008
* “Moreover, adaptation to climate change emphasizes system resilience, which refers to ‘the amount of change a system can undergo and still retain the same function and structure’ (Nelson, Adger, & Brown, 2007, p. 398). Green infrastructure can moderate the adverse impacts of climate change and may enhance our ability to deal with larger-scale extreme weather events. These contributions are usually articulated in terms of resilience, which describes the ability of communities to recover from shocks and return to a functional state within a reasonable timeframe (Pelling, 2011; Renn, 2008).”  Matthews et al 2015
* “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
*‘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===
Drill down the fact that stormwater is not waste, but rather a resource. It is not in anybody’s interest to get rid of it quickly – move away from the ‘out of sight out of mind’ mindset. Stormwater can be captured, treated and reused and these benefits can be enjoyed by nature, taxpayers, residents, municipalities.
*“Unlike the usual environmental flow problem of needing to allocate a reduced volume of water to the environment, urban stormwater runoff presents a problem of increased runoff volume, which should be prevented from reaching receiving streams and thus could be used by humans….. Urban stormwater runoff is thus revealed as the best type of problem, because solving it provides an opportunity to solve other problems such as the provision of water for human use in cities.”  Walsh et al 2012
*“stormwater will be considered to be a valuable water resource to be retained and infiltrated into the land within the Built Environment to the fullest extent possible, not a waste product”  Town of Ajax 2016 (Official Plan)
===The business case for becoming climate-ready===
Floods are expensive and they are expected to increase with climate change; it is worthwhile to invest in flood-mitigating measures to reduce the overall cost of disasters. LIDs could be more cost-effective options even for day-to-day stormwater management.
*Frequency and severity of extreme events is the most costly impact of climate change. Rise in insurance claims due to extreme weather. Taking pro-active measures can help avoid these costs

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