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Climate change

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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==.
==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==
==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. 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%.” <ref>Praskievicz, S, and H Chang. 2011. “Impacts of Climate Change and Urban Development on Water Resources in the Tualatin River Basin, Oregon.” Annals of the Association of American 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 3410 mm/yr for El Nino years (1954 – 2012) and from 1540 to 3330 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, 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==
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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