# Difference between revisions of "Climate change"

Six notable extreme rainfall events have occurred within the past thirteen years in the GTHA, resulting in damages due to flooding. This figure shows a notable extreme rainfall “near-miss” event, labelled “Lake Ontario 2012”.
Radar tracking of the August 10, 2012 extreme rainfall event. The Lake Ontario nearshore experienced sustained intensities approaching 200 mm/hr, while the southern portion of Peel Region had no measurable precipitationAny form of rain or snow.. (Source: Risk Sciences International)
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(1) The wearing away of the land surface by moving water, wind, ice or other geological agents, including such processes as gravitation creep; (2) Detachment and movement of soil or rock fragments by water, wind, ice or gravity (i.e. Accelerated, geological, gully, natural, rill, sheet, splash, or impact, etc).,
• Stabilize groundwater rechargeIncreases in groundwater storage by natural conditions or by human activity. See also artificial rechargeThe inflow of surface water to a groundwater reservoir or aquifer.,
• Reduce urban heat island,
• Lower energy use.

## Impact of observed and projected climate change on urban infrastructure

• Stormwater is sensitive to 3 main drivers – amount of imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. cover, precipitationAny form of rain or snow. 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 environmentRefers to the conditions in which an organism lives and survives or the conditions in which an organism resides. These conditions can be described as aspects of a “physical”, “social” or an “economic” environment, depending on the perspective perceived by the observer., 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
• Climate change and urbanizationThe changing of land cover and land uses from rural to urban; the growth of urban settlements. forma vicious circle: you cannot separate the two as they form a loop, whereby urbanizationThe changing of land cover and land uses from rural to urban; the growth of urban settlements. exacerbates climate change, and climate change drives people to urban centers which results in urbanizationThe changing of land cover and land uses from rural to urban; the growth of urban settlements.
• “Over the coming century, climate change scenarios project that urban regions will be expected to manage extremes of precipitationAny form of rain or snow. and temperature, increased storm frequency and intensity, and sea-level rise. Increases in problems with which urban areas are already coping may be indicating–or at least mimicking – that climate change impacts are already occurring and are likely to worsen in the future.2 In practice, these impacts will mean coping with: • Longer and hotter heat waves • Increased urban heat island (UHI) impacts such as heat related illness and higher cooling demand and costs • More damaging storms and storm surges • Greater river flooding • Increased frequency and intensity of combined sewer overflows (CSOs) • More intense and extended duration of droughts • Longer water supply shortages, and • Declines in local ecosystemA biological community, including humans and their natural environment. services, such as the loss of coastal wetlands that buffer communities against hurricanes.”  Foster et al 2011
• “With climate change comes an increased risk of intense storms, extreme precipitationAny form of rain or snow. events, flooding, and sea level rise (IPCC, 2014). This risk is more pronounced in urban areas due to the preponderance of paved, impermeable surfaces and critical infrastructure such as centralized energy grids and communications systems. EcosystemA biological community, including humans and their natural environment.-based solutions to this problem provide more permeability, slowing and sinking excess water, which in turn reduces pressure on wastewater treatment systems and diminishes the threat of floods.”  Nichol and Harford 2016
• Soil compaction is likely to reduce baseflows in catchments
• Conventional infrastructure degrades watercourses (Walsh et al 2012)
• “Nonpoint-source pollution, i.e., stormwater runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. in cities, is the main cause of stream water-quality degradation in North America (EnvironmentRefers to the conditions in which an organism lives and survives or the conditions in which an organism resides. These conditions can be described as aspects of a “physical”, “social” or an “economic” environment, depending on the perspective perceived by the observer. Canada 2001, Brown and Froemke 2012).”  in Wallace and Biastoch 2016
• “Stormwater management is a second fundamental concern when analyzing the impacts of climate change on regional water systems. The increased intensity and frequency of high- precipitationAny form of rain or snow. events will likely result in increased runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. and flooding (Wilby 2007). Additionally, future development locations and land use decisions play influential roles in determining future stormwater runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. impacts regionally. Analyzing future regional stormwater runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. patterns involves considering climate change impacts in conjunction with urban development patterns. One such study, performed on the Rock Creek BasinGround depression acting as a flow control and water treatment structure, that is normally dry. in Oregon, indicates that, given climate change projections, sprawling development patterns increase annual runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. by 5.5 percent compared to the baseline model, while a more compact development scenario results in increased annual runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. by 5.2 percent (Franczyk and Chang 2009). The researchers conclude that while regional development patterns have a significant impact on streamflow and water runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface., climate change is expected to have a greater impact on streamflow than land use change (Barlage et al. 2002; Chang 2003; Franczyk and Chang 2009). As water runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. has a strong connection to flood risk and damage in urban areas (Ashley et al. 2005), as well as impacts on the health of natural watersheds (Barlage et al. 2002), considering the future effects of climate change is extremely important.”  Larson et al 2011

## Becoming a climate-ready region through stormwater management

• 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 infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. 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 infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. 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 infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. 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
• Paragraph on the definition of resilient, adaptation and mitigation. Good paper on this  Voskamp and Van de Ven 2015
• “Land use management, including LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting., will be an important component of strategies for adaptation. Research has shown that the effects of land use and climate change on watersheds can vary, yet the two factors can operate synergistically, increasing the magnitude of stormwater runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. and overall water quality impacts (Chang, 2004; Tu & Xia, 2008).”  cited in Pyke et al 2011
• “Adaptive capacity is defined as the ability of a system to adjust its characteristics or behavior to expand its coping range to respond successfully to climate variability and change. This includes the re-sources available for adaptation as well as the ability of the system to use these resources effectively toward adaptation. Adaptive capacity may be aided or con- strained by factors both inside and outside the community (e.g., social and ecological reasons, cost, state or national regulations, etc.) Social capital is a key component (Brooks and Adger 2005), including the relationships between community members, participation in decision making processes (Moore and Koontz 2003), and the presence of leadership that is willing to advance adaptation objectives (Lowe et al. 2009).”  Tryhorn 2010
• Roseen et al 2011 (study for University of New Hampshire) have an extensive chapter on LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. as a climate change adaptation tool and have case study examples
• “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 runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface.), 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 precipitationAny form of rain or snow. events, they will improve the function and resilience of existing stormwater infrastructure by reducing runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. volumes, thereby freeing up capacity within the downstream stormwater drainage systemA system flow of gully inlets, pipes, overland flow paths, open channels, culverts and detention basins used to convey runoff to its receiving waters. City of Toronto 45 Wet Weather Flow Management November 2006”  City of Toronto 2016 (green streets technical guidelines)

## 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 environmentRefers to the conditions in which an organism lives and survives or the conditions in which an organism resides. These conditions can be described as aspects of a “physical”, “social” or an “economic” environment, depending on the perspective perceived by the observer., urban stormwater runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. presents a problem of increased runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. volume, which should be prevented from reaching receiving streams and thus could be used by humans….. Urban stormwater runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. 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
• good paper on this by Walsh et al 2012 out of Australia
• “By not harvesting stormwater to keep an appropriate proportion of it out of receiving watersWatercourses and Lake Ontario, to which Stormwater and Combined Sewer Overflows discharge., we not only forego the benefits to society of this large water resource, but also contribute to the degradation of waterways”  Walsh et al 2012
• “Over the past two decades, the paradigm governing urban stormwater management has shifted from strategies that deal with runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. as a waste in end-of-pipe systems to those in which stormwater is viewed as a resource to be infiltrated, stored and/ or re-used at the site (Fletcher et al., 2014; Ahiablame et al., 2013). “  in Vogel et al 2015
• “If a community perceives their stream is a threat (e.g., due to the damage it might cause by flooding), local managers may be pressured to enact policies that degrade a stream’s aesthetic and ecological value (e.g., through installation of formal drainage with high effective imperviousness, and stream burial), unintention- ally reinforcing negative perceptions of the stream as a drain (red loop in the figure). Conversely, if a stream is perceived as a valuable asset, local managers may respond by enacting policies that protect the stream from urbanizationThe changing of land cover and land uses from rural to urban; the growth of urban settlements., reinforcing positive perceptions of the stream as an asset through increased property value and the provision of green space and other ecosystemA biological community, including humans and their natural environment. services (green loop).”  Askarizadeh et al 2015 –review paper of how LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. fits in stormwater management
• “Climate change is likely to reduce precipitationAny form of rain or snow., and therefore runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface., in many parts of the world (Arnell 1999). Reductions in runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. volumes from pervious catchments will be greater than reductions in volumes of runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. from imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. surfaces. Thus, urban stormwater runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. should be a more reliable source of water in response to long-term changes in rainfall patterns. Further- more, the diverse, deeper rooted perennial plant communities that are possible with well-irrigated urban green spaces may also exhibit increased resistance, as they are buffered from the vagaries of our ever harsher climate.”  in Walsh et al 2016
• “stormwater will be considered to be a valuable water resource to be retained and infiltrated into the land within the Built EnvironmentRefers to the conditions in which an organism lives and survives or the conditions in which an organism resides. These conditions can be described as aspects of a “physical”, “social” or an “economic” environment, depending on the perspective perceived by the observer. to the fullest extent possible, not a waste product”  Town of Ajax 2016 (Official Plan)

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
• “The increased frequency of urban flooding due to climate change is an additional challenge for stormwater systems. Urban flooding not only creates engineering system failures, but directly causes socio-economic loss in the form of: loss of personal property, associated health and safety issues, and psychological stress and distress. Improved management of infrastructure in terms of capital assets, cost reduction, service level, environmental protection, and efficient use of water resource are essential to water infrastructure’s sustainability (Infrastructure Canada 2006; EPA 2012). A necessary step for effective implementation is to assess whether the system is moving towards or away from being sustainable.” Upadhyaya et al 2014
• “Water, wastewater and stormwater infrastructure will re- quire about $400 per household per year to fulfill the investment deficit. A municipal property tax is inadequate to raise the required funds. Therefore, additional federal and provincial funding would be needed.” Upadhyaya et al 2014 *“There are strategies that can be adapted to reduce the risks of flooding while ensuring a minimal economic impact such as revising design criteria based on revised climatic projections, revised acceptable level of risk, and revised life span of infrastructures (Mailhot and Duchesne 2010). The long-term impact was evident, for example, in the flooding that occurred in the city of Peterborough (Ontario) in 2004. It was not realized, until many years after the event, that the actual cost of the flood ranged from$50 million to $300 million (Ontario Center for Climate Impacts and Adaptation Resources 2010) because the actual cost exceeded the projected cost; some of the costs were not visualized beforehand.”  Upadhyaya et al 2014 *“In Canada homeowners can be covered for sewer overflow but they cannot be insured for overland flooding (Sandink et al. 2010). …. The direct and indirect economic bur- dens related to managing stormwaters using inadequate and un- sustainable infrastructure and funding are significant.”  Upadhyaya et al 2014 *“Cincinnati, Ohio has formally agreed to eliminate 85% of its CSO volume in order to better comply with the Clean Water Act. As part of the planning process to comply with the Clean Water Act, a large waste- water storage tunnel was proposed for the Lick Run area. This tunnel was estimated to cost roughly$250,000,000 and have a capacity of roughly 40,000,000 gallons (MSD Cincinnati, 2012). It would have been constructed deep underground in the bedrock beneath the city, connected to existing sewers by dropshafts for transporting water and personnel, and include a pump station and wastewater plant upgrades to facilitate the treatment of its volume. This proposition has been rejected in favor of a plan that includes a type of green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. (GIGreen infrastructure) called rain gardens. Green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. uses vegetation, soils, and natural processes to infiltrate and evapotranspirate rainwater, as opposed to the engineered collection systems of traditional “grey” infrastructure that capture, treat, and discharge it (USEPA, 2014c).”  in Vineyard et al 2015
• “Garden implementation is heavily favored by higher discount rates due to its cost amortization versus that of the grey alternative. Whereas standard infrastructure requires a large upfront investment and relatively minor maintenance afterward, rain gardens require a proportionally smaller initial investment but (with required upkeep) can include a relatively higher lifetime maintenance cost; this maintenance cost is, however, more straightforward than the unevenly distributed tunnel maintenance. This relationship between cost and discount rate is exacerbated by the long construction time of a storage tunnel compared to the very short startup time of a rain gardenA lot level bioretention cell designed to receive and detain, infiltrate and filter runoff, typically used for discharge from downspouts..”  in Vineyard et al 2014
• “Insurance premiums are already rising to cover the industry’s rising weather-related losses. So, in light of this new normal, it is shortsighted that all three levels of government seem to be more focused on finding tax dollars to pay for last year’s flood or ice storm instead of addressing the challenge of what to do about next year’s extreme events that we know are coming. Decision makers need to move beyond a reactive stance, and instead forge a proactive plan to improve the resilience of our infrastructure.”  Env Comm of Ontario 2014  they list green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. as a tool that local municipalities use. They critique the current state of stormwater management

## LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. as a framework for climate-ready city-regions

Provide specific examples of how LIDs are beneficial. Provide references of studies and agencies that promote the use of LIDs.

### LIDs as preferred tools

• Zhou 2014 calls for LIDs to mitigate climate change
• Loperfido et al 2014 call for LIDs to mitigate climate change  “In areas predicted to receive more frequent and more intense precipitationAny form of rain or snow. events under climate change, distributed BMPs may be an effective means to achieve some reduction in runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. volume during extreme precipitationAny form of rain or snow. events as was observed during Tropical Storm Lee.”
• “Although hydrologic improvements provided by distributed BMPs were substantial, land cover appeared to play a dominant role in reducing total runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. volume and decreasing stream response during precipitationAny form of rain or snow. events. Thus, it is important to consider land cover factors (e.g., decreased imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. cover and greater forested area) as effective stormwater BMPs with respect to urban stream hydrology in addition to the implementation of distributed BMPs.”  Loperfido et al 2014
• “This paper has provided an assessment of several alternatives in the 7.05 ha catchmentThe land draining to a single reference point (usually a structural BMP); similar to a subwatershed, but on a smaller scale. of Shockoe Creek adjacent to the SMV. These alternatives included: Existing conditions, Gray (storage infrastructure), Green-Free (free discharge GSI with uncontrolled outlets), and Green-Control (GSI with controlled outlets). In terms of hydraulic performance, Green-Control performed substantially better than Gray. In terms of volume control, however it had slightly more overflow occurrences. In addition, the Green-Control alternative also has much less discharge after the event, reducing treatment plant operational costs. As the additional cost of installing such controls is nearly negligible, these benefits of outlet controls are clearly worth deploying in GSI SCMs. The relative position of both GSI alternatives improved with the altered climate alternative, indicating that they are more resilient than the Gray alternative. Furthermore, the reductions in peak flows by Green-Control are the greatest of all alternatives, providing the most benefits in terms of minimizing nuisance flooding and erosive flows. While the Gray alternative reduced CSOA discharge to the environment from a combined Sewer system that occurs because of a precipitation event when the capacity of the interceptor sewer or treatment plant is exceeded. It consists of a mixture of sanitary wastewater and Stormwater runoff. occurrences by the largest number, the larger benefits, smallest overflow volumes, and most resilient system was obtained by the Green-Control alternative. CSOA discharge to the environment from a combined Sewer system that occurs because of a precipitation event when the capacity of the interceptor sewer or treatment plant is exceeded. It consists of a mixture of sanitary wastewater and Stormwater runoff. volume is directly related to negative ecological impacts to receiving watersWatercourses and Lake Ontario, to which Stormwater and Combined Sewer Overflows discharge.. As such, this study has demonstrated that GSI provides a more sustainable solution to CSOs than gray. Hydraulic control of discharges is strongly recommended for GSI solutions to CSOA discharge to the environment from a combined Sewer system that occurs because of a precipitation event when the capacity of the interceptor sewer or treatment plant is exceeded. It consists of a mixture of sanitary wastewater and Stormwater runoff. mitigation.”  Lucas and Sample 2015
• “Insurance premiums are already rising to cover the industry’s rising weather-related losses. So, in light of this new normal, it is shortsighted that all three levels of government seem to be more focused on finding tax dollars to pay for last year’s flood or ice storm instead of addressing the challenge of what to do about next year’s extreme events that we know are coming. Decision makers need to move beyond a reactive stance, and instead forge a proactive plan to improve the resilience of our infrastructure.”  Env Comm of Ontario 2014  they list green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. as a tool that local municipalities use. They critique the current state of stormwater management
• “Third, the effect that retention ponds have on flood frequency diminishes in the downstream direction as the proportion of unregulated subcatchments that contribute to the peak dischargeThe greatest volume of stream flow occurring during a storm event. at the outlet also increases. This means that the flood mitigation benefits of flood retention ponds are primarily local, which underscores the added value of distributed flood retention ponds in terms of their ability to disperse the flood control benefits across the catchmentThe land draining to a single reference point (usually a structural BMP); similar to a subwatershed, but on a smaller scale..”  Awalew et al 2015 – study on pondA body of water smaller than a lake, often artificially formed. configuration in a modelled catchmentThe land draining to a single reference point (usually a structural BMP); similar to a subwatershed, but on a smaller scale.. Good point to use when claiming that LIDs are better suited to mitigate floods
• “Seattle is currently developing its first comprehensive Climate Preparedness Strategy, which underscores the value of flexible, scalable approaches that allow for adaptive management in the face of climate uncertainties. Distributed GSI installations are one such approach, offering protection against back up risks or other localized pipe capacity issues that are likely to be exacerbated by increased precipitationAny form of rain or snow. under climate change. Distributed GSI prevents stormwater from entering the piped system, preserving or enhancing existing capacity. Rainwater harvestingThe practice of intercepting, conveying and storing rainwater for future use. Captured rainwater is typically used for outdoor non-potable water uses such as irrigation, or in the building to flush toilets. and reuse reduces demand on drinking water supply and may also provide emergency drinking water sources in the case of natural disasters.”  Coven et al 2015
• RunoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. mitigation through emerging approaches like green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. and low impact developmentA stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. can apply this information to design sustainable urban ecosystems [Yang et al., 2013] and to increase the resilience of watershed systems to changing land use and climatic conditions.” Ekness and Randhir 2015
• “While the challenges of stormwater management appear to be vast, overcoming them creates opportunities to make gains beyond just controlling stormwaterSurface runoff from at-grade surfaces, resulting from rain or snowmelt events.. This is especially true when incorporating green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics.. Combining stormwater controls with other urban planning investments can lead to more vibrant communities, better climate change resilience, and cost savings”……” Communities also can use stormwater controls to improve climate resilience, which is the ability to adapt to and recover quickly from climate-change-related events. Climate”  WEF Stormwater Institute 2015
• Green Infrastructure Ontario states that LIDs provide climate change mitigation benefits (GIO 2012)
• “The modelling work presented here suggests that the use of urban greenspace offers significant potential in moderating the increase in summer temperatures expected with climate change. Adding 10 per cent green in high-density residential areas and town centres kept maximum surface temperatures at or below 1961–1990 baseline levels up to, but not including, the 2080s High.”  Gill et al 2007
• The implementation of LIDs has been identified as a strategy to adapt cities to climate change in a Netherlands paper  Albers et al 2015
• In a 2009 State of the Practice Report produced by TRCAToronto and Region Conservation Authority for the Region of Peel called for the implementation of LIDs to mitigate the impacts of climate change. TRCAToronto and Region Conservation Authority, 2009
• Studies have found LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. to be effective in moderating extreme temperatures and increased surface runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. (Gill et al 2007)
• Calling for an improved assessment of LIDs and how they can mitigate climate change back in 2011 (by Pyke et al 2011). An attempt to address this is done by Zahmatkesh et al 2015 who analyze the impacts of LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. related to climate change on a watershed in New York
• An example where LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. was recognized to mitigate effects of climate change – in 2012 Hurricane Sandy – Bloomberg and Strickland (2012) acknowledged that GIGreen infrastructure played an important role in “creating a resilient city that can not only manage its stormwater but recover more quickly from the impacts of climate change.”
• “Gill, Handley, Ennos, and Pauleit (2007) found LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. to be effective in moderating potential climate change impacts such as extreme temperatures” cited in Pyke et al 2011
• Landscape and greenspace can lessen the future effects of climate change, site level adaptation strategies are crucial (Larson et al 2011)
• “A study conducted by Zahmatkesh et al. (2015) showed that the introduction of LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. had the potential to mitigate the majority of expected runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. increase due to climate change in New York City. Stack et al. (2014) also documented similar potential to reduce flood vulnerability associated with climate change through LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. retrofits in Minnesota, though integrating structural LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. practices with natural green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. networks showed the greatest resilience to flooding across a range of climate change scenarios. As climate change issues receive greater attention from local governments, the technical evidence base now being developed to demonstrate the flexibility of LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. and GIGreen infrastructure to climactic change could support broader implementation.”  Vogel et al 2015
• “As to the National Post Construction Stormwater Rule, EPA has decided to defer action on rulemaking to reduce stormwater discharges from newly developed and redeveloped sites or other regulatory changes to its stormwater program. Instead EPA is redirecting its efforts to focus on pursuing a suite of immediate actions to help support communities in addressing their stormwater challenges. EPA will provide incentives, technical assistance, and tools to communities to encourage them to implement strong stormwater programs; leverage existing requirements to strengthen municipal stormwater permits; and continue to promote GIGreen infrastructure as an integral part of stormwater management. EPA believes this approach will achieve significant, measurable, and timely results in reducing stormwater pollution and provide significant climate resiliency benefits to communities.”  Goulding et al 2014

### What can LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. offer?

The examples below contain multiple examples of what LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. can offer in light of climate change and this is why they have not been placed in individual categories below. For example, when talking about the benefits of infiltration and filtrationThe technique of removing pollutants from runoff as it infiltrates through the soil., multiple sources from the list below can be referenced. In some cases where the source talks about one benefit specifically, it has been populated under the specific category.

• GIGreen infrastructure primarily benefits the environmentRefers to the conditions in which an organism lives and survives or the conditions in which an organism resides. These conditions can be described as aspects of a “physical”, “social” or an “economic” environment, depending on the perspective perceived by the observer. by eliminating the need for traditional grey infrastructure and its associated environmental impacts. Green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. can promote improved air and water quality (Nowak et al., 2006; CWP, 2007). GIGreen infrastructure has the potential to sequester atmospheric carbon, remove atmospheric pollutants, and reduce the urban heat island effect to save energy and money in cooling costs (Odefey et al., 2012). GIGreen infrastructure can restore natural hydrology, rechargeThe addition of water to ground water by natural or artificial processes.The infiltration and movement of surface water into the soil, past the vegetation root zone, to the zone of saturation or water table. groundwaterThe water below the surface, and typically below the groundwater table., eliminate CSOA discharge to the environment from a combined Sewer system that occurs because of a precipitation event when the capacity of the interceptor sewer or treatment plant is exceeded. It consists of a mixture of sanitary wastewater and Stormwater runoff. contributions, and slow the flow of stormwater to streams to restore stream health (Dietz, 2007; Davis, 2008; Stephens et al., 2012). Tzoulas et al. (2007) suggests there are considerable social benefits to the urban green space that accompanies GIGreen infrastructure.”  in Vineyard et al 2015
• “Figure 5 compares the impacts of the Shepherd Creek rain gardens to their grey counterparts. The stormwater storage tunnel and the wastewater treatment plant together emitted more environmental impacts in every category than the base case rain gardenA lot level bioretention cell designed to receive and detain, infiltrate and filter runoff, typically used for discharge from downspouts.. Choosing the green alternative offered important reductions in the eutrophication and global warming categories, which saw 98 and 90% reductions, respectively, according to our model….. They dramatically reduce environmental impacts in every impact category (with the possible exception of ecotoxicity). Of greatest interest are their benefits to both eutrophication and global warming, which they achieve by intercepting nutrient pollution before it can reach the wastewater and by reducing the use of electricity for wastewater treatment..”  Vineyard et al 2015
• “While the benefits of blue-green measures lie in general in the variety of ecosystemA biological community, including humans and their natural environment. services that can be provided [8,9], only a selection of services specifically contributes to adaptation to extreme events. These are the urban ecosystemA biological community, including humans and their natural environment. services (and corresponding climatic hazards): water flow regulation and runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. mitigation (pluvial flooding, drought), urban temperature regulation (heat stress) and moderation of environmental extremes (pluvial flooding, heat stress and drought) [12]. These regulating ecosystemA biological community, including humans and their natural environment. services are provided by ecosystemA biological community, including humans and their natural environment. functions: the bio- physical structures or processes in ecosystems [36]. The ecosystemA biological community, including humans and their natural environment. functions that underlie the ecosystemA biological community, including humans and their natural environment. services of concern are: infiltrationThe slow movement of water into or through a soil or drainage system.Penetration of water through the ground surface., retention in the soil, adsorptionThe attachment of gas, vapour or dissolved matter onto the surface of solid materials. on kinetic energy, storage, evapotranspirationThe quantity of water transpired (given off). Retained in plant tissues, and evaporated from plant tissues and surrounding soil surfaces. Quantitatively it is usually expressed in terms of depth of water per unit area during a specified period. e.g. mm/dayThe combined loss of water to the atmosphere from land and water surfaces by evaporation and from plants by transpiration. and rainfall interceptionThe interception, storage and eventual evaporation of rainfall from vegetation canopies. [12,37]. As it differs among blue-green measures if or in which degree these processes are present, the role in adaptation to heat stress, drought and pluvial flooding varies among the measures. Based on the ecosystemA biological community, including humans and their natural environment. functions present, the following blue-green measures are distinguished in this paper: * Storage & harvesting measures, facilitating water retention in the soil, storage or rainfall interceptionThe interception, storage and eventual evaporation of rainfall from vegetation canopies.; * AttenuationReduction of peak flow and increase of the duration of the flow event. measures, slowing down runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. during a rainfall event after the storage capacity of the measure has been exceeded; * Infiltration measures, enabling groundwater rechargeIncreases in groundwater storage by natural conditions or by human activity. See also artificial rechargeThe inflow of surface water to a groundwater reservoir or aquifer.; * Cooling measures, providing evapotranspirationThe quantity of water transpired (given off). Retained in plant tissues, and evaporated from plant tissues and surrounding soil surfaces. Quantitatively it is usually expressed in terms of depth of water per unit area during a specified period. e.g. mm/dayThe combined loss of water to the atmosphere from land and water surfaces by evaporation and from plants by transpiration.; see table below for details:
• “The approach seeks to create healthier more socially cohesive and biodiverse urban environments and a connected city ecosystemA biological community, including humans and their natural environment. for people and wildlife that also builds in resilience measures against climate change in the form of storm, flood, heat, drought and pollution protection. The Cities Alive approach seeks to positively utilise the key GIGreen infrastructure components that lie within our city environments and perform essential ecosystemA biological community, including humans and their natural environment. services. A GIGreen infrastructure-led design approach aims to create a network of healthy and attractive new and upgraded city environments, sustainable routes and spaces. The approach would build on, strengthen and link existing GIGreen infrastructure components described above. Over time this resilient and networked “city ecosystemA biological community, including humans and their natural environment.” will be capable of generating a substantial range of social, environmental and economic benefits for urban citizens, whilst also providing protection against the effects of climate change.”  Arup, 2014
• “Seattle has also set an ambitious goal to be a carbon neutral city by the year 2050 and is implementing its 2013 Climate Action Plan to sharply reduce greenhouse gas emissions across all sectors. GSI implementation supports Seattle’s carbon neutrality target in three principle ways: •GSI installations in combined sewer basinsGround depression acting as a flow control and water treatment structure, that is normally dry. reduce pumping and water treatment demand, saving the associated energy and GHG emissions. •The use of compostDecayed organic material used as a plant fertilizer. Compost helps to support healthy plant growth through the slow release of nutrients and the retention of moisture in the soil. in bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. soil mixes and all compostDecayed organic material used as a plant fertilizer. Compost helps to support healthy plant growth through the slow release of nutrients and the retention of moisture in the soil.- amended soil replacement triggered by Stormwater Code results in a net increase in soil carbon/sequestration. •Trees planted and retained have direct sequestration value as well as indirect mitigation value via shading.”  Coven et al 2015
• “The core principle of LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. is the management of increased runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. typically through filtrationThe technique of removing pollutants from runoff as it infiltrates through the soil. and infiltration strategies to provide treatment and reduce runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. volumes. These measures will have similar effects for managing increased storm sizes associated with changing rainfall patterns resulting from climate change.”  Roseen et al 2012
• “Yet adaptation has been slow, mainly because some potential solutions are politically unpalatable (Byrne & Yang, 2009). Other solutions may be expensive, may impact the rights of private propertyLand owned by private individuals or companies. owners, may require major changes to existing planning systems, or may constrain future property development options (Bulkeley, 2013). Green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. however, appears to be relatively quick to implement, is comparatively inexpensive, has broad public appeal, and is politically benign (Bowler, Buyung-Ali, Knight, & Pullin, 2010; Byrne & Yang, 2009). Moreover, it could gain rapid acceptance in an age where planning is increasingly attentive to urban infrastructure (Dodson, 2009).”  cited in Matthews et al 2015
• Green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. has broad appeal, largely due to its multiple benefits (Emmanuel & Loconsole, 2015; Gill, Handley, Ennos, & Pauleit, 2007; Jim, 2015; Kambites & Owen, 2006). For example, climate change will likely magnify urban heat island effects and increase flood events for many cities (Field, Barros, Stocker, & Dahe, 2012; Lo, 2013). Such impacts will likely be exacerbated by increases in ‘hard’ surfaces associated with rapid urbanizationThe changing of land cover and land uses from rural to urban; the growth of urban settlements. (e.g. concrete, stone, tile, asphaltA mixture of mineral aggregates bound with bituminous materials, used in the construction and maintenance of paved surfaces. and tarmac) (Field et al., 2012; Gartland, 2011).”  cited in Matthews et al 2015
• LIDs are not only useful in terms of a climate agenda, but are useful anyway – aesthetic and other socio-economic benefits
• “The biophysical features of greenspace in urban areas, through the provision of cooler microclimates and reduction of surface water runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface., therefore offer potential to help adapt cities for climate change.”  Gill et al 2007
• GIGreen infrastructure’s benefits are – CO2 reduction, thermal comfort and reduced energy use (green roofA thin layer of vegetation and growing medium installed on top of a conventional flat or sloped roof, also referred to as living roofs or rooftop gardens. given as example), reduced problems with flooding and improved water quality (bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. as example), effects on air quality, health and restorative benefits, education.  Demuzere et al 2014
• Literature on LIDs to reduce runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. and improving water quality at all scales is substantial ((e.g., Davis 2005; Dietz and Clausen 2005; Fach and Geiger 2005; Hunt et al. 2006; Carter and Jackson 2007; Dietz 2007; Elliott and Trowsdale 2007; Scholz and Grabowiecki 2007; Collins et al. 2008; NRC 2008; Bedan and Clausen 2009; Davis et al. 2009; Hinman 2009; Berndtsson 2010; Fassman and Blackbourn 2010; Roy-Poirier et al. 2010; Zimmerman et al. 2010; Gregoire and Clausen 2011; Hurley and Forman 2011; Myers et al. 2011; Scholz 2011; Rowe 2011;Walsh and Pomeroy 2013).  cited in Zahmatkesh et al 2015
• The use of LIDs to manage the urban runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. problem have been recommended by Walsh et al 2012
• “The temperature benefits of green roofs extend to climate change mitigation as well. Vegetation and the growing medium on green roofs also can store carbon. Modeling has determined that green roofs may reduce building energy use for electricity consumption by 2 - 6% over conventional roofs, particularly for summer cooling.24 One study estimated carbon sequestration at 375 grams per square meter for green roofs. However, because many of the plants are small and the growing medium layer is relatively thin, green roofs tend not to have as large a carbon storage capacity as trees or urban forests.2g”  in Foster et al 2011
• “Other benefits of GIGreen infrastructure implementation in urban areas may include biodiversity protection, climate change mitigation, water management, and food production (Sussams et al., 2015).”  Vogel et al 2015

## Infiltration and FiltrationThe technique of removing pollutants from runoff as it infiltrates through the soil.

“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 runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. 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. BioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. surface storage volume and infiltration rateThe rate at which stormwater percolates into the subsoil measured in inches per hour. appeared important in determining a system’s ability to cope with increased yearly rainfall and higher rainfall magnitudes.”[1]

• “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 infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. controls > 5% of drainage areaThe total surface area upstream of a point on a stream that drains toward that point. Not to be confused with watershed. The drainage area may include one or more watersheds., 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 CSOA discharge to the environment from a combined Sewer system that occurs because of a precipitation event when the capacity of the interceptor sewer or treatment plant is exceeded. It consists of a mixture of sanitary wastewater and Stormwater runoff. levels with higher SGI in watersheds, but the differences between sewersheds create high variability in CSOA discharge to the environment from a combined Sewer system that occurs because of a precipitation event when the capacity of the interceptor sewer or treatment plant is exceeded. It consists of a mixture of sanitary wastewater and Stormwater runoff. levels.”[2]

## 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 precipitationAny form of rain or snow..”[3]

• “For combined scenarios of high climate change and high urban development, there is a projected increase in winter flows of up to 71 % and decrease in summer flows of up to 48 %.” [4]
• “We find that in situ and modeling methods are complementary, particularly for simulating historical and future rechargeThe addition of water to ground water by natural or artificial processes.The infiltration and movement of surface water into the soil, past the vegetation root zone, to the zone of saturation or water table. scenarios, and the in situ data are critical for accurately estimating rechargeThe addition of water to ground water by natural or artificial processes.The infiltration and movement of surface water into the soil, past the vegetation root zone, to the zone of saturation or water table. under current conditions. Observed (2011 – 2012) and future (2099 – 2100) rechargeThe addition of water to ground water by natural or artificial processes.The infiltration and movement of surface water into the soil, past the vegetation root zone, to the zone of saturation or water table. rates beneath the infiltration trench (1750 – 3710 mm/yr) were an order of magnitude greater than beneath the irrigated lawn (130 – 730 mm/yr). Beneath the infiltration trench, rechargeThe addition of water to ground water by natural or artificial processes.The infiltration and movement of surface water into the soil, past the vegetation root zone, to the zone of saturation or water table. 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 rechargeThe addition of water to ground water by natural or artificial processes.The infiltration and movement of surface water into the soil, past the vegetation root zone, to the zone of saturation or water table. and local groundwater resources using LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. BMPs.[5]

## 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 emphasise the need for source controlA practice or structural measure that is usually implemented at the beginning of a drainage system or at the lot level, to reduce the volume of runoff and minimize the concentration of pollution in overland flow from private property and prevent pollutants from entering Stormwater runoff or other environmental media, as described by the Ministry of Environment. 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)

1. Reduced CSOs - Discussion on CSOs – introduction of Vineyards et al 2015 has a detailed explanation of the issue.
2. Reduction of Urban Heat Island Effect
3. CO2 sequestration
4. 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

## Opportunities for LIDs in an already built-up environmentRefers to the conditions in which an organism lives and survives or the conditions in which an organism resides. These conditions can be described as aspects of a “physical”, “social” or an “economic” environment, depending on the perspective perceived by the observer.

1. Talk about retrofitting opportunities and the benefit of some LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. that take up little space
2. Case that our infrastructure is degrading, hard to upkeep, so when we are changing to new infrastructure, change to LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting.
3. Old infrastructure using old methods
• “The built environmentRefers to the conditions in which an organism lives and survives or the conditions in which an organism resides. These conditions can be described as aspects of a “physical”, “social” or an “economic” environment, depending on the perspective perceived by the observer. of an existing city is continuously changing by maintenance, modification and renewal. This inherent dynamics of the urban environmentRefers to the conditions in which an organism lives and survives or the conditions in which an organism resides. These conditions can be described as aspects of a “physical”, “social” or an “economic” environment, depending on the perspective perceived by the observer. provide opportunities for retrofitting blue-green measures synergistically with other structural changes in the urban form. Opportunities for retrofitting arise for instance when existing paved areas are removed for works on cables or for sewer rehabilitation, when buildings are renovated, when infill development takes place, and with urban renewal projects. Linking implementation of blue-green climate adaptation measures with such ‘windows of opportunity’ is greatly beneficial for a reduction of implementation costs.” [3]

### WatershedThe drainage area of a river.An area of land that drains into a river or a lake. The boundary of a watershed is based on the elevation (natural contours) of a landscape.-scale approaches to LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting.

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.”[3]
• “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 and, accordingly, which combination of measures is most beneficial to increase resilience to extreme events of a particular site.”[3]
• LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. 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 ecosystemA biological community, including humans and their natural environment. spaces.
• Green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. retrofits, which included street- connected bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. cells, reduced peak and total stormflow and increased lag times from a suburban residential headwaterReferring to the source of a stream or river. street. On Klusner Ave, a voluntary participation scheme in which 13.5 % of households had rain barrels and rain gardens or street-connected bioretentionA shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation. 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 infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. was installed. Connecting” [6]also notes: “The results of this study demonstrate promising effectiveness of catchmentThe land draining to a single reference point (usually a structural BMP); similar to a subwatershed, but on a smaller scale.-scale green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. retrofits in mitigating stormwater run-off from headwaterReferring to the source of a stream or river. 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

Action 10 = Develop Guidance for Stormwater Management

The Ministry of the EnvironmentRefers to the conditions in which an organism lives and survives or the conditions in which an organism resides. These conditions can be described as aspects of a “physical”, “social” or an “economic” environment, depending on the perspective perceived by the observer. is currently reviewing best management practicesState of the art methods or techniques used to manage the quantity and improve the quality of wet weather flow. BMPs include Source, Conveyance and End-Of-Pipe Controls. 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 controlA practice or structural measure that is usually implemented at the beginning of a drainage system or at the lot level, to reduce the volume of runoff and minimize the concentration of pollution in overland flow from private property and prevent pollutants from entering Stormwater runoff or other environmental media, as described by the Ministry of Environment. (reuse and low impact developmentA stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting.)
• sewers for conveyance
• end-of-pipe treatment works
• water conservationReduction in applied water due to more efficient water use such as implementation of Urban Best Management Practices or Agricultural Efficient Water Management Practices. The extent to which these actions actually create a savings in water supply depends on how they affect net water use and depletion.
• inflow and infiltration
• by-passes and combined sewer overflowA discharge to the environment from a combined Sewer system that occurs because of a precipitation event when the capacity of the interceptor sewer or treatment plant is exceeded. It consists of a mixture of sanitary wastewater and Stormwater runoff.

Action 3 = Promote Water Conservation

• applying proactive solutions that encourage groundwater infiltration of stormwaterSurface runoff from at-grade surfaces, resulting from rain or snowmelt events., such as increasing permeable surfaces in built-up areas.

### MECP

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 infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. are just some of the solutions we need.” MOECC 2015 – (Ontario Climate Change Strategy): “Build green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. to restore eco- systems, reduce atmospheric carbon and protect and expand carbon sinks. Green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. is inter-connected networks of green open spaces that provide a wide range of ecosystemA biological community, including humans and their natural environment. services. Benefits of green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. 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 infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. 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 infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. as defined in Toronto’s Official Plan refers to “natural and human-made elements that provide ecological and hydrologicalRelating to the properties, distribution and effects of water on and below the earth’s surface, and in the atmosphere. functions and processes” (Toronto, 2016). Examples of green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. integrated into green streets can include: alternate energy sources, high efficiency lighting, street trees, permeable surfaces, Low Impact DevelopmentLow impact development is a stormwater management and land development strategy applied at the parcel and subdivision scale that emphasizes conservation and use of on-site natural features integrated with engineered, small scale hydrologic controls to more closely mimic pre-development hydrologic functions.A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. (LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting.) 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 infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. and the natural environmentRefers to the conditions in which an organism lives and survives or the conditions in which an organism resides. These conditions can be described as aspects of a “physical”, “social” or an “economic” environment, depending on the perspective perceived by the observer.. 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 environmentRefers to the conditions in which an organism lives and survives or the conditions in which an organism resides. These conditions can be described as aspects of a “physical”, “social” or an “economic” environment, depending on the perspective perceived by the observer. 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.

According to Toronto’s Future Weather & Climate Driver Study: Outcomes Report [7], 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 infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. 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 LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. 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 precipitationAny form of rain or snow. volumes and patterns that may occur as a result of climate change.”…..

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 runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface.;
• 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 levelThe treatment of urban runoff as close to the source area as possible through application of small scale stormwater management practices on individual properties that are linked to downstream conveyance and end-of-pipe practices. to direct runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. 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 hydrologicalRelating to the properties, distribution and effects of water on and below the earth’s surface, and in the atmosphere. 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 [8]

### Town of Ajax

The Official Plan for Ajax has extensive content and calls for the promotion of LIDs to treat StormwaterSurface runoff from at-grade surfaces, resulting from rain or snowmelt events.. they also mention that new infrastructure needs to be sized properly, although they do not specially say if there are new requirements. [9]

### City of Ottawa

Green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. and low impact developmentA stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. (LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting.) 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 infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics./LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. 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 infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. however the scope of promotion is limited to giving “greater consideration” to green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. 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 infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. plans as a cost effective (and some assert cost saving) plan to address infrastructure deficits, combined sewer overflows, water resource improvements and climate risks.” [10]

### Thunder Bay

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 DevelopmentLow impact development is a stormwater management and land development strategy applied at the parcel and subdivision scale that emphasizes conservation and use of on-site natural features integrated with engineered, small scale hydrologic controls to more closely mimic pre-development hydrologic functions.A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. (LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting.) 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: Objectives include:

1. 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.
2. Identify retrofit opportunities for municipal infrastructure to minimize service disruptions related to extreme weather events.
3. Investigate areas of priority to incorporate best practices and green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. into community and land- use planning and design. The hectares of catchmentThe land draining to a single reference point (usually a structural BMP); similar to a subwatershed, but on a smaller scale. areas of LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. sites is an indicator of Goal 4.
4. Develop education and communication materials promoting the use and benefits of green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics..
5. Prepare a tool kit or resource kit for City administration with information on available best practices and latest innovations in green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. relating to community and land-use planning and design. [11]

## Other Jurisdictions

### IPCC

IPCC 2014 Summary for Policymakers calls green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. an structural/physical adaptation measure to “Urban floods in riverine and coastal areas, inducing property and infrastructure damage; supply chain, ecosystemA biological community, including humans and their natural environment., and social system disruption; public health impacts; and water quality impairment, due to sea level rise, extreme precipitationAny form of rain or snow., and cyclones” “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  green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. can mitigate the impacts of extreme events which are predicted to be more common as climate changes

### US EPA

US EPA (2016) Stormwater Management in Response to Climate Change Impacts: Lessons from the Chesapeake Bay and Great Lakes Regions – “This report provides specific examples of tools, data, methods, and actions to help stormwater managers, community environmental decision makers, and land use planners incorporate climate change into their management plans. Climate changes (e.g., the amount, timing, and intensity of rain events, droughts, and other extreme events), along with land use changes (e.g., development), can affect the amount of stormwater runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. to be managed. Local decision makers have stated a need for more information on how they can adapt local stormwater management planning and stormwater control to account for these changes.” They propose GIGreen infrastructure and LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. as ways to adapt and be resilient to climate change. Some of the goals of the held workshops were : Explore stormwater management adaptations to climate and land use changes in the Chesapeake Bay watershedThe drainage area of a river.An area of land that drains into a river or a lake. The boundary of a watershed is based on the elevation (natural contours) of a landscape., particularly green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. or other LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. strategies. Lots of mention of GIGreen infrastructure and LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. in this report with respect to dealing with climate change.

### New York City

New York City – “New York City has created a Green Infrastructure Plan and is committed to goals that include the construction of enough green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. throughout the city to manage 10% of the runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. from imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. surfaces by 2030.”  cited in Mellilo et al 2014 Zahmatkhesh et al 2015 – NYC modelling study of LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. vs no LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. scenarios. Based on the model results, it was observed that future runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. volumes increased in comparison to historical runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. volumes due to expected increase in rainfall. The monthly runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. volumes decreased when looking at the with-LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. scenarios. RunoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. increases by 44% under a projected scenario without LIDs, while runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. decreases by 17% for with-LIDs scenario. “Although the effect of LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. implementation on projected runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. based on the maximum scenario was not considerable, future runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. corresponding to a 25-year return period for the mean P scenario will correspond to a 50-year event, and runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. 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 runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. reduction was more for climate scenarios that had less precipitationAny form of rain or snow. for the future time period. Among the implemented LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. 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 runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. 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 imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. surfaces enters too quickly into the combined sewer system. The new Stormwater Rule will allow the City to more effectively manage stormwater runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. 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.)” [12]

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 infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. we build on our streets is an added safeguard that can help mitigate flash flooding during such events.” City of Philadelphia – “In 2006, the Philadelphia Water Department began a program to develop a green stormwater infrastructure, intended to convert more than one-third of the city’s imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. land cover to “Greened Acres”: green facilities, green streets, green open spaces, green homes, etc., along with stream corridor restoration and preservation.”  cited in Melillo et al 2014

### Portland

Portland Oregon – updated the city code to require on-site management for new and re-development. “Titles 24 and 25 (Building and Plumbing Regulations) State building and plumbing code requirements are implemented through the Bureau of Development Services during the development review process for private propertyLand owned by private individuals or companies.. BDS approves private parking and driveway surfaces (see Portland City Code 24.45), flood hazard areas (see Portland City Code 24.50), and installation of private downspouts, pipes and sewers, including those that lead to or from stormwater management facilities.”  Portland Stormwater Management Manual 2016 “Many of the actions that help prepare for climate change are already underway today because they benefit the community in other ways. One example is Portland’s long-established regulations and practices to protect, manage, and expand the City’s green spaces and urban forest. These efforts help to improve air quality and reduce the urban heat island effect, which in turn improves comfort and saves energy and money by reducing the need for air conditioning. To reduce flooding and improve stormwater management, significant work has been done to acquire and restore natural areas and floodplains, and to install green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. such as bioswalesLinear bioretention cell designed to convey, treat and attenuate stormwater runoff. The engineered filter media soil mixture and vegetation slows the runoff water to allow sedimentation, filtration through the root zone, evapotranspiration, and infiltration into the underlying native soil. and ecoroofs. In addition, the development of Portland’s groundwater well system not only supplements the region’s primary drinking water supply, the Bull Run watershedThe drainage area of a river.An area of land that drains into a river or a lake. The boundary of a watershed is based on the elevation (natural contours) of a landscape., but also improves Portland’s resilience to withstand potential impacts to the water supply system due to current climate variability as well as future climate change.”  City of Portland and Multnomah County 2014 (Climate change preparedness plan) “Review city codes and drainage rules to evaluate their ability to protect and improve stream flows, seeps, springs, wetlandA vegetated area such as a bog, fen, marsh, or swamp, where the soil or root zone is saturated for part of the year. function, water quality including temperature, vegetation and habitat, and stormwater management during hotter, drier, summers. Use the Natural Resource Inventory and other data to track gains and losses, and propose revisions as necessary. Evaluate and pilot planting native species that are currently considered to be at the “northern” edge of their range in Portland.”  City of Portland and Multnomah County 2014 (Climate change preparedness plan) year 2030 Objective 4 (Increase the resilience of natural systems to adapt to increased temperatures and drier summers.) “Better manage stormwater by reducing the overall imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. area (currently 34 percent) within the city through depaving, green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. (greenstreets, ecoroofs, trees, and raingardens), and expanding the urban forest canopy, natural areas and open space. Encourage or require private propertyLand owned by private individuals or companies. owners and developers to implement climate change preparation measures, including limiting or reducing imperviousA hard surface area (e.g., road, parking area or rooftop) that prevents or retards the infiltration of water into the soil. area at site-specific and district scales.” Also “Develop the Stormwater Systems Plan, and update the Stormwater Management Manual and the drainage rules to better manage increased winter precipitationAny form of rain or snow., including reevaluating the modeled “24 hour” storm event design standard. “  City of Portland and Multnomah County 2014 (Climate change preparedness plan) year 2030 Objective 6 (Increase the resilience of the natural and built environmentRefers to the conditions in which an organism lives and survives or the conditions in which an organism resides. These conditions can be described as aspects of a “physical”, “social” or an “economic” environment, depending on the perspective perceived by the observer. to more intense rain events and associated flooding.) “Begin rainfall event-based monitoring of sedimentSoil, sand and minerals washed from land into water, usually after rain. They pile up in reservoirs, rivers and harbors, destroying fish-nesting areas and holes of water animals and cloud the water so that needed sunlight might not reach aquatic plans. Careless farming, mining and building activities will expose sediment materials, allowing them to be washed off the land after rainfalls. accumulation in pipes and stormwater facilities”  City of Portland and Multnomah County 2014 (Climate change preparedness plan) year 2030 Objective 12 (Improve monitoring, evaluate effectiveness of climate change preparation actions and advance new research to support climate change preparation efforts.)

## Others

• Pyke et al 2011 – similarly to Zahmatkesh et al 2015 but for Boston, they found that the with-LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. scenario was superior for managing runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. – 29% less runoffThat potion of the water precipitated onto a catchment area, which flows as surface discharge from the catchment area past a specified point.Water from rain, snow melt, or irrigation that flows over the land surface. than conventional scenario.
• Pennsylvania – “Enacted polices to encourage the use of green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. and ecosystemA biological community, including humans and their natural environment.-based approaches for managing storm water and flooding.”  in Mellilo et al 2014
• US 3rd National Climate Assessment (Melillo et al 2014) – Key Message 11: Adaptation Opportunities and Challenges – green infrastructureNatural vegetation and vegetative technologies in urban settings such as: urban forests; green roofs; green walls; green spaces; rain gardens; bioswales; community gardens; natural and engineered wetlands and stormwater management ponds; and porous pavement systems. These systems are designed to provide multiple benefits, such as moderate temperatures, clean air and water, and improve aesthetics. 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 BasinGround depression acting as a flow control and water treatment structure, that is normally dry. Program (2015) recommends the use of LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. 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 LIDLow Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting. 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

Increases in temperature will affect evapotranspiration

## Rainfall patterns

Rainfall patterns are forecast to change [13][14]. Intensity-Duration-Frequency (IDF) curves have been forecast for a number of urban areas in Southern Ontario[15]

## Vegetation

Increased atmospheric CO2 levels will stimulate photosynthetic processes, increasing phosphorus uptake of all plants[16].

## For further information

Reach out to our colleagues at the Ontario Climate Consortium.

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