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Urban populations worldwide are expanding rapidly and consequently a large number of people are becoming exposed to hazards inherent in cites. Phenomena such as the urban heat island can exacerbate the effects of heatwaves, and land surface sealing can lead to flash flooding. Cities are also the sites of enhanced air and water pollution from non-point sources such as concentrated motor vehicle use. Climate change predictions for the UK include increased winter precipitation and an increase in frequency of summer heatwaves. This will put further pressure on urban residents and infrastructure. Roof greening can be used within climate change adaptation schemes because green roofs have a range of environmental benefits which can help urban infrastructure become more sustainable. This thesis empirically quantifies several of these benefits, and the processes influencing them, by monitoring real green roofs in Manchester. A number of novel discoveries were made. Green roofs act as passive filters of airborne particulate matter. 0.21 tonnes of PM10 (2.3% of the inputs) could be removed from Manchester city centre in a maximum extensive green roof scenario. Species and site differences in particle capture were exhibited and related to morphology and proximity to sources respectively. An intensive green roof was able to lower the monthly median overlying air temperature at 300 mm by up to 1.06 oC. A combination of drought and mismanagement caused damage to the vegetation on one of the green roofs, with a subsequent reduction in the cooling effect. Daytime air temperatures were higher than over an adjacent bare roof for a larger proportion of the day than over the undamaged roof, and lower cooling was observed at night. A site-specific methodology was devised to monitor the rainwater runoff from an intensive green roof and an adjacent bare roof. Average runoff retention of 65.7% was observed on the green roof, compared to 33.6% on the bare roof. Season and rainfall amount had significant impacts on retention, however, many other explanatory variables such as Antecedent Dry Weather Period (ADWP) and peak rainfall intensity had no demonstrable, significant impact. Intensive roof construction on 10% of the rooftops in Manchester city centre would increase annual rainfall retention by 2.3%. The runoff was characterised with regards to heavy metals and nutrients. Nutrient levels were found to be not a significant problem for water quality, however, Environmental Quality Standards (EQS) values for protection of freshwater were exceeded for concentrations of Cu, Pb and Zn. High metal concentrations within the sediments may be acting as sources of pollution, particularly in the case of Pb. The age of the green roof means that past atmospheric deposition of Pb could be contributing to the runoff quality. The multi-benefit aspect of green roofs is discussed in the light of the results of this thesis and recommendations made for policy makers and the green roof construction industry.

Urban populations continue to increase with concurrent social and economic development often occurring at the expense of natural resources. Urban areas are characterized by a high density of impervious surfaces (i.e., roads, buildings, etc.) which are central to modern economies but disrupt many functions of the natural ecosystem by limiting stormwater infiltration, increasing habitat fragmentation, and absorbing a higher percentage of solar radiation. A growing number of communities are turning to green infrastructure (GI) to alleviate these stresses by increasing infiltration, evapotranspiration, and storage of stormwater. Commonly installed GI features include bioretention cells (BRCs), green roofs, and permeable pavement (PP). Bioretention cells are depressional retention facilities planted with native plants which infiltrate and filter stormwater using an engineered sandy media. Green roofs are alternatives to traditional roofs made up of layers of constructed membranes, substrates, and vegetation. Permeable pavements are alternatives to asphalt or concrete pavements that allow infiltration of stormwater through the pavement to the substrate below. Recent studies have focused on co-benefits of and ecosystem services provided by GI, including habitat creation, temperature mitigation, and community aesthetics.This dissertation was focused on GI efficacy in both natural and built systems. Broadly, this dissertation can be separated into two sections: 1) performance of BRCs in relation to hydrology and water quality (Ch. 1 and 2), and 2) performance and interactions of GI SCMs within human built systems (Ch. 3 and 4). Simulated runoff testing was conducted on a variety of BRCs to determine the hydrological and water quality performance as a function of their design (Ch. 1). In chapter 2, BRCs were tested for their ability to contain and remove Bacillus anthracis from simulated spore contaminated stormwater. Higher fines contents in the engineered media created smaller pore spaces that retained water and trapped more pollutants. The size and location of BRCs impacted performance, especially when alongside roads where there was a higher potential for urban karst pathways. These additional, unintended pathways for stormwater to exit GI through porous utility trenches and other anthropogenic karst features were the focus of chapter 3. Urban karst interactions with GI can be identified through dye tracer or drawdown testing and often occur at connection points between GI and other infrastructure. The implications of this effect on the performance and design of GI as well as potential negative impacts to local underground infrastructure, groundwater quality, and geology were the focus of this chapter and were highlighted by several recent cases where this effect has been observed in research. Lastly, air temperature sensors were deployed at GI and gray infrastructure features across the City of Columbus to quantify whether GI could reduce the urban heat island effect (Ch. 4). Differences in air temperatures and the urban microclimate are largely non-existent within smaller GI practices such as BRCs, and are functions of planting type, density, and shading on green roofs. These four chapters highlight the momentum within the design and construction of GI to adequately manage excess stormwater, and the areas of design that could be improved to ensure proper performance related to stormwater and air temperature mitigation. The results from this dissertation will add to the growing literature of GI research to better assist the design and urban planning communities in the next stages of GI implementation. Further research into limiting the urban karst phenomenon and using GI for urban heat island mitigation should be of upmost priority, followed by replicating similar studies on the same BRCs in the future to better determine the lifespan and long-term performance of GI.

In the era of climate change, there is an increased interest in including different types of green infrastructure in building legislation as a strategy to improve the built environment. Among these different types, trees on buildings have received little attention, and there is limited literature and policies to guide their design and implementation. Therefore, this research aims to explore trees on buildings from various perspectives to enrich the scholarship and policies and to enable their implementation. To achieve this, the research includes a four-stage mixed method using qualitative and quantitative approaches.

Urban landscapes are intricate systems interacting throughout the globe. Over the past decades, urban development has widely sprawled and fragmented flyway systems and corridors. This has led to many changes in species composition and has even caused the extinction of some animals (Marzluff 1997). Recent studies have indicated that there exists a protective or restorative design to create stepping-stone connectivity in urban areas. This study looks to understanding potential benefits in urban biodiversity, animal species protection, and urban benefits of green roof designs.

Green roofs are vegetated roof structures built to provide services, such as stormwater management and habitat provisioning. As green roofs are relatively new, they can be considered a novel ecosystem with no native habitat analog. Due to their novelty, the ecological laws and ideas of ground-level ecosystems may not perfectly describe what is occurring on green roofs, and therefore green roof-specific research is needed. The goal of this dissertation was to understand the biological interactions in the green roof environment by examining the most important factors that structure plant and fungal communities, as well as how those plant and fungal communities can in turn impact ecosystem health and services. The first study was an assessment of the habitat analog approach and its ability to improve performance and ecosystem service yield of a range of different green roof systems, plant communities, and mycorrhizal inoculum treatments on an experimental test site in Cleveland, Ohio. We found that treatments following the habitat analog approach did not improve ecosystem service yield, with the blue-green roofs providing the most services with the lowest number of trade-offs. The next study compared the ability of green roof practitioners to predict patterns of plant diversity in comparison to ecological theory on a large range of green roof types, sizes, and ages in Chicago, Cleveland, and Minneapolis. Both green roof practitioner and ecological theory were equally accurate in their ability to predict patterns, with deep substrate (intensive) roofs being more amenable to generalizations than shallow substrate (extensive) roofs. Lastly, we examined the diversity and the relationships between green roof fungal communities and nearby ground-level green space in Chicago, Cleveland, and Minneapolis. On average, green roofs had higher fungal diversity when compared to ground-level green space in the urban landscape. Fungal community composition was also distinct across cities, sampling sites, and between the roof and ground-level, with some similarity between a green roof and its closest neighboring green space. Overall, both industry-derived and ground-level ecosystem theory did not perfectly prescribe the dynamics occurring on green roofs. Green roof ecosystems did not follow ecological laws consistently and may require a new ecosystem framework developed from green roof specific observations and research. The use of the habitat reconciliation framework, which involves the combination of both ecological theory and industry innovation, may provide high green roof ecosystem service yield in landscapes that would otherwise remain permanently altered from their natural state.

The increasing urbanization of land has produced expansive amounts of impervious surfaces, yielding greater quantities of runoff. This runoff can carry pollutants from the surrounding area into the water system and negatively impact the water quality. A possible solution for reducing runoff from impervious surfaces is green roofs, which can absorb and filter water. To determine a green roof's effects on water quantity and quality, an experimental green roof was studied in Cleveland, Ohio. This site contains 39 test plots that differ in combinations of plant community type (restoration or horticultural), substrate type (quasi-traditional, conventional, or open space), and the presence of mycorrhizal inoculum. From October 2017 to October 2018, water samples were collected bimonthly, along with volumetric measurements of the runoff present. The samples were tested for inorganic phosphorus and total inorganic nitrogen using nutrient assays on a microplate reader. Over the duration of the experiment, total inorganic nitrogen fluxes and concentrations were too low to be of concern. Inorganic phosphorus fluxes and concentrations were initially high, but decreased as the roof aged. Building and collection materials were analyzed for phosphorus leaching, but results rather showed possible phosphorus adsorption to certain materials. Inorganic phosphorus was most heavily influenced by substrate type and may be reduced by the use of natural, non-fertilized substrates. Total inorganic nitrogen was most heavily influenced by the biological components (plant community, mycorrhizae), and may be reduced by the presence of mycorrhizae. Manipulating design aspects of green roofs may increase their potential to be improved and refined into an efficient environmental resource.

RESEARCH QUESTIONS: • How can the effects of urban flooding in New Zealand be fixed by using sponge city techniques? • How to prevent flooding and reduce urban damage by using the sponge city strategy? • How can the sponge city methodology help to prevent future flooding in Auckland? ABSTRACT: This research aims to solve the problem of urban flooding by the sponge city concept. Through the comparison with Low Impact Urban Design, Water Sensitive Urban Design and Sustainable Urban Design, the advantages and success of sponge city are demonstrated. A sponge city is a city that acts asa sponge with an urban environment planned and constructed to soak up almost every raindrop and capture that water for reuse. There are six keywords in this project, which are infiltrate, detain, absorb, clean, use and discharge.This research will mainly focus on absorb and detain. The Sponge City can absorb more rainwater through the soil into urban aquifers efficiently. The case studies present different sites around the world to show how those cases deal with urban flooding, which includes Hans Tavsens park, Yanweizhou Park, Arroyo Seco Confluence, Cermak road and Auckland International Airport. The effects of Auckland flooding were presented by media frequently. There are three main causes which could lead to urban flooding; they are irregular terrain, temperate marine climate and urbanisation. Various data from the Whau catchment indicate a strong connection between topography and flooding, so the design area will focus on the upstream flood areas to mitigate urban flood pressure and risk. This research presents five design works, which all near or in the flooding area.These five sites will combine five different landscape techniques through thesponge city concept, which are detention pond, widen and deepen stream, raingarden, porous pavement and green roof. Then there will be a list of threedifferent design options in the first two designs to show different focused andsuccess through comparing advantage and flood capacity..

RESEARCH QUESTION: How can green roofs and living walls be used as an integrated part of urban development to increase biodiversity and re-establish the connections between people and nature? During the last few decades, global climate change has been occurring due to human activities and the over-exploitation of natural resources. With the acceleration of the global urbanization process, the urban heat island effect, air pollution, rainstorms, and other environmental problems have become increasingly severe in urban areas. The world's population is continually converging on metropolitan areas. Sprawl causes fragmentation of natural and semi-natural areas on the urban fringe (Inostroza et al., 2010, Inostroza et al., 2013), and urban densification decreases the area covered by urban green spaces within a city (Harland & van den Bosch, 2015). To resolve those issues, green roofs and living walls as part of urban landscape design have been increasingly widely favored by urban environmental researchers and designers because they are representatives of sustainable design. Moreover, green roofs and living walls not only can provide a solution to environmental issues, but also can regenerate the biodiversity of urban areas. This thesis will use existing case studies and research results to estimate the positive effects of green roofs and living walls on large-scale buildings in urban environments for the benefit of the biodiversity of ecosystems. In addition to these ecological benefits, green roofs and walls can offer usable space for people. Green roofs and living walls can be likened to the traditional ‘roof garden’ concept, but when understood as an extension of green roofs and walls, can become an extension of accessible green space from the ground floor onto urban structures to provide more high quality outdoor space for people in urban areas and better connections and circulation within and between buildings. The aim is to show how large-scale roof parks can combine amelioration of the environmental problems created by large building complexes with the provision of an accessible and valuable high amenity greenspace for people. Achieving this aim would result in the introduction of elevated green space as an important component of landscape architecture and a valuable component of the urban designer’s toolkit.

RESEARCH QUESTION: How could the development of a Living Roof Design Manual increase the effectiveness of living roof design? Living roofs are becoming increasingly common in cities throughout the world for their ability to improve climate change adaptation, energy conservation, food production, and the potential to develop more sustainable and environmentally friendly living environments. Rapid population growth, advanced stages of urbanisation and the alteration of natural environments defined by increments of hard surfaces, along with pollution and a lack of contact with nature, underline the importance and relevance of green infrastructure solutions, such as living roofs. Despite this, in New Zealand, living roofs are rarely included in developments, and if they are, most are being designed in isolation. They are often disconnected, inaccessible, consist of vegetation monocultures, lack robustness, and are inappropriate for the location. This investigation, which is comprised of three phases, aims to identify strategies for addressing these deficiencies. Phase One comprises of a literature and precedent review, which seeks to define the current situation, in Europe and locally, in terms of existing knowledge and practice. Phase Two consolidates the findings from Phase One, and focuses on the Northland region of New Zealand, to form a ‘Living Roof Design Manual’ for the city of Whangārei. The investigation culminates in Phase Three, with a living roof design for the Hundertwasser Art Centre in Whangārei that utilises the manual to optimise living roof outcomes.

The city of Melbourne in southeast Australia experiences an Urban Heat Island (UHI) effect, which is exacerbated during heatwaves, and the latter are becoming more frequent, intense and longer in southeast Australia. In addition, Melbourne is the fastest growing city in Australia. Therefore, it is urgent to understand the dynamics of UHI and impacts of future urban expansion on the UHI during heatwaves. Based on these issues, there is a crucial need to investigate the effectiveness of potential mitigation strategies to minimize UHI effects during heatwaves. The overarching aim of the thesis is to investigate the impacts of future urban expansion on the UHI during heatwave events in Melbourne, and examine the effectiveness of different Green Infrastructure (GI) scenarios such as green/cool roofs, mixed forest (MF), mixed forest and grassland (MFAG), and mixed shrublands and grasslands (MSAG) in mitigating UHI effects. The Weather Research and Forecasting (WRF) model coupled with the Single Layer Urban canopy Model (SLUCM) was used in simulating the UHI and heatwaves. Since the WRF model is known to be sensitivity to the choice of physical parameterisation options, an initial sensitivity analysis of the model was conducted and the best-possible WRF configuration to simulate the UHI during heatwaves in Melbourne was determined, among a 27-member physics ensemble. This configuration was used throughout the rest of the thesis. Urban expansion increased near surface UHI by 0.75 to 2.80 °C during the night but no substantial impacts during the day. Urban surfaces absorbed more solar heat during the day as compared to vegetated surfaces, and the absorbed heat was released slowly from evening to early morning. The storage heat in urban surfaces was the key driver in increasing UHI during the night. Urban expansion did not substantially affect human health (HTC) comfort in existing and expanded urban areas. Green roofs showed good performance in reducing roof surface UHI (1 to 3.8 °C) and near surface UHI (0.3 to 1.1 °C) during the day but not during the night, while cool roofs showed higher reductions at the roof surface UHI (2.2 to 5.2 °C) and near surface UHI (0.5 to 1.6 °C) during the day. Green roofs increased evapotranspiration and provided shading, and consequently, increased Latent Heat (LH) and substantially decreased storage heat and sensible heat, and as a result, reduced the UHI. Cool roofs reflected a major portion of incoming solar radiation due to higher albedo, and reduced the sensible heat flux and storage heat, and these were the key drivers in reducing UHI during the day. In addition, both green and cool roofs showed good potential in improving HTC from extreme to very strong during the day. Other GI scenarios such as MF, MFAG and MSAG were effective in reducing UHI effects and improving HTC during the night but no substantial reductions were occurred during the day. By increasing GI fractions from 20 to 50 %, the UHI was reduced by 0.6 to 3.4 °C for MF, 0.4 to 3.0 °C for MSAG and 0.6 to 3.7 °C for MFAG. The night time cooling was driven by reductions in storage heat as 20 to 50 % urban areas were replaced by GI, which would have led to even less radiation reaching the ground surface during the day due to their higher LAI and shade factor, and leading to lower storage heat. As the green and cool roofs showed potential in reducing UHI effects during the day while urban vegetated patches showed effectiveness during the night, therefore, a combination of green/cool roofs and urban vegetated patches could be an optimal mitigation strategy in reducing UHI effects and improving HTC during both day and night.

Short duration intense rainfall causes an increase in rainfall derived infiltration and inflow (RDII) in aging sewer networks, which leads to Sanitary Sewer Overflows (SSOs). This, in turn, causes various detrimental impacts, both on human health and the environment. This research aims to quantify the benefits of Water Sensitive Urban Design (WSUD) approaches to mitigate the negative impacts of rainfall induced SSOs. In this context, this research develops a generalised framework for assessing and mitigating the impacts of intense rainfall on the performance of the sanitary sewer network. The first part of the developed framework involves detailed hydraulic modelling to evaluate the performance of the sewer network. The second part deals with the development of SSO mitigation strategies based on popular WSUD approaches. This study also demonstrates the application of the developed framework for a case study catchment in Melbourne, Australia. A detailed hydraulic modelling to analyse the performance of the case study sewer network during a wet (2010) and a dry year (2008) has been presented. The hydraulic performance analysis found that the system experienced 23 ML of sewer overflow volume in 2010 as compared to 3.42 ML in 2008. Towards mitigating the negative impacts of SSOs, this study has implemented two commonly used WSUD approaches, namely rainwater tanks and rain gardens for the case study sewer network. A detailed hydraulic modelling has been undertaken with rainwater tanks and rain gardens (individually and in combination) for the wet year 2010. It was observed that rainwater tanks (individually) could lead to a maximum reduction in SSO volume by 33% when compared to the base case overflow volume of 23 ML. A higher reduction in SSO volume up to a maximum of 45% was observed when rain gardens were implemented in conjunction with rainwater tanks. Such an analysis will benefit the urban water authorities to develop sustainable WSUD based mitigation strategies for controlling SSOs in their sewer system. Thus, the study will be beneficial for the community and the environment.

Green roofs and solar panels are used as sustainable technologies in the built environment. As any technology, these too have their limitations, especially in hot climates like Austin. First, the efficiency of solar panels reduces as their internal resistance increases with higher temperatures. Second, the plant’s roots extend horizontally in shallow growing medium such as that in green roofs. Therefore, the plant’s roots overheat, and these green roofs become, the not-so-wanted, brown roofs. This research was developed to understand how these two technologies interact with each other as a single assembly system specifically how: 1) green roofs, through evaporation, can cool off the solar panels, and 2) solar panels can provide shade to cool off the plant’s roots. In this study, I present the results of combining green roofs and solar panels in Austin. I aim to understand how plants provide a passive form of cooling for the solar panels and if so, how power production is increased, and how the plants react to the shade produced by the solar panels and if this can keep the plant’s roots cooler.

Green roofs can be an effective mitigation strategy to offset the environmental impact that urbanization has on the environment. The roof area for the city of Atlanta and for the Georgia State University campus was used to compare the effectiveness of green roofs at removing pollutants, abating stormwater runoff, and reducing the urban heat island at different scales. Results show that the warmest part of the city is the urban core with a mean of 33.5°C, which is also the area of the city with the highest percentage of impermeable surfaces at 91%. At the GSU scale, green roofs can reduce land surface temperature in the urban core up to 2.62°C, remove up to 73 kg of atmospheric pollutants annually, and reduce stormwater runoff by up to 32.3% annually. Results were less significant at the Atlanta scale due to the large amount of vegetated surfaces that already exist.

Stormwater management in urban environments is a growing concern in the US where impervious surfaces are contributing to the increase of sewer overflow and strains on water treatment plants. These strains are caused by an excess influx of water and an influx of pollutants from fertilizing agents, roadways, and rooftops (Hilten et al. 2008). Green (vegetated) roofs are an example of green infrastructure designed, in part, to lessen the strain on these treatment plants because of their ability to retain water and nutrients (Bliss et al. 2009; Dietz 2007). An understanding of green roof dynamics, including both total runoff quantity and quality, is essential to overall urban stormwater management.

Auckland is developing fast, and the population will be much denser than now in the next 20 to 30 years. Because of the development, Auckland needs more dwellings. But usually, Aucklanders prefer individual houses for better living quality. That preference brings a problem when meeting the growing population: Auckland needs a large amount of land to have more residents, and makes the city over expanded. That expansion has already increased the travel time lowered the circulation efficiency of Auckland. Avondale was chosen as the sample area for the study because Avondale represents the general situation of the expansion of Auckland. This thesis will explore possible ways of solving the conflict between people’s ambitions for living quality and the limited land for the increasing population in Avondale. This thesis first collected and analyzed some background information of the current situation in Avondale to find out the key issues (gardening and food) and constructed the main problem (living density vs. living quality). Then, based on these issues, literature materials and design precedents that aim to respond to similar issues or in similar situations were studied to generate the starting ideas and concepts for the later design stages. The design stages then explored different possibilities in order to respond to the key issues at every scale (from a single dwelling to the entire site) on a particular site in Avondale. The result is a residential development design in response to the key issues and problems. Project site: Avondale Racecourse (Avondale Sunday Market) - Ash Street boundary.

One major concern with urban development is the increasing amount of stormwater runoff from large expanses of impervious surfaces. These impervious surfaces reduce the ability of stormwater to infiltrate into the soil and eventually groundwater, which leads to greater amounts of surface runoff. Green technology serves as a viable solution to many of the environmental problems presented by modern development. Fifteen mock, extensive green roofs were built in the fall of 2008 at the Watershed Research and Education Center in Fayetteville, Arkansas. The goals of this project were to (1) measure the amount of stormwater runoff from varying treatments and control roofs, (2) measure the stormwater runoff quality from varying treatments, and (3) study the release of nutrients over time from the green roofs with added compost. Our results show that after an initial flush of nutrients from green roofs with added compost, many nutrient concentrations, such as total organic carbon (TOC), total nitrogen (TN), nitrate-N (NO3-N), and other physiochemical properties have been reduced. However, even after two years, P concentrations in runoff water still exceed 1 mg/L from green roofs using compost in the growing matrix. Analysis of the remaining nutrients in the compost shows that TP loads from green roofs with added compost could be elevated for a number of years. The results from this study provide a benchmark for developing green roofs in Northwest Arkansas or other similar climactic regions.

In climates where air conditioning is essential for creating acceptable indoor environment in offices, green roofs increase the heat capacity and provide shade to the building. This not only lowers the ambient and indoor temperature but also provides comfort to the inhabitants by reducing the heat gain through the roof. A number of studies have confirmed the thermal benefit of using green roofs in extreme climates, however, the same lacks for composite climates. This study looks at the thermal benefits green roofs offer in composite climates by assessing their role in the city of New Delhi and formulating design guidelines for future use. The evaluation of the suitability of green roof system is carried out via the EnergyPlus module of Design Builder V 2.0. The data collected from the simulation of various building configurations, orientations, and retrofit green roofs is used to formulate strategies for future practice. The guidelines are then used to design an office building (with a green roof) in New Delhi, to highlight the success of green roof systems in Delhi.

This thesis on Low Impact Development (LID) Practices provides design guidelines and principles for three important LID practices: green roofs, rainwater harvesting and bioswales. The most important component of the thesis is the qualitative analysis of various case studies based on the LID objectives drawn from the literature review for each LID practice. Through the course of my research, I found that there was no one single source which provided information on the design guidelines accompanied by case examples which could help the designer with built examples where the LID practices have been executed. Therefore, developing this thesis document which provided all this information started as my masters thesis project. The document is designed to be used by people with a variety of expertise like landscape architects, landscape contractors, engineers and clients. The manual is organized into five chapters. The manual details the process of stormwater management and then gradually leads to the evolution of Low Impact Development Practices and detailing out three important LID practices: green roofs, rainwater harvesting, vegetated swales and briefly about infiltration systems. The LID principles outlined in this manual were developed over the last few years to address runoff issues associated with the new residential, commercial and industrial suburban developments. Information to develop this manual has been drawn from numerous sources like the Low Impact Design Strategies developed by the Prince George's County, Maryland, US EPA, Low Impact Development urban design tools and numerous other research papers. It is my hope that the manual will provide adequate information to its users by not only providing design guidelines but also provide built examples through the case studies.

This thesis sets out to establish whether low impact urban design structures can be retrofitted into existing urban catchments and what cleaning efficiencies multiple systems could achieve. Christchurch City has an intimate relationship with its waterways and wetlands, with two major lowland rivers, the Avon and Heathcote dissecting the city centre and surrounding suburbs. The large volume of stormwater runoff that enters these urban river networks, increase flooding, endanger private and public infrastructure, decrease water quality and causes erosion to riverbanks, destroying wildlife habitats. The Canterbury Regional Council is in the process of setting new stormwater discharge requirements for water that is discharged into existing river networks. Improving the quality of stormwater runoff is a challenge in existing urban areas, where land available for the development is scarce. Treatment systems such as swales, detention basins and constructed wetlands are widely acknowledged to be able to reduce pollution levels in contaminated stormwater. Many of these systems require large land areas, making them difficult to retrofit into existing developed sites. To be able to retrofit the Avon River catchment with low impact urban design (LIUD) structures, a fully integrated approach to stormwater management is needed, treating stormwater produced by different land use types as close to the source as possible. Existing research into the treatment abilities of LIUD structures is based around a single system, not what the pollution removal efficiencies would be if multiple smaller systems were combined. To establish if it is physically possible to retrofit the Avon River catchment with LIUD structures and whether these structures can treat all of the stormwater produced, a typical sub-catchment has been chosen. This sub-catchment will represent the various land use types found throughout the Avon River Catchment. The best LIUD structures for each land use have been explored through a series of cases studies based on each land use type; what their cleaning abilities are; and the benefits integrated stormwater management can provide to the local community and environment. These case studies established that it is physically possible to retrofit existing urban environments with LIUD structures, treating all of the stormwater produced by small storm events. Larger events, such as the volumes produced by a one in fifty year flood, however, are not able to be addressed through retrofitting strategies. The case studies also demonstrated that using an integrated approach would reduce stormwater contaminate levels by an average of fifty percent for small storm events and forty percent for larger storm events. Nonetheless, this significant reduction in pollution levels it is not enough to meet the Regional Councils proposed stormwater discharge requirements for urban rivers. To increase pollution removal rates the volumes of stormwater being treated would need to be significantly reduced. Further research into how this can be achieved is needed.

Stormwater management is an essential aspect of urban hydrology. Urbanized areas have large amounts of impervious surface cover (ISC) and well developed sewer and drainage networks which rapidly channel water and pollutants off of streets and into local streams. This research evaluates the use of vegetated roofs as mechanisms to reduce ISC and stormwater runoff in downtown Atlanta. A 3-D model of the study site was created so that runoff rates could be measured for various rooftop scenarios under different size storm events. The results revealed a reduction in peak runoff and an increase in both the lag time and duration of response time. The results were most significant for the smallest storm event with 2/3 of the rooftops vegetated. As these experiments use a scale model for a section of downtown Atlanta, results are likely to be applicable to similar urban environments and may provide guidance for stormwater engineers.

Our urban infrastructure systems are stressed. The decay of water infrastructure is spurring demand for innovative solutions for stormwater management. Concurrently, the transition of predominantly coal-based utilities to renewable portfolios is slow, resulting in continuing adverse health impacts from air pollution. The need for emissions management and resilient water infrastructure in cities will further increase as the world’s population continues to move to urban centers. This dissertation explores the technical, economic, and policy opportunities for vegetated roofs as one solution to stormwater and energy emissions management. The objective was to explore policy strategies to integrate green roofs into emissions management using quantitative economic and physical-chemical modeling tools. A net present value (NPV) approach was used to compare the cost of a conventional roof to a green roof accounting for benefits for stormwater, air pollution, and building energy conservation. Results indicated that, while a green roof costs 39 percent more initially, the 40-year NPV is 23 to 30 percent less mainly due to energy savings and potential health benefits from air pollution reduction. The impact of stormwater fees was minimal. The benefit of green roofs to improve air quality is novel, and had to date not been explored quantitatively. A probabilistic, fugacity-based fate and transport model, SEDUM (Sequestering Emissions: Designable Uptake Model), was developed to assess the uptake of reactive nitrogen species (NO2, NO, and HNO3). The model estimates uptake by vegetation and soil media, which were compared with dry deposition model results and water quality data. Under polluted conditions, a mean removal rate of 0.20 ± 0.01 kgNO2/m2/y was estimated using SEDUM. For a 2,000 m2 roof, this translates into a health benefit between $640 and $2426 per year. Design parameters that impact pollutant uptake were identified. Analysis of current stormwater and air quality policies showed that market-based incentives can close the cost differential once both stormwater and air quality incentives are considered. This work was sufficiently robust to demonstrate the economic and emissions mitigation potential to be included in best available control technology (BACT) consideration. Yet, market-based policy incentives are currently insufficient for widespread adoption.

Population growth has lead to an increase in development and impervious areas in urban settings. Post-development conditions cause several problems for stormwater management such as limited space for stormwater storage systems and the conveyance of pollution picked up by runoff to near by water bodies. Green Roofs with cisterns have been shown to attenuate the peak flow of storm events and reduce the pollution load leaving a site and entering nearby water bodies. The purpose of this research is to expand the available research data on green roofs with cisterns by investigating the water quality and hydrology effects of different green roof designs including depth of media, an additional pollution control layer beneath the growth media, and different drainage layer materials. Furthermore, a comparison study is performed on the cistern water quality, direct filtrate water quality, and control roof filtrate water quality. Results show that phosphorus concentrations are lower when using a pollution control layer beneath the growing media, and that evapotransporation and filtrate factor values from the 4-inch media and the 8-inch media are approximately equal for one year. However, hydrograph results show that the 8-inch media design has a lower peak flow and longer attenuation when compared to the 4-inch media design for a single storm event. Furthermore, the drainage layer material has no significant effect on the water quality or hydrology of the green roof discharge. The data also emphasizes the importance and effectiveness of the incorporation of a cistern into a green roof system.

Urbanization has dramatically altered the natural landscape by replacing pervious land cover with impervious materials.This has lead to an increase in stormwater runoff which raises a number of environmental and economic concerns.Traditionally, stormwater has been treated with costly engineering solutions including expanding infrastructure and increasing treatment capacity.However, within the last decade green infrastructure, has begun to surface throughout cities across the United States offering the possibility of minimizing the economic and environmental concerns associated with development, while providing a myriad of environmental benefits that traditional solutions exclude.This study looks at the potential contribution that green roofs can have on stormwater runoff reduction through a case study. It examines the University of Cincinnati, comparing existing runoff conditions with a projected green roof coverage scenario using TR-55. It concludes by providing policymakers with a general framework to support a green roof policy for the City of Cincinnati.