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The Ministry of Environment and Climate Change establishes design criteria for the sizing of Low Impact Development (LID) practices in the province of Ontario. The current sizing standards are based on the concept of the 90th percentile storm and require LIDs to provide enough storage capacity to store catchment runoff from a 25 mm rainfall event. The notion of 90th percentile storm means that 90% of all rainfall events have event volumes below a 25 mm rainfall event. This research examines the performance and cost of infiltration trenches and bioretention cells sized for alternative sizing standards ranging from 5–50 mm. Analytical probabilistic equations are used to determine the runoff reduction rates of infiltration trenches and bioretention cells, while the Sustainable Technologies Evaluation Program (STEP)’s LID Practices Costing Tool is used to estimate the overall cost of each LID. The costs are used to create a ratio denoted the fraction of maximum cost by dividing each cost by the cost of the 50 mm sized LID to receive a unitless ratio. This ratio is compared with the runoff reduction rates of both LIDs. Four different catchment sizes and various soil types are included to broaden the scope of the analysis and make the conclusions more dependable. Results indicate that the current sizing standard of 25 mm is probably too high and not cost-effective. In fact, depending on the type of soil and LID, little increase in performance occurs while there is a large increase in cost. A new methodology is proposed for setting sizing criteria for infiltration trenches and bioretention cells which focuses on achieving a desired capture efficiency instead of a required volume of rainfall. The method proposes using the capture efficiency, fraction of maximum cost and sizing criteria to determine what value is an economically more justifiable sizing standard based on individual catchment size and soil type. Use of the analytical probabilistic approach allows for the capture efficiency to be easily calculated and provides better sizing targets on a case by case basis. Recommending a specific capture efficiency can be more uniformly applied LID design in any soil conditions or any catchment size. This can reduce government spending when building LIDs and greatly reduce the possibility of over-design. / Thesis / Master of Applied Science (MASc)

Low impact development (LID) is an innovative stormwater management technique that was introduced in early 1990s. However, the transition to use of this more sustainable method has been slow due to technical, institutional, and regulatory barriers to LID adoption. The research questions for this study are: What constitutes LID adoption? Why do localities adopt LID? What are the major factors that influenced the level of LID adoption by local governments? Specifically, this study focused on motivations and key determinants of LID adoption by local governments. By answering these questions, we will have better knowledge about how to approach the adoption process of environmental innovations. The findings of the study will benefit any potential localities considering LID adoption. The theory of diffusion of innovations is applied as it is very flexible to investigate complex topics like environmental innovation involving multiple factors and environments. To explore the role of local governments in LID adoption, sub-theories like organizational innovation and policy adoption are reviewed. Based on these theoretical foundations, four constructs of variables which include innovation, organizations, motivations, and surrounding organizational context are investigated. The case study method is used for eight counties (Amherst, Bedford, Chesterfield, Fairfax, Isle of Wight, Roanoke, Stafford, and Spotsylvania) and two cities (City of Charlottesville, City of Roanoke) in Virginia. Key informants from each locality were selected for in-depth interviews and additional document reviews for each case are used to support multiple case studies. LID adoption consists of various forms such as regulations, practices, and plans. A combination of all forms of LID activities and programs was used to measure LID adoption level. Based on nine criteria (i.e., adoption mode, use of the term "LID" in local codes, code details, LID manuals, demonstration projects, number of LID projects after LID code adoption, education programs, task force, and incentives), localities with three levels of LID adoption have been determined. Influencing factors of innovation adoption varied depending on level of LID adoption (high, moderate, and low). Therefore, strategies to promote environmental innovation should be developed in relation to the level of innovation adoption. The research findings revealed two major determinants that influenced the level of LID adoption. One is strong champions, and the other is regulatory mandates. A champion-driven LID adoption model is found in high level LID adoption localities. Usually, individuals from local governments, NGOs, and development communities have played a critical role in LID adoption process. The local government organizations in this group are usually self-motivated for innovation adoption. Especially, the presence of strong champions was identified as a key factor to the higher level of innovation adoption. On the other hand, a regulation-driven LID adoption model is found in moderate to low level LID adoption localities. These localities are strongly influenced by state regulatory mandates. In these cases, external forces motivate local governments to adopt innovations. / Ph. D.

Climate and human activities impact the timing and quantity of streamflow and floods in different ways, with important implications for people and aquatic environments. Impacts of landscape changes on streamflow and floods are known, but few studies have explored the magnitude, duration and count of floods the landscape can influence. Understanding how floods are influenced by landscape structure provides insight into how, why and where floods have changed over time, and facilitates mapping the capacity of watersheds to regulate floods. In this study, I (1) compared nine flood-return periods of 31 watersheds across North Carolina and Virginia using long-term hydrologic records, (2) examined temporal trends in precipitation, stream flashiness, and the count, magnitude and duration of small and large floods for the same watersheds, and (3) developed a methodology to map the biophysical and technological capacity of eight urban watersheds to regulate floods. I found (1) floods with return periods ≤ 10 years can be managed by manipulating landscape structure, (2) precipitation and floods have decreased in the study watersheds while stream flashiness has increased between 1991 and 2013, (3) mapping both the biophysical and technological features of the landscape improved previous efforts of representing an urban landscape's capacity to regulate floods. My results can inform researchers and managers on the effect of anthropogenic change and management responses on floods, the efficacy of current strategies and policies to manage water resources, and the spatial distribution of a watershed's capacity to regulate flooding at a high spatial resolution. / Master of Science

As urban land expands across the globe and impervious surfaces continue to be used for constructing urban infrastructure, stormwater treatment costs and environmental damage from untreated stormwater will rise. Well designed urban landscapes can employ trees and soils to reduce stormwater runoff flowing to streams and treatment facilities. Typical urban soil, however, is compacted and restricts tree growth via high soil strength and inadequate gas exchange. A site preparation method that deeply incorporates compost and includes trees for long term carbon input and pore development was evaluated in the urban setting of Arlington, Virginia. Three species were used in that study of 25 streetside plantings. The site preparation affected soil at 15 30 cm by lowering soil bulk density by 13.3%, and increasing macro-aggregate-associated carbon by 151% compared to control plots, and resulted in 77% greater tree growth during the first year after transplant. In a second experiment, rainfall simulations were used to evaluate common landscape mulch materials for their ability to prevent compaction from traffic as well their affect on surface runoff before and after traffic. When plots were subjected to heavy rainfall, (>97 mm/h) mulches were found to reduce sediment loss 82% and 73% before and after traffic, respectively. Runoff rates from wood chips were only 0.19 ml/s faster after traffic while rates from bare soil and marble gravel with geotextile increased 2.28 and 2.56 ml/s, respectively. Management of soils, trees and landscapes for stormwater benefit could reduce cost of wastewater treatment for municipalities and can prevent environmental degradation. / Master of Science

Low Impact Development (LID) is a sustainable stormwater management approach that aims to control runoff close to its source, mimicking the natural hydrological processes such as infiltration and storage. It is being adopted by many cities, where its implementation is rapidly evolving. The LID practices are small-scale measures; therefore, they need to be widely implemented to impact significantly. The selection of LIDs depends on the land use and characteristics of the area of interest. This study focuses on residential LIDs. First, a systematic and bibliometric literature review is conducted on the residential LIDs articles published up to the year 2020; a total of 94 papers were found in the Web of Science. This review resulted that LID implementation in residential areas still needs to be investigated. To assist the City, engineers, and policy-makers in implementing the suitable LIDs for detached houses, a multi-criteria decision analysis framework incorporating a hydrological model is developed in this study. The commonly used LIDs were identified, which are rain gardens, permeable pavement, rain barrels, soakaways. Seven criteria were selected – runoff depth reduction rate, peak runoff reduction rate, installation cost, maintenance cost, retrofit cost, life cycle, and aesthetical view. For the properties of the single-detached house and LIDs, the standards of Credit Valley Conservation (CVC) and Toronto and Region Conservation Authority (TRCA) were followed. The proposed decision-making framework also was applied to a case study. This framework is still in the preliminary stage, thus holds the potential to convert into a tool that will be handy enough for the homeowners and consume less time. / Thesis / Master of Applied Science (MASc)

One of the challenges today ́s planners face with the urbanization is how to adapt the city to the climate changes, with the increasing precipitation that causes flooding. The concept of Sustainable stormwater management aims to prevent flooding and ensure good water quality, which complies with the EU Water Framework Directive. The aim of this thesis is to investigate how Sustainable stormwater management and climate adaption is implemented in municipal planning in the Bothnian Bay Water District and to map the prevailing conditions and obstacles that may occur. Semi-structured interviews were conducted with municipal planners in Luleå, Umeå, Haparanda, Kiruna, Boden, Piteå and Skellefteå. The answers were analyzed using a deductive thematic analysis method. The interview answers were coded at different levels with the research questions as a focus. This resulted in main themes and subcategories. The result shows that five of seven interviewed municipalities are in the process of implementing Sustainable stormwater management. The municipalities are aware of pollution in stormwater and the importance of good water quality, the goal is to achieve a natural flow of stormwater. Most of the municipalities work with the stormwater issue across administrative boundaries in collaboration. The climate adaptation work in the municipalities consists mainly of rainfall mapping and elevation of buildings. The greatest obstacles to the implementation are unclear division of responsibilities, lack of resources and knowledge and the question of land use. Regarding the municipality's size and geographical locations, factors such as terrain, watercourses / recipients, demographics, finances and human resources are of importance. / En av utmaningarna som urbaniseringen för med sig och som dagens planerare måste hantera är hur staden ska anpassas till klimatförändringarna; med den ökande nederbörden som orsakar översvämningar. Konceptet Långsiktigt hållbar dagvattenhantering syftar till att förhindra översvämningar och säkerställa god vattenkvalitet, vilket överensstämmer med EU: s Vattendirektiv. Syftet med denna studie är att undersöka hur Långsiktigt hållbar dagvattenhantering och klimatanpassning implementeras i kommunal planering i Bottenvikens vattendistrikt och att kartlägga rådande förutsättningar och hinder för denna implementering. Semi-strukturerade intervjuer genomfördes med tjänstepersoner i Luleå, Umeå, Haparanda, Kiruna, Boden, Piteå och Skellefteå. Svaren analyserades med hjälp av en deduktiv tematisk analysmetod. Intervjusvaren kodades på olika nivåer med forskningsfrågorna som fokus. Detta resulterade i huvudteman och underkategorier. Resultatet visar att fem av sju intervjuade kommuner arbetar med att implementera Långsiktigt hållbar dagvattenhantering. Kommunerna är medvetna om föroreningar i dagvatten och vikten av god vattenkvalitet, målet är att uppnå ett naturligt flöde av dagvatten. De flesta av kommunerna arbetar i förvaltningsövergripande samverkan med dagvattenfrågan. Klimatanpassningsarbetet i kommunerna består främst av skyfallskartering och höjdsättning av byggnader. De största hindren för implementeringen  är oklar ansvarsfördelning, brist på resurser och kunskap och frågan om markanvändning. När det gäller kommunens storlek och geografiska läge är faktorer som terräng, vattendrag / recipienter, demografi, finansiering och humankapital av betydelse.

Med ett förändrat klimat förväntas nederbörd och kraftiga skyfall öka i framtiden. Detta i kombination med en ökad urbanisering och allt fler hårdgjorda ytor i städerna leder till att befintliga dagvattensystem kommer bli överbelastade. Nederbörden förväntas öka med 10-20 procent och avrinningen med 5-25 procent under det närmaste seklet. I många städer har de naturliga avrinningsområdena försvunnit i samband med urbaniseringen och bostäder byggs på olämpliga platser med stor översvämningsrisk. Behovet av en hållbar dagvattenhantering är betydande för att undvika negativa konsekvenser i städerna framöver. Den traditionella dagvattenhantering med rörsystem blir alltmer kritiserad för att vara ohållbar. I Malmö är dagvattenfrågan högst aktuell då staden nyligen blivit drabbad av översvämningar. Studiens fokus ligger på vilken syn större fastighetsägare och VA-huvudmannen har på dagvattenhantering i ett förändrat klimat. Studien är av både kvalitativ och kvantitativ karaktär och består av två intervjuer samt en kompletterande enkätundersökning. De slutsatser som framkommit av studien är följande: Det behövs ett ökat samarbete med skyfallsproblematiken i Malmö, förändring av lagstiftningen för tydligare ansvarsförhållanden, fastställa finansieringen av åtgärder, arbeta mer mot öppna lösningar och minska fokus på ledningsnätet, öka kunskapen hos stadsplanerare och fastighetsägare, lyfta dagvattenfrågan tidigt i planprocessen samt våga arbeta mot en långsiktigt hållbar stadsplanering som inte fokuserar på kortsiktiga vinstintressen. / As a result of the changing climate precipitation and intensified rainfalls is expected to increase. This combined with an increased urbanisation and more of hard surfaces in cities causes greater pressure on exsisting storm water systems. The precipitation over Sweden is expected to increase with 10-20 percent and the run-off with 5-25 percent over the next century. Due to the urbanisation the natural drainage areas have disappeared and areas with high flood risk have been exploitated. To avoid negative consequenses in the future, sustainable storm water management is needed. Conventional storm water systems is more and more criticized of being unsustainable. The storm water issue is a highly disscused topic in Malmö as the city flooded during 2014. The focus of the study is property owner and the public water suppliers view on storm water management in a changing climate. The study uses both quantitative and qualitative methods and consists of two interviews and a supplementary questionnaire. The study’s conclusions are as followed: the need for increased cooperation with torrential rain problems in Malmö, change in legislation in terms of clarify responsibilities, determine the financing of measures, work more towards open solutions and reduce the focus on pipe-based storm water system, increase knowledge among city planners and property owners, bring up the stormwater issue early in the planning process and a determenation to work towards long-term sustainable planning rather than focusing on short- term profits.

Master of Landscape Architecture / Department of Landscape Architecture/Regional and Community Planning / Lee R. Skabelund / Hurricane Katrina displaced many New Orleans residents, leaving in its wake tens of thousands of vacant lots and buildings. In 2010, estimates show that over 57,000 properties lay empty in the city, especially in the poorer neighborhoods. These properties are not contributing to the fabric of the city; in most places, they are a sign of defeat, an eyesore, or a haven for crime. The neighborhood of St. Roch is experiencing the negative effects of these properties day in and day out and from year to year. Almost a quarter of the lots are vacant in the St. Roch neighborhood, leading to crime and creating a nuisance and a blemish on the community. Coupled with the lack of ownership there is an ailing stormwater management infrastructure leading to areas of flooding after routine storms. In addition to these concerns, there is a lack of fresh, inexpensive and accessible food throughout the area. Although St. Roch’s vacant lots have a negative effect on the community, they present a tremendous opportunity. Their dispersal around the neighborhood presents the opportunity to connect them to churches, schools, retail outlets, as well as providing other uses and services to the neighborhood. The thoughtful design of these locations will demonstrate a site-sensitive approach to the local ecology, culture, and economy of the neighborhood. Such design includes the community throughout the entire lifecycle of each site from its planning phase to the end of its use. The primary goal throughout the planning and design process is to foster stewardship for both the landscape and the community as a whole by means of collaborative planning, direct interaction with each site during implementation, and the observation and monitoring of crucial processes throughout a site’s lifecycle. The intent of this project is to apply a participatory framework to the site design process in order to rejuvenate critical areas of the St. Roch neighborhood. This project seeks to demonstrate the need for a collaborative process while allowing for a balance between the experts who help design each site and the community members who take ownership of the renewed parcels.

Connecting Urban Residents to Their Watershed with Green Stormwater Infrastructure: A case study of Thornton Creek in Seattle, Washington.