No description available.

No description available.

No description available.

Pluvial flooding originating from extreme rainfall is problematic and an increasing issue in Sweden. Higher requirements on adapting cities in urban areas to these challenges have been placed on both municipalities and the county administration. Thus, an increased need for water modelling, both in existing and planned areas have emerged. The Danish Hydrological Institute (DHI) has developed several models and tools to simulate floods and heavy rains, of which MIKE 21 is one. MIKE 21 is a dynamic model consisting of hydrological calculations in each cell, requiring modelling skills and long simulation time, but is proven to be a good and credible model. SCALGO Live, on the other hand, is a static tool simulated by raster-based algorithms and capable of giving fast results directly on the platform. However, compared to MIKE 21, SCALGO Live is not as evaluated nor is its use as widespread for simulating floods and heavy rain events. This study aims to investigate how inundation in twenty urban areas caused by cloudbursts is simulated in both programs to examine how well the result coming from SCALGO Live, is equivalent to the result from the MIKE 21-model. The comparison is made in both depth and spread using three comparative indexes, two statistical equations and one map, showing the extension of the inundation in both models. To make the models comparable, the model in MIKE 21 is made as equivalent as possible with SCALGO Live before simulation and the purpose is to investigate whether there is any type of area where the two different models are equivalent. The result shows that the flooded areas from SCALGO Live are in good agreement in most areas with the MIKE 21-model, but that the depth in the depression zones is somewhat overestimated, compared with the highest value in MIKE 21. The MIKE 21-model has a greater spread upstream, showing flowpaths if compared directly with the flooded areas from SCALGO Live, but if activating the flow accumulation tool in SCALGO Live, the differences are reduced but cannot be quantified in this study. The differences between the models increase with a higher resolution, longer flowpaths and a larger catchment, at least for the confined catchments. To conclude, SCALGO Live is best suited for smaller confined catchments where there are no long or complex flowpaths. SCALGO Live also works well at an early stage in the planning process and as a platform for combining detailed data and results. However, for the more complex areas, MIKE 21 is better suited, since various parameters can be considered.

Roads, buildings, vehicles, and human activities cause spreading of pollutants, which partly end up in stormwater. The pollutant load contains solid particles of various size, hydrocarbons, organics, metals, nutrients, and microorganisms, which can have negative effects on water quality of surface-, coastal- and ground waters. Furthermore, urban development causes hardening of ground and reduced soil permeability that promotes rapid runoff during precipitation. The conversion from permeable to impermeable surfaces therefore lead to increased volumes stormwater but also decrease in stormwater water quality.  Stormwater runoff metals are bound to various particles or occur in the dissolved fraction which is more toxic to aquatic life. Infiltration to soil, sand or other media is common practice to reduce runoff and filtrate metals and many treatment facilities and filter media have therefore been assessed for their metal removal efficiencies. High metal removal is often achieved for total metals, but removal of dissolved fraction remains elusive in many studies. Hence the importance of evaluate removal of dissolved metals before application to stormwater treatment facilities.  The experimental column study of metal removal using commercially available reactive filter media showed that all filter media removal efficiencies in the order of zinc > copper > nickel. Removal efficiencies of chromium and lead were not considerably higher in tested filter media compared to the reference filter sand. Two filter media also leached chromium during the initial part of the experiment. / Vägar, byggnader, fordon och mänskliga aktiviteter orsakar spridning av föroreningar av vilka en del förekommer i dagvatten. Urban bebyggelse orsakar också hårdgörande av ytor och reducerar jordens permeabilitet vilket skapar snabb avrinning vid nederbörd. Avrinningen innehåller bland annat partiklar, kolväten och andra organiska ämnen, metaller, näringsämnen och mikroorganismer vilka kan ha negativa effekter på yt-, kust- och grundvatten. Omvandlingen till hårdgjorda ytor orsakar därför både ökade volymer avrinning och sämre vattenkvalité.  Metaller i dagvatten är ofta bundna till olika partiklar eller förekommer i löst form där den lösta formen anses vara mest miljöfarlig. Infiltration i jord, sand eller annan media är vanliga sätt att reducera avrinning och filtrera metaller. Hög förmåga att avskilja metaller kan ofta hittas för totala koncentrationen av metall men avskiljning av den lösta formen är ofta oklar. Utvärdering av olika filtermaterials förmåga att reducera lösta metaller är därför av särskilt intresse.  Kolonnförsöken gjorda för att utvärdera metallavskiljningskapacitet med kommersiellt tillgängliga reaktiva filtermaterial har i denna uppsats visat att filtermaterialen har högst procentuell avskiljning för zink följt av koppar och därefter nickel. Krom och bly avskiljs inte mer i dessa filtermaterial än vad de gör i sandfilter. Två av filtermaterial läckte dessutom initialt höga koncentrationer krom.

Behovet av dagvattenhantering har förändrats. Klimatförändringarna medför förändringar i nederbörden med oförutsägbara väder. Om det sedan kombineras med en högre exploateringsgrad kan det ge översvämningar och skadade byggnadsverk som följd. I Gävle kommun exploateras just nu Södra Hemlingby med en blandning av bostadstyper. Dessutom byggs en ny skola, vårdboende och förskola samt idrottshall i kommunens regi. Kraven för omhändertagandet av dagvatten är skärpt från de vanliga 10-årsregnet till det mer omfattande 20-årsregnet för lokalt omhändertagande. Recipienten i området, Hemlingbybäcken, är sedan tidigare överbelastat. Detta är ett examensarbete om dagvattenhanteringen med utgångspunkt i området Södra Hemlingby, med marken för samhällsnyttiga funktioner som underlag för det lokala omhändertagandet. Den valda lösningen, kassetter, ställs mot den traditionella stenkistan. Dessutom utreds vilken påverkan det högre kravet om projektering för 20-årsregn har för de projektet. Resultatet visade att kassettmagasinet är den lösning som uppnår flest krav. Ett kassettmagasin har ett större antal möjliga fördelar än magasin utformade med stenkista. Ett dimensionerande för högre årsregn motiveras med den pågående klimatförändringen. / The need to manage stormwater in urban areas, urban runoff, has changed. With a climate that continues to change, the weather and precipitation are becoming more unpredictable each year. When this is combined with even further urbanisation of our cities, urban flooding’s will be more frequent, with immense damage as aftermath. Södra Hemlingby is currently being exploited by Gävle kommun, with a mixture of accommodations. Furthermore, Gävle kommun will build a new school, gymnasium, retirement home and pre-school, all constructed in the municipal regime. By increasing the regulations regarding how to dimension the system designed to locally deal with the urban runoff, from a 10-year rain-plan to a more comprehensive 20-year rain-plan. Hemlingbybäcken, the local recipient in the area, is already at its maximum capacity. With the core of this thesis being urban runoff, Södra Hemlingby and its surrounding area planned to contain the social structure will be the area used as a foundation when estimating the local demand for processing the urban runoff. Furthermore, this thesis will also investigate how the increasing demand for a 20-year rain-plan will influence this project. The results indicated that the solution that best fulfils the requirements, and was within the of scope this thesis, was the kassettmagasin. When compared against a tried-and-tested method stenkista, the kassettmagasin proved to have more advantages. With the effect that comes with changing in climate and weather conditions, it is motivation enough to increase the demand to dimension for a 20-year rain-plan.

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)

Located on floodplains of the Potomac River in Old Town Alexandria, Ford's Landing boasts a rich history, once known as the Ford Plant. Evolving from its industrial past, it underwent a transformative development in 1996, emerging as the rowhouse neighborhood that we now know today. Developed for a wealthy living in Old Town Alexandria, the neighborhood Ford's Landing now confronts geographical challenges exacerbated by the evolving impacts of Climate Change. In response to these challenges, 'Resilient Ford's Landing' is a project that focuses on three pivotal topics: stormwater management, urban heat island mitigation, and energy production. It strives to redefine Ford's Landing as a sustainable and resilient place by retrofitting, innovating, and tailoring solutions to the site as well as improving the quality of life for its residents while being a better, model neighbor against the adverse effects of a changing climate. / Master of Science / Ford Landing is a wealthy neighborhood of rowhouses in Old Town Alexandria that was developed in 1996. The site was originally known as the Ford Plant. Due to its location near the waterfront, the neighborhood is facing problems relating to flood, water, and climate change issues. 'Resilient Ford's Landing' is a project that focuses on tackling these challenges. It is about managing stormwater that runs through the streets of the neighborhood, creating better shade and infrastructure to reduce the presence of heat, and using renewable energy to become energy efficient. With these methods, the project's intention is to redefine Ford's Landing as a sustainable and resilient neighbor.

Floating treatment wetlands (FTWs) are an innovative best management practice that can enhance the performance of traditional retention ponds by increasing removal of the nutrients nitrogen (N) and phosphorous (P). FTWs consist of floating rafts on which wetland plants are planted, allowing the roots to be submerged below the water surface while the shoots remain above. A growing body of research has documented FTW performance with regard to urban runoff treatment, however evaluation of FTW effectiveness for treatment of agricultural runoff has received less attention. Due to high fertilization and irrigation rates, commercial nursery runoff contains much higher concentrations of N and P than runoff from urban areas. We conducted this study over two growing seasons (2015 and 2016) to assess the effectiveness of FTWs for use in commercial nursery retention ponds. In the first study we used two different nutrient concentrations, one to simulate nursery runoff (17.1 mg∙L-1 TN and 2.61 mg∙L-1 TP) and one to simulate concentrations that fall between urban and nursery runoff (5.22 mg∙L-1 TN and 0.52 mg∙L-1 TP). Four treatments were used: 1) Pontederia cordata planted in cups supported by a Beemat, 2) Juncus effusus planted in cups supported by a Beemat, 3) a Beemat with no plants, and 4) no treatment (open-water). Performance was evaluated based on a 7-day hydraulic retention time (HRT). Pontederia cordata removed between 90.3% and 92.4% of total phosphorus (TP) and 84.3% and 88.9% total nitrogen (TN), depending on initial loads. These reductions were significantly more than other treatments at both high and low nutrient loading rates. Juncus effusus performed better than the control treatments for TP removal at low nutrient concentrations, but did not perform any better than the control at higher nutrient loads. In the second study, conducted in 2016, we evaluated different plant species over two 8-week trials using simulated nursery runoff. We used five monoculture FTWs with the following species: Agrostis alba, Canna ×generalis, Carex stricta, Iris ensata, and Panicum virgatum. Additionally, two treatments were created from mixed species plantings and the final treatment consisted of an open water control mesocosm. Nutrient removal performance was evaluated over a 7-day HRT. P removal (phosphate-P) by FTW treatments ranged from 26.1% to 64.7% for trial 1 and 26.8% to 63.2% for trial 2. Trial 1 N removal (sum of ammonium-N, nitrate-N, and nitrite-N) efficiencies ranged from 38.9% to 82.4%, and trial 2 ranged from 12.9% to 59.6%. Panicum virgatum removed significantly more N and P than the control and any other FTW treatment in the second study. Both studies indicated, depending upon plant species, that FTWs can effectively remove nitrogen and phosphorous from urban and commercial nursery retention ponds. / Master of Science / Floating treatment wetlands (FTWs) are used to enhance the nutrient removal performance of stormwater retention ponds. FTWs consist of a buoyant raft on which wetland plants are planted, allowing the shoots to extend above the water surface while the roots stay submerged. The purpose of this research was to evaluate FTW nutrient removal performance in a commercial nursery environment where runoff has much higher concentrations of nitrogen and phosphorous than urban stormwater. The study spanned across two growing seasons (2015 and 2016), during which, different plant species and nutrient concentrations where evaluated. The first study evaluated Pontederia cordata and Juncus effuses as well as two control treatments at a high nutrient concentration and a low nutrient concentration. The Pontederia cordata performed better than the other treatments at both the high and low initial nutrient concentrations. In the second study, the following species were evaluated using a combination of mixed and monoculture plantings: Agrostis alba, Canna ×generalis, Carex stricta, Iris ensata, and Panicum virgatum. Panicum virgatum removed significantly more nitrogen and phosphorous than any other FTW treatment in the second study. Both studies indicated that FTWs can be effective technologies for nutrient removal from urban and commercial nursery retention ponds.

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.