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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
141

Enhancement and Evaluation of a Rainfall-Runoff Single Event Model

Salazar Mejia, Germania 12 May 2012 (has links)
Planning and design of stormwater facilities (including best management practices and low impact development) involve the calculation of peak flows and runoff volumes. Rainfall-runoff models are frequently utilized to estimate this information. A userriendly rainfall-runoff tool (LIDIA) was developed using Visual Basic for Applications in Microsoft Office Excel. This research showed comprehensive guidelines on how to setup a model in LIDIA and reported the first evaluation of LIDIA using field data. LIDIA hydrologic module was tested using 10-minute rainfall, land cover, soil series, land cover management, and runoff data from two small watersheds in North Mississippi. Eleven storm events, over a period of seven months were used for the one evaluation site and 11 storm events were used for the second case study. Overall the development and results of LIDIA tool showed in this study are positive in keeping the enhancement of the model.
142

APPROACHING URBAN SUSTAINABILITY THROUGH RESTORATION ECOLOGY AND GREEN INFRASTRUCTURE / NATIVE PLANT PERFORMANCE ON A RIPARIAN BUFFER RESTORATION AND FEASIBILITY OF A CONSTRUCTED WETLAND AT AN URBAN PARKING LOT

Matties, Reyna 17 November 2017 (has links)
Most cities are dominated by asphalt and concrete, which blocks the natural movement of rain water. Wetlands, riparian buffers, and roadsides are being lost or degraded in urban areas due to human development. Cities can be designed to benefit humans and nature by using techniques from green infrastructure and restoration ecology to improve urban sustainability. Parking lot M on McMaster University's west campus, constructed in 1968 on a former floodplain, directs the highly saline parking lot runoff into the adjacent Ancaster Creek. Natural groundwater sources along the surrounding hillslopes are directed into pipes under the parking lot and into the creek. A one-hectare riparian buffer restoration at lot M was used to assess the viability of depaving asphalt and establishing native plants through a vegetation study. Total native plant biomass was found to be similar to non-native plant biomass and was affected by road-salt salinity from the parking lot. Species richness per quadrat was higher for non-native plants, and greater for both non-native and native plants where less salt was present. Key hydrological fluxes were examined at the parking lot that could contribute to a proposed 0.6 hectare constructed wetland on the parking lot, known as “McMarsh.” Potential wetland water storage is in surplus year round, with an average storage of 265 mm/month. Successful restorations require maintenance following the establishment of native species. Management and maintenance of the restoration can help decrease non-native species. Engaging with the community through outreach and education on restoration projects is important for a successful restoration and increasing urban sustainability in cities. / Thesis / Master of Science (MSc) / Most cities are dominated by asphalt and concrete, which blocks the natural movement of rain water. Wetlands, riparian buffers, and roadsides are being lost or degraded in urban areas due to human development. Cities can be designed to benefit humans and nature by using techniques from green infrastructure and restoration ecology to improve urban sustainability. Parking lot M on McMaster University's west campus, constructed in 1968 on a former floodplain, directs the highly saline parking lot runoff into the adjacent Ancaster Creek. Natural groundwater sources along the surrounding hillslopes are directed into pipes under the parking lot and into the creek. A one-hectare riparian buffer restoration at lot M was used to assess the viability of depaving asphalt and establishing native plants through a vegetation study. Total native plant biomass was found to be similar to non-native plant biomass and was affected by road-salt salinity from the parking lot. Species richness per quadrat was higher for non-native plants, and greater for both non-native and native plants where less salt was present. Key hydrological fluxes were examined at the parking lot that could contribute to a proposed 0.6 hectare constructed wetland on the parking lot, known as “McMarsh.” Potential wetland water storage is in surplus year round, with an average storage of 265 mm/month. Successful restorations require maintenance following the establishment of native species. Management and maintenance of the restoration can help decrease non-native species. Engaging with the community through outreach and education on restoration projects is important for a successful restoration and increasing urban sustainability in cities.
143

Reframing the Ditch

Hersch, Nicole Susan 13 August 2019 (has links)
Reframing the Ditch explores the application of native canopy using green street tools as a method to move beyond minimums and improve biological diversity of stormwater conveyances in a way that is consistent with visual landscape preference theory. Small stream water quality impairment is an issue found in 83% of stream headwaters in the Eastern United States. The Clean Water Act (1972), which regulates pollutant discharge into U.S. surface waters, mandates that municipalities create an implementation plan to improve water quality of their impaired streams. Water quality impairment is often exacerbated when headwater streams flow through urban areas. Urban areas are concentrations of human activity and as such bring concentrations of impermeable surfaces and stormwater runoff. As development increases, dedicated space for stormwater changes. Natural flow patterns that interacted with stratified layers of native vegetation often become constrained to ditches and pipes with little or no vegetation within the conveyance corridor. Reframing the Ditch creates an approach to help municipalities improve water quality of headwater streams by addressing water quality in ditches before water reaches the stream. The objective of urban conveyance systems is to move stormwater runoff into waterways as quickly as possible. When we design these conveyances to simply minimize stormwater interference, we ignore the potential contribution this land has for our public urban systems. This project looks for an intermediary between minimums and maximums. Maximums, also known as restoration, allows for messy, dynamic systems that are not hydrologically or visually appropriate in most urban environments. This thesis reveals ditches as complex landscapes that require high preforming vegetation, which ultimately limits the number of native species suitable for such harsh environments. Additionally, the more impermeable an environment is and the farther a ditch is from the top of the watershed, the more stormwater runoff there is, and the more space is required to process water and improve water quality. Cost, lack of available vegetation and lack of space may limit the application of this design in most circumstances. However, there are appropriate landscapes where this design methodology can provide valuable insight for landscape implementation plans aimed at improving water quality, while also providing public space, enriching neighborhood aesthetics and highlighting the function of our urban drainage systems. / Master of Landscape Architecture / The Environmental Protection Agency, through the Clean Water Act, dictates what is an appropriate level of contamination in streams and rivers within the United States. Waterway impairment is a widespread issue affecting 83% of headwater streams in the Eastern United States. Improving the quality of headwater streams, the smallest parts of stream and river networks, is generally thought of as the first opportunity to improve water quality downstream. Reframing the Ditch suggests an alternate first opportunity by looking at how we can improve water quality by addressing design of the urban ditch. Urban ditches, mostly in the form or open channels or curb-and-gutters, collect and move stormwater runoff. Ditches, typically have little vegetation and work to more water as quickly and efficiently as possible. When we eliminate vegetation from urban ditches, we also eliminate valuable function. In natural stream processes, vegetation slows, filters, and infiltrates water, improving water quality, while also improving biodiversity and providing habitat. However, theses natural stream processes are dynamic and messy systems that are often not appropriate for urban settings. In order to define a design method that is appropriate for urban settings, Reframing the Ditch utilizes a green street toolkit to create a strong sense of place, while processing stormwater, within our public rights-of way. By focusing on the application of native urban canopy within a drainage network, we can adhere to landscape preference and increase biodiversity. The design reveals that ditches are complex, context specific landscapes. While there is opportunity to increase utility of these spaces, there is complexity and cost to doing so. Layering utility into our stormwater conveyances is a valuable design strategy that serves individuals, neighborhoods, municipalities and watersheds. This project is an effort to help municipalities reframe their ditches, by providing ecological and social benefit, and ultimately improving water quality downstream.
144

Nedbrytning av totalt organiskt kol i dagvatten på Stockholm Arlanda flygplats / Degradation of total organic compounds in stormwater at Stockholm Arlanda Airport

Lorin, Moa January 2024 (has links)
Swedavia är ett statligt ägt bolag som äger och driver tio flygplatser i Sverige, varav Stockholm Arlanda Airport är en. Flygplatsen har ett miljötillstånd där ett utredningsvillkor kallat U4 finns. Prövotidsutredningen syftar främst till att utvärdera reningseffekten hos dagvattenanläggningarna vid flygplatsen, med slutgiltiga villkor om utsläpp av bl.a. organiska föreningar och näringsämnen. När det under vintertid bildas snö- och isbeläggningar på flygplanen och banorna riskerar det att delvis påverka den aerodynamiska förmågan men också orsaka otillräcklig friktion mellan flygplansdäcken och marken. För att förhindra att olyckor sker eller att plan inte lyfter används framför allt kaliumformiat och propylenglykol som av-isning och halkbekämpningsmedel. Följden av att använda dessa blir förhöjda halter löst TOC (Total Organic Carbon) i dagvattnet och det kan leda till syrefria förhållanden i recipienten, vilket i detta fall är Märstaån. Swedavia har, med det primära syftet att rena dagvattnet på av-isning-och halkbekämpningsmedel, anlagt flera dagvattenanläggningar på flygplatsområdet. Dessa består av dammar som genom biologisk nedbrytning och sedimentering ska rena vattnet med avseende på TOC. Enligt ett prövotidsvillkor som uppkom i samband med miljödomen för flygplatsen ska slutgiltiga halter bestämmas och den potentiella reningseffektiviteten av dagvattnet ska undersökas. Reningseffektiviteten har dock visat sig vara svår att fastställa då dammarna kontinuerligt fylls på med vatten och att vattnet leds förbi dammarna via bypass-funktion vid för stora vattenflöden. Då reningseffektiviteten i dammarna fortfarande inte är fastställd är denna studies syfte att utvärdera reningseffekten och om den kan förbättras. Ett inkubationsförsök för nedbrytning gjordes med en experimentuppställning där vattenprover från Arlanda inkuberades i 3 olika temperaturer (5°C, 10°C och 23°C) med kategorierna låg/hög TOC-halt och med/utan tillsats av makronäringsämnena fosfor och kväve (N och P), enligt Redfield förhållandet 106:16:1. Försöket pågick i 33 dagar och kontinuerliga vattenprover togs för att sedan analysera TOC-halten. Resultatet visade att näringstillsats, enligt Redfieldförhållandet, inte hade någon statistisk signifikant påverkan på nedbrytningshastigheten vid 5°C och 10°C. Det fanns dock en statistisk signifikant skillnad vid 23°C, vilket tyder på att näringstillsats är gynnsamt för nedbrytningen vid högre temperaturer. Vid jämförelser mellan nedbrytningshastigheterna vid olika temperaturer fanns det en statistisk signifikant skillnad mellan proverna, förutom för kategorin med hög initialhalt utan näring. Vid låg initialhalt och en temperatur på 5°C, 10°C och 23°C kunde en reduktion av TOC på 65-73%, 83-86% samt 80-90% för respektive temperatur observeras efter en inkubationstid på 33 dagar. För proverna som startade med hög initialhalt i temperaturerna 5°C, 10°C reducerades TOC med 4-42% och 11-16%, och för 23°C skiljde sig nedbrytningen mellan kategorierna näringstillsats/ingen näringstillsats. Utan näring ökade TOC-halten med 38% och med näring reducerades den med 88 % efter 33 inkubationsdagar. En ökning av halten tyder på felkällor i metoden. Nedbrytningshastigheten och tiden för 100% nedbrytning vid låg och hög initialhalt för olika förutsättningar för hela perioden var mellan 0.34-1.02 mg/l respektive 8.45-11.47 mg/l TOC per dag samt 30-47 respektive 39-84 dagar. Efter en vecka var spannet mellan nedbrytningshastigheter för låga och höga initialhalter 1.63-6.98 mg/l respektive 33.21-83.28 mg/l TOC per dag och reningskapacitetenefter en vecka var 33-100% respektive 30-81%. De förbättringar som kan föreslås, baserat på resultatet i studien, är att se över möjligheten att ha ett kostnadseffektivt uppvärmt system, eventuellt genom att nyttja spillvärme på flygplatsen. Vid uppvärmning kan ett alternativ vara att tillföra näringsrikt avloppsvatten, för att upprätthålla en effektiv nedbrytning. Om detta inte är möjligt bör man överväga möjligheten att introducera ett ytterligare reningssteg, som ett biofilter som reducerar TOC-halten innan vattnet lagras i dammarna. Mer studier krävs dock för att kunna dra välgrundade slutsatser från arbetet, eftersom det i studien uppkommit osäkerheter i resultatet. / Swedavia is a state-owned company that owns and operates ten airports in Sweden, of which Stockholm Arlanda Airport is one. The airport has an environmental permit where an investigation condition called U4 exists. The investigation condition primarily aims to evaluate the treatment of stormwater at the airport, with final conditions regarding emissions of e.g. organic compounds and nutrients. Snow and ice deposits form on airplanes and runways during winter, this affects the aerodynamic ability of the airplanes and cause insufficient friction between the airplane tires and the ground. To prevent crashes or planes not taking off, anti-icing agents such as mono propylene glycol and potassium formate are being used. The consequence of using these agents is increased levels of dissolved organic material in the stormwater and in the worst case this can lead to oxygen depletion in the recipient, which in this case is Märstaån. Swedavia has, with the primary purpose of purifying stormwater, built several stormwater facilities in the airport area. These consist of ponds that through biological decomposition depletes the water of the dissolved organic material. According to the trial period investigation, the final conditions for the storm water should be decided and the potential TOC-removal efficiency from the storm water needs to be evaluated. However, it has been hard to establish how well the ponds reduction of TOC work since water continuously fills up the ponds and because water sometimes gets bypassed when there are high flows. Since the reduction of TOC in the ponds is still not determined, the the purpose of this study was to evaluate the TOC-removal efficiency and whether it can be improved. Experimental incubations for degradation of TOC where conducted with water samples from Arlanda, incubated at 3 different temperatures (5°C, 10°C and 23°C) with the categories low/high TOC content and with/without addition of nutrients, according to the Redfield ratio 106:16:1. The experiment lasted 33 days and continuous water samples were taken to then analyze the TOC content. The result showed that nutrient addition according to the Redfield ratio had no statistically significant influence on the degradation, except at 23°C, which suggests that nutrient addition is beneficial at higher temperatures. When comparing the degradation rates at different temperatures, there was a statistically significant difference between the samples, except for the high initial content category without added nutrients. At a low initial content and a temperature of 5°C, 10°C and 23°C, a TOC-reduction of 65-73%, 83-86% and 80-90% was observed for the respective temperature after 33 days of incubation. For the samples that started with a high initial content in the temperatures 5°C, 10°C, a TOC removal of 4-42% and 11-16% was observed and for 23°C, the TOC-removal differed between the the samples without and with addition of nutrients. Without added nutrient, the TOC content increased by 38% and with added nutrient, it was reduced by 88 % after 33 days of incubation. An increase in the TOC content indicates sources of error in the method. The degradation rate and time to 100% degradation at low and high initial content for different conditions and the entire test period was between 0.34-1.02 mg/l respectively 8.45-11.47 mg/l TOC per day and 30-47 and 39-84 days respectively. After a week the range of degradation rates for low and high initial concentrations was 1.63-6.98 mg/l respectively 33.21-83.28 mg/l TOC per day and the TOC-removal capacity after one week was 33-100% respectively 30-83%. The improvements suggested, based on the results of the study, is to investigate the possibility of having a cost-effective heated pond system, possibly if there is waste heat to use from the airport. When heating, an alternative may be to add nutrient-rich wastewater, to maintain efficient degradation. If this is not possible, consideration should be given to the possibility of introducing an additional step for TOC-removal, such as a biofilter that reduces the TOC content before the water is stored in the ponds. However, more studies are required to draw well-founded conclusions from the study, as there were uncertainties in the results.
145

Stormwater evaluation and site assessment - a multidisciplinary approach for stormwater Best Management Practices (BMPs)

Padmanabhan, Aarthi January 1900 (has links)
Master of Landscape Architecture / Department of Landscape Architecture/Regional and Community Planning / Lee R. Skabelund / Stormwater management is typically approached from different perspectives by practicing professionals. As such, stormwater planning/design is not always completed as a multi-disciplinary coalition of experts using holistic and synergistic methods. For a number of years, engineers and design professionals, particularly landscape architects, have been employing various strategies and techniques to address on-site stormwater management in terms of water quality and quantity. There is increasing awareness that in order to create solutions that are effective over both the short and long-term a landscape architect’s approach needs to account for the health, safety and welfare perspectives carried by engineers, the unique aspects of particular project sites, their surroundings and bio-regional context, as well as the perceptions of clients, other key stakeholders, and the broader public. This research investigates the various criteria integral to developing an analytic framework for ecologically-appropriate stormwater planning/design (Sustainable Stormwater Evaluation and Site Assessment or SSWESA). SSWESA is proposed as a type of decision-tree for site analysis of sustainable systems pertaining to stormwater. Using the SSWESA process is expected to help researchers and professionals make better planning and design decisions as they select and implement appropriate best management practices (BMPs) for a given site and context. My intent in developing SSWESA is to help designers assess existing and potential stormwater functions at the site scale in order to promote sustainable planning and design based upon the important principle: “First, do no harm”. It is also my intent to promote further research related to sustainability by providing references and sources from experts in the various fields related to ecologically-based stormwater management. A review of the literature related to ecological factors relevant to low impact stormwater management assisted in the development and refinement of the criteria for stormwater assessment and evaluation. In this report, the SSWESA framework is tested on a public school property in Manhattan, Kansas to demonstrate how the framework is applied and to understand the questions and issues that arise from its use.
146

La diffusion du contrôle à la source des eaux pluviales urbaines : confrontation des pratiques à la rationalité hydrologique / The diffusion of source control for urban stormwater management : a comparison between the current practices and the hydrological rationality

Petrucci, Guido 11 July 2012 (has links)
La gestion des eaux pluviales urbaines connait une évolution majeure depuis les années 1960 : d'une stratégie basée sur l'évacuation rapide et totale des eaux pluviales de la ville, on passe progressivement à une stratégie de contrôle à la source (CS). Ces 10 dernières années ont vu une généralisation du CS, ainsi qu'en témoigne l'augmentation du nombre de réglementations de rejet. Ces dernières imposent, dans les nouvelles parcelles urbanisées, la réalisation d'ouvrages ayant pour fonction de réguler et/ou de retenir les eaux pluviales : les techniques alternatives (TA). Une systématisation de ces réglementations ne va pas manquer de générer dans l'avenir de nombreux bassins versants urbains fortement équipés en TA, et dont le comportement hydrologique sera déterminé par les réglementations appliquées. Il apparaît que le choix d'une réglementation par une collectivité est un choix complexe et, d'une collectivité à l'autre, des logiques différentes sont appliquées, dont la cohérence globale peut être discutée. Cette thèse questionne et analyse les politiques de CS, et en particulier les réglementations de rejet, dans une perspective de compréhension de leurs effets hydrologiques dans le long terme. Elle comprend deux analyses complémentaires : nous étudions d'abord l'évolution des politiques de CS dans six collectivités en France, afin de déterminer les logiques appliquées dans le choix des réglementations. Nous présentons ensuite une analyse hydrologique des conséquences de ces réglementations sur le comportement de bassins versant urbains "modèles". Cette analyse, centrée sur la modélisation hydrologique des bassins, permet de questionner les politiques de CS actuelles, mais aussi de discuter des outils que l'hydrologie urbaine peut fournir pour permettre la mise en place de politiques de CS cohérentes, en phase avec le fonctionnement hydrologique des bassins versants / Urban stormwater management is facing a major evolution since 1960: from a strategy based on the complete and fast conveyance of stormwater outside of the urban area, to a strategy based on source control (SC). Recently, SC is becoming a common practice, in connection with the increasing diffusion of flow regulations. These regulations prescribe, for all new urban development, to build facilities (Best Management Practices, BMP) to reduce the flow-rate or the volume of stormwater entering the sewer system. A wide application of flow regulations will determine the future hydrological behaviour of many urban catchments. The choice of a regulation is a complex task for local authorities, involving several logics, whose global coherence can be discussed. This thesis analyses SC policies and regulations and discusses them in terms of their long-term hydrological effects. Two complementary approaches are developed. The first is based on the analysis of the evolution of SC policies in six French authorities, and it aims to define and discuss the logics applied. The second consists in the hydrological modelling of the consequences of SC regulations on the behaviour of two experimental catchments. This hydrological analysis allows (i) to evaluate the pertinence of actual SC policies and (ii) to discuss which tools urban hydrology can provide to support the development of coherent SC policies, according to the hydrological functioning of urban catchments
147

Parcel-Level Green Stormwater Management Policy: What New Orleans Can Learn from Philadelphia’s Parcel-Based Utility Fee

Riggs, Spence 18 December 2014 (has links)
The Greater New Orleans Urban Water Plan promotes the ideology of integrating green infrastructure into the City’s water management strategy to cultivate resiliency. In order to develop enough green infrastructure to have a significant impact on the hydrological functioning of the area, New Orleans officials are investigating different options for encouraging property owners to manage their stormwater on-site. Philadelphia Water Department’s parcel-based stormwater utility fee has been offered as a model for working within the constraints of the municipal government’s regulatory authority to increase the water retention capacity of individual properties. This thesis provides an analysis of Philadelphia Water Department’s stormwater utility policy and offers recommendations to other cities, like New Orleans, that are considering adopting a similar policy in their jurisdiction.
148

En jämförelse mellan gröna-, metall- och gråa tak för ett oisolerat parkeringshus utifrån dess olika temperaturer och dagvattenhantering

Andersson, Emelie, Aziz, Shniar January 2019 (has links)
Since climate change increases and changes constantly, it contributes to higher average temperatures, ice melting and has a great impact on our ecosystem. This will then lead to a warmer climate, which means increased precipitation and milder winters. One of the reasons to climate change is urbanization, meaning people moving to the cities. To succeed in changing the climate, international cooperation and common goals are required. At the northern part of Brynäs, in the municipality of Gävle, work is currently in progress around the area where the factory of Läkerol was once standing. The area continues to be rebuilt and the outcome will eventually be called Godisfabriken. There, amongst other, a car park will be built for the newly built homes. The aim of this study is to compare metal roofs, grey concrete roofs and green roofs within the two aspects of stormwater management and temperature. Then analyse which alternative of these three roofs would be most advantageous for the car park of Godisfabriken.   The focused roofs are green, metal and concrete. A green roof is when it's completely or partly covered by a layer of vegetation and metal roofs are different sheet roofs with steel and aluminium-zinc. Grey roofs are made of concrete which works as both floor and ceiling. A building's roof affects which air temperature the surroundings has with its slope, vegetation and surrounding buildings. Another problem with urbanization and a warmer climate is stormwater management, which means rain and melted snow from roofs, parking areas and other hard surfaces.   The method includes a literature study and calculations. The literature study gave research on temperature for all roofs as well as stormwater management for green roofs. Calculations were made for stormwater management and temperature with its flow, absorption, reflectance and heat transfer.   The literature study and the calculations showed that green roofs have a high SRI value of 80 while the remaining roof is at around 40. The higher SRI, the lower surface temperatures on the material. This is proven in both methods when green roofs according to the literature study received a maximum surface temperature of 38 °C and 48 °C. According to the literature study green roofs can preserve more than 50 % of the rainwater. They also had a water flow rate of 1.97 l/s, which is less than half of what the metal roof got in the calculations. Since green roofs had both low air and surface temperatures, as well as longer drainage times and most absorbed water, green roofs are a more suitable choice than metal and grey concrete. / Eftersom klimatförändringarna förändras och konstant ökar bidrar det till en högre medeltemperatur, att isen smälter och att ekosystemet påverkas. Detta kommer då leda till ett varmare klimat vilket medför ökad nederbörd och mildare vintrar. En av orsakerna är urbanisering vilket betyder att människor flyttar till städer. För att lyckas förändra klimatet krävs internationellt samarbete och gemensamma mål.   Vid norra Brynäs i Gävle kommun pågår just nu arbete runt området där Läkerolfabriken en gång stod. Gamla Läkerolområdet kommer slutligen bli Godisfabriken. Där kommer det uppföras ett parkeringshus till det nybyggda bostäderna. Syftet med denna studie är att jämföra metalltak, gråa betongtak och gröna tak inom de två aspekterna dagvattenhantering och temperatur, därefter analysera vilket alternativ av dessa tre tak som skulle vara mest fördelaktigt för Godisfabrikens parkeringshus.   De fokuserade taken var grönt-, metall- och betong tak. Ett grönt tak är då taket är helt eller delvis täckt av ett lager vegetation. Metalltak är olika plåttak med stål och aluminium-zink, gråa tak syftar på betongbjälklag som fungerar både som golv och tak. En byggnads tak påverkar vilken lufttemperatur omgivningen har, även takets lutning samt växtlighet och byggnaderna runt om. Ett annat problem med urbanisering och varmare klimat är dagvattenhanteringen, vilket innebär regn- och smältvatten från bland annat tak, parkeringsytor och andra hårdgjorda ytor.   Metoden innefattar en litteraturstudie samt beräkningar. Litteraturstudien gav forskning om temperatur för samtliga tak samt dagvattenhantering för gröna tak. Beräkningar genomfördes för dagvattenhantering och temperatur med dess flöde, absorption, reflektans och värmeöverföring.   Litteraturstudien och beräkningarna visade att gröna tak har ett högt SRI (Solar Reflectance Index) värde på 80 medan resterande tak låg på runt 40. Ju högre SRI desto lägre yttemperaturer på materialet. Detta bevisas i båda metodvalen då gröna tak enligt litteraturstudie fick en maximal yttemperatur på 38 °C och 48 °C enligt beräkningarna. De hade även ett dagvattenflöde på 1,97 l/s, vilket är mindre än hälften av vad metalltaken på 4,93 l/s fick vid beräkningarna och kan enligt litteraturstudien bevara mer än 50 % av regnvattnet. Då gröna tak hade både låga luft- och yttemperaturer samt längre avrinningstid och mest absorberat vatten visar det att gröna tak är ett mer lämpligt val än metall- och gråa betongtak.
149

Primary Production and Nutrient Dynamics of Urban Ponds

Rolon dos Santos Mérette, Muriel 01 February 2012 (has links)
In urban areas, stormwater management ponds (SWPs) are built to mitigate polluted runoff. Although these ponds are increasing in numbers, their ecology is not well understood. Physical and chemical characteristics of 17 SWPs in the City of Ottawa were measured to determine the drivers of phytoplankton biomass (Chl. a) and primary production (PP). While total phosphorus was the best predictor of algal biomass in the ponds (as in lakes), the imperviousness of the catchment could also predict Chl. a. Planktonic PP in two ponds measured seasonally was more closely related to water residence time than to nutrient concentrations with rates approaching at times the theoretical maximum for aquatic systems. In one pond, whole ecosystem metabolism, estimated using diel changes in dissolved oxygen and δ18O-O2, suggested that these hypereutrophic systems were net sinks for carbon in the summer but likely sources to the atmosphere at other times of the year.
150

Effektivisering av ekologisk dagvattenhantering i stadsmiljö / Efficiency of ecological stormwater management in urban areas

Backström, Martin, Wikström, Ludvig January 2013 (has links)
I Jönköping har problemet med översvämningar, erosion och materialtransport varit ett stort problem i Strömsbergsbäcken i Jönköpings kommun. Detta har tillviss del orsakats av ett ökat dagvattenutsläpp i bäcken, vilket skapar kraftigaflödestoppar då den ursprungliga fåran inte är ”dimensionerad” för den ökadevattenmängden. Syftet med arbetet är att effektivisera ekologisk dagvattenhantering i stadsmiljö med högt dagvattenutsläpp. Målet med arbetet är i sin tur att framställa underlag för hur ekologisk dagvattenhantering i stadsmiljö kan genomföras och att rapporten skall kunna ge värdefull kunskap till liknande sammanhang. För attuppfylla målet har följande tre frågeställningar utformats som utgör en väsentligdel av arbetet: Hur kan belastningen på det allmänna dagvattennätet minskas? Hur kan föroreningsföljderna av dagvattenavrinning i stadsmiljö minskas? Vilka åtgärder är lämpliga för att effektivisera ekologisk dagvattenhantering i  Strömsbergsbäcken? Metoderna som använts för att besvara frågeställningarna är litteraturstudie, dokumentanalys och fallstudie. Resultaten visar på att vattenflödena från fyra av nio upptagningsområden som har sitt utlopp i Strömsbergsbäcken bör genomgå någon form av åtgärd som bromsar eller minskar dagvattenflödena innan det återgår till den naturliga vattencykeln. Dagvattenflödet kan minskas genom att anlägga åtgärder i området innan vattnet når vattendraget. Flödena kan också minskas genom åtgärder i anslutning tillbäcken, vid de utloppen där de största flödena förekommer. En väsentlig lösning för Strömsbergsbäcken är t.ex. att bygga om den befintliga branddammen, som ligger intill ett av utloppen, till en fördröjningsdamm för att bromsa en del av flödena i bäcken. / In the city of Jönköping problems with the irregular flow, erosions and transport of sediment materials are recurring in the brook Strömsbergsbäcken. The problems is somewhat caused by an increased flow of storm water in the brook, which leads to high flow peaks in some parts of the brook since the original furrow is not dimensioned for the increased amount of water. The purpose of this project work is to make ecological drainage management in urban environments with a high amount of storm water discharge more efficient. The objective with the report is to create valuable material of how to accomplish ecological drainage management in urban areas and that the report will be useful for future similar connections. To fulfill the objective, the following three questions have been designed as a significant part of the final project report: How can the load on the general drainage system be reduced? How can the pollution effects of storm water runoff in urban areas be reduced? Which treatments are appropriate to enhance the ecological storm water management in Strömsbergsbäcken ? The methods that have been used to solve these questions are document- and literature studies, and also a case study.The thesis results shows that the storm water flows from four of the nine areas that has its outlets in Strömsbergsbäcken, need to be treated through some kind of a solution or method that delays the water flow. The treatment could be performed in the area, before the storm water reaches the storm water network, which leads to Strömsbergsbäcken. The storm water flows can also be reduced by treatments adjacent to the outlets in the brook, where the largest flow peaks occurs. For example an essential solution to decrease the flows in Strömsbergsbäcken is to reconstruct the old dam located near one of the outlets into a basin, which will delay the stormwater flows.

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