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Dagvattendammars reningseffekt : påverkande faktorer och metodik för statistisk modellering / Reduction of Pollutants in Storm Water Ponds : Governing Parameters and Methods for Statistical ModellingFlorberger, Jenny January 2006 (has links)
Storm water is defined as runoff from precipitation such as rain or snow. It is collected in sewage disposal systems and since it mainly originates from urban areas it can contain high levels of heavy metals, nutrients and oil etc. Polluted storm water is currently treated by different methods such as wet ponds, constructed wetlands and filter strips. This study investigates these methods, which in earlier studies have shown to give varying results regarding their treatment efficiency. This thesis has been written on commission of SWECO VIAK and was aimed at studying those parameters that may affect the treatment efficiency of nutrients and heavy metals in storm water treatment facilities (STF:s). Through literature studies the dominating treatment processes in ponds and wetlands were examined. The flow pattern was then simulated in four different storm water ponds, of varying shape and size, by using a physically based computer model. The residence time distribution for each pond could then be calculated as well as the hydraulic efficiency, which is a measure on how well the inflowing water is spread throughout a pond. Finally a multiple regression analysis was performed. This analysis examined how the reduction of lead, copper, zinc and cadmium depends on the following factors: the specific pond area, the variance of the residence time distribution, the hydraulic efficiency and the concentration of incoming metals and suspended solids. The specific pond area is a factor which is defined as the pond area divided by the reduced run off area. The results from the multiple regression analysis indicate that an increasing content of inflowing suspended solids leads to a better treatment efficiency regarding lead and copper. The specific area showed to have some effect on the treatment efficiency, but this effect was less than that of the content of inflowing suspended solids. The reduction of cadmium depended mainly on the specific area and the incoming concentration of cadmium. An increasing reduction of zinc could to some extent be explained by an increasing specific area. The results from this analysis and earlier studies are emphasizing the fact that adsorption to particles and sediment is one of the main processes for a good separation of heavy metals from storm water. Longer measurements series from additional treatment facilities are needed to build a statistical model which, in the future, can be used to predict the treatment efficiency of storm water ponds. / Dagvatten är regn- och smältvatten som samlas upp i avloppssystem. Då detta vatten huvudsakligen härstammar från urban bebyggelse så kan det innehålla höga halter tungmetaller, närsalter och olja med mera. Idag behandlas förorenat dagvatten bland annat genom nyttjande av dammar, våtmarker och översilningsytor. Dessa behandlingsalternativ har dock visat sig ge varierande resultat med avseende på dess reningseffektivitet. Detta arbete har utförts på uppdrag av konsultföretaget SWECO VIAK och syftade till att studera vilka parametrar som påverkar reningseffekten av närsalter och tungmetaller i dagvattendammar. Genom litteraturstudier undersöktes de dominerande reningsprocesserna i dammar och våtmarker. Därefter modellerades strömningen i 4 dammar med varierande form och storlek. Vid detta arbete erhölls en fördelning av uppehållstiden hos vattnet för respektive damm samt ett värde på den hydrauliska effektiviteten, vilken är ett mått på hur väl det inströmmande vattnet sprids ut i dammen. Slutligen utfördes en multipel regressionsanalys. Vid denna analys undersöktes hur reningen av bly, koppar, zink och kadmium beror av den specifika dammarean, variansen hos vattnets uppehållstidsfördelning, den hydrauliska effektiviteten samt inkommande metall- och TSS-koncentration (suspenderat material). Den specifika dammarean är en faktor vilken defineras som kvoten mellan dammens area och dess reducerade avrinningsområde. Resultaten från den multipla regressionen tyder på att en ökad inkommande halt av suspenderat material till dammen har störst betydelse för en förbättrad avskiljning av bly och koppar. Även den specifika arean och metallkoncentrationen i inflödet visade sig ha en viss, men något mindre, betydelse. Reduktionen av kadmium berodde däremot till störst del av den specifika arean och inkommande kadmiumkoncentration. En ökad reduktion av zink förklarades till viss del av en ökad specifik area. Resultatet att halten av suspenderat material i hög grad avgör reningen samt tidigare studier understryker det faktum att adsorption till partiklar och sediment verkar vara en av de viktigaste processerna för en god avskiljning av tungmetaller. Längre mätserier från fler dagvattendammar krävs dock för att i framtiden ta fram en statistisk modell vilken skulle kunna användas till att prediktera reningseffekten.
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Estimation of Storm Buffer Width for a Sandy BeachLee, Fang-Chun 17 May 2012 (has links)
On the basis of coastal disaster mitigation and protection, a beach must have sufficient width for preventing the destruction to public facilities, as well as protecting the safety of life and private property during storm events. The requirement of such a horizontal extent from the initial shoreline to the probable erosion landward to safeguard against the onslaught of a storm is referred to as ¡¥storm beach buffer width¡¦. Upon neglecting the effects of global warming and sealevel rise on a beach and berm with profile in equilibrium, numerical calculations are conducted first to validate the range of the most important parameters (K »P £` ) in the SBEACH model using the results of profile changes available from the CERC¡¦s large wave tank (LWT) tests in 1960s. These results are then applied to assess the profile changes for a beach with a vertical seawall and the other without sufficient berm, subject to the normal incidence of storm waves over a specific duration. Finally, a total of 48 cases with sufficient beach width are then investigated, from which a multiple linear regression model is proposed to determine the extent of berm retreat, as well as the location and height of a submerged offshore bar, for the benefit of coastal profession on preliminary design of storm buffer.
Our modeling results using SBEACH reveal that: (1) A seawall without or with insufficient fronting beach could result in serious scour at its toe and even the total loss of the entire beach berm; (2) A beach with sufficient berm, natural or artificially nourished, is capable of protecting the back beach, despite the temporary erosion in the early hours of a storm action; (3) Under the same conditions of wave height and period, a wide buffer is necessary for a beach with small mean sand grain, and the berm height should be designed at 1.6 times of the designed storm surge level, in order to effectively absorb storm wave energy and maintain the provision of a storm buffer; and (4) The multiple linear regression model proposed in this study can be used to evaluate the scour depth and retreat of the berm, as well as the width of a storm beach buffer, upon the input of wave conditions and mean beach sand grain etc.
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Modellering av avrinning från gröna tak : Avrinningskoefficienter och modellparametrar / Modelling runoff behaviour from green roofs : Runoff coefficients and model parametersAndersson, Camilla January 2015 (has links)
Expansion och förtätning av städer leder till att såväl areal som andel hårdgjord yta ökar i våra stadsmiljöer. Detta genererar en ökad dagvattenavrinning eftersom regnvattnet inte har samma möjlighet att infiltrera i naturmarker och grönområden. Den ökade mängden dagvatten riskerar att orsaka problem i områden där ledningsnätet dimensionerats för de dagvattenmängder som tidigare varit aktuella. Att utöka ledningsnätets kapacitet är ofta mycket kostsamt och det är därför önskvärt att istället minska belastningen på de befintliga systemen. En allt vanligare metod för detta är att byggnaders takyta bekläds med växter, så kallade gröna tak. De gröna taken har potential att minska den avrunna volymen, fördröja avrinningen och dämpa de maximala flödena. Det råder dock osäkerheter kring hur dessa förmågor påverkas av bland annat olika väderförhållanden och takets vattenmättnadsgrad samt vid olika typer av nederbördshändelser. Syftet med detta examensarbete var att undersöka möjligheten att simulera avrinningen från gröna tak med hjälp av en befintlig funktion i modelleringsprogrammet SWMM från US Environmental Protection Agency samt med hjälp av Mike Urban från företaget DHI. Ett mål var att sedan använda en av modellerna för att utvärdera hur gröna tak kan påverka belastningen på ett befintligt ledningsnät. Mätdata avseende bland annat nederbörd, avrinning och potentiell avdunstning erhölls från Veg Tech AB och AgroTech A/S. Mätningarna hade utförts vid företagens demonstrationsanläggning i Taastrup, Danmark, och omfattade avrinning från gröna tak med tre olika tjocklekar: 4 cm moss-sedum, 7 cm sedum-ört-gräs och 11 cm sedum-ört-gräs, samt ett hårdgjort referenstak. Inledande dataanalyser av de gröna takens kapacitet visade att takens magasineringskapacitet ökade med en ökad taktjocklek, där de tjockare taken kunde fullständigt magasinera större nederbördshändelser än vad som var fallet för det tunnaste taket. En analys av sambandet mellan nederbördsmängd och avrunnen volym visade ett starkare samband för regn med 60 och 120 minuters varaktighet än vad som var fallet för kortare varaktigheter. Jämförelser av resultaten hos de båda modelleringsprogrammen visade på olika styrkor och svagheter och ingen av programvarorna gav en i alla avseenden tillfredställande simulering av avrinningen. Mike Urban gav generellt en högre förklaringsgrad men gav alltid en överskattning av den avrunna volymen över en längre tidsperiod. SWMM gav en bättre överensstämmelse med uppmätt avrinning än Mike Urban under de första månaderna av simuleringsperioden, men gav generellt en förskjutning av avrinningsförloppet. För kalibreringen mot 4 cm taktjocklek gav SWMM också en mer korrekt avrunnen långtidsvolym, medan den för de andra konstruktionerna gav liknande resultat som var fallet för Mike Urban. I ett exempel användes en av modellerna för att simulera avrinningen från MAX IV-laboratoriet i Lund. Resultaten visade att det då laboratoriet täckts med gröna tak endast behövdes ett en fjärdedel så stort fördröjningsmagasin för att översvämningar skulle undvikas på ett nedströms beläget fiktivt ledningsnät än vad som var fallet för hårdgjorda tak. / Larger and denser cities result in increasing amounts of impervious surfaces in urban areas. This generates an increase in storm water runoff, as the rainwater is prevented from infiltrating in natural soils and instead flows along the paved surfaces. The increased amount of storm water runoff is liable to cause problems in areas where the storm water system has been designed to handle the amounts of runoff previously generated in the area. Upsizing the capacity of the pipelines is usually costly, and it is therefore desirable to instead reduce the load on the existing system. One way of achieving this is to cover the rooftops with vegetation, so called green roofs. Green roofs are growing in popularity and have the potential to reduce the rate and volume of runoff, as well as attenuating the peak discharge. There are however uncertainties regarding how their abilities are affected by for example the antecedent weather conditions and the moisture content of the roof, as well as by various storm events. The purpose of this Master’s Thesis was to study the possibility to simulate the runoff from green roofs using an existing function in the modelling software SWMM by US Environmental Protection Agency, and using Mike Urban by the company DHI. An additional objective was to use on of the designed models to evaluate how green roofs can affect the load on an existing storm water system. Measurements of precipitation, runoff and potential evapotranspiration were obtained from Veg Tech AB and AgroTech A/S. The measurements had been carried out at their demonstration site in Taastrup, Denmark, and included runoff from green roofs of three different thicknesses: 4 cm moss-sedum, 7 cm sedum-herb-grass and 11 cm sedum-herb-grass, as well as an impervious roof used as reference. Initial analyses of the data showed that the storage capacity increased with an increased roof thickness. The thicker roofs were able to completely retain the rainfall from larger storm events than what was the case for the thinnest roof. An analysis of the relationship between precipitation depth and runoff volume showed a stronger correlation for rains with 60 and 120 minutes duration than what was the case for shorter durations. Comparisons of the two models’ performance showed different strengths and weaknesses, and none of the models were able to simulate runoff in a way that was satisfactory in all aspects. Mike Urban generally gave a higher coefficient of determination but consistently overestimated the discharged volume for extended time periods. SWMM gave a better conformity in observed runoff than Mike Urban during the first months of the simulation period, but generally gave a time lag in the runoff hydrograph. For the 4 cm roof calibration, SWMM also gave a more correct long-time runoff volume, while both models performed similarly for the other roof thicknesses. In an example, one of the models was used to simulate the runoff from the MAX IV laboratory in Lund. The results showed that in order to avoid flooding in the fictitious downstream storm water network, there had to be a four times larger detention pond in the case where conventional roofs where used compared to the scenario using green roofs.
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Wasser, Paradigma elementarer Kraft in der Literatur : Mythos, Naturwissenschaft, Kunst und Sprache : ausgewählte Textbeispiele von Johann Wolfgang v. Goethe, Wilhelm Raabe, Theodor Storm, Theodor Fontane, Ingeborg Bachmann und Günter Eich /Hartmann, Christina Alexandra. January 2009 (has links)
Zugl.: Augsburg, Universiẗat, Diss., 2009.
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Avaliação do desempenho hidráulico de um sistema de drenagem de águas pluviais urbanas / Evaluation of the hydraulic performance of a urban stormwater drainage systemBoldrin, Andressa Juliana, 1985- 12 September 2014 (has links)
Orientador: José Anderson do Nascimento Batista / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-26T09:40:37Z (GMT). No. of bitstreams: 1
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Previous issue date: 2014 / Resumo: O crescimento urbano acelerado gera a necessidade de implantação de infraestruturas que impermeabilizam o solo, aumentando o escoamento superficial e motivando a implantação de sistema de drenagem de águas pluviais urbanas. A ausência de planejamento e da integração entre as entidades responsáveis pelo gerenciamento da infraestrutura urbana associada à ocupação inadequada do espaço urbano ocasiona inundações. Considerando esta situação dos sistemas de drenagem de águas pluviais, o presente trabalho tem o objetivo de avaliar o desempenho hidráulico de um sistema de drenagem de águas pluviais urbanas em funcionamento, identificando a localização e as causas de possíveis deficiências por intermédio do índice de desempenho hidráulico proposto por BENNIS et al. (2003). A área de estudo escolhida foi a área de contribuição do sistema de drenagem de águas pluviais urbanas do Campus Universitário "Professor Zeferino Vaz". Normalmente em áreas urbanas os dados hidrológicos disponíveis restringem-se apenas aos dados pluviométricos. Por isso foram utilizados métodos de transformação de chuva-vazão para o cálculo das vazões afluentes à rede de drenagem. Após a determinação da vazão, foram averiguadas as condições hidráulicas utilizando o método do UDFCD (Distrito de Drenagem Urbana e Controle de Inundações) e o programa computacional SWMM (Modelo de Gerenciamento de Águas Pluviais da Agência de Proteção Ambiental dos Estados Unidos). Por meio do índice de desempenho hidráulico de BENNIS et al. (2003), foi possível verificar o grau de sobrecarga de cada trecho da rede de drenagem urbana. Além disso, a elaboração da matriz da condição hidráulica da rede de drenagem possibilitou identificar a origem e as causas das sobrecargas em cada trecho. Os resultados obtidos pelo método UDFCD e pelo modelo SWMM, sistematizados por meio do índice de desempenho hidráulico possibilitaram avaliar globalmente o sistema de drenagem de águas pluviais da área de estudo. As sobrecargas e os extravasamentos foram identificados, incluindo as causas e consequências de suas ocorrências / Abstract: The accelerated urban growth generates the need for deployment of infrastructures that seals the soil, increasing runoff and motivating the implementation of urban stormwater drainage system. The absence of planning and integration between the entities responsible for the management of urban infrastructure associated with the inadequate occupation of urban space cause flooding. Considering this situation of stormwater drainage system, the present study aims to assess the hydraulic performance of an urban stormwater drainage system in operation, identifying the location and causes of possible deficiencies through the hydraulic performance index proposed by BENNIS et al. (2003). The study area was chosen at stormwater drainage system catchment area of the University Campus "Professor Zeferino Vaz". Typically in urban areas the available hydrological data are restricted only to rainfall data. For this reason methods of transformation of rainfall ¿ runoff were applied for the calculation of drainage network flows. After determining the flow rate, were verified the hydraulic conditions using the UDFCD (Urban Drainage and Flood Control District) method and the computational program SWMM (Storm Water Management Model of the Environmental Protection Agency of the United States). Through the hydraulic performance index proposed by BENNIS et al. (2003) was possible to verify the degree of surcharge of each pipe of the urban stormwater drainage network. Furthermore, the development of the matrix design of the hydraulic conditions of the urban stormwater drainage network allowed identifies the origin and causes of the surcharges in each pipe section. The results obtained by UDFCD method and SWMM model were organized through of the hydraulic performance index and it possible an overall assessment of the urban stormwater system of the study area. Surcharges and overflows were identified, including their causes and consequences of their events / Mestrado / Recursos Hidricos, Energeticos e Ambientais / Mestra em Engenharia Civil
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Processing data sources with big data frameworks / Behandla datakällor med big data-ramverkNyström, Simon, Lönnegren, Joakim January 2016 (has links)
Big data is a concept that is expanding rapidly. As more and more data is generatedand garnered, there is an increasing need for efficient solutions that can be utilized to process all this data in attempts to gain value from it. The purpose of this thesis is to find an efficient way to quickly process a large number of relatively small files. More specifically, the purpose is to test two frameworks that can be used for processing big data. The frameworks that are tested against each other are Apache NiFi and Apache Storm. A method is devised in order to, firstly, construct a data flow and secondly, construct a method for testing the performance and scalability of the frameworks running this data flow. The results reveal that Apache Storm is faster than Apache NiFi, at the sort of task that was tested. As the number of nodes included in the tests went up, the performance did not always do the same. This indicates that adding more nodes to a big data processing pipeline, does not always result in a better performing setup and that, sometimes, other measures must be made to heighten the performance. / Big data är ett koncept som växer snabbt. När mer och mer data genereras och samlas in finns det ett ökande behov av effektiva lösningar som kan användas föratt behandla all denna data, i försök att utvinna värde från den. Syftet med detta examensarbete är att hitta ett effektivt sätt att snabbt behandla ett stort antal filer, av relativt liten storlek. Mer specifikt så är det för att testa två ramverk som kan användas vid big data-behandling. De två ramverken som testas mot varandra är Apache NiFi och Apache Storm. En metod beskrivs för att, för det första, konstruera ett dataflöde och, för det andra, konstruera en metod för att testa prestandan och skalbarheten av de ramverk som kör dataflödet. Resultaten avslöjar att Apache Storm är snabbare än NiFi, på den typen av test som gjordes. När antalet noder som var med i testerna ökades, så ökade inte alltid prestandan. Detta visar att en ökning av antalet noder, i en big data-behandlingskedja, inte alltid leder till bättre prestanda och att det ibland krävs andra åtgärder för att öka prestandan.
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Automated dust storm detection using satellite images. Development of a computer system for the detection of dust storms from MODIS satellite images and the creation of a new dust storm database.El-Ossta, Esam E.A. January 2013 (has links)
Dust storms are one of the natural hazards, which have increased in frequency in the recent years over Sahara desert, Australia, the Arabian Desert, Turkmenistan and northern China, which have worsened during the last decade. Dust storms increase air pollution, impact on urban areas and farms as well as affecting ground and air traffic. They cause damage to human health, reduce the temperature, cause damage to communication facilities, reduce visibility which delays both road and air traffic and impact on both urban and rural areas. Thus, it is important to know the causation, movement and radiation effects of dust storms. The monitoring and forecasting of dust storms is increasing in order to help governments reduce the negative impact of these storms. Satellite remote sensing is the most common method but its use over sandy ground is still limited as the two share similar characteristics. However, satellite remote sensing using true-colour images or estimates of aerosol optical thickness (AOT) and algorithms such as the deep blue algorithm have limitations for identifying dust storms. Many researchers have studied the detection of dust storms during daytime in a number of different regions of the world including China, Australia, America, and North Africa using a variety of satellite data but fewer studies have focused on detecting dust storms at night. The key elements of this present study are to use data from the Moderate Resolution Imaging Spectroradiometers on the Terra and Aqua satellites to develop more effective automated method for detecting dust storms during both day and night and generate a MODIS dust storm database. / Libyan Centre for Remote Sensing and Space Science / Appendix A was submitted with extra data files which are not available online.
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Analysis of storm surge impacts on transportation systems in the Georgia coastal areaRestrepo, Ana Catalina 18 November 2011 (has links)
Many Climate Scientists believe that global warming will produce more extreme weather events such as tropical storms, hurricanes, intense rainfall, and flooding. These events are considered to be the most catastrophic natural events for transportation systems especially in coastal areas. Due to the severe damage from storm surge and flooding. Evaluating the magnitude of possible storm surges and their impacts on transportation systems in coastal areas is fundamental to developing adaptation plans and impact assessments to mitigate the damage.
This thesis focuses on existing transportation systems in the Georgia coastal area that could be affected by several storm surges. An existing storm surge model is used to estimate the storm surges and the surge heights based on the category, direction, and forward speed of a storm. The ground elevation of the ports, interstates, state roads, railroads, and the principal airports on the Georgia coast are identified through a GIS analysis using the national elevation data set. Having the storm surge elevation and the elevation of the existing infrastructure, a GIS study is performed to identify those parts of the transportation system that will be affected by each type of storm giving results such as the length or sections of transportation assets under or above the surge elevation. A literature review of storm surge, rising sea levels, and their impacts on coastal bridges, roads, airports, ports, and railroads is presented in the thesis. Also, a description of the software used to analyze and estimate the impacts of climate change on transportation systems is described.
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Paviršinių nuotekų charakterizavomo tyrimai metalo laužo įmonėje / Pre-investigation of stormwater quality at metals scrap processing PLANTŽimančiūtė, Jurgita 16 June 2005 (has links)
In the Master’s Thesis “Pre-investigation of Stormwater Quality at Metals Scrap Processing Plant” the literature review of 136 sources was performed with the focus on storm water pollution, physical and chemical properties of specific pollutants, origins of the pollution and pathways of the pollutants transport to the environment. Types of industrial storm water samples and sampling methodologies are described as well. Raprinfall data calculation are performed for the design of industrial storm water collection and treatment systems. The comprehensive analyses of storm water treatment are done. The experimental part of the work was carried out at the metal scrap processing industry with paved and unpaved aeries of the surfaces. During the research the industrial storm water screening characterisation was done at different locations of the whole territory. The treatment technology, including the sedimentation tank, retention tank and filtration trench was selected and calculated for the treatment of storm water of the investigated industry. The generalized conclusions and results of the work can be useful for state institutions, research institutions and the enterprises engaged in storm water management.
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Utveckling av metod för att synliggöra och värdera ekosystemtjänster i öppen dagvattenhanteringHagström, Erika January 2016 (has links)
Nature provides various services to society that humans are completely dependent on for their survival. These services are called ecosystem services, and can be, for example, clean air, clean water and pollination of crops. To live close to nature and green areas is also important for our well being. Although we are often aware of the values that nature creates and its importance, green areas are often replaced with buildings and roads as the big cities grow and densify. The ongoing densification of cities, combined with the projected climate changes will result in that the capacity of storm water pipes is likely to be insufficient during major rainstorms which can create big problems with, for example, flooding. The increasing challenges of storm water management resulted in that open storm water solutions began to be used as supplement to the storm water pipes. Open water solutions are designed to take care of water in a way that mimics nature's way of taking care of rainfall. These open water systems are a form of urban ecosystems and, in addition to dampen the water flows, can provide a range of other ecosystem services. The aim of this thesis was to create a method for integrating and valuing ecosystem services in the design of open storm water management and thus make the values from ecosystem services visible. The thesis was limited to investigating seven different open storm water solutions: green roofs, infiltration of lawns, temporary damming on specially constructed flood areas, percolation trenches, natural streams, ponds and wetlands. In addition to the ability to manage and control large water flows, 11 ecosystem services were identified that can be obtained from the open storm water solutions: drinking water, non-potable water, natural water purification, carbon sequestration and storage, local climate control and air purification, noise reduction, pollination, habitat and biodiversity, activity based cultural values, aesthetic values and resource for research and education. The values of the ecosystem services were determined in a semi-quantitative survey in which 16 people responded to questions examining to what extent they consider that ecosystem services can be obtained in the various storm water solutions. The values of the ecosystem services also depend largely on the site's potential and how the solutions are designed. Factors that can affect the value of the ecosystem services with respect to these aspects were investigated in a literature study and in the questionnaire study. The results of the literature study and questionnaire study formed the basis for the non-site adapted assessment tool that was developed as the last step in the thesis. The tool was designed in Excel and consists of three steps. Step 1 aims to weight the ecosystem services by the sites’ potential, step 2 involves the actual valuation and possible adaption to alternative design, and in step 3 a factor is calculated as a measure of the values obtained from ecosystem services created from open storm water solutions in relation to the total area. The aim is that the assessment tool should be used as a complement to an investigation about which storm water treatment solution that is most suitable in a project. / Naturområden och grönytor levererar olika tjänster som människan är helt beroende av för sin överlevnad. Dessa tjänster kallas ekosystemtjänster och är exempelvis ren luft, rent vatten och pollinering av grödor. Närhet till naturen och grönområden har också stor betydelse för människans välbefinnande, till exempel genom att ha en stressdämpande effekt. Trots att vi är medvetna om värdena som naturen skapar, byggs grönytor i städer bort i takt med att de växer och förtätas. Täta städer innebär stora arealer hårdgjorda ytor vilket också resulterar i större volymer dagvatten då nederbörden inte kan infiltrera ner i marker och istället rinner av på ytan. Ledningarnas kapacitet riskerar att överskridas vid stora skyfall vilket kan orsaka stora problem med översvämningar. Problemet kommer dessutom förvärras i framtiden med de väntade klimatförändringarna. Ökande utmaningar med dagvattenhanteringen har resulterat i att öppna dagvattenlösningar började användas som komplement till ledningar under mark. Öppna dagvattenlösningar innebär att vattnet tas omhand på ett sätt som efterliknar naturens sätt att ta hand om nederbörd, och är en form av urbana ekosystem som, utöver att dämpa vattenflöden, kan tillhandahålla en rad andra ekosystemtjänster. Syftet med detta examensarbete var att skapa en metod för att integrera och värdera ekosystemtjänster i utformningen av öppen dagvattenhantering och därmed synliggöra ekosystemtjänsternas värden. Examensarbetet avgränsades till att utreda sju olika öppna dagvattenlösningar: gröna tak, infiltration på gräsytor, tillfällig uppdämning på översvämningsytor, svackdiken, naturliga diken och bäckar, dammar samt våtmarker. 12 ekosystemtjänster identifierades kunna erhållas från de öppna dagvattenlösningarna. Dessa var dricksvattenresurs, icke drickbart vatten, vattenrening, kolbindning och lagring, klimatreglering och luftrening, bullerreducering, flödesreglering, pollinering, livsmiljöer och biologisk mångfald, aktivitetsbaserade kulturella värden, estetiska värden samt resurs för forskning och utbildning. Ekosystemtjänsternas värden hos de olika dagvattenlösningarna bestämdes i en semikvantitativ enkätstudie där 16 personer fick värdera dagvattenlösningarnas kapacitet att bidra till de olika ekosystemtjänsterna. Värdena beror också till stor del på platsens förutsättningar och hur de utformas. Vilka faktorer som kan påverka värdet av ekosystemtjänsterna med avseende på dessa aspekter utreddes i en kvalitativ litteraturstudie. Resultatet från litteraturstudien samt enkätstudien utgjorde grunden för det icke platsanpassade värderingsverktyget som togs fram som det sista steget i examensarbetet. Verktyget utformades i Excel och består av tre steg där steg 1 syftar till att vikta ekosystemtjänsternas värden efter platsens förutsättningar, i steg 2 sker själva värderingen samt en eventuell anpassning till alternativ utformning och i steg 3 beräknas en faktor fram som är ett mått på ekosystemtjänsternas värden som fås från öppna dagvattenlösningar i förhållande till den totala arean. Syftet är att värderingsverktyget ska användas som ett komplement till en utredning om vilken dagvattenhantering som är lämpligast i ett projekt.
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