Dagvattenhanteringen är ett aktuellt ämne i dagens stadsplanering. Forskning som denna studie utgår ifrån visar hur dagens traditionella system inte klarar av kommande klimatförändringar med mer och intensivare nederbörd. Dagvatten för med sig föroreningar samt miljögifter som kväve och fosfor, men även tungmetaller som klorid, olja, organiska miljögifter och bakterier. Det traditionella systemet leder dagvatten ofta rakt ut i våra vattendrag via recipienterna då endast 8 procent av Sveriges dagvatten blev renat år 2016. För en djupare förståelse kring detta utgår studien ifrån teorier inom hållbar utveckling, antropocentrism, ekocentrism samt det rumsliga perspektivet. Materialet består av litteratur, artiklar, tidigare forskning samt fyra intervjuer. Informanterna består av en konsult, en som arbetar på en branschorganisation och två från Karlstad kommun för att få förståelse kring dagvattenhantering, hur en hållbar dagvattenhantering definieras och hur Karlstads kommuns vision för dagvattenhanteringen ser ut. I resultatet för denna uppsats har det framkommit att informanternas syn på dagvatten stämmer överens med Naturvårdsverkets riktlinje av hållbar dagvattenhantering. Karlstad kommuns visioner kring dagvatten lever även upp till denna definition. Utifrån materialet kan uppsatsen visa på att informanterna har en bred kunskap kring framtidens klimatpåverkan på dagvatten samt dess åtgärder. Teorierna har kopplats med resultatet där det går att förstå hur det rumsliga perspektivet påverkas beroende på hur dagvatten hanteras och att en intergenerationell antropocentrism samt svag ekocentrism kan utläsas från intervjuerna. / The stormwater management is topical in today’s urban planning. The research that this study is based of shows how today's traditional system can not cope with future climate change with more intense precipitation. Stormwater also spreads pollution and environmental toxins such as nitrogen and phosphorus, but also heavy metals as chloride, oil, organic pollutants and bacteria. The traditional system often leads the stormwater straight into our waters via the recipients. Only 8 percent of Sweden's stormwater was purified in 2016. For a deeper understanding about this, the study is based on theories in sustainable development, anthropocentrism, ecocentrism and the spatial perspective. The study is based on the theories above, previous research as well as four interviews with a consultant, one who works on a industry sector organisation and two people who works on Karlstad kommun. The people are chosen for a deeper understanding about stormwater, how a sustainable stormwater management is defined and how Karlstad kommuns visions for stormwater management are. The result of this thesis has revealed that the informants view of stormwater is in line with the Swedish Environmental Protection Agency's guideline on sustainable stormwater management. The visions of stormwater in Karlstad kommun also live up to this definition. Based on the empirical data, the essay can show that the informants have a broad knowledge of future climate impact on the subject and its measures. The theories are linked with the result, where it is possible to see how the spatial perspectives are affected depending on how stormwater is managed and that an intergenerational anthropocentrism and weak ecocentrism perspective can be read from the interviews.

The quantity of stormwater runoff from the city of Adelaide almost matches the demand for drinking water. It therefore becomes increasingly important as an alternative source for water supply. This research focused at the Parafield Stormwater Harvesting Facility near Adelaide in order to better understand: (1) nutrient dynamics between the water column, sediments and plant community, (2) allochthonous and autochthonous sources of nutrients and (3) nutrient retention capacity of the reed bed. A weekly monitoring programme for the physical and chemical parameters of the water column, sediment and plant community was carried out over three years for specific locations within the reed bed. Ordination and clustering of the time series data revealed distinctive seasonal and spatial nutrient patterns. The concentrations for total nitrogen (TN) showed high concentrations for the summer period (1.04 to 1.86 mg/L) and low concentration for the winter season (0.25 to 0.46 mg/L). For the other nitrogen fractions in form of nitrate (NO₃⁻) and ammonium (NH₄⁺) the seasonal patterns were different to that of TN. In NO₃⁻ the concentrations were high during the summer and winter seasons and NH₄⁺ showed high concentration during the spring. The seasonality for total phosphorus (TP) showed high concentration for the spring period (0.049 to 0.163 mg/L) and low concentration for the other seasons (0.01 to 0.019 mg/L). A similar pattern has been observed for phosphate (PO₄³ ⁻) as well. The dissolved organic carbon (DOC) concentrations showed high concentrations during the summer period (21.36 to 31.64 mg/L) and low concentration during the winter seasons (5.48 to 7.14 mg/L). The seasonal pattern for the nutrient contents of the plant community showed highest concentrations during summer (5.5 to 34.2 gTN/kg) and lowest concentrations in winter (0.2 to 7.7 gTN/kg). Nutrient concentrations in the sediments were highest during the non-growing seasons (autumn and winter). This result indicated that the function of sediments changes seasonally from being a sink during the non-growing season by accumulating both allochthonous and autochthonous nutrients in the rainy season, and becoming a source during the growing seasons due to nutrient release from anaerobic sediments supporting the growth of the macrophyte community. Overall the function of sediment in reed bed pond of the Stormwater Harvesting Facility was to be a source of nutrients and therefore no accumulation of nutrients occurred during the study period. The research has demonstrated that the reed bed currently performs as a reasonable nutrient retention system with following nutrient removal rates: 0.85 mg TN /m²/day, 0.79 mg NO₃⁻ /m²/day, 0.28 mg NH₄⁺/m²/day, 0.05 mg TP /m²/day, 0.04 mg PO₄³ ⁻ /m²/day, and 5.75 mg DOC /m²/day. Seasonal difference in the water retention time showed that the for most of the nutrients the removal performance was most effective during autumn and winter with the exception of the removal performance of P forms, which most effective during spring and summer. For TN, NO₃⁻ and DOC the RE was most efficient at a residence time > 15days, for TP and PO₄³ ⁻ it is 5-10 days and for NH₄⁺ it is <;5days. Time–series modelling of the monitoring data resulted in rule-based prediction models for the different nutrients. Sensitivity analyses of the models revealed key driving variables for the nutrient dynamics of the reed bed. The prediction results revealed that the DO was the key driving variable influencing the nutrient concentrations in the water column and therefore to improve the water quality of the treatment water DO levels have to maintained above the threshold of 4 mg/L. Beside DO other key driving variables were turbidity, ORP and the nutrient levels from the previous site. Therefore the control of these parameters would be the start to develop a management plan for best-practice management in terms of water quality at the Parafield Stormwater Harvesting Facility. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1458926 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Science, 2010

<p>Stormwater run-off from surfaces such as roads or rooftops is often polluted with heavy metals and nutrients. Many of these substances can cause great damage in biota if they end up in the recipient. In Sweden constructed wetlands and ponds for treatment of stormwater are frequently used, since research has shown that these treatment ponds are reducing stormwater pollution considerably to a low cost. The knowledge of these pollutant removal mechanisms and how follow-up and assessment of the ponds should be performed is still limited.</p><p>To determine the pollutant removal efficiency of the stormwater ponds it is recommended that flow-weighted water samples are collected from both the inflow and the outflow of the pond. This method demands considerable resources of time and money for installations and analysis. Alternative methods for assessing pollutant removal are requested, methods with lower costs but relevant results. This thesis is investigating whether sediment sampling could be such an alternative.</p><p>Sediment core samples were taken in four stormwater ponds where flow-weighted water sampling has been performed as well. This makes it possible to compare the two methods. A method of sampling recently sedimented material was also tried out by constructing and placing sediment traps on the pond floor. Analysis of concentration of six heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) and phosphorus were carried out.</p><p>The results show i.e. that the concentrations of heavy metals and phosphorus in the pond sediments decrease as the distance from the pond inlet increase. Comparing the two methods shows that the results from the sediment sampling are in the same order of magnitude as the results from the water sampling. Consequently, the conclusion states that a well executed sediment sampling may be an alternative to flow-weighted water sampling.</p> / NOS dagvatten

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.

Stormwater run-off from surfaces such as roads or rooftops is often polluted with heavy metals and nutrients. Many of these substances can cause great damage in biota if they end up in the recipient. In Sweden constructed wetlands and ponds for treatment of stormwater are frequently used, since research has shown that these treatment ponds are reducing stormwater pollution considerably to a low cost. The knowledge of these pollutant removal mechanisms and how follow-up and assessment of the ponds should be performed is still limited. To determine the pollutant removal efficiency of the stormwater ponds it is recommended that flow-weighted water samples are collected from both the inflow and the outflow of the pond. This method demands considerable resources of time and money for installations and analysis. Alternative methods for assessing pollutant removal are requested, methods with lower costs but relevant results. This thesis is investigating whether sediment sampling could be such an alternative. Sediment core samples were taken in four stormwater ponds where flow-weighted water sampling has been performed as well. This makes it possible to compare the two methods. A method of sampling recently sedimented material was also tried out by constructing and placing sediment traps on the pond floor. Analysis of concentration of six heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) and phosphorus were carried out. The results show i.e. that the concentrations of heavy metals and phosphorus in the pond sediments decrease as the distance from the pond inlet increase. Comparing the two methods shows that the results from the sediment sampling are in the same order of magnitude as the results from the water sampling. Consequently, the conclusion states that a well executed sediment sampling may be an alternative to flow-weighted water sampling. / NOS dagvatten

The quantity of stormwater runoff from the city of Adelaide almost matches the demand for drinking water. It therefore becomes increasingly important as an alternative source for water supply. This research focused at the Parafield Stormwater Harvesting Facility near Adelaide in order to better understand: (1) nutrient dynamics between the water column, sediments and plant community, (2) allochthonous and autochthonous sources of nutrients and (3) nutrient retention capacity of the reed bed. A weekly monitoring programme for the physical and chemical parameters of the water column, sediment and plant community was carried out over three years for specific locations within the reed bed. Ordination and clustering of the time series data revealed distinctive seasonal and spatial nutrient patterns. The concentrations for total nitrogen (TN) showed high concentrations for the summer period (1.04 to 1.86 mg/L) and low concentration for the winter season (0.25 to 0.46 mg/L). For the other nitrogen fractions in form of nitrate (NO₃⁻) and ammonium (NH₄⁺) the seasonal patterns were different to that of TN. In NO₃⁻ the concentrations were high during the summer and winter seasons and NH₄⁺ showed high concentration during the spring. The seasonality for total phosphorus (TP) showed high concentration for the spring period (0.049 to 0.163 mg/L) and low concentration for the other seasons (0.01 to 0.019 mg/L). A similar pattern has been observed for phosphate (PO₄³ ⁻) as well. The dissolved organic carbon (DOC) concentrations showed high concentrations during the summer period (21.36 to 31.64 mg/L) and low concentration during the winter seasons (5.48 to 7.14 mg/L). The seasonal pattern for the nutrient contents of the plant community showed highest concentrations during summer (5.5 to 34.2 gTN/kg) and lowest concentrations in winter (0.2 to 7.7 gTN/kg). Nutrient concentrations in the sediments were highest during the non-growing seasons (autumn and winter). This result indicated that the function of sediments changes seasonally from being a sink during the non-growing season by accumulating both allochthonous and autochthonous nutrients in the rainy season, and becoming a source during the growing seasons due to nutrient release from anaerobic sediments supporting the growth of the macrophyte community. Overall the function of sediment in reed bed pond of the Stormwater Harvesting Facility was to be a source of nutrients and therefore no accumulation of nutrients occurred during the study period. The research has demonstrated that the reed bed currently performs as a reasonable nutrient retention system with following nutrient removal rates: 0.85 mg TN /m²/day, 0.79 mg NO₃⁻ /m²/day, 0.28 mg NH₄⁺/m²/day, 0.05 mg TP /m²/day, 0.04 mg PO₄³ ⁻ /m²/day, and 5.75 mg DOC /m²/day. Seasonal difference in the water retention time showed that the for most of the nutrients the removal performance was most effective during autumn and winter with the exception of the removal performance of P forms, which most effective during spring and summer. For TN, NO₃⁻ and DOC the RE was most efficient at a residence time > 15days, for TP and PO₄³ ⁻ it is 5-10 days and for NH₄⁺ it is <;5days. Time–series modelling of the monitoring data resulted in rule-based prediction models for the different nutrients. Sensitivity analyses of the models revealed key driving variables for the nutrient dynamics of the reed bed. The prediction results revealed that the DO was the key driving variable influencing the nutrient concentrations in the water column and therefore to improve the water quality of the treatment water DO levels have to maintained above the threshold of 4 mg/L. Beside DO other key driving variables were turbidity, ORP and the nutrient levels from the previous site. Therefore the control of these parameters would be the start to develop a management plan for best-practice management in terms of water quality at the Parafield Stormwater Harvesting Facility. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1458926 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Science, 2010

I takt med expandering och förtätning av städer byggs gröna ytor bort medan andelen hårdgjorda ytor ökar. Regn och smältvatten kan inte infiltrera genom de hårdgjorda ytorna vilket innebär att det istället avrinner som dagvatten. Samtidigt som urbaniseringen bidrar till ökad dagvattenavrinning och nederbördsmängderna i ett framtida klimat förväntas öka, blir det allt viktigare att planera för hur dagvatten ska omhändertas i nya bebyggelseområden. Inom flera svenska kommuner ställs idag krav på att dagvatten skall omhändertas inom privata fastigheter innan det ansluts till det allmänna dagvattennätet. Parallellt med detta innebär förtätningen att byggherrar idag ofta åläggs anlägga gårdar med underliggande garage, så kallade underbyggda gårdar. Det fanns ett behov av att förtydliga och undersöka dagens situation gällande dagvattenhantering i kombination med underbyggda gårdar.Examensarbetets syfte var att samla och skapa ny kunskap om dagvattenhantering på underbyggda gårdar och undersöka hur olika aktörer ser på kraven som ställs på dagvattenhantering. Kvalitativa intervjuer med representanter från de tre aktörsgrupperna VA-huvudmän, ansvariga för detaljplan och byggherrar genomfördes. Syftet var även att utforma ett verktyg för att belysa beröringspunkter mellan dagvattenhantering på underbyggda gårdar och andra intressen inom privata fastigheter.Examensarbetet avgränsades till att studera dagvattenåtgärderna gröna tak, växtbäddar och fördröjningsmagasin. Förutom dagvattenhantering identifierades fem intressen inom kvartersmark som bör bejakas på underbyggda gårdar: landskapsarkitektur, arkitektur, konstruktion, förvaltning och VVS. Ett verktyg utformades och inkluderade de tre dagvattenåtgärderna samt de fem intressena. Checklistor utformades för att beskriva beröringspunkter mellan dagvattenhantering på underbyggda gårdar och de fem intressena. Verktyget består av fyra steg: Nutida och framtida bebyggelse, Dagvattenkrav, Val av dagvattenåtgärder samt Vidare rekommendationer eller förslag på korrigeringar.Intervjuresultaten påvisar att flera intervjupersoner upplever att det är svårt att ställa krav på dagvattenhantering då rättsläget är osäkert, samtidigt upplever byggherrar att kraven kan vara svåra att nå på underbyggda gårdar, främst på grund av platsbrist. Checklistornas punkter är tänkta att fungera som vägledande aspekter att beakta vid dagvattenhantering på underbyggda gårdar och behjälpa avvägning av olika intressen. Förhoppningen är att checklistorna kan bidra till en ökad förståelse för förhållandena mellan dagvattenhantering på underbyggda gårdar och andra intressen. Examensarbetets resultat visar på att en samverkan mellan de olika intressena behövs för att skapa förutsättningar för en god dagvattenhantering. För att funktionen ska hålla över tid är det även viktigt att gemensamt kommunicera kring syftet med den underbyggda gården. / With the expansion and densification of cities, green areas are removed while the proportion of hard surfaces are increased. Rain and melt water are not allowed to infiltrate through the hard surfaces, and instead it runs off like stormwater. With this and the expected increase of precipitation due to climate changes, it is becoming increasingly important to plan for the disposal of stormwater in new urban areas. Several Swedish municipalities are today providing restrictions regarding the diversion of stormwater on private properties and requirements that need to be met before connection to the public water network. Meanwhile, densification means that builders today are often forced to build residential yards on underground garages. There was a need to clarify and investigate today's situation regarding stormwater treatment in combination with underground garages.The purpose of this thesis was to analyse today's state of knowledge about stormwater treatment on yards with underground garages and to investigate how different actors experience the requirements. Qualitative interviews with representatives from the three groups of actors, stormwater sewer operators, planning divisions and developers were conducted. The aim was also to design a tool for highlighting connections between stormwater management and other interests on private properties.This thesis was delimited to study green roofs, plant beds and detention tanks. Five interests were identified on yards with underground garages: landscape architecture, architecture, construction, management and HVAC. A tool was designed including the stormwater facilities containing four steps: Today’s and future construction, Stormwater requirements, Choice of facilities and Further recommendations or suggestions for corrections. Within the tool, four checklists were established to describe connections between stormwater treatment on yards with underground garages and the interests.The interview results show that several interviewees find it difficult to impose restrictions for stormwater management due to legal uncertainties. Meanwhile developers find following the restrictions can be difficult with yards with underground garages, mainly due to lack of space. The checklists are intended to serve as guiding points that should be taken into consideration in stormwater management on underground garages and to help balance different interests. The hope is that the checklists can contribute to an increased understanding of the relationships between stormwater management with underground garages and other interests. The results of the thesis show that interaction between the various interests is needed to create conditions for a good stormwater management and that communication about a joint purpose for the yard with an underground garage is important for maintaining the function of the yard.

Förtätning av stadsmiljöer bidrar till hårdläggning och borttagande av gröna ytor i naturliga och redan exploaterade områden. Detta minskar möjlighet till infiltration och evapotranspiration av vatten, vilket ökar ytavrinning av regn- och smältvatten. Regn- och smältvatten i urbana miljöer, även kallat dagvatten, har traditionellt hanterats genom snabb avledning till VA-verk eller närmaste recipient. Idag går utvecklingen mot att hantera dagvattnet lokalt och nära källan till vattnet genom att efterlikna den naturliga vattencykeln. Den största utmaningen iatt hantera dagvatten lokalt anses inte bero på avsaknad av rätt teknik utan ett kommunikativt problem mellan berörda parter. För att främja en långsiktig och hållbar dagvattenhantering krävs en gemensam vision vid upphandlingen, vilket kräver nya forum att diskutera hur hanteringen bör gå till. En förvaltningsövergripande planering mot gemensammamål kan minimera risken att valet av system vid upphandlingfrämst styrs av ekonomi och tidigare erfarenheter. Istället kan fokus läggas på vilka lösningar som är mest hållbara i det specifika området. Att belysa detta tidigt i upphandlingsskedet skapar goda förutsättningar för genomförande. Syftet med detta examensarbete varatt ta fram ett beslutsstöd som dels underlättar den förvaltningsövergripande planeringen vid upphandling av dagvattensystem och dels främjar en hållbar hantering av dagvatten. Beslutsstödet möjliggör att hänsyn tas till det specifika områdets samhälleliga och naturgivna förutsättningar. Metoden bygger på multikriterieanalys ochstödet har designats så att det enkelt går att ta fram grundförutsättningar för jämförelsen tidigt i planeringsskedet, vilket sedan analyseras och justeras tillsammans med de parter som berörs av dagvattenhanteringen för det specifika området. Till exempel kommunala förvaltningar inom stadsplanering, miljöoch VA. Designen bygger på etablerade metoder gällande fördröjningskrav, föroreningsbelastning och dimensionering av system för dagvattenhantering. För att testa beslutsstödets relevans har en fallstudie av ett område under upphandling för exploatering i Uppsala kommun genomförts. Det framtagna beslutsstödet utgörs av fyra delar; systemalternativ, multikriterieanalys, fördröjningskrav och föroreningsbelastning. Systemalternativ ger förslag till tekniker som kan utgöra system för dagvattenhantering. Multikriterieanalys innefattar en systemanalytisk jämförelse där systemför dagvattenhanteringutvärderas och viktas enligt 21 kriterium relaterade till hållbar dagvattenhantering. Fördröjningskrav och föroreningsbelastning beräknar mängdvatten som bör fördröjas efter exploatering respektive reningseffekt på förorenat dagvatten beroende på systemalternativ. I fallstudien jämförs fyra systemalternativ frånvälgrundade utvärderingar av varje kriterium, vilket ger en hög trovärdigheti studiens utfall. Utfallet från fallstudien visar attsystem som innefattar öppenhantering av dagvatten är lämpligt i det undersökta området.Utvärderingavbeslutsstödetpekar på att stödet kanbidra till en förbättradkommunikation mellan berörda parter inom en upphandlingoch att utvalda kriterierna har potential attbidra till en hållbar dagvattenhantering under planeringsprocessen. / The ongoing urbanization contributes to decreaseinfiltration and evaporation of water, compared to natural environments. This affect the natural water cycle, leading to an increased surface runoff of rain and melt water, also known as stormwater. Stormwater has by tradition been managed by diverting it to wastewater treatment plants or to the closest receiving waters. Today, it isconsidered to be more sustainable and modern managing the stormwater locally, close to the source by imitating a natural water cycle. The problem of realizing this modern management is not caused by inadequate modern techniques, but a communicative problem between the concerned parties. To promote a long term and sustainable management, a commonvision is required. This demands new forums for discussion. All concerned partiesshould pursue a common goal to minimize the risk of the system being chosen based on economy and previous experience. Focus should be pointed to solutions that are sustainable in the specific area. This should be elucidated in the procurement stage to create good conditions for implementation. The objective with this thesis wasto elaborate a decision supportmethod, facilitating communication between the concerned parties at the procurement stage of stormwater management. The decision support will promotea long term and sustainable solution, and consider the specific area with regard to social conditions and nature. By using multiple-criteria decision analysis, systems of stormwater management will be compared based on problems and advantages of stormwater in an urban environment and an optimal solution can be identified. The decision support has been designedto easily retrieve basic conditions for the comparison early in the procurement stage, which then can be analyzed in view of opinions from the different concerned parties. The design is based on established methods concerning delay demands, pollution load and dimensioning of systems of stormwater management. To test the relevance of the decision support, a case study of an area currently under procurement for exploitation in Uppsala was performed. The developed decision support consists of four sections; “Multiple-criteria decision analysis”, “Alternatives of systems”, “Delay demands” and “Pollution load”. “Multiple-criteria decision analysis” includes analytical comparison where different systems of stormwater management are evaluated and weighted according to 21 criteria related to sustainable stormwater management. “Alternatives of systems”, suggests stormwater techniques which can form a system ofstormwater management. “Delay demands” calculates how much water that should be delayed after exploitation and “Pollution load” calculates the purification effect on polluted stormwater depending on choice of systems. The case study reveals that the support can contribute to better communication between concerned parties within procurement and that the best suited system of stormwater management for the case study area are systems that manage stormwater locally near the source of water.

Huvudsyftet med den här studien var att undersöka vilka parametrar som har störst inverkan på trädens vattentillgång i BlåGrönGråa-system (BGG-system), utvecklat av Edge, och vilka förbättringar som kan göras för att vegetationen bättre ska klara av torka. Ett annat mål med denna studie var attundersöka hur väl det går att efterlikna och simulera BGG-system i modelleringsverktyget MIKESHE, utvecklad av Danish Hydraulic Institute (DHI). För att undersöka vilka parametrar som har störst inverkan på BGG-systems vattenhalt varierades; storleken på tillrinningsområdet, crop factor, växtsubstrat, djup på regnbäddarna, växtval, dräneringsdjup och dräneringshastigheten. Alla simuleringarna genomfördes med meteorologisk data för perioden 1991-2020 för att underöka hur årsvariationer påverkar vattenhalten i systemet. Resultaten visar att stadsträd som inte erhåller något tillskott av vatten via tillförsel av dagvatten kommer utsättas för extremt ogynnsamma förhållanden när det kommer till vattentillgång, och att den parameter som har störst inverkan på vattenhalten i BGG-system är storleken på tillrinningsområdet. För att ytterligare förbättra vattentillgången för träden i BGG-system kan växtsubstratet förbättras genom att öka mängden växttillgängligt vatten. Detta föreslås dock framförallt för större träd eller då tillrinningsområdet inte kan utökas ytterligare. Variationen av djupet på regnbäddarna har relativt liten effekt på resultatet, vilket delvis kan förklaras av andra val i satta parametrar. Växtvalet visar sig i denna studie har liten effekt på vattenhalten, vilket delvis beror på modellens utformning och valdaparametrar. Variationen av dräneringsdjupet och dräneringshastigheten visar sig inte ha någon effekt på de resultat som undersöks i denna studie. Modellen som har satts upp beskriver systemet på ett tillförlitligt sätt, och är ett bra första steg föratt ytterligare öka förståelsen för trädens förutsättningar i dagvattenhantering. Men för att kunna dramer långtgående slutsatser om hur träden klarar av torrperioder behöver ytterligare undersökningargenomföras på BGG-system. / The main purpose of this study was to investigate which parameters have the greatest impact on thetrees’ water supply in BlueGreenGray-systems (BGG-system), developed by Edge, and what improvements can be made to the system to make the vegetation able to withstand periods of droughts better. Another aim of this study was to investigate how well it is possible to imitate and simulate BGG-systems in the modeling tool MIKE SHE, developed by the Danish Hydraulic Institute (DHI). To investigate which parameters have the greatest impact on the water content in BGG-systems the following parameters was varied; the size of the catchment area, crop factor, plant substrate, depth of the rain beds, plant selection, drainage depth and drainage rate. All simulations were performed with meteorological data for the period 1991-2020 to investigate how annual variations affect the watercontent in the system. The results show that city trees that do not receive any addition of water via the supply of stormwater will be exposed to extremely unfavorable conditions when it comes to water supply, and that the parameter that has the greatest impact on the water content in BGG-systems is the size of the catchment area. To further improve the water supply for the trees in a BGG-system, the plant substrate can be improved by increasing the amount of plant available water. However, this is mainly proposed for larger sized trees or when the catchment area cannot be expanded further. The variation in the depth of the rain beds has a relatively small effect on the result, which can be partly explained by other choices in set parameters. The choice of plant in this study has little effect on the water content, which is partly due to the model’s design and selected parameters. The variation of the drainage depth and the drainage rate does not appear to have any effect on the results examined in this study. The model that has been set up describes the system in a reliable way, and is a good first step to furtherincrease the understanding of the trees conditions in stormwater management. However, in order tobe able to draw more far-reaching conclusions about how trees cope with dry periods, further studiesneed to be carried out on BGG-systems.

This dissertation argues that stormwater management is fragmented both at that vertical fragmentation (at the level of intergovernmental relations) and horizontal fragmentation (within the level of governments). The first essay focuses on the institutional arrangements used by states to implement stormwater management policies. Building on the race to the bottom literature, I examine the impact of the institutional arrangement centralization on state water quality in California, Texas, Virginia, and Minnesota. A five-year (2013-2018) permitting cycle was used to analyze five dimensions: formalism, coercion, education, prioritization, and accommodation.There is an inverse relationship between the quality of stormwater and the degree of centralization in the institutional arrangements adopted by state governments to implement their stormwater management policies. The second essay focuses on a local government's decision to join an inter-local agreement to comply with federal/state stormwater management policies. Building on the transaction cost framework, the study used a cross-sectional design to analyze a case study. The case study consists of 119 cities subjected to stormwater regulation requirements in northern Texas during 2017. The dependent variable is the membership of the regional inter-local agreement, and the independent variables are the number of neighboring cities and population density. Community wealth, public works spending, stormwater fees, government type, and the percent of the population over 65 were used as control variables. Logistic regression was used for data analysis. This study concludes that the increase in the number of neighboring regulated local governments is associated with an increase in the likelihood of a decision by the regulated local government to join an interlocal agreement (ILA), as well as finding that an increase in the population density is associated with an increase in the likelihood of a decision by the regulated local government to join the ILA. In addition, the study found that the type of government also affects a decision to enter into a cooperative relationship to meet the regulative burdens associated with implementing the stormwater management policies imposed by state/federal governments. The results found in this dissertation contribute to bridging the gap in our knowledge on the impact of the institutional framework adopted by the states to implement environmental policy through empirically evaluating the effect of institutional arrangements (as represented in the States general MS4 permits) on the policy output (reducing the level of stormwater pollution).