No description available.

Green urban drainage systems are used to avoid flooding and damages to people and property, while limiting the downstream flooding and water quality problems caused by pipe-based drainage systems. Computer models are used to analyse and predict the performance of such systems for design and operation purposes. Such models are simplifications of reality and based on uncertain measured data, so uncertainties will be involved in the modelling process and its outcomes, which can affect the design and operation of these systems. These uncertainties have been investigated extensively for traditional pipe-based urban drainage systems, but not yet for green alternatives. Therefore, the overall objective of this thesis is to contribute to improved applicability and reliability of computer models of green urban drainage systems. Specifically, the thesis aims to (1) improve understanding of the uncertainties arising from (a) model structure and (b) calibration data selection, (2) evaluate two alternative calibration methods for green urban drainage models, (3) discuss desirable structural features in urban drainage models, and (4) evaluate several sensors for hydrometeorological measurements in urban catchments. The effects of model structure uncertainty were investigated using long-term simulations of synthetic catchments with varying soil types and depths for three different models. First, it was found that surface runoff could be a significant part of the annual water balance in all three models, depending on the soil type and depth considered. Second, differences were found in how sensitive the different models were to changes in soil type and depth. Third, the variation between different models was often large compared to the variation between different soil types. Fourth, the magnitude of inter-annual and inter-event variation varied between the models. Overall, the findings indicate that significant differences may occur in urban drainage modelling studies, depending on which model is used, and this may affect the design or operation of such systems. The uncertainty from calibration data selection was investigated primarily by calibrating both a low- and high-resolution stormwater model using different sets of events. These event sets used different rainfall-runoff statistics to rank all observed events before selecting the top six for use in calibration. In addition, they varied by either calibrating all parameters simultaneously, or by calibrating parameters for impervious and pervious surfaces separately. This last approach sped up the calibration process. In the validation period the high-resolution models performed better than their low-resolution counterparts and the two-stage calibrations matched runoff volume and peak flows better than single-stage calibrations. Overall, the way in which the calibration events are selected was shown to have a major impact on the performance of the calibrated model. Calibration data selection was also investigated by examining different ways of including soil water content (SWC) observations in the calibration process of a model of a swale. Some model parameters could be identified from SWC, but not from outflow observations. Including SWC in the model evaluation affected the precision of swale outflow predictions. Different ways of setting initial conditions in the model (observations or an equilibrium condition) affected both of these findings. The precipitation sensors used in this thesis showed generally satisfactory performance in field calibration checks. Different types of precipitation sensors were associated with different requirements for maintenance and data acquisition. Sensors for sewer pipe flow rates showed good agreement with a reference instrument in the laboratory, as long as installation conditions were good. Higher pipe slopes and upstream obstacles lead to larger measurement errors, but this last effect was reduced by increasing water levels in the pipe. Sensor fouling was a source of errors and gaps in field measurements, showing that regular maintenance is required. The findings show that the evaluated flow sensors can perform satisfactorily, if measurement sites are carefully selected. / Reliable modeling of green infrastructure in green urban catchments / Assessment and modeling of green infrastructure for urban catchments

Stormwater is an important transport pathway for pollutants from the urban environment into receiving water bodies, and, thus, it contributes to the deterioration of urban surface waters. The aim of this Licentiate thesis was to advance the understanding of the contributions of urban stormwater pollutants from building surface materials, and evaluate the implications for stormwater quality. Furthermore, this thesis also aims to (i) identify which pollutants can be expected to be released from building surface materials that are commonly used in the urban environment and (ii) estimate the magnitude of released pollutant concentrations in comparison to those from other important sources (e.g., those related to transportation, industries or atmospheric deposition). The material presented in the thesis includes a critical literature review of the sources of stormwater pollution, as well as laboratory and outdoor pilot studies of the pollutants released from commonly used building surface materials.  It was identified in the literature review that the current state of knowledge varies between source categories. Metallic building envelopes were early recognised as one of the major sources of metals in stormwater and, in many larger cities, they were identified as one of the main contributors of e.g., Cu, Pb and Zn to stormwater. Many building surface materials are also important contributors of pesticides. Recent research suggested that building surface materials (roofing membranes, plastic materials, concrete, paints and coatings, etc.) were important sources of organic micropollutants, but relatively few studies reported on such micropollutant releases from specific materials, or their concentrations in runoff. Results from the outdoor pilot study indicate that several of the 10 materials studied may contribute environmentally relevant concentrations of chemical substances commonly found in stormwater. Specific building surface materials were shown to be important sources of such metals as Cu and Zn: in the outdoor pilot study copper roofing sheets released Cu into rainwater at average concentrations of 3090 µg/L, zinc sheets released average Zn concentrations of 7770 µg/L, and galvanised steel released average Zn concentrations of 3530 µg/L. These concentrations exceed those measured from other sources (e.g., road runoff) by more than an order of magnitude. Moreover, nonylphenols (NPs) were released from PVC membranes, and bitumen shingles and felt. One of the PVC materials tested released, on average, NP concentrations of 26 µg/L, which were of the same order of magnitude as concentrations measured in road runoff. The same PVC also released an average concentration of 455  µg/L Diisononyl phthalate, DINP, but too little of data was available for comparisons to others sources. When comparing the laboratory leaching and outdoor pilot experiments, laboratory studies were efficient in identifying pollutant sources, and studying the effects of specific influential factors, but only the outdoor study produced realistic approximations of the released concentrations and loads of pollutants.

Snow deposited in urban areas is exposed to pollutants originating from traffic, wet and dry atmospheric deposition, de-icing chemicals and traction materials. The conventional pollutants found in urban snow include solids (TSS), metals (Zn, Cu, Cd, Pb, etc.), Polycyclic Aromatic Hydrocarbons (PAHs), and chlorides. Microplastics (MPs) are emerging pollutants of interest and their presence in urban snow was reported only recently. The pollutants accumulate in snow deposits over time and may be released when snow melts, and the resulting snowmelt may carry pollutants to the receiving waters. Understanding the concentrations and mass loads of pollutants in snow and pollutant behaviour during snowmelt is helpful for planning and developing site-specific snow management practices. The overall aim of this thesis was to evaluate the quality of snow in urban areas, with respect to: (i) quantity of metals, PAHs and MPs in urban snow storage piles and roadside snowbanks, (ii) compare the quality of snow collected in the same catchment during repeated sampling campaigns and evaluate the effect of the sampling design on estimation of pollutant loads in snow piles, and (iii) investigate the pollutant release patterns and temporal variations in their concentrations in water leaving the melting snow piles (in laboratory). For such studies, snow samples were collected from snow storage piles in Frihamnen (a port facility in Stockholm, Sweden) and roadside snowbanks in Luleå and Umeå cities in Northern Sweden. The quality of snow collected in the three study areas varied considerably, because of differences in such area characteristics as the annual precipitation and snowfall, the population, average daily traffic, land use activities, and snow management activities. The average values of major parameters in analysed snow samples were as follows: TSS - 1500 mg/L, conductivity- 2.1 mS/cm, Zn – 870 µg/L, Cu – 240 µg/L, Cd – 0.48 µg/L, Cr – 120 µg/L, Pb – 50 µg/L and the sum of 16 PAHs – 3.5 µg/L. Microplastics were abundant in urban snow samples, with the following descending order of concentrations: black road wear particles, consisting of bitumen and tire wear particles,  mean = 19300 ± 47400 particles/L; road marking paints with the mean of 430 ± 998 particles /L; and, plastics particles, mean 33 ± 34 particles /L. No correlations were found between the numbers of MP particles and the site-specific parameters. Comparison of snow pile sampling designs revealed that systematic 1-m square grid sampling yielded the best estimates of mass loads (BEML) of pollutants, compared to single snow cores, or horizontally composed core samples. The mass loads estimated from composite or single snow column sampling deviated up to 50 and 400%, respectively, from BEML. Results of the laboratory snow melting indicated that PAHs in the snow samples were mostly attached to the particles; only 10% of the total PAHs burden was contributed by the meltwater and the rest stayed on the ground with the sediment residue. The dissolved concentrations of PAHs were below the detection limit (0.010 µg/L) in all the analysed samples except for Fluoranthene and Pyrene with concentrations ranging between 0.01 and 0.02 µg/L. PAHs displayed a delayed release from snow piles, which was similar to that of TSS. Truly dissolved fractions (<3000 MWCO, Molecular Weight Cutoff) of Zn, Cu and Cd represented 71-90% of dissolved fractions in the snow samples collected in Luleå (snow without road salt) and 74-98% in those from Umeå (snow with added road salt). Both dissolved and truly dissolved metals showed advanced releases from all the snow piles. The influence of road salt on releases of metals and PAHs from laboratory snow piles was hard to discern, because of great differences in snow quality characteristics at both locations.

No description available.

No description available.

En hållbar hantering av vatten och avlopp (VA) är avgörande för att skydda miljön och människors hälsa. Ansvaret kan dock inte enbart läggas på VA-sektorn, utan hela samhället behöver vidta åtgärder för att hantera utmaningar relaterade till befolkningstillväxt, urbanisering och klimatförändringar. I denna studie tillämpades en backcastingmetod för att föreslå en väg mot framtidsvisionen: Hållbar hantering av vatten och avlopp i staden år 2070, under ett förändrat klimat. En grupp experter bedömde att följande nyckelfaktorer är särskilt viktiga för att uppnå visionen: ”VA-systemet tillhandahåller säkert vatten” ”Vattenanvändningen i staden är hållbar” ”VA-systemet bidrar till den cirkulära ekonomin” ”VA-systemet bidrar inte till övergödning” ”VA-systemet sprider minimalt med föroreningar” ”VA-systemet är klimatresilient” Baserat på dessa nyckelfaktorer identifierades indikatorer, möjligheter, hinder samt åtgärder i nutid. Enligt expertgruppen är det särskilt kritiskt och brådskande att vidta åtgärder för att minska belastningen på VA-systemet. Belastningen kan exempelvis reduceras genom minskad dricksvattenförbrukning, ökad återanvändning av vatten, reducerade vattenförluster, lokal hantering av dagvatten, implementering av källsorterande avloppsystem och uppströmsåtgärder. Dessutom var investeringskostnader ett återkommande hinder, och det är därför viktigt att politiker är medvetna om behovet för att kunna utforma effektiva lagar och styrmedel. För att analysera åtgärdernas effekter inkluderades även beräkningsexempel med Uppsala tätort som fallstudie. Analysen visade att Uppsala inte kommer att uppnå framtidsvisionen med nuvarande målsättningar. En rekommendation till Uppsala är därför att tillämpa backcasting för att identifiera och kvantifiera ytterligare åtgärder med utgångspunkt i denna studie. Denna rekommendation riktas även till Svenskt Vatten, men även till andra sektorer där det är nödvändigt att bredda perspektivet för att se helheten och nya vägar framåt, istället för att begränsas av det befintliga systemet. / Sustainable management of water and wastewater (W&WW) is crucial for protecting the environment and human health. However, the responsibility cannot solely rest on the W&WW sector, but the entire society needs to take action to deal with challenges related to population growth, urbanization and climate change. In this study, a backcasting method was applied to propose a pathway towards the future vision: Sustainable urban water and wastewater management in 2070, under a changing climate. A group of experts assessed the following keyfactorsas particularly important to achieve the vision: "The W&WW system provides safe water" "Water usage in the city is sustainable" "The W&WW system contributes to the circular economy" "The W&WW system does not contribute to eutrophication" "The W&WW system spreads minimal pollutants" "The W&WW system is climate resilient" Based on these key factors, indicators, opportunities, obstacles, and actions in the present were identified. According to the expert group, it is particularly critical and urgent to take actions to reduce the burden on the W&WW system. The burden can be reduced, for example through decreased drinking water consumption, increased reuse of water, reduced water losses, local management of stormwater, implementation of source-sorting wastewater systems and upstream measures. In addition, investment costs were a recurring obstacle, and it is therefore important that the politicians are aware of the need to be able to design effective laws and policies. In order to analyze the effects of the actions, calculations examples with Uppsala as a case study were included. The analysis showed that Uppsala will not achieve the future vision with current objectives. A recommendation for Uppsala is therefore to apply backcasting to identify and quantify additional actions based on this study. This recommendation is also directed towards Svenskt Vatten, but also to other sectors where it is necessary to broaden the perspective to see the whole picture and new pathways forward, instead of being limited by the existing system.

No description available.

Simhallar används som fritidscenter, för sport eller som terapeutisk rehabilitering, och i Stockholms kommun finns det 15 kommunala simanläggningar samt väldigt många privata i form av till exempel hotellpooler. Ett relativt ouppmärksammat problem som finns med dessa pooler ligger i de kemiska reaktioner som händer i vattnet. Natriumhypoklorit, som används för reningen, reagerar i bassängen med organiskt material och bildar Adsorberbara Organiska Halider (AOX) och Extraherbara Organiska Halider (EOX). Dessa fastnar i filtret på anläggningen lokalt och fritt klor kan bilda ytterligare AOX i spillvattennätet. När detta händer behöver filtren genomgå backspolning och detta genererar koncentrerat förorenat vatten.  Dessa föreningar är skadliga för människor och djur samt ibland även att komma i direktkontakt med. Dessa ämnen har visat sig kunna bioackumulera i levande organismer och har där orsakat problem såsom nedsatt reproduktiv förmåga och andra cellskador. Ämnena har även observerats ansamlas i dyn i vattendrag.  I denna kandidatuppsats har jag studerat hur många badanläggningar som finns i upptagningsområdet för Käppalaverket, Bromma och Henriksdals avloppsreningsverk. Med denna information har jag tagit reda på hur mycket vatten som genereras av pooler på dessa anläggningar och kompletterat dessa siffror med hjälp av schablonvärden inskaffade från förvaltare och uppskattade från inkomna värden.  Jag fann 188 st badanläggningar inom det undersökta området, varav 70 st var plaskdammar. Dessa anläggningar genererade cirka 278 000 kubikmeter vatten, och denna mängd motsvarar mellan 0.10 och 0.145 procent av det totala inflödet till de olika reningsverken. Slutsatsen blev att reningsverk kanske inte passar som mottagare av backspolvatten i dagsläget, och att mer undersökningar behöver göras för att göra ämnet klarare och säkrare. / Swimming pools are used as leisure centers, for sports or as therapeutic rehabilitation, and in Stockholm municipality there are 15 municipal swimming facilities and very many private ones in the form of, for example, hotel pools. A relatively inattentive problem with these pools lies in the chemical reactions that take place in the water. Sodium Hypochlorite reacts in the pool with organic material to form Adsorbable Organic Halides (AOX) and Extractable Organic Halides (EOX). These get stuck in the filter at the plant locally and free chlorine can form additional AOX in the wastewater network. These compounds are harmful for humans and animals to ingest and sometimes even to come into direct contact with. These substances have been studied to bioaccumulate in living organisms and have caused problems such as impaired reproductive capacity and other cell damage. The substances have also been observed to accumulate in dunes in watercourses. These substances that are created then get stuck in the filtration systems that are located locally at the plants due to pressure differences in these. When this happens, the filters need to be backwashed and this generates concentrated contaminated water.  In the background, I have examined different kinds of disinfection methods in swimming pools, as well as different ways to treat wastewater of AOX and EOX in treatment plants. This was done to build a good background to the issue at hand of AOX and EOX.  In this bachelor's thesis, I have studied how many swimming facilities there are in the catchment area of the Käppalaverket, Bromma treatment plant, and Henriksdal treatment plant. With this information, I have found out how much water is generated by pools at these facilities and supplemented these figures using standard values obtained from managers and estimated from received values.

The management of urban runoff has evolved along with the advancement of understanding of runoff environmental impacts. Besides the impacts on water quality in the receiving waters, the impacts on the urban hydrologic regime include reduced infiltration by the sealing of pervious land, reduced evapotranspiration by removal of vegetation, and the resulting increase of stormwater runoff peaks and volumes causing flooding, and ultimately degradation of receiving waters. In such considerations, urban stormwater management benefits from the implementation of Green Infrastructure which includes decentralized vegetative controls that capture and infiltrates rain where it falls and thus reduces and improves stormwater runoff. An example of small scale elements of Green Infrastructure are traditional grass swales. Through shallow depressions with mild side slopes grass swales collect and infiltrate stormwater from parking lots and roads, while runoff flows are attenuated and further conveyed depending on the hydraulic loading. Grass swales usually operate reliably and their maintenance needs are well understood. Their hydrological performance is, beside their dimensions and the contributing area, determined mainly by hydraulic and soil-related hydrological parameters that change with the intensity of the storm. Yet, because swales discharge to downstream drainage elements, either to the conventional sewer system or to other stormwater management facilities, the knowledge of the underlying inter-related processes and influential factors that govern the hydraulic and hydrological performance of grass swales is required. Against this background, this thesis is devoted to such questions as (i) what are the differences in the hydraulic and hydrological performance of the studied swales, (ii) how do soil characteristics, including the antecedent soil moisture, influence the swale water balance for various hydraulic loadings; and (iii) how can the related hydrological processes be simulated in high-resolution and reliably predicted using a grid-based, distributed model. For this purpose, full-scale studies were performed in three 30-m grass swale sections in Luleå, Northern Sweden, by collecting hydraulic and hydrological data based on routine storm events mimicking block-rainfall storm events of 2 months and 3 years recurrence. The resulting runoff and soil moisture data were used to calculate the swale water balance, to derive event hydrographs and to obtain calibration and validation data for model simulations. The experimental results showed that the relative swale flow volume reduction decreased with an increasing soil moisture and indicated the transition in dominating swale functions: at low initial SWC, runoff was highly attenuated (up to 74%), but for high SWC, the conveyance function dominated (with attenuation as low as 17%). Runoff flow peaks were reduced, proportionally to the volume reductions. Swale outflow hydrograph lag times varied between 5 to 15 minutes and decreased with increasing soil moisture. The swale wetness affected runoff formation, attenuation and subsequent outlet discharge and, for the short-duration events tested, only the top soil layer contributed to these findings. In the three swales tested, soils, initial soil water content, saturated hydraulic conductivity and topography varied spatially significantly. Double-ring infiltrometer measurements resulted in values of 1.78, 4.04 and 9.41 cm/hr (n=9) in the three swales tested and deviated from estimates from averages of spatially integrated infiltration rates. However, with regard to spatial variability, only the topography, described as irregularities in the swale bottom slopes affected the swale runoff dissipation and conveyance in the early phase of the events. Together with estimates of the water stored in the top soil layer, 4-32% of runoff volumes from the mimicked 2-month storm were temporarily stored. The distributed model Mike SHE was found capable of simulating swale drainage processes, when properly calibrated. Close agreement (NSE>0.8) was found not only for the measured and simulated swale outlet hydrographs, but also for the changes of the soil moisture in the top soil layer, which shows rapid increase up to the saturated soil water content, but minor or no progression in depths of 0.2 m. The model output was little sensitive to the initial soil water content, especially for low inflow which resulted in larger residuals in simulated runoff peak flows and volumes. As in field measurements, spatial variability of the initial soil water content had no effect on the swale outflow, but the accuracy of the topographical representation. The thesis findings include several implications regarding effects of the assessed parameters in the application of the model for swale flow simulation and eventually the design of grass swales. / Urban dagvattenhantering har utvecklats parallellt med en ökad förståelse för dagvattnets allmänna miljöpåver­kan. Utöver ytvattenkvalitén i recipientvatten påverkas även den hydrologiska regimen genom reducerad infilt­rationsförmåga i mark orsakad av allt tätare ytskikt samt reducerad evapotranspiration orsakad av minskad vegetationsutbredning. Detta ger både förhöjda toppflöden och avrinningsvolymer, vilket kan resultera i över­svämning och slutligen en försämrad ytvattenkvalité i recipienterna. Dagens urbana dagvattensystem förändras mot en högre grad av grön infrastruktur som en central systemkomponent. Decentraliserad omhändertagning av dagvatten såsom svackdiken utjämnar och för bort dagvattensflöden, samtidigt som de fungerar tillförlitligt och deras underhållsåtgärder är välkända. Uppbyggda med små svackor och låglutande slänter samlar svackdiken in och infiltrerar dagvatten från parkeringsytor och vägar. Dessa svackdikens hydrologiska funktion bestäms av en rad faktorer, utöver teknisk dimensionering och avrinningsområdets storlek och hydrologi, även av hydraulik och jordartsrelaterad hydrologi som förändras beroende på respektive nederbördstillfälles intensitet och varak­tighet. Eftersom svackdikens utflöde passerar nedströms liggande dagvattentekniker/anordningar, antingen konventionella ledningssystem eller andra teknologier, krävs full förståelse och kunskap om de faktorer som styr svackdikens hydraulik och hydrologi. Mot denna bakgrund fokuserar avhandlingen på frågorna (i) vilka skillnader finns med avseende på hydraulisk och hydrologisk prestanda för de studerade svackdiken, (ii) i vilken mån påverkar markartsförhållanden, inklu­sive ingående markfuktighet, svackdikens vattenbalans vid varierande hydraulisk belastning; samt (iii) hur och i vilken mån kan ovanstående simuleras högupplöst och förutsägbart, via den rutnätsbaserade distribuerade mo­dellen Mike SHE. Därför har fullskaliga studier bedrivits i två 30 m långa svackdiken i Luleå kommuns södra stadsområde, där hydrauliska och hydrologiska data insamlats baserat på standardiserade nederbördsförlopp, återskapande blockregn med 2 månaders och 3 års återkomsttid. Data för avrinning och markfukthalter använ­des för att beräkna svackdikenas vattenbalans, nederbördförloppens hydrografer samt erhålla kalibrering- och valideringsdata för modellsimuleringar. Resultaten från experimenten visade att den volymetriska flödesre­duktionen minskade relativt sett med ökande markfukthalt, indikerande en övergång för svackdikets domine­rande funktionalitet: vid låga initiala SWC var avrinningen tydligt dämpad (upp till 74%), medan för höga SWC innebar att transportfunktionen dominerade (med dämpningsgrad ner mot 17%). Avrinnande momentana topp­flöden reducerades proportionellt mot volymreduktionen. Laggtiden för svackdikets utflödeshydrograf varierade mellan 5 och 15 minuter och reducerades med ökande markfukthalt. Fuktförhållandena i svackdiket påverkade avrinningsförloppet, flödesdämpning och efterföljande utsläpp, och enbart svackdikets översta markskikt berör­des under de kortvariga bevattningscyklerna. I de tre testade svackdikena varierade jordart, initial markfukthalt, mättad hydraulisk konduktivitet och topografi signifikant. Mätningar med dubbelrings infiltrometrar gav föl­jande resultat, 1.78, 4.04 samt 9.41 cm/h (n=9), vilket avvek från medelvärdesbaserat estimat från spatialt inte­grerade infiltrationshastigheter. Med avseende på spatial variabilitet påverkade endast svackdikenas topografi, i form av ojämnheter i och nära dikesbotten, avrinningsförloppen och bortledning under den inledande fasen av regnhändelsen. Sammantaget med uppskattningar av den lagrat vatten i marklagrets toppskikt, bedöms 4-32% av svackdikets ytavrinning från ett simulerade nederbördtillfälle med 2 månaders återkomststid kunna lagras tillfälligt. Mike SHE befanns kapabel att med god noggrannhet kunna reproducera naturbundna dräneringsför­lopp och flöden i svackdiken, förutsatt tillbörlig kalibrering. God överensstämmelse (NSE>0.8) framkom inte bara mellan uppmätta och simulerade utgående hydrografer, utan också beträffande ändring av markfukthalt i ytligt marklager med snabb höjning av fukthalt upp emot full vattenmättnad. Däremot framkom endast mindre (eller total frånvaro av) överensstämmelse vad gäller markdjup av 0.2 m. Modellens output uppvisade låg käns­lighet för ursprunglig markfukthalt, speciellt gällande lågt flöde vilket resulterade i större residualer för simule­rade toppflöden och avrinningsvolymer. För fältförsöken framkom att den initiala markfukthaltens spatiala variabilitet inte påverkade utflödet från svackdiket – i motsats till noggrannheten i dikets topografiska repre­sentation. Denna uppsats belyser samband och följdverkningar beträffande påverkan från undersökta parametrar på en modell för flödes- och vattenföring i ett svackdike och framledes framtida design av svackdiken.