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  • 1. Abiye, T. A.
    et al.
    Bhattacharya, Prosun
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Arsenic concentration in groundwater: Archetypal study from South Africa2019Ingår i: Groundwater for Sustainable Development, ISSN 2352-801X, Vol. 9, artikel-id 100246Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    South Africa does not have significant surface water resources, which is often easily affected by unpredictable and rapidly changing climatic variables, due to its location in the arid and semi-arid climatic setting. In large part of the country, groundwater from weathered and fractured crystalline rocks plays pivotal role in sustaining the livelihood, often it contains toxic metals released from the host rocks. The host rocks that are responsible for arsenic release in groundwater are primarily enriched due to metamorphism and igneous processes that resulted in the enrichment of economic minerals. Preliminary assessment indicates that the main arsenic containing minerals are arsenopyrite (FeAsS), arsenical oxide, sulpharsenide, arsenopyritical reefs, leucopyrite, löllingite (FeAs2) and scorodite (FeAsO4·2H2O). Owing to the release of arsenic from highly mineralized rocks that constitute the aquifers, arsenic concentration in the groundwater reaches up to 253 μg/L (Namaqualand), 6150 μg/L (west of Johannesburg), about 500 μg/L in the Karoo aquifers, considerably higher than the WHO guideline value of 10 μg/L. Acid mine drainage from coal and gold mining is also found to be an important source of arsenic and other toxic metals in groundwater.

  • 2.
    Adem Esmail, Blal
    et al.
    Department of Civil, Environmental, and Mechanical Engineering, University of Trento, Via Mesiano 77, Trento, 38123, Italy.
    Geneletti, Davide
    Department of Civil, Environmental, and Mechanical Engineering, University of Trento, Via Mesiano 77, 38123 Trento, Italy.
    Design and impact assessment of watershed investments: An approach based on ecosystem services and boundary work.2017Ingår i: Environmental impact assessment review, ISSN 0195-9255, E-ISSN 1873-6432, Vol. 62, s. 1-13Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Watershed investments, whose main aim is to secure water for cities, represent a promising opportunity for large-scale sustainability transitions in the near future. If properly designed, they promote activities in the watershed that enhance ecosystem services while protecting nature and biodiversity, as well as achieving other societal goals. In this paper, we build on the concepts of ecosystem services and boundary work, to develop and test an operative approach for designing and assessing the impact of watershed investments. The approach is structured to facilitate negotiations among stakeholders. Its strategic component includes setting the agenda; defining investment scenarios; and assessing the performance of watershed investments as well as planning for a follow-up. Its technical component concerns data processing; tailoring spatially explicit ecosystem service models; hence their application to design a set of “investment portfolios”, generate future land use scenarios, and model impacts on selected ecosystem services. A case study illustrates how the technical component can be developed in a data scarce context in sub-Saharan Africa in a way that is functional to support the steps of the strategic component. The case study addresses soil erosion and water scarcity-related challenges affecting Asmara, a medium-sized city in Eritrea, and considers urban water security and rural poverty alleviation as two illustrative objectives, within a ten-year planning horizon. The case study results consist in spatially explicit data (investment portfolio, land use scenario, impact on ecosystem services), which were aggregated to quantitatively assess the performance of different watershed investments scenarios, in terms of changes in soil erosion control. By addressing stakeholders' concerns of credibility, saliency, and legitimacy, the approach is expected to facilitate negotiation of objectives, definition of scenarios, and assessment of alternative watershed investments, ultimately, to contribute to implementing an adaptive watershed management.

  • 3.
    Ahlberg, Jesper
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Biogeofysik.
    Gustafsson, David
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Biogeofysik.
    Distributed snow modelling integrating ground penetrating radar data for improved runoff predictions in a Swedish mountain basin2009Ingår i: EGU General Assembly 2009, 2009Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Operational forecasts of snow melt runoff in Sweden are currently running with precipitation and temperature as the main input variables and calibrated with runoff data, and there is an interest to make better use of new measurement systems for distributed snow data. At the same time, various data assimilation techniques are becoming more frequently used in hydrological modeling, in order to reduce uncertainties related to both model structure errors and errors in input and calibration data. Thus, it is important to address not only what type of snow data that can be used to improve the model predictions, but also what type of input data and model structures that are optimal in relation to the available snow data. The objective of this study is to investigate to what extent the runoff predictions can be improved by assimilation of temporal and spatially distributed snow data, and if the improvements depend on the choice of model structures, for instance the use of energy balance or day-degree snow models. In order to achieve these objectives a new distributed snow model has been implemented into the hydrological modeling framework HYSS/HYPE. This model can easily be setup with either an energy balance model or a day-degree model for the snow pack calculations, and it is easy to run the model with different spatial resolutions. In the fully distributed case, snow drift processes are implicitly included in the model through a precipitation distribution model, based on topographical information and wind direction. The model was applied to a mountain basin in northern Sweden used for hydropower production, where extensive snow measurements were taken during the last two winters 2007-2009. A climate station is located at the outlet of the regulation lake, including automated point measurements of snow depth, snow mass (snow pillow), snow wetness and snow temperature. Distributed snow cover data was sampled using ground-penetrating radar from snow mobiles. Measurements were taken at the time of the maximum snow cover, providing a data set with snow depth, snow density, snow water equivalent along 20 km long transects in representative areas of the basin. The precipitation distribution model was calibrated using the distributed SWE data from the GPR measurements. Application of the calibrated model to previous years without available snow data show that the runoff predictions was improved compared to calibrations without the distributed snow data, however the improvements were larger for the energy balance compared to the day-degree model. Further developments will include assimilation of the temporal and spatial snow data to adjust the distribution of various input variables, for instance air temperature and wind speed.

  • 4.
    Ahlberg, Jesper
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Biogeofysik.
    Gustafsson, David
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Biogeofysik.
    Snow melt runoff simulations using ensemble Kalman filter assimilation of distributed snow data2010Konferensbidrag (Övrigt vetenskapligt)
  • 5. Al-Yaarubi, A. H.
    et al.
    Pain, C. C.
    Grattoni, C. A.
    Zimmerman, Robert W.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Navier-Stokes Simulations of Fluid Flow Through a Rock Fracture2013Ingår i: Dynamic Fluids and Transport Through in Fractured Rock, American Geophysical Union (AGU), 2013, s. 55-64Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    A surface profilometer was used to measure fracture profiles every 10 microns over the surfaces of a replica of a fracture in a red Permian sandstone, to within an accuracy of a few microns. These surface data were used as input to two finite element codes that solve the Navier-Stokes equations and the Reynolds equation, respectively. Numerical simulations of flow through these measured aperture fields were carried out at different values of the mean aperture, corresponding to different values of the relative roughness. Flow experiments were also conducted in casts of two regions of the fracture. At low Reynolds numbers, the Navier-Stokes simulations yielded transmissivities for the two fracture regions that were closer to the experimental values than were the values predicted by the lubrication model. In general, the lubrication model overestimated the transmissivity by an amount that varied as a function of the relative roughness, defined as the standard deviation of the aperture divided by the mean aperture. The initial deviations from linearity, for Reynolds numbers in the range 1-10, were consistent with the "weak inertia" model developed by Mei and Auriault for porous media, and with the results obtained computationally by Skjetne et al in 1999 on a two-dimensional self-affine fracture. In the regime 10 < Re < 40, both the computed and measured transmissivities could be fit very well to a Forchheimer-type equation, in which the additional pressure drop varies quadratically with the Reynolds number.

  • 6.
    Andersson, Edwin
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Gulding, William
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Högvattenföring ochriskbedömning i svensk miljö2019Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Rapporten ämnar utvärdera potentiella begränsningar inom vattenkraftsindustrin i relation till högvattenföring under ett skiftande klimat. Detta görs genom en litteraturstudie gällande lagar och föreskrifter, samt med en modellering av de flödesförändringar som uppstår i den övre delen av Pite älv i norra Sverige som en konsekvens av ett skiftande klimat. Modelleringen görs med HBV-96 och fyra olika scenarion med ett modellerat referensflöde. Vattenkraftsindustrin är för det mesta reglerad privat med egenkontroller, med krav för inrapportering till länsstyrelsen för de dammar vars bristning kan orsaka stor skada.Modelleringen och scenarierna fann en tendens till svagare vårfloder som en konsekvens av ökad medeltemperatur. Ökningen i medeltemperatur har inga observerade direkta effekter på vattenföring under sensommar och höst, men potential för indirekt påverkan finns. Om nederbörd ökar, som förväntat, kommer vi se en ökning i volym av vatten i älven. Resultatet ser ingen krav för anpassning till större flöden i en snar framtid då de kraftigaste flödena under våren kommer minska, däremot lär ett skifte i beteendet av den årliga vattenföringen ske med ett flöde som är mer beroende av nederbörd istället för snösmältning. Detta medför en uppmaning till förändring i korttidsstrategi med hjälp av större marginal i dammens vattenhöjd tillsammans med modellering och väderprognoser, främst under sensommar och höst.

  • 7. Bazilian, Morgan
    et al.
    Rogner, Holger
    Howells, Mark
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Energisystemanalys.
    Hermann, Sebastian
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Energisystemanalys.
    Arent, Douglas
    Gielen, Dolf
    Steduto, Pasquale
    Mueller, Alexander
    Komor, Paul
    Tol, Richard S.J.
    Yumkella, Kandeh K.
    Considering the energy, water and food nexus: Towards an integrated modelling approach2011Ingår i: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 39, nr 12, s. 7896-7906Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The areas of energy, water and food policy have numerous interwoven concerns ranging from ensuring access to services, to environmental impacts to price volatility. These issues manifest in very different ways in each of the three "spheres", but often the impacts are closely related. Identifying these interrelationships a priori is of great importance to help target synergies and avoid potential tensions. Systems thinking is required to address such a wide swath of possible topics. This paper briefly describes some of the linkages at a high-level of aggregation - primarily from a developing country perspective - and via case studies, to arrive at some promising directions for addressing the nexus. To that end, we also present the attributes of a modelling framework that specifically addresses the nexus, and can thus serve to inform more effective national policies and regulations. While environmental issues are normally the 'cohesive principle' from which the three areas are considered jointly, the enormous inequalities arising from a lack of access suggest that economic and security-related issues may be stronger motivators of change. Finally, consideration of the complex interactions will require new institutional capacity both in industrialised and developing countries.

  • 8.
    Bhattacharya, Prosun
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljögeokemi och ekoteknik.
    Ahmed, K.M.
    Hasan, M.A.
    Broms, S.
    Fogelström, J.
    Jacks, Gunnar
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljögeokemi och ekoteknik.
    Sracek, O.
    von Brömssen, Mattias
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljögeokemi och ekoteknik.
    Routh, J.
    Mobility of arsenic in groundwater in a part of Brahmanbaria district, NE Bangladesh2006Ingår i: Managing Arsenic in the Environment: From soil to human health / [ed] Naidu, R., Smith, E., Owens, G., Bhattacharya, P. Nadebaum. P., Melbourne, Australia: CSIRO Publishing , 2006, s. 95-115Kapitel i bok, del av antologi (Refereegranskat)
  • 9.
    Bhattacharya, Prosun
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630).
    Claesson, Mattias
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630).
    Fagerberg, Jens
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630).
    Bundschuh, Jochen
    Storniolo, Angel del R.
    Martin, Raul A.
    Thir, Juan Martin
    Sracek, Ondra
    Natural arsenic in the groundwater of the alluvial aquifers of Santiago del Estero Province, Argentina2005Ingår i: Natural Arsenic in Groundwater: Occurrence, Remediation and Management / [ed] Bundschuh, J; Bhattacharya, P; Chandrasekharam, D, London: Balkema, 2005, s. 57-65Konferensbidrag (Refereegranskat)
    Abstract [en]

    Natural occurrences of arsenic has been documented in groundwater of the shallow aquifers of the Chaco-Pampean Plain, Argentina. The distribution of arsenic and mechanisms of its mobilization in the shallow alluvial aquifers was investigated around the city of Santiago del Estero in Northwestern Argentina in order to provide an insight into the complex hydrological and geochemical conditions that yields high As concentrations in groundwater. Significant spatial variations of total arsenic (As-tot) concentrations were observed with an average value of 743 mu g/L. Arsenate was a dominant species in most samples. Average concentrations of Al, Mn, and Fe were 360 mu g/L, 574 mu g/L, and 459 mu g/L, respectively. The 7M HNO3 extraction of sediments and volcanic ash-layer indicated AS(N03) concentrations ranging between 2.5-7.1 mg/kg. AS(N03) indicated a significant positive correlation with Mn-N03, Al-N03, and Fe-N03. Oxalate extractions revealed significant fractions of As (Aso(ox)) in the sediments (0.4-1.4mg/kg) and a dominance of oxalate extractable Al- and Mn. Speciation calculations indicate that Al oxide and hydroxides have the potential to precipitate in the groundwater, suggesting that As adsorption processes may be to some extent controlled by Al oxides and hydroxides. Mobility of As at local scale seems to depend on high pH values, related to the dissolution of carbonates driven by cation exchange, and dissolution of silicates. There is a clear relationship of As with F, V, B and Si, suggesting their common origin in volcanic ash layer. Preliminary conceptual model of arsenic input includes release of As and Al from dissolution of volcanic ash layer, precipitation of Al oxides and hydroxides followed by adsorption of As on Al and Fe phases in sediments, and release of As under high pH conditions.

  • 10.
    Bhattacharya, Prosun
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Mukherjee, A.
    Mukherjee, A. B.
    Groundwater Arsenic in India: Source, Distribution, Effects and Alternate Safe Drinking Water Sources2013Ingår i: Reference Module in Earth Systems and Environmental Sciences, Elsevier, 2013Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Elevated natural groundwater arsenic, a carcinogen, has created a severe environmental health crisis in several parts of India. Since the discovery of groundwater arsenic and arsenicosis in West Bengal, in 1984, a huge wealth of information has been generated by groundwater arsenic research during the last three decades. The principal mechanism of arsenic mobilization in groundwater is believed to be reductive dissolution of Fe-oxyhydroxides in aquifer sediments. Arsenic enriched groundwater used for irrigation also leads to long-term risks for arsenic enrichment in the soils and bioaccumulation in crops. Various studies are ongoing to develop a holistic approach for arsenic mitigation.

  • 11.
    Bhattacharya, Prosun
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljögeokemi och ekoteknik.
    von Brömssen, M.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljögeokemi och ekoteknik.
    Hasan, M.A.
    Jacks, Gunnar
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljögeokemi och ekoteknik.
    Ahmed, K.M.
    Sracek, O.
    Jakariya, M.
    Huq, S.M.I.
    Naidu, R.
    Smith, E.
    Owens, G.
    Arsenic mobilisation in the Holocene flood plains in South-central Bangladesh: Evidences from the hydrogeochemical trends and modeling results2008Ingår i: Groundwater for Sustainable Development: Problems, Perspectives and Challenges / [ed] Bhattacharya, P., Ramanathan, AL., Mukherjee A.B., Bundschuh, J., Chandrasekharam, D. Keshari, A.K., The Netherlands: Taylor and Francis/A.A. Balkema , 2008, s. 283-299Kapitel i bok, del av antologi (Refereegranskat)
  • 12.
    Bishop, Adrian N.
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Fidan, Baris
    Anderson, Brian D. O.
    Dogancay, Kutluyil
    Pathirana, Pubudu N.
    Optimal Range-Difference-Based Localization Considering Geometrical Constraints2008Ingår i: IEEE Journal of Oceanic Engineering, ISSN 0364-9059, E-ISSN 1558-1691, Vol. 33, nr 3, s. 289-301Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper proposes a new type of algorithm aimed at finding the traditional maximum-likelihood (TML) estimate of the position of a target given time-difference-of-arrival (TDOA) information, contaminated by noise. The novelty lies in the fact that a performance index, akin to but not identical with that in maximum likelihood (ML), is a minimized subject to a number of constraints, which flow from geometric constraints inherent in the underlying problem. The minimization is in a higher dimensional space than for TML, and has the advantage that the algorithm can be very straightforwardly and systematically initialized. Simulation evidence shows that failure to converge to a solution of the localization problem near the true value is less likely to occur with this new algorithm than with TML. This makes it attractive to use in adverse geometric situations.

  • 13.
    Blomgren, Axel
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Industriell ekologi.
    Stockholms grundvattenkvalitet: Bidrag till övergödningen av ytvattendrag och sjöar i Stockholmsområdet2016Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Övergödning är ett av Sveriges mest allvarliga miljöproblem. Genom utsläpp till följd av antropogen verksamhet läcker näringsämnen ut i vattnet. Den senaste undersökningen av Stockholms stads grundvatten har kartlagt halterna av kväve och fosfor. Eftersom grundvatten är en del utav det hydrologiska kretsloppet, och efter en viss omsättningstid övergår till ytvatten, påverkar kvalitén hos grundvattnet recipienten samt det ekosystem som denna ingår i. Rapporten ämnar undersöka halterna av kväve och fosfor i grundvattnet utifrån befintliga bedömningsgrunder samt kartlägga huruvida grundvattnet bidrar till övergödning av Stockholms kommuns ytvattenförekomster. Detta är av vikt för kommunens vattenförvaltning i linje med EU:s vattendirektiv och mål om god status för vattenförekomster, men även för att verka mot landets miljökvalitetsmål.

    Miljöförvaltningens undersökning av grundvattenkvaliteten visar på höga halter av fosfor samt ammoniumkväve. Halterna av nitrat samt nitrit är enbart höga i vissa av provpunkterna. Halterna av främst fosfor och ammoniumkväve kan enligt bedömningsgrunder ha övergödande effekt på ytvattendrag. En översiktlig undersökning baserad på grundvattnets strömningsriktning visar att kommunens vattenförekomster får ett tillskott av vatten via grundvattnet inom kommunen. Detta finns representerat i kvalitetsundersökningen av grundvattnet varpå slutsatsen dras att ytvattenförekomsterna inom kommunen påverkas negativt av grundvattnet. 

  • 14. Bulbul, A.
    et al.
    Bhattacharya, Prosun
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljögeokemi och ekoteknik.
    Huq, S.M.I.
    Gunaratna, K.R.
    Arsenic uptake by fresh water green alga, Chlamydomonas2008Ingår i: Groundwater for Sustainable Development: Problems, Perspectives and Challenges / [ed] Bhattacharya, P., Ramanathan, AL., Mukherjee A.B., Bundschuh, J., Chandrasekharam, D. Keshari, A.K., The Netherlands: Taylor and Francis/A. A. Balkema , 2008, s. 389-396Kapitel i bok, del av antologi (Refereegranskat)
  • 15.
    Bundschuh, Jochen
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630).
    Bhattacharya, ProsunKTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Miljögeokemi och ekoteknik.Chandrashekharam, D.
    Natural Arsenic in Groundwater: Occurrence, Remediation and Management2005Samlingsverk (redaktörskap) (Refereegranskat)
  • 16.
    Bundschuh, Jochen
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Bhattacharya, Prosun
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljögeokemi och ekoteknik.
    von Brömssen, Mattias
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljögeokemi och ekoteknik.
    Jakariya, Md
    Jacks, Gunnar
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljögeokemi och ekoteknik.
    Thunvik, Roger
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljöbedömning och -förvaltning.
    Litter, M.I.
    Garcia, M.E.
    Arsenic-safe aquifers as a socially acceptable source of safe drinking water: What can rural Latin America learn from Bangladesh experiences?2009Ingår i: Natural Arsenic in Groundwater of Latin America: Occurrence, health impact and remediation, The Netherlands: CRC Press/Balkema , 2009, s. 677-685Kapitel i bok, del av antologi (Refereegranskat)
  • 17. Bäckstrom, M.
    et al.
    Karlsson, S.
    Bäckman, L.
    Folkeson, Lennart
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljöbedömning och -förvaltning.
    Lind, B.
    Mobilisation of heavy metals by deicing salts in a roadside environment2004Ingår i: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 38, nr 3, s. 720-732Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The seasonal variations of some selected heavy metals (Cd, Cu, Pb and Zn) and principal anions in soil solutions were monitored as a function of distance from the road at two field sites in Sweden. During the winter, the conductivity, concentrations of dissolved sodium and chloride increased dramatically due to the application of deicing agents (i.e. NaCl). Due to ion exchange, the pH decreased one unit in the soil solutions, whereas the concentrations of total organic carbon decreased due to coagulation and/or sorption to stationary solids. The heavy metal concentrations increased during the winter, but through different mechanisms. Cadmium concentrations in the aqueous phase increased as a response to ion exchange, possibly also enhanced by the formation of chloride complexes. Similarly, the concentrations of zinc increased, due to ion exchange, with calcium and protons. The mechanisms of mobilisation for copper and lead were not that clear probably due to association with coagulated or sorbed organic matter in combination with colloid dispersion.

  • 18.
    Campagne, Antoine
    et al.
    LEGI, Université Grenoble Alpes.
    Alfredsson, Henrik
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Chassagne, Rémi
    LEGI, Université Grenoble Alpes.
    Micard, Diane
    LMFA, École Centrale de Lyon.
    Mordant, Nicolas
    LEGI, Université Grenoble Alpes.
    Segalini, Antonio
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Sommeria, Joel
    LEGI, Université Grenoble Alpes.
    Viboud, Samuel
    LEGI, Université Grenoble Alpes.
    Mohanan, Ashwin Vishnu
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Lindborg, Erik
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Augier, Pierre
    LEGI, Université Grenoble Alpes.
    First report of the MILESTONE experiment: strongly stratified turbulence and mixing efficiency in the Coriolis platform2016Ingår i: VIIIth International Symposium on Stratified Flows (ISSF), 2016, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    Strongly stratified turbulence is a possible interpretation of oceanic and atmospheric mea-surements. However, this regime has never been produced in a laboratory experiment be-cause of the two conditions of very small horizontal Froude number Fh and large buoyancy Reynolds number R which require a verily large experimental facility. We present a new attempt to study strongly stratified turbulence experimentally in the Coriolis platform.The flow is forced by a slow periodic movement of an array of six vertical cylinders of 25 cm diameter with a mesh of 75 cm. Five cameras are used for 3D-2C scanned horizontalparticles image velocimetry (PIV) and stereo 2D vertical PIV. Five density-temperatureprobes are used to measure vertical and horizontal profiles and signals at fixed positions.The first preliminary results indicate that we manage to produce strongly stratified tur-bulence at very small Fh and large R in a laboratory experiment.

  • 19.
    Campana, Pietro Elia
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Energiprocesser.
    Zhang, J.
    Univ Maryland, Dept Geog Sci, College Pk, MD 20742 USA..
    Yao, T.
    Sci Syst & Applicat Inc SSAI, Lanham, MD 20706 USA.;NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Andersson, S.
    Swedish Meteorol & Hydrol Inst, SE-60176 Norrkoping, Sweden..
    Landelius, T.
    Swedish Meteorol & Hydrol Inst, SE-60176 Norrkoping, Sweden..
    Melton, F.
    NASA ARC CREST, Moffett Field, CA 94035 USA.;Calif State Univ Monterey Bay, Sch Nat Sci, Seaside, CA 93955 USA..
    Yan, Jerry
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Energiprocesser. Malardalen Univ, Future Energy Ctr, Sch Business Soc & Engn, SE-72123 Vasteras, Sweden.;KTH Royal Inst Technol, Dept Chem Engn, SE-10044 Stockholm, Sweden..
    Managing agricultural drought in Sweden using a novel spatially-explicit model from the perspective of water-food-energy nexus2018Ingår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 197, s. 1382-1393Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Using a multi-disciplinary approach, this paper integrated spatial analysis with agricultural and energy system modelling to assess the impacts of drought on crop water demand, water availability, crop yield, and electricity requirements for irrigation. This was done by a novel spatially-explicit and integrated water-food-energy nexus model, using the spatial climatic data generated by the mesoscale MESAN and STRANG models. In this study, the model was applied to quantify the effects of drought on the Swedish irrigation sector in 2013, a typical drought year, for a specific crop. The results show that drought can severely affect the crop yield if irrigation is not applied, with a peak yield reduction of 18 t/ha, about 50 % loss as compared to the potential yield in irrigated conditions. Accordingly, the water and energy requirements for irrigation to halt the negative drought effects and maintain high yields are significant, with the peaks up to 350 mm and 700 kWh per hectare. The developed model can be used to provide near real-time guidelines for a comprehensive drought management system. The model also has significant potentials for applications in precision agriculture, especially using high-resolution satellite data.

  • 20.
    Carstens, Christoffer
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Vattenvårdsteknik.
    In the Pipe or End of Pipe?: Transport and Dispersion of Water-borne Pollutants and Feasibility of Abatement Measures2012Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Eutrophication is one of the key environmental problems of today, both in terms of complexity and magnitude. For the Baltic Sea (BS), eutrophication is an acute problem, leading to hypoxic conditions at the bottom; a situation that is sustained and amplified, when phosphorus is released from hypoxic sediments. Reducing nutrient loading is a top political priority but the present situation is believed to require active measures within the catchments and recipients to reduce both loading and adverse effects. Implementation of effective and cost-efficient abatement methods requires understanding of natural processes in watersheds, streams and recipients as well as technological expertise in order to compare the effects of measures of different kinds and locations. This thesis tries to combine process understanding of catchment transport behaviour, especially in coastal zones, and feasibility of certain technologies for reducing nutrient loading and effects of eutrophication in-situ. The over-arching theme is the fate of the individual contaminant, from injection to removal. Transport and dispersion in catchments are investigated, combining physically-based, distributed, numerical groundwater models with Lagrangian stochastic advective reactive solute (LaSAR) transport modelling. The approach is powerful in the sense that it incorporates catchment structural, geomorphological dispersion in the numerical model with hydrodynamic and sub-scale dispersion as well as uncertainty in the LaSAR framework. The study exemplifies the complex nature of transport time distributions in catchments in general and when varying source size and location, importance of dispersion parameters and retention due to molecular diffusion. It is shown that geomorphological control on dispersion is present even for relatively heterogeneous systems and that neither the mean residence time nor a statistical distribution may provide accurate representations of hydrological systems. To combat internal loading of P from sediments in-situ, large-scale aeration of deep waters, halocline ventilation, has been suggested. This study further investigates the feasibility of wave-powered devices to meet the energy demands for such an operation. It is shown that the required amount of oxygen needed to keep the sediments at oxic conditions could be provided, cheaply and efficiently, through the use of wave power.

  • 21.
    Cheemakurthy, Harsha
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Zhang, Meng
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Garme, Karl
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Marina system.
    Burman, Magnus
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Ehlers, S.
    Germany.
    Franz Von Bock, R. U.
    Germany.
    Polach, x
    Germany.
    Statistical estimation of uncertainties associated with ship operations in fresh water ice2018Ingår i: Proceedings of the International Offshore and Polar Engineering Conference, International Society of Offshore and Polar Engineers , 2018, s. 1608-1615Konferensbidrag (Refereegranskat)
    Abstract [en]

    Operational Time Window (OTW) and its confidence level are important for vessels operating in ice covered waters. This can be evaluated by quantifying all contributing factors in terms of their influence along with respective associated uncertainties. For a case study involving a barge operating in Lake Mälaren, Sweden, five criteria are evaluated, and associated uncertainties are quantified using Variation Mode and Effect Analysis (VMEA) to give individual contribution towards overall uncertainty. Ship resistance due to ice and ice loads dominated over other criteria with highest contributions to uncertainty at 28% and 72% respectively.

  • 22.
    Chen, Yuanying
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik. Stockholm Univ, Dept Phys Geog, S-10691 Stockholm, Sweden..
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    Destouni, Georgia
    Stockholm Univ, Dept Phys Geog, S-10691 Stockholm, Sweden..
    Scenarios of Nutrient-Related Solute Loading and Transport Fate from Different Land Catchments and Coasts into the Baltic Sea2019Ingår i: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 11, nr 7, artikel-id 1407Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study uses controlled numerical experimentation to comparatively simulate and investigate solute transport and concentration responses and patterns in the Baltic Sea for various solute releases from the land through two different coastal cases. These cases are the Swedish Kalmar County coast and the Polish coast of the Vistula River outlet. For equivalent solute releases, the coastal flow conditions and their interactions with main marine currents determine the local coastal solute spreading, while the overall spreading over the Baltic Sea is similar for the two coastal cases, despite their large local differences. For nutrient-proportional solute release scenarios, the highly-populated Vistula catchment yields much greater total, but smaller per-capita nutrient impacts, in the Baltic Sea than the Kalmar County catchment. To be as low as from the Vistula catchment, the per-capita nutrient contribution from Kalmar County would have to be reduced much more than required on average per Swedish inhabitant by the Baltic Sea Action Plan. This highlights an unfairness issue in the per-capita distribution of nutrient load allowance among the Baltic countries, which needs to be considered and handled in further research and international efforts aimed to combat the Baltic Sea eutrophication.

  • 23.
    Coello-Balthasar, Zairis
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Miljöbedömning och -förvaltning.
    Phumpiu, Patricia
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Vattenförvaltning.
    Balfors, Berit
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Miljöbedömning och -förvaltning.
    Gustafsson, Jan-Erik
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Vattenförvaltning.
    Assessment of causes leading to an insufficient water supply in Tegucigalpa, Honduras2011Ingår i: WIT Transactions on Ecology and the Environment, ISSN 1743-3541, Vol. 145, s. 27-38Artikel i tidskrift (Refereegranskat)
  • 24.
    Cucarella Cabañas, Victor
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Phosphorus recycling from wastewater to agriculture using reactive filter media2007Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis focused on testing the suitability of reactive filter media used for phosphorus (P) removal from wastewater as fertilizers, thus recycling P to agriculture. The work compared the P sorption capacity of several materials in order to assess their suitability as a source of P for plants. The selected materials (Filtra P, Polonite and wollastonite) were saturated with P and used as soil amendments in a pot experiment. The amendments tended to improve the yield of barley and ryegrass compared with no P addition. The amendments also increased soil pH, P availability and cation exchange capacity in the studied soils. The substrates studied here can be of particular interest for acid soils. Of the materials studied, Polonite appears to be the most suitable substrate for the recycling of P from wastewater to agriculture

  • 25.
    Cucarella, Victor
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Zaleski, Tomasz
    Department of Soil Science and Soil Protection, Agricultural University of Cracow, Poland.
    Mazurek, Ryszard
    Department of Soil Science and Soil Protection, Agricultural University of Cracow, Poland.
    Phosphorus sorption capacity of different types of opoka2007Ingår i: Annals of Warsaw University of Life Sciences – SGGW Land Reclamation, ISSN 1898-8857, Vol. 38, s. 11-18Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Phosphorus sorption capacity ofdifferent types of opoka. The bedrock opoka hasbeen lately reported as an appropriate reactivemedia for onsite wastewater treatment systemsdue to its high phosphorus (P) sorption capacity.However, variations on its chemical compositionmay affect its reactivity with P, therefore leadingto a variable P removal effi ciency. In this paper,the P-sorption capacity of three different typesof opoka from the region of Miechów, Poland,is reported. According to the silica and carbonatecontent, opoka samples were classifi ed as light--weight and heavy-weight opoka. When heatedover 900°C, opoka showed a very high P-sorptioncapacity that was well correlated to its Ca content.P-sorption isotherms from batch experiments withan artifi cial P solution were plotted and fi tted tothe Langmuir and Freundlich adsorption models.The Freundlich isotherm appeared to model betterthe P-sorption of light opoka and the Langmuirisotherm of heavy opoka, suggesting differentdominating mechanisms of P-sorption by lightand heavy opoka.

  • 26.
    Cucarella, Victor
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Zaleski, Tomasz
    Department of Soil Science and Soil Protection, Agricultural University of Cracow.
    Mazurek, Ryszard
    Department of Soil Science and Soil Protection, Agricultural University of Cracow.
    Renman, Gunno
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Effect of reactive substrates used for phosphorus removal from wastewater on the feritlity of acid soils2008Ingår i: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 99, nr 10, s. 4308-4314Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Reactive substrates used in filter systems can reduce phosphorus (P) pollution and, once saturated with P, may be recycled in agriculture. These substrates are usually calcium carbonate derivates with high pH values, which may be particularly beneficial for acid soils. Three reactive substrates (Filtra P, Polonite and wollastonite) saturated with P were used as amendments to an acid soil in a pot experiment. Substrate amendments tended to improve ryegrass yield and P uptake compared with control and potassium phosphate treatments. Polonite produced the highest yield/amendment ratio, while Polonite and Filtra P significantly increased the concentrations of P and Ca in the ryegrass. Addition of all three substrates increased the pH, AL-extractable P and cation exchange capacity of soils during the experiment. These substrates can therefore be applied to acid soils in order to recycle P and improve soil properties.

  • 27.
    Cvetkovic, Vladimir
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Vattenvårdsteknik.
    Carstens, Christoffer
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Vattenvårdsteknik.
    Selroos, Jan-Olof
    Destouni, Georgia
    Water and solute transport along hydrological pathways2012Ingår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 48, nr 6, s. W06537-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A Lagrangian framework for material transport along hydrological pathways is presented and consequences of statistically stationary space-time flow velocity variations on advective transport are investigated. The two specific questions addressed in this work are: How do temporal fluctuations affect forward and backward water travel time distributions when combined with spatial variability? and Can mass transfer processes be quantified using conditional probabilities in spatially and temporally variable flow? Space-time trajectories are studied for generic conditions of flow, with fully ergodic or only spatially ergodic velocity. It is shown that forward and backward distributions of advective water travel time coincide for statistically stationary space-time variations. Temporal variability alters the statistical structure of the Lagrangian velocity fluctuations. Once this is accounted for, integration of the memory function with the travel time distribution is applicable for quantifying retention. Further work is needed to better understand the statistical structure of space-time velocity variability in hydrological transport, as well as its impact on tracer retention and attenuation.

  • 28.
    Cvetkovic, Vladimir
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Fiori, A.
    Dagan, G.
    Tracer travel and residence time distributions in highly heterogeneous aquifers: Coupled effect of flow variability and mass transfer2016Ingår i: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The driving mechanism of tracer transport in aquifers is groundwater flow which is controlled by the heterogeneity of hydraulic properties. We show how hydrodynamics and mass transfer are coupled in a general analytical manner to derive a physically-based (or process-based) residence time distribution for a given integral scale of the hydraulic conductivity; the result can be applied for a broad class of linear mass transfer processes. The derived tracer residence time distribution is a transfer function with parameters to be inferred from combined field and laboratory measurements. It is scalable relative to the correlation length and applicable for an arbitrary statistical distribution of the hydraulic conductivity. Based on the derived residence time distribution, the coefficient of variation and skewness of residence time are illustrated assuming a log-normal hydraulic conductivity field and first-order mass transfer. We show that for a low Damkohler number the coefficient of variation is more strongly influenced by mass transfer than by heterogeneity, whereas skewness is more strongly influenced by heterogeneity.

  • 29. Dagan, G.
    et al.
    Fiori, A.
    Jankovic, I.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630).
    Tailing of the breakthrough curve in aquifer contaminant transport: The impact of permeability spatial variability2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    A contaminant plume of mass Mo is inserted at time t = 0 at an injection plane at × = 0 in an aquifer of spatially variable conductivity K. The log-conductivity Y = InK is modelled as stationary and isotropic, of univariate distribution f(Y), and of finite integral scale I. The flow of water is uniform in the mean (natural gradient) and the plume is of large transverse extent relative to the integral scale. Advective transport and longitudinal spread are quantified by the solute mass arrival ("breakthrough curve", BTC) M(t,x) at a control plane at × &gt; I. For a large plume (ergodic conditions) the relative mass flux μ(t,x) = (l/Mo)M/t is approximately equal to the probability density function of travel times of solute particles f(τx) and the latter is used to analyse transport. f(τx) is derived by adopting a structural model of the aquifer that contains spherical or cubic inclusions of uniform size and of independent Y that fill the space. Such a structure can represent any formation of given f(Y) and I. The flow and transport solutions are obtained by a simple semianalytical model and by accurate numerical simulations. The travel time distribution at few control planes is determined for a log-normal f(K) first. Under the assumption of weak heterogeneity, i.e. for small variance σy 2 and for x»I, the travel time distribution is symmetrical and Gaussian. Subsequently, by using the semi-analytical model and numerical simulations we derive f(τx) for a highly heterogeneous formation of σ y 2 = 2. The main finding is f(τx) is highly skewed due to the presence of a thin, but long tail, for large travel times. The tail is of significance to applications that deal with aquifer pollution and remediation. The tail is related to the large residence time of solute particles in blocks of low conductivity. A simple relationship is established between the tail of f(Y) for low K and that f(τx) for large τ. To further examine the impact of the log-conductivity distribution on BTC tailing, a non-Gaussian model, the subordinate model, is adopted for f(Y). This distribution depends on an additional parameter Is; travel time distribution tends to normal for Is→0, whereas the tails of the two distributions are different for Is &gt; 0. This choice reflects the difficulty of identification of the tail of f(Y) based on field data. The relevance of results to applications is examined in terms of impact of conductivity spatial distribution, as well as influence of plume size (non-ergodic behaviour) and diffusion.

  • 30.
    Darracq, Amélie
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630).
    Greffe, Fanny
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630).
    Hannerz, Fredrik
    Destouni, G.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Vattenvårdsteknik.
    Nutrient transport scenarios in a changing Stockholm and Mälaren valley region, Sweden2005Ingår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 51, nr 3-4, s. 31-38Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Norrstrom catchment, west of Stockholm, covers most of the Malaren valley. Provision of drinking water from Lake Malaren is an absolute precondition for continued growth in the region. Stockholm County's population is expected to increase by 600,000 people before 2030. Current climate change predictions anticipate significant temperature and precipitation increases. We implement the PolFlow model embedded in PCRaster for quantifying water and substances fluxes on the catchment scale over a 30-year time horizon. We formulate scenarios for changes in water quality and quantity due to climate change and population development. Results indicate a mild impact from climate change on surface flow rates but substantial effects on sub-surface residence times. Population development slightly affects nutrients loads. Using source apportionment and sensitivity analysis, we identify a number of critical parameters/processes to be further studied, in order for future results to be more reliable and usable in a water resources management context.

  • 31. Davy, P.
    et al.
    Darcel, C.
    Le Goc, R.
    Munier, R.
    Selroos, J. O.
    Ivars, Diego Mas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Jord- och bergmekanik.
    DFN, why, how and what for, concepts, theories and issues2018Ingår i: 2nd International Discrete Fracture Network Engineering Conference, DFNE 2018, American Rock Mechanics Association (ARMA), 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    DFN – Discrete Fracture Network – is primarily a modeling framework for fractured geological systems that aims to integrate field data into simulations of flow and/or deformation. It is complementary to, or competing with, continuum methods with both advantages of easily integrating the statistical properties of fracture networks, and of not assuming any homogenization scale. The core element is the DFN conceptual model, which makes a functional link between data from different sources, prior knowledge and medium models. We discuss some fundamental issues about this conceptual model, namely (i) the upscaling of small-scale measurements to site-scale relationships, (ii) intrinsic variability versus geological determinism, (iii) the way to incorporate a priori knowledge, (iv) the transformation of a statistical description into a medium model, (v) the critical characteristics (length scales, scaling laws or physical properties) of fractures for a given DFN application. The main product of the DFN conceptual model is medium models, whose role is to extrapolate/interpolate data with a faithful representation of the geological system. The way in which fracture correlations are taken into account, or not, in the generation process plays an important control on the connectivity and flow properties of medium models.

  • 32. de Barros, F. P. J.
    et al.
    Bellin, A.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Dagan, G.
    Fiori, A.
    Aquifer heterogeneity controls on adverse human health effects and the concept of the hazard attenuation factor2016Ingår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 52, nr 8, s. 5911-5922Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We analyze the probability distribution of the hazard attenuation factor for a noncarcinogenic reactive compound captured by a well in heterogeneous porous formations. The hazard attenuation factor is defined as the ratio between the hazard index HI at a detection well and at the source. Heterogeneity of the aquifer is represented through the multi-indicator model (a collection of blocks of independent permeability) while flow and transport are solved by the means of the self-consistent approach that is able to deal with any degree of heterogeneity. Due to formation heterogeneity, HI is a random variable and similar for hazard attenuation index. The latter can be fully characterized by its cumulative distribution function (CDF), which in turn can be related to the statistics of the travel time of solute particles, from the source to the detection well. The approach is applied to the case of a solute which undergoes decay and a well with a screen much smaller than the correlation scale of hydraulic conductivity. The results show that the probability of exceeding a given acceptable threshold of the hazard index is significantly affected by the level of heterogeneity comparable to the one observed for the MADE site, and the distance between the source and the well.

  • 33.
    de Strasser, Lucia
    et al.
    KTH.
    Lipponen, Annukka
    Howells, Mark
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Energisystemanalys.
    Stec, Stephen
    Brethaut, Christian
    A Methodology to Assess the Water Energy Food Ecosystems Nexus in Transboundary River Basins2016Ingår i: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 8, nr 2Artikel i tidskrift (Refereegranskat)
  • 34.
    Dehkordi, Seyed Emad
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik. University of Western Ontario, Canada.
    Olofsson, Bo
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Schincariol, Robert A.
    Effect of groundwater flow in vertical and horizontal fractures on borehole heat exchanger temperatures2015Ingår i: Bulletin of Engineering Geology and the Environment, ISSN 1435-9529, E-ISSN 1435-9537, Vol. 74, nr 2, s. 479-491Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Vertical closed loop systems, also known as borehole heat exchangers (BHEs), are a popular way of extracting the ground source heat energy. Primary factors affecting the performance of BHEs are the thermal and hydrogeological properties of the subsurface. Groundwater flow is known to potentially influence heat transport and system performance. The effect of groundwater movement is more commonly studied under homogeneous conditions. However, in heterogeneous fractured rocks, BHEs are more common than horizontal or open loops due to lack of sufficient soil layers and productive aquifers. The finite-element modelling shows that fractures can play an important role in BHE functioning. Especially, vertical open fractures (≥1 mm) near the borehole (≤10 m) can have a considerable impact. Although increase in fracture aperture continuously affects the subsurface and BHE temperatures, the increase in its effect progressively lessens. Depending on the distance and aperture, one major fracture influencing the BHE operation performance can be identified; yet a larger number of fractures may govern heat transport (thermal plume outline) and thermal recovery. Individually, horizontal fractures may have less influence than vertical fractures. However, as the density of horizontal fractures increases, their impact can be major, exceeding that of fracture aperture. In particular, we propose that measurements of rock thermal properties be combined with fracture mapping, to better analyse the thermal response testing results and integrate the configuration of fractures in design and layout of the BHE(s). This is particularly valid for (vertical) fractures not intersecting with the borehole.

  • 35.
    Dehkordi, Seyed Emad
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Schincariol, Robert A.
    Olofsson, Bo
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Impact of Groundwater Flow and Energy Load on Multiple Borehole Heat Exchangers2014Ingår i: Ground Water, ISSN 0017-467X, E-ISSN 1745-6584Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of array configuration, that is, number, layout, and spacing, on the performance of multiple borehole heat exchangers (BHEs) is generally known under the assumption of fully conductive transport. The effect of groundwater flow on BHE performance is also well established, but most commonly for single BHEs. In multiple-BHE systems the effect of groundwater advection can be more complicated due to the induced thermal interference between the boreholes. To ascertain the influence of groundwater flow and borehole arrangement, this study investigates single- and multi-BHE systems of various configurations. Moreover, the influence of energy load balance is also examined. The results from corresponding cases with and without groundwater flow as well as balanced and unbalanced energy loads are cross-compared. The groundwater flux value, 10−7 m/s, is chosen based on the findings of previous studies on groundwater flow interaction with BHEs and thermal response tests. It is observed that multi-BHE systems with balanced loads are less sensitive to array configuration attributes and groundwater flow, in the long-term. Conversely, multi-BHE systems with unbalanced loads are influenced by borehole array configuration as well as groundwater flow; these effects become more pronounced with time, unlike when the load is balanced. Groundwater flow has more influence on stabilizing loop temperatures, compared to array characteristics. Although borehole thermal energy storage (BTES) systems have a balanced energy load function, preliminary investigation on their efficiency shows a negative impact by groundwater which is due to their dependency on high temperature gradients between the boreholes and surroundings.

  • 36.
    Earon, Robert
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Dehkordi, Seyed Emad
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Olofsson, Bo
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Groundwater Resources Potential in Hard Rock Terrain: A Multivariate Approach2014Ingår i: Ground Water, ISSN 0017-467X, E-ISSN 1745-6584Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Groundwater resources are limited and difficult to predict in crystalline bedrock due to heterogeneity and anisotropy in rock fracture systems. Municipal-level governments often lack the resources for traditional hydrogeological tests when planning for sustainable use of water resources. A new methodology for assessing groundwater resources potential (GRP) based on geological and topographical factors using principal component analysis (PCA) and analysis of variance (ANOVA) was developed and tested. ANOVA results demonstrated statistically significant differences in classed variable groups as well as in classed GRP scores with regard to hydrogeological indicators, such as specific capacity (SC) and transmissivity. Results of PCA were used to govern the weight of the variables used in the prediction maps. GRP scores were able to identify 79% of wells in a verification dataset, which had SC values less than the total dataset median. GRP values showed statistically significant correlations using both parametric (using transformed datasets) and non-parametric methods. The method shows promise for municipal or regional level planning in crystalline terrains with high levels of heterogeneity and anisotropy as a hydrogeologically and statistically based tool to assist in assessing groundwater resources. The methodology is executed in a geographic information systems environment, and uses often readily available data, such as geological maps, feature maps and topography, and thus does not require expensive and time-consuming aquifer tests.

  • 37. Engqvist, A
    et al.
    Stenstrom, Petter
    KTH, Tidigare Institutioner, Mark- och vattenteknik.
    Archipelago strait exchange processes - an overview2004Ingår i: Deep-sea research. Part II, Topical studies in oceanography, ISSN 0967-0645, E-ISSN 1879-0100, Vol. 51, nr 4-5, s. 371-392Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Archipelagos consist of a set of islands forming a collection of basins interconnected by straits, and are typically characterized by widely varying spatial and temporal scales regarding geometry and forcing conditions. Focusing on the strait exchange parameterization, we describe an archipelago water exchange model in which the archipelago is subdivided into a network of discrete basins and interconnecting straits and where the time integration assumes a series of quasi-steady states. We propose an algorithm that should be sufficiently flexible to provide reasonable strait exchange estimates under the variety of forcing conditions encountered in the Stockholm archipelago. We start from the functional formulation of two-layer hydraulic theory, which allows numerical schemes to be designed that, given the forcing conditions at the ends of a given strait, distinguish between maximal and sub-maximal flow cases and solve the flow accordingly. We relax the assumption of two homogeneous layers when necessary, using an approximate method based on a self-similarity assumption and with the sea-level difference over the strait as an explicit part of the problem. This method allows exchange flows with two groups of layers to be solved for the same set of geometries that the pure two-layer theory can handle, including sill-contraction combinations and non-rectangular cross-sections. We further show how aspiration of dense water from below the sill crest can be quantified with hydraulic theory, and be included in the method for stratified strait exchange. Rotational control in wide straits and in parallel straits connecting the same two basins is treated with a simple but robust scheme. We evaluate the calculations with data from the Oxdjupet strait in the Stockholm archipelago. Simulations with a three-dimensional, non-hydrostatic numerical model are performed to compensate for sparsity in data.

  • 38. Engqvist, Anders
    et al.
    Stenström, Petter
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Flow regimes and long-term water exchange of the Himmerfjarden estuary2009Ingår i: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 83, nr 2, s. 159-174Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A numerical model of processes determining the water exchange encountered in Baltic coastal archipelagos is calibrated and validated against salinity and temperature field data spanning two decades with approximately bi-weekly resolution assessed in the Himmerfjärden estuary. This area is resolved into 17 basins interconnected by 38 individual straits of varying geometrical properties using GIS-based methods. All formulations of the strait exchange flows are free from parameters that need calibration and permit computations of the flow through a strait contraction with or without a coincident sill under a flow classification scheme, of which the first one (a) consists of two groups of multiple layers including aspirated layers from levels beneath the sill crest. The other regimes are as follows. (b) Pure barotropic flow; (c) rotationally controlled flow and (d) plug-flow, which serves as resort solution for flow situations that cannot be solved with (a) and also for computation of the barotropic part of the total flow. For long canals where friction effects act to reduce the flow, a fifth exchange regime is used. The vertical mixing formulation is based on energy balances between supplied wind energy and its work against buoyancy forces. The values of semi-empirical parameters involved in the mixing scheme have been established by calibration against measured data of the first decade period. A statistical evaluation is performed comparing the model results with the measurements of the second decade. It is found that the accuracy of the model is yet limited by the poor temporal resolution in the boundary and the thermal forcing. The overall accuracy of this approach is found to be comparable to earlier model studies in the same area. Since the exchange flows are now based on first principles and are applied to four times more basins, it seems that this more articulated model approach can confidently be applied to more complex archipelago areas.

  • 39.
    Ezhova, Ekaterina
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Centra, SeRC - Swedish e-Science Research Centre.
    Cenedese, Claudia
    Brandt, Luca
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Centra, SeRC - Swedish e-Science Research Centre.
    Interaction between a Vertical Turbulent Jet and a Thermocline2016Ingår i: Journal of Physical Oceanography, ISSN 0022-3670, E-ISSN 1520-0485, Vol. 46, nr 11, s. 3415-3437Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The behavior of an axisymmetric vertical turbulent jet in an unconfined stratified environment is studied by means of well-resolved, large-eddy simulations. The stratification is two uniform layers separated by a thermocline. This study considers two cases: when the thermocline thickness is small and on the order of the jet diameter at the thermocline entrance. The Froude number of the jet at the thermocline varies from 0.6 to 1.9, corresponding to the class of weak fountains. The mean jet penetration, stratified turbulent entrainment, jet oscillations, and the generation of internal waves are examined. The mean jet penetration is predicted well by a simple model based on the conservation of the source energy in the thermocline. The entrainment coefficient for the thin thermocline is consistent with the theoretical model for a two-layer stratification with a sharp interface, while for the thick thermocline entrainment is larger at low Froude numbers. The data reveal the presence of a secondary horizontal flow in the upper part of the thick thermocline, resulting in the entrainment of fluid from the thermocline rather than from the upper stratification layer. The spectra of the jet oscillations in the thermocline display two peaks, at the same frequencies for both stratifications at fixed Froude number. For the thick thermocline, internal waves are generated only at the lower frequency, since the higher peak exceeds the maximal buoyancy frequency. For the thin thermocline, conversely, the spectra of the internal waves show the two peaks at low Froude numbers, whereas only one peak at the lower frequency is observed at higher Froude numbers.

  • 40. Feiccabrino, James
    et al.
    Gustafsson, David
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Biogeofysik.
    Lundberg, Angela
    Surface-based precipitation phase determination methods in hydrological models2013Ingår i: Hydrology Research, ISSN 1998-9563, Vol. 44, nr 1, s. 44-57Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We compared solid and liquid precipitation mass output from three categories of common model precipitation phase determination schemes (PPDS) to the recorded precipitation phase in a set of 45 years of 3-hour manual meteorological observations from 19 Swedish meteorological stations. In the first category of rain/snow thresholds, it was found that rain/snow air temperature threshold (ATT) is a better precipitation phase indicator than a rain/snow dew point temperature threshold. When a rain/snow ATT of 0.0 degrees C (a default value used in some recent models) was replaced by 1.0 degrees C, misclassified precipitation was reduced by almost one half. A second category of PPDS use two ATTs, one snow and one rain, with a linear decrease in snow fraction between. This category identified precipitation phase better than a rain/snow ATT at 17 stations. Using all observations from all the meteorological stations, a final category using an air-temperature-dependent snow probability curve resulted in slightly lower misclassified precipitation mass at 13 of the 19 stations. However, schemes from the linear decrease in snow fraction category had the lowest misclassified precipitation mass at four meteorological stations.

  • 41. Feiccabrino, James
    et al.
    Lundberg, Angela
    Gustafsson, David
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Improving surface-based precipitation phase determination through air mass boundary identification2012Ingår i: Hydrology Research, ISSN 1998-9563, Vol. 43, nr 3, s. 179-191Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Most hydrological models apply one empirical formula based on surface air temperature for precipitation phase determination. This approach is flawed as surface precipitation phase results from energy exchanges between falling precipitation and air in the lower atmosphere. Different lower atmospheric conditions cause different precipitation phase probabilities for near-freezing temperatures. Often directly measured lower atmospheric conditions are not available for remote areas. However, meteorological observations occurring before/after similar air mass boundaries have similar atmospheric conditions that vary from most other observations. Therefore, hydrological models can indirectly account for lower atmospheric conditions. Twenty years of manual observations from eight United States weather stations were used to compare misclassified precipitation proportions when analyzing (a) all precipitation observations together and (b) identified cold air mass boundary observations (CAB) and non-CAB observations separately. The CAB observations were identified by a rapid surface air temperature decrease. A two-surface air temperature threshold method with one threshold all snow (T-S degrees C) and one all rain (T-R degrees C) having a linear snow fraction decrease between the thresholds was used. The T-S (0 degrees C), and T-R (4 degrees C) values for CAB were 1 degrees C warmer than for non-CAB (-1 degrees C, 3 degrees C). Analyzing CAB and non-CAB separately reduced misclassified precipitation 23%, from 7.0 to 5.4%.

  • 42. Fiori, A.
    et al.
    Bellin, A.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik.
    de Barros, F. P. J.
    Dagan, G.
    Stochastic modeling of solute transport in aquifers: From heterogeneity characterization to risk analysis2015Ingår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 51, nr 8, s. 6622-6648Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The article presents a few recent developments advanced by the authors in a few key areas of stochastic modeling of solute transport in heterogeneous aquifers. First, a brief review of the Lagrangian approach to modeling plumes longitudinal mass distribution and temporal (the breakthrough curve) mass arrival, is presented. Subsequently, transport in highly heterogeneous aquifers is analyzed by using a recently developed predictive model. It relates the non-Gaussian BTC to the permeability univariate pdf and integral scale, with application to the MADE field observations. Next, the approach is extended to transport of reactive solute, combinnig the effects of the random velocity field and multirate mass transfer on the BTC, with application to mass attenuation. The following topic is modeling of the local concentration field as affected by mixing and dilution due to pore scale dispersion. The results are applied to the analysis of concentration measurements at the Cape Cod field experiment. The last section incorporates the results of the preceding ones in health risk assessment by analyzing the impact of concentration prediction on risk uncertainty. It is illustrated by assessing the effect of identification of macrodispersivity from field characterization and transport modeling, upon the probability of health risk.

  • 43. Fiori, A.
    et al.
    Dagan, G.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630).
    Jankovic, I.
    Tailing of the breakthrough curve in aquifer contaminant transport: Equivalent longitudinal macrodispersivity and occurrence of anomalous transport2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    We analyse the mass arrival (breakthrough curve) at control planes at × of a plume of conservative solute injected at time t = 0 in the plane × = 0. The formation is of random three-dimensional stationary and isotropic conductivity K, characterized by the univariate normal distribution f(Y), Y = lnK, and the integral scale I. The flow is uniform in the mean, of velocity U, and longitudinal transport is quantified by f(z,x), the probability density function (pdf) of travel time r at x. We characterize transport by an equivalent longitudinal macrodispersivity αL(x), which is proportional to the variance of the travel time. If αL is constant, transport is coined as Fickian, while it is anomalous if αL increases indefinitely with x. If f(z,x) is normal (for × I), transport is coined as Gaussian and the mean concentration satisfies an ADE with constant coefficients. For the subordinate structural model transport is anomalous, in spite of the closeness of the conductivity distribution to the lognormal one. To further analyse anomalous behaviour, a relationship is established between the shape of f(K) for K→0 and the behaviour of αL, arriving at criteria for normal or anomalous transport. The model is used in order to compare results with the recent ones presented in the literature, which are based on the Continuous Time Random Walk (CTRW) approach. It is found that a class of anomalous transport cases proposed by CTRW methodology cannot be supported by a conductivity structure of finite integral scale.

  • 44. Follin, Sven
    et al.
    Stigsson, Martin
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    A transmissivity model for deformation zones in fractured crystalline rock and its possible correlation to in situ stress at the proposed high-level nuclear waste repository site at Forsmark, Sweden2014Ingår i: Hydrogeology Journal, ISSN 1431-2174, E-ISSN 1435-0157, Vol. 22, nr 2, s. 299-311Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Forsmark site was recently proposed by the Svensk Karnbranslehantering AB (SKB) to serve as the potential site for construction of a future geological repository for spent high-level nuclear fuel at about 470 m depth in fractured crystalline rock. The considerations included, among other things, distance from regionally significant deformation zones with highly strained rock, lithological homogeneity, low hydraulic conductivity, groundwater salinity with an acceptable range, and lack of potential mineral resources. This report describes the calculation of transmissivity of deduced deformation zones at Forsmark and the transmissivity model used in the regional groundwater flow modeling carried out in support of the integrated site description. Besides significant decrease with increasing depth (more than four orders of magnitude over a depth of about 1 km), the calculated transmissivity values also reveal considerable spatial variability along the strikes of the zones, i.e. lateral heterogeneity (more than two orders of magnitude). A hydro-mechanical coupling is discussed, based on presented models for the tectonic evolution and the principal stress tensor. Tentatively, laboratory-scale relationships developed from normal stress experiments on a single fracture in crystalline rock can be used to estimate the maximum values of transmissivity of deduced deformation zones at Forsmark.

  • 45.
    Frampton, Andrew
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Stochastic analysis of fluid flow and tracer pathways in crystalline fracture networks2010Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Miljökonsekvensbedömningar av toxiskt avfall i djupt bergförvar kräver engrundläggande förståelse av grundvattenströmning samt hur detta påverkartransportfenomet. Därför är det viktigt att kunna integrerafältundersökningsdata från berggrundsmätningar med metoder som kan användas föratt utvärdera och förutsäga potentiella konsekvenser på omgivningen.I denna avhandling undersöker jag flödes- och transportegenskaper i diskretaspricknätverk genom stokastisk analys av eulerska och lagrangeskafältbeskrivningar. Analysen sker genom en kombination av dels numeriska flödes-och transportsimuleringar som är konfigurerade enligt tillgänglig fältdata, samtdels med oberoende teoretiska analytiska och semi-analytiska metoder som gerdjupare insyn i relevanta konstitutiva egenskaper. Resultat visar att dennumeriska simuleringsmetoden för diskreta spricknätverk kan både konditionerastill fältdata och bestyrkas gentemot mätbara kvantiter. Detta är av betydelse dåde teoretiska metoderna i sin tur är främst evaluerade gentemotsimuleringsresultat. Därmed utvecklas en bestyrkt metodik som kansammanlänka och i viss mån omvandla fältdata till uppskattningar av mängdenspårämnen i ett utflöde. Resultat indikerar att denna metodik är robust avseendeflera antaganden som har används i simuleringskonfigurationen.En särskild urvalsalgoritm introduceras som kan erhålla en lagrangesktransportbeskrivning utifrån ett eulerskt strömningsfält. även denna utvärderasavseende vissa simuleringsantaganden och resultat tyder på att den är robust förde undersökta fallen. Vidare föreslås en viss generalisering av lösningen tillden advektiva-dispersionsekvationen samt av ensidigt stabila (one-sided stable)sannolikhetsfördelningar som metod för att prediktera advektiva kvantitetergenom upskalning av transportfördelningar i rummet. Denna modell kombineras meden tidigare utvecklad metod för transportretention för att uppskatta reaktivagenombrottsfördelningar. Således blir det möjligt att prediktera reaktivtransport d v s rumslig upskalning av genombrottstider för spårämnestransport.Metoden används också för att evaluera ett linärt dispersionsantagande, därresultat indikerar att även advektiv transport kan påvisa icke-linärt beteende.Transport i spricknätverk utvärderas bland annat för modellantaganden avseendeinjektionsmetod, heterogenitet i spricknätverk, konstitutiva relationer mellanapertur och transmissivitet samt mellan transmissivitet och spricklängd, ochmodelleringsskala samt dimension. Beträffande hydrauliska testmetoder ochflödesanalys introduceras en simuleringsmetod för att konditioneraspricktransmissivitet från flödesmätningar. Detta jämförs med etthomogeniseringsantaganden som inte sällan används i fältundersökningar för atttolka flödesmätningar till spricktransmissivitet, och resultat tyder på attdetta antagande kan betydligt undervärdera transmissivitet.

  • 46.
    Frampton, Andrew
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Numerical and analytical modelling of advective travel times in realistic three-dimensional fracture networks2011Ingår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 47, nr W02506, s. 16pp-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Travel time distributions obtained from advective transport in multiple realisations of realistic discrete fracture network simulations are analysed using the truncated one-sided stable distribution, which has previously been shown to generalise both the advection-dispersion solution as well as one-sided stable distributions. Using this model it is shown that the Fickian assumption inherent in the advection-dispersion equation generally fails, despite that the first two moments of travel time essentially scale linearly with distance. It is also observed that the equally probable realisations drawn from the ensemble can produce a wide range of behaviour under the current configuration, such that Fickian conditions are almost obtained in some cases for increasing scales. Based on a small-scale calibration against particle breakthrough, the model is then shown to successfully predict limiting bounds of transport for a one order of magnitude increase in scale. Correlation in particle velocity is explicitly shown to be significant for scales close to the characteristic Lagrangian segment length. The network configuration is obtained from extensive site characterisation data at the Laxemar region in Sweden, and represents a block scale domain of reasonably sparse background fractures.

  • 47.
    Frampton, Andrew
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Significance of injection modes and heterogeneity on spatial and temporal dispersion of advecting particles in two-dimensional discrete fracture networks2009Ingår i: Advances in Water Resources, ISSN 0309-1708, E-ISSN 1872-9657, Vol. 32, nr 5, s. 649-658Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigate the impact of injection mode (flux and resident injection) and heterogeneity in hydraulic properties on dispersion of advecting particles in two-dimensional discrete fracture network models, using a Monte Carlo method. We find that the injection mode has a significant effect on dispersion: The resident injection mode exhibits anomalous features of transport whereas the flux injection mode tends to Gaussian transport; this observation is easily understood by considering phase diagrams where a limited number of particles entering low velocity fractures greatly increase macrodispersion. In spite of a sizeable portion of negative longitudinal velocities, it is shown that multiple crossings are negligible when quantifying longitudinal macrodispersion. A simple probabilistic expression of particle mass balance is shown to predict well the spatial distribution of advecting particles.

  • 48.
    Frampton, Andrew
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Upscaling particle transport in discrete fracture networks: 1. Nonreactive tracers2007Ingår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 43, nr 10, s. W10428-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study tracer transport through discrete fracture networks and develop a methodology for upscaling particle breakthrough curves on the basis of fracture segment data. Our prime interest is to model the early arrival and peak of tracer breakthrough curves, i.e., to capture the bulk of the tracer mass arrival. This study is based on two-dimensional discrete fracture network simulations, combined with a truncated one-sided stable distribution as a model for upscaling particle transitions. Results indicate that this model can accurately capture the bulk mass and peak of the breakthrough distributions for an upscaled distance of at least 1 order of magnitude in terms of transport scale, which for our simulations is about 2 orders of magnitude greater than the mean fracture segment scale. We also introduce an accurate mapping algorithm for transforming Eulerian into Lagrangian flow statistics, without a priori knowledge of network connectivity.

  • 49.
    Frampton, Andrew
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Cvetkovic, Vladimir
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Upscaling particle transport in discrete fracture networks:  2. Reactive tracers2007Ingår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 43, nr 10, s. W10429-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study sorbing tracer transport through discrete fracture networks using astochastic Lagrangian framework, combined with the methodology for upscalingparticle breakthrough curves developed in the first part of this article series.Results indicate that this procedure can accurately predict expected normalizedtracer discharge for an upscaled distance of 1 order of magnitude in terms oftransport scale, which for our simulations is about 2 orders of magnitudegreater than the mean fracture segment scale. Specifically, we show theimportance of retaining the correlation between the water residence time τ andthe hydrodynamic control of retention β in order to make accurate tracerdischarge predictions. Also, we show that the extreme tails of τ and β distributions have essentially no impact on tracer discharge. These results areillustrated using the unlimited diffusion model, and for two hypotheticaltracers with properties designed to capture the behavior of many commonlyoccurring natural radionuclides.

  • 50.
    Frampton, Andrew
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Vattenvårdsteknik.
    Vladimir, Cvetkovic
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Vattenvårdsteknik.
    Inference of field scale fracture transmissivities in crystalline rock using flow log measurements2010Ingår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 46, nr 11, s. W11502-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Characterization of transmissivity for crystalline rock is conducted through simulation by conditioning against borehole flow rates obtained from high-resolution, in situ field measurements during extraction pumping. Full three-dimensional discrete fracture network simulations are carried out according to specifications obtained from site characterization data in a stochastic Monte Carlo setting. A novel method of conditioning is thereby introduced and applied using nonparametric comparison tests, which provide quantifiable measures of accuracy enabling evaluation of simulated results against field measurements. The assumption of a constitutive relationship ( perfect correlation) between fracture size and transmissivity is adopted. The method is evaluated against both single and multiple realizations, various domain size, and fracture length configurations and shown to be robust for the cases considered. When the introduced method of conditioning is applied, transmissivity parameterization can be inferred to a narrow range with a quantifiable accuracy in terms of a probability value. Results indicate that elementary interpretation of transmissivity based on homogenization of a porous medium will generally underestimate transmissivity. Further implications on advective transport for natural flow conditions are briefly evaluated, indicating advective breakthrough times can be overestimated up to a factor of about 10 in the median.

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