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  • 1. Aaltonen, J.
    et al.
    Olofsson, Bo
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Direct current (DC) resistivity measurements in long-term groundwater monitoring programmes2002In: Environmental Geology, ISSN 0943-0105, E-ISSN 1432-0495, Vol. 41, no 6, p. 662-671Article in journal (Refereed)
  • 2.
    Ackerberg, Björn
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Application of some statistical methods for evaluation of groundwater observations2002Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    With the objective of reviewing different statisticalmethods for evaluation of groundwater data and the design of agroundwater observation network, a comprehensive literaturesurvey was performed. The literature survey focuses on spatialstatistics (geostatistics) but also includes methods toevaluate time-series of groundwater data and the determinationof the sampling frequency. A method is developed which providesa means of quantifying the accuracy of an existing groundwatermonitoring network with regards to spatial interpolation andthe locations of the corresponding observation points. Thespatial interpolation method of ordinary kriging was used. Aresult from ordinary kriging was estimated (interpolated)levels at unmeasured points, but also a kriging variance. Thekriging variance can be interpreted as a measure of theestimation accuracy and used as a criterion for network design.Design of a monitoring network for groundwater levels in anarea includes the selection of: - the number of observationpoints and - the spatial locations of observation points.The method was applied to design a monitoring network inan area in a glaciofluvial deposit, the Nybro esker, which isthe main aquifer for the water supply of the Kalmar-Nybroregion in the southeast of Sweden. This thesis shows that it ispossible to quantify the accuracy of an existing observationnetwork using the average kriging variance as a measure ofaccuracy. It is also possible to describe how this krigingvariance changes (increases) when the observation network isreduced. By using this variance is it possible to rank thedifferent points in the network as to their relativeimportance. It is thus possible to identify the points, whichare to be removed when the observation network is reduced, onepoint at a time. This study shows that a monitoring network inthe study area could be reduced by 35% while the increase inaverage estimation (kriging) variance is only about 10%.Although the method is applied to groundwater levels in aglaciofluvial deposit, it is applicable also to other variablesthat can be considered regionalized and to other geologicalenvironments.

  • 3.
    Ahmad, Arslan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Sustainability and Environmental Engineering. KWR Water Cycle Res Inst, Nieuwegein, Netherlands.;WUR, Dept Environm Technol, Wageningen, Netherlands..
    Cornelissen, Emile
    KWR Water Cycle Res Inst, Nieuwegein, Netherlands.;Nanyang Technol Univ, Nanyang Environm & Water Res Inst, Singapore Membrane Technol Ctr, Singapore, Singapore.;Univ Ghent, Particle & Interfacial Technol Grp, Ghent, Belgium..
    van de Wetering, Stephan
    Brabant Water NV Breda, Breda, Netherlands..
    van Dijk, Tim
    Brabant Water NV Breda, Breda, Netherlands..
    van Genuchten, Case
    Univ Utrecht, Fac Geosci, Dept Earth Sci Geochem, Utrecht, Netherlands..
    Bundschuh, Jochen
    Univ Southern Queensland, Int Ctr Appl Climate Sci, West St, Toowoomba, Qld, Australia.;Univ Southern Queensland, Deputy Vice Chancellors Off Res & Innovat, Toowoomba, Qld, Australia.;Univ Southern Queensland, Fac Hlth Engn & Sci, Toowoomba, Qld, Australia..
    van der Wal, Albert
    WUR, Dept Environm Technol, Wageningen, Netherlands.;Evides Water Co NV Rotterdam, Rotterdam, Netherlands..
    Bhattacharya, Prosun
    KTH, Superseded Departments (pre-2005), Land and Water Resources Engineering. Univ Southern Queensland, Int Ctr Appl Climate Sci, West St, Toowoomba, Qld, Australia..
    Arsenite removal in groundwater treatment plants by sequential Permanganate-Ferric treatment2018In: JOURNAL OF WATER PROCESS ENGINEERING, ISSN 2214-7144, Vol. 26, p. 221-229Article in journal (Refereed)
    Abstract [en]

    The Dutch drinking water sector is actively investigating methods to reduce arsenic (As) to < 1 mu g/L in drinking water supply. We investigated (1) the effectiveness of sequential permanganate (MnO4-)-ferric (Fe(III)) dosing during aeration-rapid sand filtration to achieve < 1 mu g/L As (2) the influence of MnO4--Fe(III) dosing on preestablished removal patterns of As(III), Fe(II), Mn(II) and NH4+ in rapid sand filters and (3) the influence of MnO4--Fe(III) dosing on the settling and molecular-scale structural properties of the filter backwash solids. We report that MnO4--Fe(III) dosing is an effective technique to improve arsenite [As(III)] removal at groundwater treatment plants. At a typical aeration-rapid sand filtration facility in the Netherlands effluent As concentrations of < 1 mu g/L were achieved with 1.2 mg/L MnO4--and 1.8 mg/L Fe(III). The optimized combination of MnO4-and Fe(III) doses did not affect the removal efficiency of Fe(II), Mn(II) and NH4+ in rapid sand filters, however, the removal patterns of Fe(II) and Mn(II) in rapid sand filter were altered, as well as the settling behaviour of backwash solids. The characterization of backwash solids by Fe K-edge X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) showed that the changed settling velocity of backwash solids with MnO4-Fe(III) in place was not due to changes in the molecular-scale structure of Fe-precipitates that constitute the major portion of the backwash solids.

  • 4.
    Ahmed, K. Matin
    et al.
    Univ Dhaka, Dept Geol.
    Bhattacharya, Prosun
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Hasan, Md. Aziz
    Univ Dhaka, Dept Geol.
    Akhter, S. Humayun
    Univ Dhaka, Dept Geol.
    Alam, S. M. Mahbub
    Univ Dhaka, Dept Geol.
    Bhuyian, M. A. Hossain
    Univ Dhaka, Dept Geol.
    Imam, M. Badrul
    Univ Dhaka, Dept Geol.
    Khan, Aftab A.
    Univ Dhaka, Dept Geol.
    Sracek, Ondra
    Masaryk Univ, Fac Sci, Dept Mineral Petrol & Geochem.
    Arsenic enrichment in groundwater of the alluvial aquifers in Bangladesh: an overview2004In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 19, no 2, p. 181-200Article in journal (Refereed)
    Abstract [en]

    Arsenic in the groundwater of Bangladesh is a serious natural calamity and a public health hazard. Most groundwater from the shallow alluvial aquifers (<150 m), particularly in the Holocene plain lands, are vulnerable to As-enrichment. Delta plains and flood plains of the Ganges-Brahmaputra river system are moderately to severely enriched and more than 60% of the tube wells are affected. Shallow aquifers in the Meghna river basin and coastal plains are extremely enriched with more than 80% of the tube wells affected. Aquifers in the Pleistocene uplands and Tertiary hills are low in As. The vertical lithofacies sequence of the sediments from highly enriched areas of the country show two distinct lithofacies associations-a dominantly sandy channel-fill association and a fine-grained over bank association. The sediments can be grouped into 4 distinct lithofacies, viz. clay, silty clay, silty sand and sand. Thin section petrography of the As-enriched aquifer sands shows that the sands are of quartzolithic type and derived from the collision suture and fold thrust belt of the recycled orogen provenance. Groundwater is characterized by circum-neutral pH with a moderate to strong reducing nature. The waters are generally of Ca-Mg-HCO3 or Ca-Na-HCO3 type, with HCO3- as the principal anion. Low SO42- and NO3-, and high dissolved organic C (DOC) and NH4+ concentrations are typical chemical characteristics of groundwater. The presence of dissolved sulfides in these groundwaters indicates reduction Of SO4. Total As concentration in the analyzed wells vary between 2.5 and 846 mug l(-1) with a dominance of As(III) species (67-99%). Arsenic(III) concentrations were fairly consistent with the DOC and NH4+ contents. The HNO3 extractable concentrations of As (As-NO3) in the sediments (0.5-17.7 mg kg(-1)), indicate a significant positive correlation with Fe-NO3, Mn-NO3, Al-NO3 and P-NO3. The concentrations Of S-NO3 (816-1306 mg kg(-1)) peaked in the clay sediments with high organic matter (up to 4.5 wt.%). Amounts of oxalate extractable As (As..) and Fe (Fe x) ranged between 0.1-8.6 mg kg(-1) and 0.4-5.9 g kg(-1), respectively. Arsenic(ox) was positively correlated with Fe-ox, Mn-ox, and Al-ox in these sediments. Insignificant amounts of opaque minerals (including pyrite/arsenopyrite) and the presence of high As contents in finer sediments suggests that some As is incorporated in the authigenically precipitated sulfides in the reducing sediments. Moreover, the chemical extractions suggest the presence of siderite and vivianite as solid phases, which may control the aqueous chemistry of Fe and PO43-. Reductive dissolution of Fe oxyhydroxide present as coatings on sand grains as well as altered mica (biotite) is envisaged as the main mechanism for the release of As into groundwater in the sandy aquifer sediments.

  • 5.
    Arcelus, Alejandro
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Hydrology of riparian wetlands: a methodology study in carbo wetlands, Uruguay2002Licentiate thesis, comprehensive summary (Other scientific)
  • 6.
    Arm, Maria
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Mechanical Properties of Residues as Unbound Road Materials - experimental tests on MSWI bottom ash, crushed concrete and blast furnace slag2003Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    For recycled aggregates and industrial by-products to beused correctly in road construction, it is necessary to knowtheir properties. Existing material specifications and testmethods for aggregates used in Sweden and in many othercountries are indirect and are based on empiricism. Over theyears they have been adjusted to conventional aggregates, whichmakes the introduction of new materials difficult. Research oftheir properties is being conducted in many places althoughknowledge has been inadequately disseminated.

    The objective of this thesis is to increase knowledge of themechanical properties of certain selected residues for improveddesign of pavements using these residues.

    The study has concentrated on residues in unbound roadlayers. The materials selected were processed municipal solidwaste incinerator (MSWI) bottom ash, crushed concrete andair-cooled blast furnace slag (AcBFS). The deformation onloading, the possible strength development over time and theresistance to mechanical and climatic action were studied inthe laboratory and in the field. The results were compared withthose of the conventional aggregates they could possiblyreplace, such as sand, gravel and crushed rock. The methodsused in the laboratory were cyclic load triaxial tests, LosAngeles tests, micro-Deval tests and freeze-thaw tests. In thefield, test sections with residues and reference sections withconventional aggregates in the unbound layers were monitored bymeans of falling weight deflectometer (FWD) measurements.

    The laboratory results showed that a high content ofunburned material in MSWI bottom ash limits the resilientmodulus but not the permanent deformation to the same extent.Both laboratory and field results showed several years’growth in stiffness for unbound layers with crushed concreteand AcBFS, which is not present for unbound layers with naturalaggregates. This was thought to be caused by calciumdissolution and precipitation in the compacted material layer.A special investigation of the material in question, togetherwith knowledge of the planned construction, could permit ahigher value to be used in the design modulus than for crushedrock and thus benefit from the increased stiffness.

    The Los Angeles test and other tests developed forsingle-sized aggregates did not really justify the performanceof the materials studied. Recycled aggregates and otherresidues, as well as conventional unbound road materials,should be analysed using cyclic load triaxial tests in thelaboratory and FWD measurements in the field, both of whichtake into account the whole composite material or layer.Consequently, a new methodology for material assessment andcomparison is proposed, based on permanent deformations incyclic load triaxial tests.

    According to the laboratory and field tests, some bottom ashcould be used, not only in embankments and capping layers butalso to bear the stress levels expected in a sub-base. Recycledaggregates and other residues should be used near the source ofproduction and not necessarily in roads with low trafficvolumes. Their properties should be used to the greatestpossible extent although their limitations must be taken intoaccount.

    Key Words:residues; unbound materials; MSWI bottom ash;crushed concrete; blast furnace slag; mechanical properties

  • 7.
    Ask, Daniel
    KTH, Superseded Departments, Land and Water Resources Engineering.
    New developments of the Integrated Stress Determination Method and application to the Äspö Hrad Rock Laboratory, Sweden2004Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    This thesis presents new developments of the IntegratedStress Determination Method (ISDM) with application to the AspoHard Rock Laboratory (HRL), Oskarshamn, Sweden. The newdevelopments involve a 12-parameter representation of theregional stress field in the rock mass. The method isapplicable to data from hydraulic fracturing, hydraulic testson pre-existing fractures (HTPF), and overcoring data fromCSIR- and CSIRO-type of devices. When hydraulic fracturing/HTPFdata are combined with overcoring data, the former may be usedto constrain the elastic parameters, i.e. the problem involves14 model parameters.

    The Swedish Nuclear Fuel and Waste Management Co. (SKB),have conducted a vast amount of rock stress measurements at theAspo Hard Rock Laboratory (HRL) since the late 1980s. However,despite the large number of stress measurement data collectedin this limited rock volume, variability in the stress fieldexists. Not only does the result vary depending on measuringtechnique, e.g. overcoring data indicated larger stressmagnitudes compared to hydraulic fracturing data; the resultsare also affected by existing discontinuities, indicated bynon-linear stress magnitudes and orientations versus depth.

    The objectives for this study are therefore threefold: (1)find explanations to the observed differences between existinghydraulic and overcoring stress data at the Aspo HRL; (2)explain the non-linear stress distribution indicated byexisting stress data; and (3) apply the ISDM, including the newdevelopments, based on the results obtained in step 1 and2.

    To evaluate the observed differences between existinghydraulic and overcoring stress data, a detailedre-interpretation was conducted. Several measurement-relateduncertainties were identified and corrected for when possible,which effectively reduced the discrepancies between thehydraulic and overcoring measuring results.

    Modeling studies managed by SKB have shown that theredistribution of the stresses at Aspo HRL to a large extentcan be correlated to the NE-2 Fracture Zone, which divides therock stress data into two stress domains. The effect of thiszone was confirmed in this study, and the re-analyzed datasuggest an orientation of σ1equal to 124oN±13ofor the NW domain and 139oN±18ofor the SE domain. Later, the application of theISDM further verified the influence of the NE-2 Fracture Zoneon the regional stress field. The results in the vicinity ofthe NE-2 Fracture Zone indicate that σ1is perpendicular to the zone, whereas the σ2and σ3coincide with the plane defined by the zone(strike 21oN, dip 77otowards SE). However, the principal stressmagnitudes seem less influenced by the zone.

    The amount of data located outside the zone of influencefrom the NE-2 Fracture Zone is limited, and the regional stresstensor is hence difficult to define. Most likely, theorientation of the regional σ1is trending about 140oN.

  • 8.
    Bahrekazemi, Mehdi
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Lime-cement columns as a countermeasure against train-induced ground vibration2002Licentiate thesis, comprehensive summary (Other scientific)
  • 9.
    Baresel, Christian
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Larsén, Karin
    Destouni, Georgia
    Gren, Ing-Marie
    Economic Analysis of Mine Water Pollution Abatement in a Catchment2004In: Mine Water and the Environment, ISSN 1025-9112, E-ISSN 1616-1068, Vol. 1, p. 57-68Article in journal (Refereed)
  • 10.
    Beekman, Gertjan
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Social change and water resources planning and development2001Licentiate thesis, monograph (Other scientific)
  • 11. Ben-Gal, A.
    et al.
    Karlberg, L.
    Jansson, Per-Erik.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Shani, U.
    Temporal robustness of linear relationships between production and transpiration2003In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 251, no 2, p. 211-218Article in journal (Refereed)
    Abstract [en]

    Seasonal dependence of biomass production on transpiration has been previously reported for a number of crops under salinity and drought. Linear yield (Y) to transpiration ( T) relationships have been utilized in plant-growth and water-uptake models to estimate yield based on predicted transpiration values. The relationship is often employed for time steps that are very small compared with the whole season measurements, even though no empirical validation exists for such application. This work tests the hypothesis that linear Y-T relationships are valid throughout the life span of crops under varied natural conditions and levels of environmental stress. Effects of salinity and water supply on growth, water use and yields of tomatoes ( Lycopersicon esculentum Mill.) were studied for two distinct conditions of potential transpiration. Linear relationships between relative Y and relative ET were found to be consistent throughout the life span of the crops for both growing seasons. Water-use efficiency increased together with plant growth as a result of changes in the plant's surface area to volume ratio. This empirical validation of linear Y-T relationships for short time periods is beneficial in confirming their usefulness in growth and water uptake models.

  • 12.
    Bhattacharya, Prosun
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Jacks, G.
    Ahmed, K. M.
    Routh, J.
    Khan, A. A.
    Arsenic in groundwater of the Bengal Delta Plain aquifers in Bangladesh2002In: Bulletin of Environmental Contamination and Toxicology, ISSN 0007-4861, E-ISSN 1432-0800, Vol. 69, no 4, p. 538-545Article in journal (Refereed)
  • 13.
    Bhattacharya, Prosun
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Mukherjee, A. B.
    Jacks, G.
    Nordqvist, S.
    Metal contamination at a wood preservation site: characterisation and experimental studies on remediation2002In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 290, no 03-jan, p. 165-180Article in journal (Refereed)
    Abstract [en]

    The aim of this investigation was to determine the occurrence of As, Cu, Cr and Zn in the soil at an abandoned wood preservation unit and to examine some possible extractants for the contaminants in the soil. The mean As content of the contaminated surface soils (0-10 cm) was 186 mg kg(-1), where as the mean concentrations of Cu, Cr and Zn in soils from the contaminated area were 26, 29 and 91 mg kg(-1), respectively. The elevated As content in the mineral soils is related to adsorption of inorganic As phases in the fine grained fractions, which are characterised by large surface area and high positive surface charge under the current acidic conditions. Cu and Cr were found to be rather mobile, which is reflected in their lower abundance in soils and significant accumulation in sediments in the drainage leaving the area. The fine fraction of the soil (<0.125 mm) has an average metal content increased by nearly 34% as compared to the <2-mm fraction conventionally used for the analysis and assessment of soil contamination. The <2-mm fraction constitutes approximately 65% of the total weight while the fine fraction (< 0.125 mm) constitutes approximately 10%. These facts, taken together, are essential for the choice of remediation measures. Oxalate solutions have been tested as extractants for soil remediation. Dark acid oxalate extraction dissolves the amorphous Al- and Fe-oxides and hydroxides and mobilises the adsorbed inorganic As species. Oxalate also acts as a ligand for the cationic heavy metals, releasing them from exchangeable sites. With a three-step sequential leaching, up to 98-99% of the metals could be removed. At lower concentrations and higher pH, the leaching decreased to approximately 70%.

  • 14.
    Bhattacharya, Prosun
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Tandukar, N.
    Neku, A.
    Valero, A. A.
    Mukherjee, A. B.
    Jacks, G.
    Geogenic arsenic in groundwaters from Terai Alluvial Plain of Nepal2003In: Journal de Physique IV: Colloque, ISSN 1155-4339, E-ISSN 1764-7177, Vol. 107, p. 173-176Article in journal (Refereed)
    Abstract [en]

    The origin and mobility of arsenic (As) in the groundwater environment has received serious attention in recent years. Recent studies have reported naturally occurring As in groundwaters of the Terai Alluvial Plains (TAP) in southern Nepal, where groundwater exploitation has increased since the 1960s. The source of As in TAP is geogenic and leached primarily due to weathering of As bearing rocks and sediments in the Himalayas. In our present study, we have investigated the groundwater chemistry in the central part of the TAP in Nawalparasi district. TAP groundwaters are near-neutral to alkaline, with predominantly reducing character and high HCO3-, low SO4- and NO3- concentrations. Elevated HCO3 levels possibly result due to the oxidation of organic matter, low SO42- levels reflect sulfate reduction. Elevated NH4+ concentrations in these groundwaters suggest dissimilatory nitrate reduction in the aquifers. Total arsenic (As,.,) levels in groundwater varied from 1.7 mug/L to as high as 404 mug/L with dominance of As(III) species and elevated levels of dissolved Fe and Mn. Arsenic is mobilized in groundwaters as a result of desorption of As-oxyanions adsorbed onto Fe- and Mn-oxides as well as reductive dissolution of these surface reactive phases from the sediments along with release of As in anoxic groundwaters.

  • 15.
    Bhattacharya, Prosun
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Welch, A. H.
    Ahmed, K. M.
    Jacks, Gunnar
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Naidu, R.
    Arsenic in groundwater of sedimentary aquifers2004In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 19, no 2, p. 163-167Article in journal (Refereed)
  • 16.
    Boman, Eva
    KTH, Superseded Departments, Land and Water Resources Engineering.
    The effects of noise and gender on children's episodic and semantic memory2004In: Scandinavian Journal of Psychology, ISSN 0036-5564, E-ISSN 1467-9450, Vol. 45, no 5, p. 407-416Article in journal (Refereed)
    Abstract [en]

    The main objectives in the present study were to examine meaningful irrelevant speech and road traffic noise effects on episodic and semantic memory, and to evaluate whether gender differences in memory performance interact with noise. A total of 96 subjects, aged 13-14 years (n= 16 boys and 16 girls in each of three groups), were randomly assigned to a silent or two noise conditions. Noise effects found were restricted to impairments from meaningful irrelevant speech on recognition and cued recall of a text in episodic memory and of word comprehension in semantic memory. The obtained noise effect suggests that the meaning of the speech were processed semantically by the pupils, which reduced their ability to comprehend a text that also involved processing of meaning. Meaningful irrelevant speech was also assumed to cause a poorer access to the knowledge base in semantic memory. Girls outperformed boys in episodic and semantic memory materials, but these differences did not interact with noise.

  • 17. Borgesson, L.
    et al.
    Chijimatsu, M.
    Fujita, T.
    Nguyen, T. S.
    Rutqvist, J.
    Jing, Lanru
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Thermo-hydro-mechanical characterisation of a bentonite-based buffer material by laboratory tests and numerical back analyses2001In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 38, no 1, p. 95-104Article in journal (Refereed)
    Abstract [en]

    This paper presents some laboratory tests performed on the bentonite used as buffer material in the engineered barrier experiment in Kamaishi mine in Japan and a collective effort of four research groups to characterise the coupled thermo-hydro-mechanical behaviour of the bentonite by comparing numerical calculations with the laboratory test results. Each research group used finite element programs with constitutive models capable to simulate both liquid and vapour flux of water, heat transfer, volume change, swelling pressure and mechanical deformation. Numerical calibrations were performed against results obtained from three types of laboratory tests: water infiltration tests, thermal gradient tests and swelling pressure tests. Parameter values, which could not be directly measured in laboratory tests, were obtained with these calculations.

  • 18. Brogowski, Zygmunt
    et al.
    Renman, Gunno
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Characterization of opoka as a basis for its use in wastewater treatment2004In: Polish Journal of Environmental Studies, ISSN 1230-1485, E-ISSN 2083-5906, Vol. 13, no 1, p. 15-20Article in journal (Refereed)
    Abstract [en]

    Opoka, as a silica-calcite sedimentary rock, occurs in south-eastern Europe and Russia. Stratigraphical studies down to 8 in depth were performed in Belzec, Poland, where samples were taken for further analyses. Vertical layers represented a heavy-weight opoka consisting of relatively more CaCO3 than the horizontal layers of lightweight opoka dominated by SiO2. Opoka had a mean bulk density of 1.34 g/cm(3), a porosity of 44.5 % and a specific surface area of 64 m(2)/g. Opoka, especially after heated to over 900degreesC can be used as reactive filter media for phosphorus removal. Maximum sorption capacity was 119.6 g PO4-P/ kg. Element analysis of the rock did not reveal any anomaly from that expected, and it was concluded that its element content does not devaluate opoka as a sorbent used in ecological wastewater treatment.

  • 19.
    Brokking, Peter
    et al.
    KTH, Superseded Departments, Infrastructure.
    Schmidtbauer Crona, Jan
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Eriksson, Inga-Maj
    Swedish National Road Administration.
    Balfors, Berit
    KTH, Superseded Departments, Land and Water Resources Engineering.
    SEA in Swedish Transportation Policy-making and Planning: Political Ambitions and Practice2004In: European Environment, ISSN 0961-0405, E-ISSN 1099-0976, Vol. 14, no 2, p. 94-104Article in journal (Refereed)
    Abstract [en]

    Since the mid-1990s, the aim to incorporate SEA into Swedish strategic transportation planning has been repeatedly expressed in government documents and directives. To support a successful implementation, efforts have been made to develop tools and methods for the integration of SEA into strategic transportation planning. These efforts concern, for example, the application of SEA in corridor development and long-term transportation planning. The practical experiences of SEA in strategic transportation planning have been influenced by the ambiguity of the scope and structure of SEA. In this paper the process of implementing the SEA in Swedish transportation planning will be reviewed. The review relates to political ambitions and practice, and highlights the methodological development of SEA applications in the Swedish transport sector.

  • 20. Bundschuh, J.
    et al.
    Farias, B.
    Martin, R.
    Storniolo, A.
    Bhattacharya, Prosun
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Cortes, J.
    Bonorino, G.
    Albouy, R.
    Groundwater arsenic in the Chaco-Pampean Plain, Argentina: Case study from Robles County, Santiago del Estero Province2004In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 19, no 2, p. 231-243Article in journal (Refereed)
    Abstract [en]

    In large parts of rural Argentina people depend on groundwater whose As content exceeds the Argentine drinking water standards (0.05 mg l(-1)). The most affected areas are located in the Chaco-Pampean Plain, where aquifers comprise Tertiary loess deposits (in the Pampean Plain) and Tertiary and Quaternary fluvial and aeolian sediments (in the Chaco Plain). Robles county is located in the alluvial cone of the Dulce River consisting of loess (aeolian), and gravel, silt, sand and clay (alluvial) deposits. In the shallow aquifers, more than 48% of the 63 studied wells show As at toxic levels (maximum 4.8 mg l(-1)), while in the deep groundwater the concentration is below 0.05 mg l(-1). The pH of the shallow groundwaters range between 6.5 and 9 and generally have high electrical conductivity with mean values of 2072 and 1693 muS/cm(-1) in the years 1998 and 1999, respectively. Arsenic concentrations are high in the alkaline Na-HCO3 type groundwaters, where As correlates positively with Na+ and HCO3-. Moreover, As correlates positively with Mo, U, and V, while a negative correlation was observed with Ca2+ and Mg2+. The potential sources of groundwater As are: (i) layers of volcanic ash with 90% of rhyolitic glass; (ii) volcanic glass dispersed in the sediments; and (iii) clastic sediments of metamorphic and igneous origin. Great lateral variability in the concentration of groundwater As is caused by several hydrogeological and hydrogeochemical factors.

  • 21.
    Bäckström, Ann
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Investigation of the correlation of fracture frequency and electric resistivity in impact craters in crystalline rocks2004Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Impact craters are formed when a large meteorite or comethits the Earth. At the impact a shock wave is released causingabundant fracturing in the surrounding bedrock. This type offracturing is intense and occurs throughout a very large volume(>100 km3) of the bedrock. Fractures of this type have beenobserved in deep drilling, to 5 km depth, in thePuchezh-Katunki Impact Crater. At theses depths the ambienttemperature is high. Thus impact structures are candidates forpotential heat-exchange sources for extraction of geothermalenergy.

    There is a relation between fracture intensity and electricresistivity in bedrock predominated by impact-generatedfractures. In crystalline bedrock changes in electricresistivity is mainly due to fracturing which is the mainsource of porosity in these rocks. Electric resistivity methodsare highly sensitivity to porosity. Furthermore highfracture-intensities have generally been associated with lowelectric resistivity. Electro-magnetic methods like Very LowFrequency Resistivity (VLF-R) and Magnetotellurics (MT) canindirectly measure electric resistivity to relatively largedepths in the bedrock.

    This study will quantify the relationship between fractureintensity and electric resistivity which can be used as aprospecting tool for geothermal energy resources at largedepth.

    To meet that end, a method for fracture mapping on outcropsin Swedish terrain and a method to calculate thethree-dimensional fracture frequency from two-dimensionalfracture data has been developed. The fracture traces measuredin two dimensions on outcrops are assumed to represent avertical surface and must be converted to a three-dimensionalmeasure of the fracture frequency per unit volume. Spacing, dipand trace length of fractures have been accounted for. Thebiases associated with the mapping method have also beenaccounted for (II).

    The correlation between impact-induced fracturing andelectric resistivity in crystalline rocks in the Lockne Areashows that the extent of impact fracturing in crystalline rockscan be measured with electro-magnetic or electric techniques.In addition the electric resistivity of crystalline basementand impact generated Tandsby Breccia from the Lockne Craterwere determined (I).

    The relation between fracture frequency and electricresistivity in fresh water conditions using the VLF-R method isestablished from data collected from both two drill holes andfrom numerous outcrops in the Björkö region. Apreliminary quantification of the fracture frequency has beenmade. The MT resistivity models, related to the two drillholes, show that porosity and mineral-conductivity variationsof the bedrock affect this relation more than the salinityvariations in the bore-hole fluid. Further research is neededto establish a firm relation between fracture frequency,salinity of rock fluid, conductivity and porosity in order tovalidate the MT resistivity models (III).

    Keywords:Electric resistivity, Fracture frequency,Impact generated fractures, Electro-magnetic techniques, VLF-Rmethod, MT method, Window-mapping technique, Three-dimensionalfracture calculations, heat-exchange structure, geothermalenergy.

  • 22. Cesano, D.
    et al.
    Bagtzoglou, A. C.
    Olofsson, Bo
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Quantifying fractured rock hydraulic heterogeneity and groundwater inflow prediction in underground excavations: the heterogeneity index2003In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 18, no 1, p. 19-34Article in journal (Refereed)
  • 23.
    Cesano, Daniele
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Olofsson, Bo
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Bagtzouglou, A.
    Parameters regulating groundwater inflows into hard rock tunnels - a statistical study of the Bolmen tunnel in southern Sweden2000In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 15, no 2, p. 153-165Article in journal (Refereed)
    Abstract [en]

    Inflow of groundwater into tunnels has always been a major technical and environmental problem for underground constructions. Predictions of groundwater inflow using analytical and numerical tools have often failed due to generalization and simplification of important parameters, especially in heterogeneous media such as crystalline rocks. In order to identify those parameters that regulate inflows, a systematic statistical analysis has been carried out at a tunnel constructed in the hard crystalline rocks of southern Sweden. The parameters included topographically, technically and geologically important variables in the hard crystalline rocks as well as in the overburden. The study revealed that many factors related to the rock quality, as well as to the overburden-such as the number of fractures, the thickness of the overburden, the soil type and the amount of pregrouting-regulated the leakage. It seems that a clear difference exists between the parameters that regulate the major and the minor leakage. The minor leakage is associated more with the drainage of the rock mass, while the major leakage is clearly associated with different parameters in the overburden. Unless the overburden anal the rock mass are considered as an interrelated system, predictions of groundwater inflows are likely to fail.

  • 24.
    Cheng, Hua
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Cvetkovic, Vladimir
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Hydrodynamic control of tracer retention in heterogeneous rock fractures2003In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 39, no 5, p. 1130-1139Article in journal (Refereed)
    Abstract [en]

    We investigate the statistical properties of a Lagrangian random variable beta[T/L], which has been shown to quantify hydrodynamic impact on retention [Cvetkovic et al., 1999], using Monte Carlo simulations of flow and transport in a single fracture. The "local cubic law'' of water flow is generalized to a power law Qsimilar tob(n), where Q is the flow rate, b is the half aperture, and nless than or equal to3. Simulations of flow and particle transport are carried out assuming "local cubic law'' (n=3) and "local quadratic law'' (n=2), and for two typical flow configurations: uniform flow and radially converging flow. We find that beta is related to tau as betasimilar totau(m), where m is dependent on the power n and the configuration of flow and transport. Simulation results for uniform flow indicate that betasimilar totau(n/n-1) for a small source section; as the source section increases, we have the convergence to betasimilar totau. For radially converging flow, we find betasimilar totau for a small source section and a convergence to beta=const for an increasing source section. Simulation results for both flow configurations are consistent with the results for a homogeneous fracture. The results for a homogeneous fracture provide reasonable bounds for simulated beta. The correlation between beta and Q is relatively weak for all cases studied.

  • 25.
    Cheng, Hua
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Cvetkovic, Vladimir
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Impact of temperature increase on nuclide transport in crystalline rock on the near field scale2004In: Coupled Thermo-Hydro-Mechanical-Chemical Processes in Geo-Systems: Fundamentals, Modelling, Experiments and Applications, Elsevier , 2004, 2, p. 413-418Chapter in book (Other academic)
    Abstract [en]

    The TRUE (“Tracer Retention Understanding Experiments”) programme at the Äspö Hard Rock Laboratory (Winberg et al., 2000, 2002) has since 1995 generated a unique database for quantifying retention of radionuclides in crystalline rock on the 5-30m scales. Temperature conditions in the TRUE analysis were about 15°C. In this study, we consider the effect of temperature increase to ca 60°C consistent with conditions after say 1000 years in the rock volume surrounding a KBS-3 type of repository, anticipated to persist over a relatively long time. Temperature elevation will decrease the mean aperture of a conducting fracture by approximately 30%, which in turn will enhance retention. Furthermore, diffusion in the rock matrix will increase at elevated temperatures by approximately factor 4, further enhancing retention. Sorption coefficients are assumed to be unchanged since there is still considerable uncertainty regarding sorption and its change with increasing temperature. We show that elevated temperature on the near field scale enhances nuclide retention, thereby providing an additional safety margin.

  • 26. Chijimatsu, M.
    et al.
    Jing, Lanru
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Engineering Geology and Geophysics.
    Millard, A.
    Nguyen, T. S.
    Rejeb, A.
    Rutqvist, Jonny
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Souley, M.
    Sugita, Y.
    Building Confidence in the Mathematical Models by Calibration With A T-H-M Field Experiment2004In: Coupled Thermo-Hydro-Mechanical-Chemical Processes in Geo-Systems — Fundamentals, Modelling, Experiments and Applications, Elsevier, 2004, no C, p. 193-198Chapter in book (Refereed)
    Abstract [en]

    Geological disposal of nuclear fuel wastes relies on the concept of multiple barrier systems. In order to predict the performance of these barriers, mathematical models have been developed, verified and validated against analytical solutions, laboratory tests and field experiments within the international DECOVALEX project. These models in general consider the full coupling of thermal (T), hydrological (H) and mechanical (M) processes that would prevail in the geological media around the repository. This paper shows the process of building confidence in the mathematical models by calibration with a reference T-H-M experiment with realistic rock mass conditions and bentonite properties and measured outputs of thermal, hydraulic and mechanical variables.

  • 27.
    Cvetkovic, Vladimir
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Colloid-facilitated tracer transport by steady random ground-water flow2000In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 12, no 9, p. 2279-2294Article in journal (Refereed)
    Abstract [en]

    We study the transport of reactive solute in a three-phase system (water-solid matrix-colloids) in natural porous media. Semianalytical (integral) solutions are derived for the first time, which can be used for computing expected concentration, mass flux, or discharge for the dissolved as well as for colloid-bounded tracer. The results are based on a few simplifying assumptions: advection-dominated transport, linear mass transfer reactions, and steady-state colloidal concentration. Derived semianalytical expressions capture the main features of colloid-facilitated transport (the reversible-equilibrium and irreversible-kinetic sorption of tracers on colloids), and are applicable for the general class of linear sorption processes on the porous matrix. Derived solutions account for spatial variability of flow and sorption parameters, which is relevant for field-scale applications. We apply the theoretical results to the transport of neptunium and plutonium, using flow and transport data from the alluvial aquifer near Yucca Mountain, Nevada. Based on the zeroth and first temporal moment, dimensionless indicators are proposed for assessing the potential impact of colloid-facilitated tracer transport in aquifers. Generic sensitivity curves show the importance of tracer-colloid kinetic rates. Even very low irreversible rates (which will generally be difficult to determine in the laboratory) may yield observable effects for sufficiently long transport times. The obtained results can be used for assessing the significance of colloid-facilitated tracer transport under field conditions, as well as for setting further constraints on relevant parameters which need to be estimated in the field.

  • 28.
    Cvetkovic, Vladimir
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Cheng, Hua
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Contaminant transport in aquifers with spatially variable hydraulic and sorption properties1998In: Proceedings of the Royal Society of Edinburgh. Section A Mathematics, ISSN 0308-2105, E-ISSN 1473-7124, Vol. 454, p. 2173-2207Article in journal (Refereed)
  • 29.
    Cvetkovic, Vladimir
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Cheng, Hua
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Transport of reactive tracers in rock fractures1999In: Journal of Fluid Mechanics, ISSN 0022-1120, E-ISSN 1469-7645, Vol. 378, p. 335-336Article in journal (Refereed)
  • 30.
    Cvetkovic, Vladimir
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Cheng, Hua
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Wen, X. -H.
    Analysis of nonlinear effects on tracer migration in heterogeneous aquifers using Lagrangian travel time approach1996In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 32, no 6, p. 1671-1680Article in journal (Refereed)
    Abstract [en]

    Advective transport in a heterogeneous two-dimensional aquifer is simulated and quantified by the statistical moments of tracer travel time and transverse displacement. These moments depend on the statistics of the Lagrangian velocity given as a function of space rather than time. A comparison is made with first-order results that appear to be robust for log transmissivity variance at least up to 1. Lagrangian statistics for travel time clearly expose a few essential features of nonlinear transport: nonstationary distribution and the increasing integral scale of the Lagrangian velocity. These reflect the tendency of streamlines to concentrate into relatively few flow paths ('preferential flow') for increasing log transmissivity variance. Two simple empirical relationships are identified that in combination with first-order results for the flow capture the main features of nonlinear transport. The proposed methodology can readily be generalized for analyzing advective transport under more complex flow conditions and for establishing relatively simple analytical models for estimating solute mass flux in heterogeneous aquifers.

  • 31.
    Cvetkovic, Vladimir D.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    On the significance of hydrodynamic control for radionuclide retention in fractured porous media2004In: Coupled Thermo-Hydro-Mechanical-Chemical Processes in Geo-Systems — Fundamentals, Modelling, Experiments and Applications, Elsevier, 2004, no C, p. 507-511Chapter in book (Refereed)
    Abstract [en]

    It is demonstrated that the approximate means of quantifying hydrodynamic control of retention is reasonably accurate for low values of the transport resistance on the 100m and 1000m scales; for high values, the approximate expression may significantly underestimate retention. Our results emphasize the need for further development of practical methodologies for quantifying statistical distributions of transport resistance by effectively combining field measurements, numerical simulations and theoretical/analytical considerations.

  • 32.
    Cvetkovic, Vladimir
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Haggerty, R.
    Transport with multiple-rate exchange in disordered media2002In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics: Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, ISSN 1063-651X, E-ISSN 1095-3787, Vol. 65, no 5Article in journal (Refereed)
    Abstract [en]

    We investigate transport of particles subject to exchange using the continuous-time random-walk framework. Transition is controlled by macroscale, and exchange by both macroscale and microscale disorder. A wide class of exchange mechanisms is represented using the multiple-rate exchange model. Particles are transported along random trajectories viewed as one-dimensional lattices. The solution of the transport problem is obtained in the form of the crossing-time density, h(t; L), at an exit surface L; h is dependent on two functions, g and f. g characterizes exchange controlled by microscale disorder. The joint density f is central for the solution as it relates the microscale and macroscale disorder along random trajectories. For the case of transition and exchange disorder, we show that power-law exponent eta (characterizing microscale disorder) and power-law exponents alpha(tau) and alpha(mu) (characterizing macroscale disorder), define two regions delimited by a line alpha(tau) = alpha(mu)(eta + 1): One in which the asymptotic transport is dominated by transition, and one in which it is dominated by the exchange. For the case of transition disorder with uniform exchange, both transition and exchange cart influence the late-time behavior of h(t). Microscale exchange processes will unconditionally influence the late-time behavior of h(t) only if eta<0. If η>0, exchange will dominate at late time provided that transition is asymptotically Gaussian.

  • 33.
    Cvetkovic, Vladimir
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Painter, S.
    Outters, N.
    Selroos, J. O.
    Stochastic simulation of radionuclide migration in discretely fractured rock near the Aspo Hard Rock Laboratory2004In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 40, no 2, p. W02404-Article in journal (Refereed)
    Abstract [en]

    We study the migration of sorbing tracers through crystalline rock by combining relatively simple transport measures with particle tracking in a discrete fracture network. The rock volume is on a 100 m scale and is a replica of a thoroughly characterized site at the Aspo Hard Rock Laboratory, Sweden. Flow is driven by generic boundary conditions consistent with the natural gradient in the region. The emphasis is on the global effect of fracture-to-fracture hydraulic variability where individual fractures are assumed to be of uniform aperture. The transport measures are conditioned on two random variables: the water residence time (tau) and a parameter which quantifies the hydrodynamic control of retention (beta). Results are illustrated for two radionuclides: technetium (strongly sorbing) and strontium (weakly sorbing). It is found that the assumption of streamline routing or full mixing at fracture intersections has comparatively little impact on transport. The choice of the cubic or quadratic hydraulic law (i.e., relation between transmissivity and aperture) strongly affects water residence times but has little impact on average transport since it does not affect the statistics of beta. If the statistics of beta are known, then the distribution of water residence time (tau) is of little importance for transport. We assess the applicability of a linearized model beta = tau/b(ret) using two different approaches to estimate the effective retention'' aperture 2b(ret): from transmissivity data and from fracture density and flow porosity data. Under some conditions, these conventional estimates may provide acceptable representation of transport. The results stress the need for further studies on upscaling of tau, beta distributions as well as on estimating effective parameters for hydraulic control of retention.

  • 34.
    Cvetkovic, Vladimir
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Painter, S.
    Selroos, J. O.
    Comparative measures of radionuclide containment in the crystalline geosphere2002In: Nuclear science and engineering, ISSN 0029-5639, E-ISSN 1943-748X, Vol. 142, no 3, p. 292-304Article in journal (Refereed)
    Abstract [en]

    A probabilistic model for assessing the capacity of a fractured crystalline rock volume to contain radionuclides is developed The rock volume is viewed as a network of discrete fractures through which radionuclides are transported by flowing water. Diffusive mass transfer between the open fractures and the stagnant water in the pore space of the rock matrix allow radionuclides access to mineral grains where physical and chemical processes-collectively known as sorption-can retain radionuclides. A stochastic Lagrangian framework is adopted to compute the probability that a radionuclide particle will be retained by the rock, i.e., the probability that it will decay before being released from the rock volume. A dimensionless quantity referred to as the containment index is related to this probability and proposed as a suitable measure for comparing different rock volumes; such a comparative measure may be needed, for example, in a site selection program for geological radioactive waste disposal. The probabilistic solution of the transport problem is based on the statistics of two Lagrangian variables: T, the travel time of an imaginary tracer moving with the flowing water, and beta, a suitably normalized surface area available for retention. Statistics of tau and beta may be computed numerically using site-specific discrete fracture MP network simulations. Fracture data from the well-characterized Aspo Hard Rock Laboratory site in southern Sweden are used to illustrate the implementation of the proposed containment index for six radionuclides (Sn-126, I-129, Cs-135, Np-237, Pu-239, and Se-79). It is found that fractures of small aperture imply prolonged travel times and hence long tails in both beta and tau. This, in turn, enhances retention and is favorable from a safely assessment perspective.

  • 35.
    Cvetkovic, Vladimir
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Painter, S.
    Turner, D.
    Pickett, D.
    Bertetti, P.
    Parameter and model sensitivities for colloid-facilitated radionuclide transport on the field scale2004In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 40, no 6Article in journal (Refereed)
    Abstract [en]

    We investigate the potential effects of inorganic colloids on radionuclide transport in groundwater using generic sensitivity studies and an example based on the alluvial aquifer near Yucca Mountain, Nevada. Our emphasis is on kinetically controlled sorption of radionuclides on mobile and immobile colloids. Three kinetic sorption models are considered for the sensitivity analysis: bilinear, Langmuir, and linear. Plutonium is assumed to be injected into the Yucca Mountain alluvial aquifer at a constant rate and follows a random stream tube to a monitoring boundary. The linear sorption model provides a reasonable upper bound on colloid-facilitated plutonium transport for the site-specific conditions. In the absence of colloid filtration and retardation, colloids enhance the plutonium discharge by a large factor over the situation without colloids. Exchange of plutonium between solution and reversibly attached colloids makes colloid retardation relatively ineffective at reducing colloid-facilitated transport except when the retardation factor is large. Irreversible removal of colloids (filtration) is more effective than retardation at reducing colloid-facilitated transport. For fixed filtration rate the degree of attenuation depends sensitively and nonmonotonically on the rate of plutonium desorption from colloids. These results emphasize the need for accurate measurements of rates of desorption from colloids as well as in situ studies of filtration of naturally occurring colloids.

  • 36.
    Dargahi, Bijan
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Scour development downstream of a spillway2003In: Journal of Hydraulic Research, ISSN 0022-1686, E-ISSN 1814-2079, Vol. 41, no 4, p. 417-426Article in journal (Refereed)
    Abstract [en]

    The scouring process downstream of spillways is an important research topic of value in engineering practice. The objectives of the present experimental study were to examine the similarity development of scour profiles, the controlling scour mechanism and predictions of the scour geometry. No experimental evidence was found in support of the similarity assumption for the scouring process. Scouring downstream of a spillway is controlled by large secondary flows and a vortex system induced by a hydraulic jump. The main dimensionless parameters controlling the scouring process are the relative operating head, the relative sediment size, and the relative roughness of the scour protective plate. The maximum scour depth and the rate of sediment transport can be estimated by using simple, power-type equations that relate the scour geometry to the controlling scour parameters.

  • 37.
    Dargahi, Bijan
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Three-dimensional flow modelling and sediment transport in the River Klaralven2004In: Earth Surface Processes and Landforms, ISSN 0197-9337, E-ISSN 1096-9837, Vol. 29, no 7, p. 821-852Article in journal (Refereed)
    Abstract [en]

    A three-dimensional flow model that uses the RNG k-epsilon turbulence model and a non-equilibrium wall function was applied to the River Klaralven in the southwest part of Sweden. The objectives were to study the nature of the flow in the river bifurcation and to investigate the short-term sediment transport patterns in the river. The effectiveness of three-dimensional flow models depends upon: (1) how well the river geometry and it surface roughness are modelled; and (2) the choice of the closure model. Improvements were obtained by modelling the river in two parts: the entire river reach, and a selected part. Composite Manning coefficients were used to account for roughness properties. The method requires a calibration process that ensures the water surface profiles match the field data. The k-epsilon model under-predicted both the extent of flow separation zones and the number of secondary flow regions having a spiral motion, in comparison with the RNG k-epsilon model. The 3-D model could predict with good accuracy both the general and secondary flow fields in the river. The results agreed well with the 3-D velocity measurements using an acoustic Doppler current profiler. A conceptual model was developed that accounts for the development of secondary flows in a river bifurcation having two bends. The main flow feature in the river cross-sections was the existence of multiple counter-rotating spiral motions. The number of spiral motions increased as the river bends were approached. The river bends also caused vorticity intensification and increased the vertical velocities. The application of the 3-D flow model was extended by solving the sediment continuity equation. The sediment transport patterns were related to the secondary flow fields in the river. The sediment transport patterns at the river bifurcations are characterized by the growth of a sandbank.

  • 38.
    Dargahi, Bijan
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Three-dimensional modelling of ship-induced flow and erosion2003In: Proceedings of the Institution of Civil Engineers: Water and maritime engineering, ISSN 1472-4561, E-ISSN 1753-7800, Vol. 156, no 2, p. 193-204Article in journal (Refereed)
    Abstract [en]

    Ship-induced erosion by propeller jets causes considerable damage in canals, harbours, locks and waterways. jet velocity reaching the bed could be as high as 15 m/s depending on the ship and the machinery. The objectives of the present study were to investigate the nature of the propeller jet flow and to estimate the rate of erosion caused by the jet. Three-dimensional numerical models can be used to simulate ship-induced propeller flows provided the propeller can be replaced with a simpler geometry. The study modelled the propeller flow by one lower and one upper jet flow. The turbulent characteristics, such as the turbulence intensities and the energy balance of the lower jet, are similar to a flat wall boundary layer flow. The application of the three-dimensional flow model was extended by numerically solving the sediment continuity equation. The computations were based on the lower part of the jet velocity profiles. The method enables the scour cavity induced by a stationary ship with a running engine to be calculated. The computed scour cavity agreed well with the field data.

  • 39.
    Destouni, Georgia
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Prieto, Carmen
    KTH, Superseded Departments, Land and Water Resources Engineering.
    On the possibility for generic modeling of submarine groundwater discharge2003In: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 66, no 1-2, p. 171-186Article in journal (Refereed)
    Abstract [en]

    We simulate large-scale dynamics of submarine groundwater discharge (SGD) in three different coastal aquifers on the Mediterranean Sea. We subject these aquifers to a wide range of different groundwater management conditions, leading to widely different net groundwater drainage from land to sea. The resulting SGD at steady-state is quantifiable and predictable by simple linearity in the net land-determined groundwater drainage, defined as total fresh water drainage minus groundwater extraction in the coastal aquifer system. This linearity appears to be general and independent of site-specific, variable and complex details of hydrogeology, aquifer hydraulics, streamlines and salinity transition zones in different coastal systems. Also independently of site-specifics, low SGD implies high seawater content due to seawater intruding into the aquifer and mixing with fresh groundwater within a wide salinity transition zone in the aquifer. Increasing SGD implies decreasing seawater content, decreased mixing between seawater and fresh groundwater and narrowing of the salinity transition zone of brackish groundwater in the aquifer.

  • 40.
    Eklund, Daniel
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Penetrablity for cementitious injection groups2003Licentiate thesis, monograph (Other scientific)
    Abstract [en]

    Grouting as a method of strengthening and sealing rock, soiland concrete is widely spread. The possibilities of sealingstructures are of great importance in both economical andenvironmental point of view. The costs of grouting have incertain projects been as high as the cost for the blasting andexcavation of the tunnel. To improve the technique of groutingwith cement based material, it is necessary to focus on theproperties of the used grout mixture.

    The ability of a grout to penetrate cavities, channels andporous material, the penetrability, depends on two things, therheology and the filtration stability. Extensive laboratorytests on stable, low w/c-ratio, injection grouts show that themost significant limitation to their penetrability is thetendency of cement grains to agglomerate into an impermeablefilter cake. The ability of a grout to pass constrictions ofthe flow path without clogging can be designated filtrationstability. An inert material is used for the investigations inthis work.The inert material, which is crushed dolomite stone,does not react with the added water in the suspension.

    Performed tests show that the grain size distribution is ofgreat importance for the filtration phenomenon. According toperformed experiments with inert material, it seems to beadvantageous for the penetrability to have a grain sizedistribution not containing too much fine grains and not toomuch coarser grains. It reasonable to believe that the grainsize distribution should be relatively steep (narrow grain sizerange) between minimum and maximum grain size.

    Correlations between different parameters have been studiedin order to identify possible connections. No clear correlationbetween the filtration stability (FS) and measured values asfor example grain size distribution or volumetric concentrationof grains has so far been identified. The best correlation forfiltration stability is found between the grain sizedistribution parameter d´ and filtration stability (FS).d´ [µm]is a grain size which corresponds to a amountof grains, normally about 50- 60 % of the total grain sizecontent for grouting cements. d´ is an output parameterfrom the Rosin Rammler Sperling Bennet (RRSB) distribution.Plotting the RRSB grain distribution is a way of describing thedistribution of different grain sizes in a mixture.

  • 41. Engqvist, A
    et al.
    Stenstrom, Petter
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Archipelago strait exchange processes - an overview2004In: Deep-sea research. Part II, Topical studies in oceanography, ISSN 0967-0645, E-ISSN 1879-0100, Vol. 51, no 4-5, p. 371-392Article in journal (Refereed)
    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.

  • 42.
    Fardin, Nader
    KTH, Superseded Departments, Land and Water Resources Engineering.
    The effect of scale on the morphology, mechanics and transmissivity of single rock fractures2003Doctoral thesis, monograph (Other scientific)
    Abstract [en]

    This thesis investigates the effect of scale on themorphology, mechanics and transmissivity of single rockfractures using both laboratory and in-situ experiments, aswell as numerical simulations. Using a laboratory 3D laserscanner, the surface topography of a large silicon-rubberfracture replica of size 1m x 1m, as well as the topography ofboth surfaces of several high-strength concrete fracturereplicas varying in size from 50mmx50mm to 200mm x 200mm, werescanned. A geodetic Total Station and an in-situ 3D laser radarwere also utilized to scan the surface topography of a largenatural road-cut rock face of size 20m x 15m in the field. Thisdigital characterization of the fracture samples was then usedto investigate the scale dependency of the three dimensionalmorphology of the fractures using a fractal approach. Thefractal parameters of the surface roughness of all fracturesamples, including the geometrical aperture of the concretefracture samples, were obtained using the Roughness-Lengthmethod.

    The results obtained from the fractal characterization ofthe surface roughness of the fracture samples show that bothfractal dimension, D, and amplitude parameter, A, for aself-affine surface are scale-dependent, heterogeneous andanisotropic, and their values generally decrease withincreasing size of the sample. However, this scale-dependencyis limited to a certain size—defined as the stationaritythreshold, where the surface roughness parameters of thefracture samples remain essentially constant beyond thisstationarity threshold. The surface roughness and thegeometrical aperture of the tested concrete fracture replicasin this study did not reach stationarity due to the structuralnon-stationarity of their surface at small scales. Although theaperture histogram of the fractures was almost independent ofthe sample size, below their stationarity threshold both theHurst exponent, Hb, and aperture proportionality constant, Gb,decrease on increasing the sample sizes.

    To investigate the scale effect on the mechanical propertiesof single rock fractures, several normal loading and directshear tests were performed on the concrete fracture replicassubjected to different normal stresses under Constant NormalLoad (CNL) conditions. The results showed that both normal andshear stiffnesses, as well as the shear strength parameters ofthe fracture samples, decrease on increasing the sample size.It was observed that the structural non-stationarity of surfaceroughness largely controls the contact areas and damage zoneson the fracture surfaces as related to the direction of theshearing.

    The aperture maps of the concrete fracture replicas ofvarying size and at different shear displacements, obtainedfrom numerical simulation of the aperture evolution duringshearing using their digitized surfaces, were used toinvestigate the effect of scale on the transmissivity of thesingle rock fractures. A FEM code was utilized to numericallysimulate the fluid flow though the single rock fractures ofvarying size. The results showed that flow rate not onlyincreases on increasing the sample size, but also significantlyincreases in the direction perpendicular to the shearing, dueto the anisotropic roughness of the fractures.

    Key words:Anisotropy, Aperture, Asperity degradation,Contact area, Finite Element Method (FEM), Flow analysis,Fractals, Fracture morphology, Heterogeneity,Stress-deformation, Surface roughness, Roughness-Length method,Scale dependency, Stationarity, Transmissivity, 3D laserscanner.

  • 43.
    Fardin, Nader
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Feng, Q.
    Stephansson, Ove
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Application of a new in situ 3D laser scanner to study the scale effect on the rock joint surface roughness2004In: International Journal of Rock Mechanics And Mining Sciences, ISSN 1365-1609, E-ISSN 1873-4545, Vol. 41, no 2, p. 329-335Article in journal (Refereed)
  • 44. Feng, Q.
    et al.
    Fardin, N.
    Jing, Lanru
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Stephansson, O.
    A new method for in-situ non-contact roughness measurement of large rock fracture surfaces2003In: Rock Mechanics and Rock Engineering, ISSN 0723-2632, E-ISSN 1434-453X, Vol. 36, no 1, p. 3-25Article in journal (Refereed)
    Abstract [en]

    This paper presents a new method for in-situ non-contact measurements of fracture roughness by using a total station (TS). The TS is a non-reflector geodetic instrument usually used for measuring control points in surveying and mapping. By using a special-developed program, the TS can be used as a point-sensor laser scanner to scan a defined area of the fracture surface automatically, in field or in laboratory, at a distance away from the target surface. A large fracture surface can be automatically scanned with a constant interval of the sampling points, both within a defined area or along a cross-section of the exposed rock face. To quantify fracture roughness at different scales and obtain different densities of the scanned points, the point interval can be selected with the minimum interval of I rum. A local Cartesian co-ordinate system needs to be established first by the TS in front of the target rock face to define the true North or link the measurements to a known spatial co-ordinate system for both quantitative and spatial analysis of fracture roughness. To validate the method, fracture roughness data recorded with a non-reflector TS was compared with the data captured by a high-accuracy 3D-laser scanner. Results of this study revealed that both primary roughness and waviness of fracture surfaces can be quantified by the TS in the same accuracy level as that of the high accuracy laser scanner. Roughness of a natural fracture surface can be sampled without physical contact in a maximum distance of tens of meters from the rock faces.

  • 45. Feng, Q.
    et al.
    Sjogren, P.
    Stephansson, O.
    Jing, Lanru
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Measuring fracture orientation at exposed rock faces by using a non-reflector total station2001In: Engineering Geology, ISSN 0013-7952, E-ISSN 1872-6917, Vol. 59, no 1-2, p. 133-146Article in journal (Refereed)
    Abstract [en]

    Measurements of fracture orientation are usually taken by using a compass-inclinometer device on exposed rock faces. The drawbacks when using this method is that it is time-consuming if many fractures are measured and that measurement might be impossible if the rock face cannot be safely reached physically. To improve field mapping of rock fractures, a method for applying a non-reflector total station to measuring fracture orientation is presented in this paper. A non-reflector total station is a geodetic device that captures three-dimensional co-ordinates of target points without using a reflector. Therefore, physical touching the rock surfaces is no longer required. To determine a fracture orientation, co-ordinates of a set of points on the exposed fracture surface are captured at a distance from the rock face. The best-fit plane of the exposed fracture surface is defined by the co-ordinates of the target points, and the orientation (e.g. dip angle and dip direction) of the fracture surface is determined as that of its best-fit plane. This paper presents the technical procedure and a portable system designed for the field mapping of fracture orientation. Results of a case study performed at an exposed rock face are also included.

  • 46. Fiori, A.
    et al.
    Berglund, S.
    Cvetkovic, Vladimir
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Dagan, G.
    A first-order analysis of solute flux statistics in aquifers: The combined effect of pore-scale dispersion, sampling, and linear sorption kinetics2002In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 38, no 8Article in journal (Refereed)
    Abstract [en]

    [1] We consider steady groundwater flow of uniform mean in aquifers of random, spatially variable, hydraulic conductivity. Analytical expressions for the statistical moments of mass fluxes of sorbing solutes in presence of pore-scale dispersion are derived, where the reactive solutes undergo first-order sorption kinetics. The developments which lead to the analytical formulation of the solute flux are rigorous in the first-order analysis framework, and results obtained are valid for weakly heterogeneous formations. The methodology is exemplified for a two-dimensional aquifer, assuming that the source is of small transverse extent compared to the heterogeneity length scales. The examples show that pore-scale dispersion has a relatively small effect on the mean point flux, whereas the point flux variance shows much larger sensitivity to pore-scale dispersion. The variance first decreases as the reaction rate departs from the nonreactive limit, but for equilibrium reactions it is of the same order as for nonreactive solutes. The effect of averaging the solute flux over a finite sampling area is also investigated. It is found that for the expected area-averaged flux the mixing effect induced by sampling tends to supersede that caused by pore-scale dispersion. On the contrary, pore-scale dispersion may have a strong effect on the flux variance also when sampling effects are taken into account.

  • 47.
    Fridolf, Tina
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Dam safety in a hydrological perspective-Case study of the historical water system of Sala Silver Mine2004Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    The old water system in Sala, formerly belonging to thesilver mine, is analysed with regard to dam safety focusing onthe hydrological aspects. The hydrological safety of the riskclass I dams in the area, built in the 16th century, is notconsidered adequate according to the Swedish guidelines fordesign flood determination. A review is made of internationalprinciples for design flood determination. The overview showsthat there is no common principle used internationally whendealing with design flood for dams. In some countries there isan ambition to implement risk assessment for evaluation ofhydrological safety. However, at present Australia is the onlycountry that has fully integrated risk assessment in theirdesign flood guidelines. A risk assessment of the water systemin Sala shows that neither increasing the spillway capacity norimplementing flood mitigation measures in the watershed haveany significant effect on dam safety in the area. Nothingindicates that watersheds with a high presence of mires, likein the Sala case, should be particularly well suited forimplementing flood mitigation in the watershed as a dam safetymeasure. In order to safely handle the design flood in Sala andavoid dam failure due to overtopping the flood needs to bediverted from the water system.

    Key words:dam safety; design flood; flood mitigation;hydrological; risk assessment

  • 48.
    Ghebremichael, Kebreab Afwerki
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Moringa seed and pumice as alternative natural materials for drinking water treatment2004Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Pumice and the Moringa oleifera (MO) seed were investigated as alternative natural materials for drinking water treatment based on problems identified at the Stretta Vaudetto water treatment plant in Eritrea.

    Lab and pilot scale studies showed that pumice was a suitable alternative material for dual media filtration. Conversion of the sand filters at Stretta Vaudetto to pumice-sand media would significantly improve performance of the filtration units. The coagulant protein from the MO seed was purified in a single-step ion exchange purification method. The parameters for batch purification were optimized that can be readily scaled up. This will promote its use in water treatment.

    A small volume coagulation assay method was developed that simplified and expedited the coagulation activity experiments. MO coagulant protein (MOCP) possessed considerable coagulation and sludge conditioning properties as alum. It also showed antimicrobial effects against bacteria, some of which are antibiotic resistant. The coagulation and antimicrobial properties of MOCP render it important in water treatment.

  • 49.
    Ghebremichael, Kebreab
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Hultman, Bengt
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Alum sludge dewatering using Moringa oleifera as a conditioner2004In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 158, no 1, p. 153-167Article in journal (Refereed)
    Abstract [en]

    An active component of Moringa oleifera ( MO) has been used in comparison with synthetic polymers and alum for the conditioning of chemical sludge from a drinking water treatment plant. The comparison was based on dewatering characteristics of the conditioned sludge determined by capillary suction time (CST), specific resistance to filtration (SRF), sand column drainage and shear strength tests. The results indicated that MO showed comparable conditioning effect as alum. Polyelectrolytes were more effective than MO and alum. Sludge conditioned with MO and alum, as in dual chemical conditioning, showed better results than MO alone. According to CST, SRF and sand drainage results, optimum doses for MO, alum and polyelectrolytes were 125, 63, and 1.8 kg/t, respectively. Comparison of the two polyelectrolytes showed that the cationic polyelectrolyte was more effective. For sand drainage tests both polyelectrolytes improved the drainage rate by 2 orders of magnitude. MO and alum improved the drainage rate by about 4.2 times. On the other hand, the improvements in cake solids concentration were similar for all the chemical conditioners. Flocs from MO and alum were relatively stronger compared to those of the polyelectrolytes. From the results of the study it could be concluded that MO alone or in combination could be effectively used and replace alum for dewatering of chemical sludge.

  • 50.
    Grünfeld, Katrin
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Interactive visualization applied to multivariate geochemical data: A case study2003In: Journal de Physique IV: Colloque, ISSN 1155-4339, E-ISSN 1764-7177, Vol. 107, p. 577-580Article in journal (Refereed)
    Abstract [en]

    Geochemical survey data have commonly been analysed combining methods from several disciplines - statistics, geostatistics, geographic information technology, visualization. In initial stages of analysis, tables are often used to describe the data and present statistical measures. For too often the original data are manipulated in one or another way, for example, using mathematical transformations, or interpolation of points to a surface. It is the author's opinion that raw geochemical data should be used in initial stages of data description, thus preserving the original details. This is not a simple task, as geochemical data are commonly complex, multivariate, and collected on irregular grid. Data contain outliers, element contents vary within thousands of ppm (parts per million), and different chemical elements may be correlated. In the present study a graphical approach has been used to study distribution of 5 heavy metals in glacial till. Using interactive visualization and multiple linked views of the data, the following issues were addressed: multi-element outliers, spatial trends, multi-element correlations and patterns. Interactive graphical techniques proved to be especially suitable for studying outliers and identifying and locating samples that are redundant and may be removed from data without loss of information. Visualization using linked views gave valuable insights about metal correlations and spatial trends. As the development of appropriate tools for analysing multivariate spatial data are still in its early stages, visualization freeware seems to be a good alternative providing powerful, easy to use and intuitive techniques for exploratory data analysis.

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