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  • 301.
    Gingborn, Nicklas
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Wåhlén, Hanna
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Investigating sustainable mitigation alternatives for groundwater in Matlab Upazila, Bangladesh.:  A Minor Field Study.2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Since the late 20th century most people in rural Bangladesh use hand pumped tube wells to extract groundwater as their primary source of water. In 1993 it was officially recognized that many of the Holocene groundwater aquifers contain elevated levels of arsenic (As) and that millions of people in Bangladesh are exposed and at risk for mass poisoning. The need to focus efforts to areas with scarce supply of safe drinking water has raised the need to quickly locate and identify these areas. Mitigation options evaluated in this study focus on 1) how to target As safe aquifers and 2) how to identify As safe tube wells

    An attempt to target As safe shallow aquifers based on sediment color was evaluated. The majority of 30 new tube wells screened in off-white sand sediments have As safe water with respect to both the WHO and the national guideline, but including the failed attempts to target off-white sediments at shallow depths, the success rate of the method was considered to be too low.

    This study also attempt to validate platform color as a rapid low-cost screening tool for As by relating platform color to water chemistry in 103 tube wells. Different classification methods were tested to develop recommendations for the future use of this method. The results showed that a simplified color classification was better than a detailed classification at predicting water chemistry of iron (Fe), manganese (Mn) and As.

    Recently, Mn has also emerged as a possible widespread problem in the Bengal Basin. Although not thoroughly investigated, present evidence indicates that a high concentration of Mn in drinking water affects the intellectual function in children. The occurrence of both low As and low Mn concentrations in shallow aquifers was found to be very unlikely since only one out of 133 tested wells had this water chemistry composition. Instead it was showed that the highest Mn concentrations occur in As-safe aquifers. Therefore WHO should consider reintroducing their previous health based guideline value for Mn to highlight the potential risk of excessive exposure, since more people risk being exposed to Mn when As-safe shallow aquifers are targeted.

  • 302.
    Girtz, Anne Marie
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    Hydraulic and Hydrodynamic Stormwater Model for the Västanfors Area of the Municipality of Fagersta, Sweden: Climate Change Impacts and Future Stormwater Management2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Global temperatures and frequency of extreme weather events have increased over the last decade, with 2015 globally the warmest year on record. Future climate models are consistent with this trend, predicting larger year-to-year variations in precipitation, more precipitation in larger single events, and more frequent extreme events.

    Changes in weather phenomena due to climate change will impact the infrastructure in cities and therefore the vulnerability of society. Today’s urban stormwater systems are closely related to local hydrological characteristics, with systems designed to accommodate specific ranges of rainfall based on historical data. An increase in rainfall or extreme weather events may result in capacity problems for these systems and in turn, negative impacts to people and the environment.

    Stormwater management in Sweden is guided by municipal plans and country-wide design standards. Within these documents there is information on who is responsible and what standards must be met, but there is a lack of specific requirements on how to undertake these tasks. Recently, Svenskt Vatten has started to recognize the need for a more defined stormwater management methodology, and commissioned a study titled ‘Guidelines for the modelling of wastewater carrying systems and stormwater systems’.

    While larger municipalities have the resources to develop hydraulic models, smaller municipalities are often left out of this drive for proactive management. Often, there is no requirement for master planning initiatives, and more realistically, no budget to implement such initiatives. Thus, stormwater management is left to conventional methods and often undertaken on an as-needed basis, with minimal long-term planning.

    This thesis shows how a hydraulic computer model can serve as a simple, low-cost tool to assist municipalities – especially those of smaller size - in the sustainable planning and management of their stormwater systems. A case study was used to exemplify the objective, by demonstrating a proposed methodology that can be used to assess the impacts of climate change on urban infrastructure.

    This study was undertaken in collaboration with ÅF Infrastructure AB in Stockholm and the municipality of Fagersta, Sweden.

  • 303.
    Gontier, Mikael
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Biodiversity in environmental assessment: tools for impact prediction2005Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Urbanisation and infrastructure developments impact on the surrounding natural environment and threaten biodiversity. The fragmentation of natural habitats in particular is a major obstacle for the preservation of biodiversity in a long-term perspective. In the planning process, both the environmental impact assessment and strategic environmental assessment processes play a central role in the identification and prediction of impacts on biodiversity. At the same time, the devel-opment of GIS technologies and GIS-based ecological models offer new perspectives in the elaboration of predictions. In order to analyse current practices and identify the need for im-provements in the environmental impact process, a review of environmental impact assessment reports was carried out. Further, a review of existing GIS methods and GIS-based ecological models is presented. The results of the review of environmental impact assessment reports show a lack of predictions in current biodiversity assessments. These asssessments often concentrate on impacts at the local scale, failing to consider large-scale and widespread impacts at the ecosys-tem and landscape levels. The review of GIS methods and GIS-based ecological models demon-strate the possibility to generate quantitative predictions for a specific area as well as for it’s sur-rounding environment. At the same time, the flexibility and reproducibility of such methods would allow predictions to be made for different alternatives or scenarios, therefore providing decision makers with relevant information of potential impacts on biodiversity. This would, in turn, result in an improved integration of biodiversity issues in physical planning and contribute to a sustainable development.

  • 304.
    Gontier, Mikael
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Management and Assessment.
    Integrating landscape ecology in environmental impact assessment using GIS and ecological modelling2006In: From landscape research to landscape planning / [ed] Tress, B., Tress, G. and Opdam, P., Springer, 2006, p. 345-354Chapter in book (Refereed)
    Abstract [en]

    Ecological assessment in environmental impact assessment and strategic environmental assessment processes requires improvements. The descriptive and qualitative nature of many ecological assessments suggests a need to develop and implement quantitative and predictive methods to assess problems such as fragmentation and impacts on biodiversity. Such tools, from basic GIS applications to more advanced ecological models, already exist and have reached a level of development that allows practical implementation outside the research sphere. The chapter presents a literature review on the potential application and advantages of ecological models and GIS-based methods in carrying out ecological assessments in the Environmental Impact Assessment and Strategic Environmental Assessment processes. The implementation of such tools translates into practice certain concepts of landscape ecology related to ecological dynamic or spatial and temporal scales. Although data requirements and the complexity of ecological models are limitations to their reproducibility and application range, the integration of landscape-ecology concepts in ecological assessment through the use of ecological models and GIS tools would contribute to the sustainable management of landscapes and their ecological resources. Finally, I argue that predictive modelling and GIS tools can also serve as a platform to integrate other landscape components that can be characterized spatially such as recreational and cultural values.

  • 305.
    Gontier, Mikael
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Management and Assessment.
    Scale issues in the assessment of ecological impacts using a GIS-based habitat model: A case study for the Stockholm region2007In: Environmental impact assessment review, ISSN 0195-9255, E-ISSN 1873-6432, Vol. 27, no 5, p. 440-459Article in journal (Refereed)
    Abstract [en]

    Environmental Impact Assessment (EIA) and Strategic Environmental Assessment (SEA) provide two interlinked platforms for the assessment of impacts on biodiversity caused by human developments. Although it might be too early to draw conclusions on the efficiency of SEA to assess such impacts, a number of persistent problems have been identified in the case of EIA. Some of these shortcomings concern the lack of proper prediction and impact quantification, and the inadequate/insufficient assessment of cumulative effects. A number of problems are related to the scale(s) at which the assessment is performed. SEA may provide a more adequate framework than EIA to discuss scale-related issues (i.e. cumulative impacts) but it also requires the use of adapted tools. This paper presents a case study where a GIS-based habitat model for the lesser spotted woodpecker is tested, validated and applied to a planning scenario in the Stockholm region in Sweden. The results show that the method adopted offers great prospects to contribute to a better assessment of biodiversity-related impacts. Even though some limitations remain in the form of data requirement and interpretation of the results, the model produced continuous, quantified predictions over the study area and provided a relevant basis for the assessment of cumulative effects. Furthermore, this paper discusses potential conflicts between different scales involved in the assessment - related to administrative boundaries, ecological processes, data availability, the method adopted to perform the assessment and temporal aspects.

  • 306.
    Gontier, Mikael
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Management and Assessment.
    Spatial prediction tools for biodiversity in environmental assessment2008Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Human activities in the form of land use changes, urbanisation and infrastructure developments are major threats to biodiversity. The loss and fragmentation of natural habitats are great obstacles for the long term preservation of biodiversity and nature protection measures alone may not be sufficient to tackle the problem. Environmental impact assessment (EIA) and strategic environmental assessment (SEA) play a central role in identifying, predicting and managing the impacts of human activities on biodiversity. The review of current practice suggests that the complexity of the task is underestimated and that new methodological approaches encompassing the entire landscape are needed. Spatial aspects of the assessment and the lack of information on scale-related issues are particular problems affecting the appropriate assessment of cumulative effects. In parallel with the development and establishment of EIA and SEA, spatial modelling is an expanding field in ecology and many derived applications could be suitable for the prediction and assessment of biodiversity-related impacts. The diversity of modelling methods suggests that a strategy is needed to identify prediction methods appropriate for EIA and SEA. The relevance and potential limitations of GIS-based species distribution and habitat models in predicting impacts on biodiversity were examined in three studies in the greater Stockholm area. Distinct approaches to habitat suitability modelling were compared from the perspective of environmental assessment needs and requirements. The results showed that model performance, validity and ultimate suitability for planning applications were strongly dependent on empirical data and expert knowledge. The methods allowed visual, qualitative and quantitative assessment of habitat loss, thus improving decision support for assessment of impacts on biodiversity. The proposed methods allowed areas of high ecological value and the surrounding landscape to be considered in the same assessment, thereby contributing to better integration of biodiversity issues in physical planning.

  • 307.
    Gontier, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Management and Assessment.
    Balfors, Berit
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Management and Assessment.
    Mörtberg, Ulla
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Management and Assessment.
    Biodiversity in environmental assessment: current practice and tools for prediction2006In: Environmental impact assessment review, ISSN 0195-9255, E-ISSN 1873-6432, Vol. 26, no 3, p. 268-286Article in journal (Refereed)
    Abstract [en]

    Habitat loss and fragmentation are major threats to biodiversity. Environmental impact assessment and strategic environmental assessment are essential instruments used in physical planning to address such problems. Yet there are no well-developed methods for quantifying and predicting impacts of fragmentation on biodiversity. In this study, a literature review was conducted on GIS-based ecological models that have potential as prediction tools for biodiversity assessment. Further, a review of environmental impact statements for road and railway projects from four European countries was performed, to study how impact prediction concerning biodiversity issues was addressed. The results of the study showed the existing gap between research in GIS-based ecological modelling and current practice in biodiversity assessment within environmental assessment.

  • 308.
    Gontier, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Management and Assessment.
    Eggers, Sönke
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala.
    Mörtberg, Ulla
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Management and Assessment.
    Lindström, Åke
    Department of Ecology, Lund University.
    Modelling habitat preferences and differences in two Parus species in an urbanising region2008In: Conservation Biology, ISSN 0888-8892, E-ISSN 1523-1739Article in journal (Refereed)
  • 309.
    Gontier, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Management and Assessment.
    Mörtberg, Ulla
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Management and Assessment.
    Balfors, Berit
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Management and Assessment.
    Comparing GIS-based habitat models for applications in EIA and SEA2010In: Environmental impact assessment review, ISSN 0195-9255, E-ISSN 1873-6432, Vol. 30, no 1, p. 8-18Article in journal (Refereed)
    Abstract [en]

    Land use changes. urbanisation and infrastructure developments in particular. cause fragmentation of natural habitats and threaten biodiversity. Tools and measures must be adapted to assess and remedy the potential effects on biodiversity caused by human activities and developments. Within physical planning, environmental impact assessment (EIA) and strategic environmental assessment (SEA) play important roles in the prediction and assessment of biodiversity-related impacts from planned developments. However, adapted prediction tools to forecast and quantify potential impacts on biodiversity components are lacking. This study tested and compared four different CIS-based habitat models and assessed their relevance for applications in environmental assessment. The models were implemented in the Stockholm region in central Sweden and applied to data on the crested tit (Parus cristatus), a sedentary bird species of coniferous forest. All four models performed well and allowed the distribution of suitable habitats for the crested tit in the Stockholm region to be predicted. The models were also used to predict and quantify habitat loss for two regional development scenarios. The study highlighted the importance of model selection in impact prediction. Criteria that are relevant for the choice of model for predicting impacts on biodiversity were identified and discussed. Finally, the importance of environmental assessment for the preservation of biodiversity within the general frame of biodiversity conservation is emphasised.

  • 310.
    Gontier, Mikael
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Olofsson, Bo
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Areell sårbarhetsbedömning för grundvattenpåverkan av vägföreningar2003Report (Other academic)
  • 311.
    Gonzales, Valentina
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    Åberg, Henrietta
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    Seepage, stability and pollution transport of an upstream tailing dam with COMSOL.2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the early years of the 20th century the first tailing dams were constructed, the upstream tailing dam being the first type. Before this the tailings were disposed in the nearest stream or river. This caused legal issues between farmers and the mining companies, which ended the random discharge of the tailings. During the 20th century many tailing dams collapsed raising questions whether the technology is sufficient and safe. The known failures are just a fraction of the actual number since not all failures are documented. If a tailing dam were to break the consequenses could be fatal not only on impact but longterm, affecting many generations to come. This paper analyses an active tailing dam in China using the software COMSOL 3.4. The main aspects are the seepage, stability and pollution transport of the unsaturated upstream tailing dam. The results indicate that the dam at this point in time is stable, based on the aspects studied, the inputdata and models that were created.

  • 312.
    González Sánchez, María Fernanda
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    Separate treatment of wash water from sand filter using disc filter technology.2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study is to evaluate the convenience and effectiveness of using a disc filter to treat washing water from the sand filters at Sundet wastewater treatment plant. The disc filter is used aiming for the reduction of suspended solids and phosphorus. The study was divided in two main experimental stages. During the first stage laboratory jar-tests were performed in order to identify which flocculation aid was more suitable, this was further on used to improve the water treatment. Based on the laboratory trials results, two different polymers (1 and 2) were chosen to be tested at pilot scale. The second stage involved the pilot filter operation itself; this period was as well divided in two sub-stages where filter cloths with two different pore openings were tested. During the first sub-stage the pilot operated with an 18 μm pore opening filters cloth and both polymers. At the end of the first half polymer 1 showed to be more efficient and so it was further used throughout the second sub-stage in combination with a 10μm pore opening filter cloth. As from theoretical knowledge the phosphorus and suspended solid removal were expected to be between 75% and 90%, results which were achieved during both laboratory trials and pilot filter. The best results were observed with the 10μm pore opening filter cloth and polymer 1. Also, additional results from pilot trials performed at Sundet after the study period are presented.

  • 313.
    Gotovac, Hrvoje
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    A multi-resolution approach for modeling flow and solute transport in heterogeneous porous media2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Subsurface processes are usually characterized by rare field experiments, sparse measurements,multi-resolution interpretations, stochastic description, related uncertainties and computational complexity. Over the last few decades, different computational techniques and strategies have become indispensable tools for flow and solute transport prediction in heterogeneous porousmedia. This thesis develops a multi-resolution approach based on Fup basis functions with compactsupport, enabling the use of an efficient and adaptive procedure, closely related to currentunderstood physical interpretation. All flow and transport variables, as well as intrinsic heterogeneity,are described in a multi-resolution representation, in the form of a linear combination ofFup basis functions. Each variable is represented on a particular adaptive grid with a prescribedaccuracy. The methodology is applied to solving problems with sharp fronts, and to solving flowand advective transport in highly heterogeneous porous media, under mean uniform flow conditions.The adaptive Fup collocation method, through the well known method of lines, efficientlytracks solutions with sharp fronts, resolving locations and frequencies at all spatial and/or temporalscales. The methodology yields continuous velocity fields and fluxes, enabling accurate andreliable transport analysis. Analysis of the advective transport proves the robustness of the firstordertheory for low and mild heterogeneity. Moreover, due to the accuracy of the improved Monte-Carlo methodology, this thesis presents the effects of high heterogeneity on ensembleflow and travel time statistics. The difference between Eulerian and Lagrangian velocity statisticsand the importance of higher travel time moments are indicative of high heterogeneity. The thirdtravel time moment mostly describes a peak and late arrivals, while higher moments are requiredfor early arrivals which are linked with the largest uncertainty. A particular finding is the linearityof all travel time moments, which implies that in the limit an advective transport in multi-Gaussian field becomes Fickian. By comparison, the transverse displacement pdf converges to aGaussian distribution around 20 integral scales after injection, even for high heterogeneity. Thecapabilities of the presented multi-resolution approach, and the quality of the obtained results,open new areas for further research.

  • 314.
    Gotovac, Hrvoje
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Andricevic, Roko
    Univ. Split.
    Gotovac, Blaz
    Univ. Split.
    Multi-resolution adaptive modeling of groundwater flow and transport problems2007In: Advances in Water Resources, ISSN 0309-1708, E-ISSN 1872-9657, Vol. 30, p. 1105-1126Article in journal (Refereed)
    Abstract [en]

    Many groundwater flow and transport problems, especially those with sharp fronts, narrow transition zones, layers and fingers, require extensive computational resources. In this paper, we present a novel multi-resolution adaptive Fup approach to solve the above mentioned problems. Our numerical procedure is the Adaptive Fup Collocation Method (AFCM), based on Fup basis functions and designed through a method of lines (MOL). Fup basis functions are localized and infinitely differentiable functions with compact support and are related to more standard choices such as splines or wavelets. This method enables the adaptive multi-reso In tion approach to solve problems with different spatial and temporal scales with a desired level of accuracy using the entire family of Fup basis functions. In addition, the utilized collocation algorithm enables the mesh free approach with consistent velocity approximation and flux continuity due to properties of the Fup basis functions. The introduced numerical procedure was tested and verified by a few characteristic groundwater flow and transport problems, the Buckley-Leverett multiphase flow problem, the 1-D vertical density driven problem and the standard 2-D seawater intrusion benchmark-Henry problem. The results demonstrate that the method is robust and efficient particularly when describing sharp fronts and narrow transition zones changing in space and time.

  • 315.
    Gotovac, Hrvoje
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Water Resources Engineering.
    Andricevic, Roko
    Adaptive Fup multi-resolution approach to flow and advective transport in highly heterogeneous porous media: Methodology, accuracy and convergence2009In: Advances in Water Resources, ISSN 0309-1708, E-ISSN 1872-9657, Vol. 32, no 6, p. 885-905Article in journal (Refereed)
    Abstract [en]

    In this paper, we present a new Monte-Carlo methodology referred to as Adaptive Fup Monte-Carlo Method (AFMCM) based on compactly supported Fup basis functions and a multi-resolution approach. We consider for illustration 2-D steady, linear and unidirectional flow and advective transport defined on a domain of size 64I(Y) * 32I(Y) with isotropic exponential correlation heterogeneity structure and sigma(2)(Y) up to 8. Accuracy and convergence issues are rigorously analyzed for each realization as well as for the ensemble. Log-conductivity is presented by continuous function at high resolution level (n(Y) = 4-32 points per integral scale) reproducing very accurately prescribed statistics. The flow problem is the most demanding Monte-Carlo step due to satisfying detailed log-conductivity properties. Presented methodology inherently gives continuous and mesh-free velocity fields, which enables the construction of a new efficient and accurate particle tracking algorithm. Results indicate that resolutions n(Y) = 8 and n(h) = 32 enable very accurate flow solutions in each realization with mass balance error less than 3% and accurate ensemble velocity statistics. Results show that the proposed AFMCM enables tracking of an unlimited number of injected particles and calculates required transport variables as continuous functions with desired relative accuracy (0.1%) in each realization. Furthermore, we show that the resolution n(Y) = 8 yields a quite accurate pdf of the transverse displacement and travel time. All required flow and transport variables require 500 Monte-Carlo realizations in order to stabilize fluctuations of the higher-order moments and the probability density functions.

  • 316.
    Gotovac, Hrvoje
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Andricevic, Roko
    Flow and travel time statistics in highly heterogeneous porous media2009In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 45, no W07402Article in journal (Refereed)
    Abstract [en]

    In this paper we present flow and travel time ensemble statistics based on a new simulation methodology, the adaptive Fup Monte Carlo method (AFMCM). As a benchmark case, we considered two-dimensional steady flow in a rectangular domain characterized by multi-Gaussian heterogeneity structure with an isotropic exponential correlation and lnK variance sigma(2)(Y) up to 8. Advective transport is investigated using the travel time framework where Lagrangian variables (e. g., velocity, transverse displacement, or travel time) depend on space rather than on time. We find that Eulerian and Lagrangian velocity distributions diverge for increasing lnK variance due to enhanced channeling. Transverse displacement is a nonnormal for all sigma(2)(Y) and control planes close to the injection area, but after xI(Y) = 20 was found to be nearly normal even for high sigma(2)(Y). Travel time distribution deviates from the Fickian model for large lnK variance and exhibits increasing skewness and a power law tail for large lnK variance, the slope of which decreases for increasing distance from the source; no anomalous features are found. Second moment of advective transport is analyzed with respect to the covariance of two Lagrangian velocity variables: slowness and slope which are directly related to the travel time and transverse displacement variance, which are subsequently related to the longitudinal and transverse dispersion. We provide simple estimators for the Eulerian velocity variance, travel time variance, slowness, and longitudinal dispersivity as a practical contribution of this analysis. Both two-parameter models considered (the advection-dispersion equation and the lognormal model) provide relatively poor representations of the initial part of the travel time probability density function in highly heterogeneous porous media. We identify the need for further theoretical and experimental scrutiny of early arrival times, and the need for computing higher-order moments for a more accurate characterization of the travel time probability density function. A brief discussion is presented on the challenges and extensions for which AFMCM is suggested as a suitable approach.

  • 317.
    Gotovac, Hrvoje
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Cvetkovic, Vladimir
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Andricevic, Roko
    Significance of higher order moments to the completecharacterization of the travel time pdf in heterogeneous porous media using the maximum entropyprinciple2010In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 46, no W05502Article in journal (Refereed)
    Abstract [en]

    The travel time formulation of advective transport in heterogeneous porous media is of interest both conceptually, e. g., for incorporating retention processes, and in applications where typically the travel time peak, early, and late arrivals of contaminants are of major concern in a regulatory or remediation context. Furthermore, the travel time moments are of interest for quantifying uncertainty in advective transport of tracers released from point sources in heterogeneous aquifers. In view of this interest, the travel time distribution has been studied in the literature; however, the link to the hydraulic conductivity statistics has been typically restricted to the first two moments. Here we investigate the influence of higher travel time moments on the travel time probability density function (pdf) in heterogeneous porous media combining Monte Carlo simulations with the maximum entropy principle. The Monte Carlo experimental pdf is obtained by the adaptive Fup Monte Carlo method (AFMCM) for advective transport characterized by a multi-Gaussian structure with exponential covariance considering two injection modes (in-flux and resident) and lnK variance up to 8. A maximum entropy (MaxEnt) algorithm based on Fup basis functions is used for the complete characterization of the travel time pdf. All travel time moments become linear with distance. Initial nonlinearity is found mainly for the resident injection mode, which exhibits a strong nonlinearity within first 5I(Y) for high heterogeneity. For the resident injection mode, the form of variance and all higher moments changes from the familiar concave form predicted by the first-order theory to a convex form; for the in-flux mode, linearity is preserved even for high heterogeneity. The number of moments sufficient for a complete characterization of the travel time pdf mainly depends on the heterogeneity level. Mean and variance completely describe travel time pdf for low and mild heterogeneity, skewness is dominant for lnK variance around 4, while kurtosis and fifth moment are required for lnK variance higher than 4. Including skewness seems sufficient for describing the peak and late arrivals. Linearity of travel time moments enables the prediction of asymptotic behavior of the travel time pdf which in the limit converges to a symmetric distribution and Fickian transport. However, higher-order travel time moments may be important for most practical purposes and in particular for advective transport in highly heterogeneous porous media for a long distance from the source.

  • 318.
    Gotovac, Hrvoje
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Gotovac, Blaz
    Maximum entropy algorithm with inexact upper entropy bound based on Fup basis functions with compact support2009In: Journal of Computational Physics, ISSN 0021-9991, E-ISSN 1090-2716, Vol. 228, no 24, p. 9079-9091Article in journal (Refereed)
    Abstract [en]

    The maximum entropy (MaxEnt) principle is a versatile tool for statistical inference of the probability density function (pdf) from its moments as a least-biased estimation among all other possible pdfs. It maximizes Shannon entropy, satisfying the moment constraints. Thus, the MaxEnt algorithm transforms the original constrained optimization problem to the unconstrained dual optimization problem using Lagrangian multipliers. The Classic Moment Problem (CMP) uses algebraic power moments, causing typical conventional numerical methods to fail for higher-order moments (m > 5-10) due to different sensitivities of Lagrangian multipliers and unbalanced nonlinearities. Classic MaxEnt algorithms overcome these difficulties by using orthogonal polynomials, which enable roughly the same sensitivity for all Lagrangian multipliers. In this paper, we employ an idea based on different principles, using Fup(n) basis functions with compact support, which can exactly describe algebraic polynomials, but only if the Fup order-n is greater than or equal to the polynomial's order. Our algorithm solves the CMP with respect to the moments of only low order Fup(2) basis functions, finding a Fup(2) optimal pdf with better balanced Lagrangian multipliers. The algorithm is numerically very efficient due to localized properties of Fup(2) basis functions implying a weaker dependence between Lagrangian multipliers and faster convergence. Only consequences are an iterative scheme of the algorithm where power moments are a sum of Fup(2) and residual moments and an inexact entropy upper bound. However, due to small residual moments, the algorithm converges very quickly as demonstrated on two continuous pdf examples - the beta distribution and a bi-modal pdf, and two discontinuous pdf examples - the step and double Dirac pdf. Finally, these pdf examples present that Fup MaxEnt algorithm yields smaller entropy value than classic MaxEnt algorithm, but differences are very small for all practical engineering purposes.

  • 319.
    Granlund, Nils
    et al.
    Luleå University of Technology.
    Gustafsson, David
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Lundberg, Angela
    Luleå University of Technology.
    Snow Salinity Influence on the Relationship between Electrical: Conductivity of Snow and Snow Wetness2009In: 65th Annual Eastern Snow Conference, 2009Conference paper (Other academic)
  • 320. Granlund, Nils
    et al.
    Lundberg, Angela
    Feiccabrino, James
    Gustafsson, David
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Laboratory test of snow wetness influence on electrical conductivity measured with ground penetrating radar2009In: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 40, no 1, p. 33-44Article in journal (Refereed)
    Abstract [en]

    Ground penetrating radar operated from helicopters or snowmobiles is used to determine snow water equivalent (SWE) for annual snowpacks from radar wave two-way travel time. However, presence of liquid water in a snowpack is known to decrease the radar wave velocity, which for a typical snowpack with 5% (by volume) liquid water can lead to an overestimation of SWE by about 20%. It would therefore be beneficial if radar measurements could also be used to determine snow wetness. Our approach is to use radar wave attenuation in the snowpack, which depends on electrical properties of snow (permittivity and conductivity) which in turn depend on snow wetness. The relationship between radar wave attenuation and these electrical properties can be derived theoretically, while the relationship between electrical permittivity and snow wetness follows a known empirical formula, which also includes snow density. Snow wetness can therefore be determined from radar wave attenuation if the relationship between electrical conductivity and snow wetness is also known. In a laboratory test, three sets of measurements were made on initially dry 1m thick snowpacks. Snow wetness was controlled by stepwise addition of water between radar measurements, and a linear relationship between electrical conductivity and snow wetness was established.

  • 321. Granlund, Nils
    et al.
    Lundberg, Angela
    Gustafsson, David
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    Laboratory study of the influence of salinity on the relationship between electrical conductivity and wetness of snow2010In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 24, no 14, p. 1981-1984Article in journal (Refereed)
    Abstract [en]

    Snow water equivalent of a snowpack can be estimated using ground-penetrating radar from the radar wave two-way travel time. However, such estimates often have low accuracy when the snowpack contains liquid water. If snow wetness is known, it is possible to take it into account in the estimates; it is therefore desirable to be able to determine snow wetness from already available radar data. Our approach is based on using radar wave attenuation, and it requires that the relationship between electrical conductivity and wetness of snow should be known. This relationship has been tentatively established in previous laboratory experiments, but only for a specific liquid water salinity and radar frequency. This article presents the results of new laboratory experiments conducted to investigate if and how this relationship is influenced by salinity. In each experiment, a certain amount of snow was melted and a known amount of salt (different for different experiments) was added to the water. Water salinity was measured, and the water was added step-wise to a one-meter thick snowpack, with radar measurements taken between additions of water. Our experiments have confirmed the earlier established linear relationship between electrical conductivity and wetness of snow, and they allow us to suggest that the influence of liquid water salinity on electrical conductivity is negligible when compared to the influence of liquid water content in snow.

  • 322.
    Granlund, Nils
    et al.
    Luleå University of Technology.
    Lundberg, Angela
    Luleå University of Technology.
    Gustafsson, David
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Ahlberg, Jesper
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Wetterhall, Fredrik
    Sveriges Meteorologiska och Hydrologiska Institut.
    Towards better predictions of snow melt runoffs: Measuring Snow Depth and Density Using Ground Penetrating Radar2009Conference paper (Other academic)
    Abstract [en]

    Snow melt runoff predictions by hydrological models are essential for efficient hydropower production in the Scandinavian countries, similar to many areas with a substantial amount of snow precipitation. Operational models in Sweden are currently based on precipitation and temperature as the main input variables and calibrated with runoff data, but there is an interest to make better use of new measurement systems for distributed snow data, especially the total amount of snow in the catchment area of interest. The main objective of our project is to investigate the potential improvements in runoff predictions in relation to the choice of model structure and measurement systems, as well as measurement accuracy. This involves comparing different methods for estimating the total amount of snow in a catchment area as well as improving their accuracy. Here we present the result of such comparison based on data from case studies conducted in Sweden. Our approach involves automated single point measurements over a long period in combination with high resolution distributed measurements over a large area during critical periods. Stationary measurements are performed at a snow measurement station, with snow density and wetness estimated with a low-frequency impedance sensor band, snow depth measured using an ultrasonic depth gauge, and temperature measured at several (fixed) snow depths and at the snow surface. The station, located at Lake Korsvattnet in Swedish mountains, operates continuously during the whole winter season. Measurements of snow depth and density over large lateral distances are performed using multi-offset ground penetrating radar (GPR) operated from a snow mobile. These measurements are conducted once a year, in late winter, when the amount of snow is expected to reach its maximum before snow melt begins. Since 2007 and during the duration of the project, yearly measurements have been and will be taken in two Swedish mountain basins important for hydropower, Lake Korsvattnet and Lake Kultsjön. The radar system used is a multi-channel RAMAC/GPR system with shielded 800 and 1600 MHz antennas. The antennas are attached to a snow mobile sledge forming an array, which allows us to use the common midpoint method to calculate both radar propagation velocity and two-way travel time of radar pulses. For dry snow this gives snow density and depth via an empirical formula establishing the relationship between electrical permittivity (i.e. propagation velocity) and snow density. Note that for wet snow additional information about liquid water content in snow is required, which can be estimated, for example, from radar wave attenuation. However, for the purpose of this presentation we assume that the snow is dry. The results of GPR measurements taken from a snow mobile are compared with results obtained by two other methods. The first comparison is with manual measurements taken with traditional snow tubes along a 1000 m measurement profile at the area of Lake Korsvattnet. In this case a log-linear relationship between snow depth and density is used to interpret GPR data (note that this relationship is obtained from analysis of radar data itself). The other comparison is with GPR measurements taken from a helicopter along a 12 km transect in the area of Lake Kultsjön.

  • 323.
    Grünfeld, Katrin
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Dealing with outliers and censored values in multi-element geochemical data: a visualization approach using XmdvTool2005In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 20, no 2, p. 341-352Article in journal (Refereed)
    Abstract [en]

     Dealing with geochemical data also means coping with their underlying limitations that are related to sampling, analytical techniques, and other characteristics of the data. This paper discusses the issue of data cleaning, using a regional geochemical dataset of 6 heavy metals in glacial till. Interactive data manipulation techniques provided in the freeware visualization system XmdvTool were used for exploring both metal concentrations reported as under the detection limit, and high or extreme values (outliers) in the dataset. The proposed integrated visual evaluation (IVE) approach for selective removal of outliers outperformed simple removal of the highest concentrations of metals, showing that existing spatial multi-element fingerprints in data could be recognized and preserved by IVE. The uniqueness of visualization is in simultaneous display of both multivariate and spatial information. Being simple and interactive, integrated visual evaluation can be recommended as a valuable complementary tool in cleaning and analysing multielement geochernical data.

  • 324.
    Grünfeld, Katrin
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Integrating spatio-temporal information in environmental monitoring data: a visualization approach applied to moss data2005In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 347, no 1-3, p. 1-20Article in journal (Refereed)
    Abstract [en]

    Large-scale environmental monitoring data being sparse and collected on irregular grids, which may differ from year to year, are difficult to analyse and present. The traditional techniques from statistics and Geographic Information Systems (GIS) may not be useful given the often relatively small sample size combined with varying sampling density. In this study, the freeware visualization package XmdvTool was used for integration and exploration of monitoring data from three surveys of terrestrial mosses. Data on contents of Cu, Ni, Pb, V and Zn in mosses within an area of 300×300 km in southern Sweden, sampled in 1985 (177 samples), 1990 (156 samples) and 1995 (188 samples), were integrated and visualized using parallel coordinate and scatterplot display techniques. Several interesting findings about multi-element composition of samples, as well as changing temporal trends in the relations of five metals were made during interactive visual discovery. Visualization techniques for high-dimensional data may have limitations considering, for example, number of variables, ranges of data values, and spatial scales. Nevertheless, interactive data manipulation tools encourage the process of visual exploration, and the unique way of integrating spatial, temporal and multi-element components of moss data provided visual insights that are not possible to gain with traditional analysis tools.

  • 325.
    Grünfeld, Katrin
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    The separation of multi-element spatial patterns in till geochemistry of southeastern Sweden combining GIS, principal component analysis and high-dimensional visualization2007In: Geochemistry: Exploration, Environment, Analysis, ISSN 1467-7873, E-ISSN 2041-4943, Vol. 7, no 4, p. 303-318Article in journal (Refereed)
    Abstract [en]

    The chemical composition of glacial till is a product of parentrocks, glacial and post-glacial processes and reflects the geogenicvariation of chemical elements. Contrasting chemical compositionof rock types together with spatial variation in distributionpatterns of metals in the fine fraction of till in southeasternSweden assists in the identification of the signatures reflectingparent rocks in glacial till samples. The spatial patterns ofCu, Co, Ni, Pb, V and Zn in 1411 till samples were presentedby point symbol maps, followed by the extraction of multi-elementassociations by employing principal component analysis (PCA)and interactive high-dimensional visualization. The most influentialmulti-element spatial patterns in till data could be separatedusing either the numerical (PCA) or the visual approach. However,more information was extracted by combining the two techniques.In addition, interactive visualization provided an objectivepresentation of complex information in sparse lithogeochemicaldata. The study resulted in new knowledge about the naturalvariation of the levels of six elements in till, and a graphicalpresentation to convey information about and compare multi-elementgeochemical signatures.

  • 326.
    Grünfeld, Katrin
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Visualization, integration and analysis of multi-element geochemical data2005Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    generated large databases containing information on the concentrations of chemical elements in rocks, surface sediments and biogeochemical materials. Regional geochemical data being imprecise, multivariate, spatially auto-correlated and non-normally distributed pose specific problems to the choice of data analysis methods. Commonly several methods are combined, and the choice of techniques depends on the characteristics of data as well as the purpose of study. One critical issue is dealing with extreme data values (or outliers) in the initial stages of analysis. Another common problem is that integrated analysis of several geochemical datasets is not possible without interpolating the point data into surfaces. Finally, separation of anthropogenic influences from natural geochemical background in the surface materials is an issue of great importance for environmental studies.

    This study describes an approach to address the above-mentioned problems by a flexible combination and use of GIS and multivariate statistical techniques with high-dimensional visualization. Dynamically linked parallel coordinate and scatterplot matrix display techniques allow simultaneous presentation of spatial, multi-element and qualitative information components of geochemical data. The plots not only display data in multi-dimensional space, but also allow detailed inspection of the data with interactive multi-dimensional brushing tools. The results of the study indicate that these simple high-dimensional visualization techniques can successfully complement the traditional statistical and GIS analysis in all steps of data processing, from data description and outlier identification through data integration, analysis, validation, and presentation of results. The outcomes of the study include: a visual procedure towards intelligent data cleaning where potentially significant information in very high element concentrations is preserved, methods for integration and visual analysis of geochemical datasets collected in different grids, estimation of geochemical baseline concentrations of trace metals in till geochemistry of southeastern Sweden, use of multi-element spatial fingerprints to trace natural geochemical patterns in biogeochemistry, and a new graphical approach to present multi-element geochemical data summaries and results from numerical analysis.

  • 327.
    Grünfeld, Katrin
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Lax, Kaj
    Identification of the natural levels of Co, Cu, Ni, Pb, V and Zn in biogeochemical data from southeastern Sweden: use of multi-element signaturesManuscript (Other academic)
  • 328. Guha, D. K.
    et al.
    Henkel, Herbert
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Engineering Geology and Geophysics.
    Jacks, Gunnar
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Abandoned on-shore deep wells: a potential for geothermal energy resource for rural Bangladesh2005In: Proceedings of the World Geothermal Congress 2005: paper 2214, 2005Conference paper (Other academic)
  • 329.
    Gumbricht, Thomas
    et al.
    KTH, Superseded Departments, Land and Water Resources Engineering.
    McCarthy, Jenny
    KTH, Superseded Departments, Land and Water Resources Engineering. KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Management and Assessment.
    McCarthy, T. S.
    Channels, wetlands and islands in the Okavango Delta, Botswana, and their relation to hydrological and sedimentological processes2004In: Earth Surface Processes and Landforms, ISSN 0197-9337, E-ISSN 1096-9837, Vol. 29, no 1, p. 15-29Article in journal (Refereed)
    Abstract [en]

    The Okavango wetland in northern Botswana is one of the world's largest inland deltas. The delta is a dynamic environment with shifting channel routes, causing growth and decay of flanking wetlands, and giving birth to islands. Primary island nuclei are formed by fluvial processes and bioengineering, and subsequently grow into secondary larger islands of irregular shape by clastic and chemical sedimentation, and later by coalescence. This article presents classifications and quantitative estimations of channels, wetlands and islands of the Okavango Delta. Islands were classified dependent on composition, pattern of composition, shape and juxtaposition. 90 per cent of all islands in the entire wetland were identified, with a classification accuracy of 60 to 85 per cent. Smaller islands of the nucleus types dominate the upper parts of the delta, whereas larger secondary islands are more common in the distal part, a reflection of the age of the islands. Islands in the entry valley of the delta, the Panhandle, are larger in the top end - the primary region of recent elastic sedimentation. The overall size distribution of islands in the delta, however, shows no clumps, indicating that island growth is a uniform process over time and space. The total area flooded at least every decade is approximately 14 000 km(2), of which 9000 km(2) is classified as actual wetland. Channel meandering decreases from the Panhandle to the distal part of the delta, with the abandoned Thaoge channel as an exception. Occurrence of fluvially formed islands in the distal delta indicates that the water flow and area of inundation must once have been much larger.

  • 330.
    Gustafsson, David
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Measurements of snow water equivalent using multiple-offset ground-penetrating radar2006In: , 2006Conference paper (Other academic)
    Abstract [en]

    Ground-penetrating radar (GPR) measurements of snow water equivalent depend onaccurate information of the radar wave propagation velocity in the snow cover, aswell as on the relationship between the dielectric constant and snow density. This paperevaluates a simplified procedure to derive snow water equivalent from GPR traveltime data only, using multiple-offset GPR antennas arranged in an array. The dielectricconstant and the depth of the snow cover are determined by multi-channel measurementsusing several combinations of transmitter and receiver antennas in the array,based on basic common-mid-point principles. This set-up enables continuous determinationof both snow cover depth and snow density along the measurement profile,which reduces the uncertainties due to spatial variation of snow density. The measurementsystem is evaluated using manual snow depth and snow density measurements attwo sites in northern Sweden during winter 2004/2005. Results show that the spatialvariation of both snow depth and snow density were improved with the multi-offsetmeasurements compared to the use of a single channel measurement.

  • 331.
    Gustafsson, David
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Ahlberg, Jesper
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Granlund, Nils
    Luleå University of Technology.
    Lindström, Göran
    Sveriges meteorologiska och hydrologiska institut.
    Wetterhall, Fredrik
    Sveriges meteorologiska och hydrologiska institut.
    Lundberg, Angela
    Luleå University of Technology.
    Distribuerade system för förbättrade snö- och avrinningsprognoser. Integration i hydrologiska modeller: Delrapport 12009Report (Other academic)
  • 332.
    Gustafsson, David
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Granlund, Nils
    Luleå University of Technology.
    Lundberg, Angela
    Luleå University of Technology.
    Multi-offset impulse radar for snow water equivalent measurements2008In: Proceedings of the 65th Annual Meeting of Eastern Snow Conference, 2008Conference paper (Other academic)
  • 333.
    Gustafsson, David
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Gärdenäs, Annemieke
    Department of Soil and Environment, Swedish University of Agricultural Sciences.
    Eckersten, Henrik
    Department of Ecology and Crop Production, Swedish University of Agricultural Sciences.
    Simulated carbon and water processes of forest ecosystems in Forsmark and Oskarshamn during a 100-year period2006Report (Other academic)
  • 334.
    Gustafsson, David
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Magnusson, Jan
    WSL Swiss Federal Institute for Snow and Avalanche Research.
    Granlund, Nils
    Luleå University of Technology.
    Impulse radar measurements of snow interception: laboratory tests and field application to a forest stand in northern Sweden2009Conference paper (Other academic)
    Abstract [en]

    Snow melt runoff is a dominating water resource in many alpine and high latitude regions. Therefore, hydrological model predictions and information on the amount of snow are important for efficient management of for instance hydropower production. Snow interception and evaporation of snow from forest canopies is known to reduce the snow cover accumulation in forest areas compared to open areas, but there is a need for better process understanding in order to improve the model predictions. The exchange of heat and water between snow cover, canopy, and atmosphere involve many processes that can be difficult to observe at the relevant scales. Particularly, the snow interception storage is difficult to observe on a forest stand level compared with snow cover development and forest evaporation. In this study, a new application of ground penetrating impulse radar (GPR) to measure the total amount, spatial distribution and phase of the interception storage in the forest canopy is presented. The propagation velocity and frequency dependent attenuation of a broadband impulse radar wave can be used to give a direct estimate of the complex effective dielectric permittivity. The real part of the effective dielectric permittivity, estimated from the propagation velocity alone, can be used to estimate either the mass of liquid water or the mass of dry snow on the canopy if a suitable mixing formula for the effective permittivity is known. However, to separate between liquid and frozen interception additional information that we intend to get from the attenuation is needed. It has been shown for snow that the liquid water content can be estimated from the imaginary component of the effective permittivity alone. Thus, the contribution from liquid water to the real component can be subtracted, and the remaining fraction depended only on the amount of frozen snow. Laboratory experiments were performed with a GPR system, measuring the propagation velocity and frequency dependent attenuation through a sample of Norway spruce branches loaded with different amount of liquid water and snow. The results were used to establish empirical mixing formulas relating imaginary and real components of the effective dielectric permittivity to the volumetric fraction of liquid and frozen water. The obtained formulas were tested in a field application in northern Sweden, in a homogeneous stand dominated by Norway spruce. The mass of snow stored in the tree canopies were measured in two ways: firstly by measuring the weight of a single tree scaled to a forest stand average and secondly using impulse radar measurements through a small section of the forest. The transmitting and receiving antennas were placed in two small towers, separated horizontally by 15 m. The amount of intercepted snow determined from the radar measurements compared well with the measurements from the single tree weighing lysimeter, especially during cold conditions. Systematic differences were observed in situations with melting snow on the trees, when the estimation of liquid water content was overestimated by the frequency attenuation method. However, this might be due to a combination of uncertainties in the mixing models and inadequate corrections for drift in the measurement system. Overall, the results were promising and showed that impulse radar can be used to study snow interception.

  • 335.
    Gustafsson, David
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Physics.
    Magnusson, Jan
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Physics.
    Grelle, Achim
    Swedish University of Agricultural Sciences.
    Lundberg, Angela
    Luleå University of Technology.
    Impact of snow interception on water and energy balance of a forest stand in northern Sweden: combining measurements with impulse radar and eddy-correlation with numerical modelling2007Conference paper (Other academic)
  • 336.
    Gustafsson, David
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Sommer, Wolfram
    Sommer Mess- Systemtechnique, Austria.
    Measurement of liquid water content in snow and its applications in snow hydrological modeling2010Conference paper (Other academic)
  • 337.
    Gustafsson, David
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Stähli, Manfred
    WSL Swiss Federal Institute for Forest Snow and Landscape Research.
    Lundberg, Angela
    Luleå University of Technology.
    A Multi-criteria parameterisation of a numerical forest snow processes model: analysis of parameter uncertainty and governing processes2006In: , 2006Conference paper (Other academic)
  • 338.
    Gustafsson, Jan-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Water Management.
    Intervention: the actors of the European water policy2008Conference paper (Refereed)
  • 339.
    Gustafsson, Jan-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Water Management.
    Public or Private Management of Water Utilities2007In: Urban Water Management / [ed] Plaza E., The Baltic University Forum Press , 2007, p. 27-32Chapter in book (Refereed)
  • 340.
    Gustafsson, Jan-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Water Management.
    Stockholm Water Company is threatened by an ideological saving politics2008In: 7th International Conference Environmental Engineering, Vols 1-3 / [ed] Cygas, D; Froehner, KD, 2008, p. 543-549Conference paper (Refereed)
    Abstract [en]

    The paper gives a brief account of the commercialisation of water supply and sanitation provision (the VA-service) in Sweden, and thereafter a detailed analysis of the recent management changes inside the Stockholm Water Company after the general election in September 2006. The paper is based on company protocols, published articles from various sources and the author's informal talks with some of the concerned actors. In the discussion it is argued that the focus on "core business" and the dismantling of the Stockholm Water Company is ideological driven.

  • 341.
    Gustafsson, Jan-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Water Management.
    Sweden Higher Education Politics: Independent Universities or Commercialised Universities under the Governance of the European Union2005Conference paper (Refereed)
  • 342.
    Gustafsson, Jan-Erik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Water Management.
    Koku, John E.
    Achieving the MDG's in Ghana: Rhetorics or Reality?2007In: ECOSYSTEMS AND SUSTAINABLE DEVELOPMENT VI, 2007, Vol. 106, p. 331-349Conference paper (Refereed)
    Abstract [en]

    The original meaning of the concept sustainability or sustainable development might in an altruistic way have referred to building societies based on a sound environmental practice. This paper shows that the structural adjustments programs (SAP), Poverty Reduction Strategies and the Millennium Development goals (MDG's) compel the Ghanian government to favour economic and fiscal sustainability. This neo-liberal policy has led to increasing inequalities, widening regional disparities, migration from rural areas to quickly grown up peri-urban areas basically within a huge informal sector, and unplanned capital formation and development at large, making claims to achieve the MDG's by 2015 illusory. A way forward for Ghana should be to gradually fence off from the world market and learn from the development efforts of the Kwame Nkrumah first independent government.

  • 343.
    Gustafsson, Jon Petter
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Arsenate adsorption to soils: Modelling the competition from humic substances2006In: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 136, no 02-jan, p. 320-330Article in journal (Refereed)
    Abstract [en]

    There is currently no agreement to what extent humic substances may compete with arsenate and other anions for oxide adsorption sites in soils, and how to model this interaction. In this study, batch experiments were made in which the competition between fulvic acid and arsenate was studied in a spodic Bs horizon. Additional experiments were performed in which the pH and concentration dependence of arsenate adsorption was studied in four soils. The results showed that fulvic acid decreased the adsorption of AsO4, probably because of competition effects. The K-d value of AsO4 adsorption to the four studied soils differed by three orders of magnitude at pH 5. The introduction of an irreversibly sorbed component RO- into the Three-Plane CD-MUSIC model, and the optimisation of RO- using the K-d of AsO4 for one sample from each data set, permitted the use of the model to predict AsO4 adsorption under different conditions. On the whole, the predictions were reasonably close to measured values, but the model failed in 3 of 4 soils at high surface coverage. A strong relationship between the optimised RO- value and the observed pyrophosphate-extractable C value supported the assumption that RO- can be considered as being an adsorbed humic functional group. The large concentrations of RO- compared to those of adsorbed PO4 and SO4 suggest that humic substances may be the most important competitors for anion adsorption sites in many soils.

  • 344.
    Gustafsson, Jon Petter
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Geochemical modelling of arsenic adsorption to oxide surfaces2007In: Arsenic in soil and groundwater environment: Biogeochemical Interactions, Health Effects and Remediation / [ed] Bhattacharya, P., Mukherjee, A.B., Bundschuh, J., Zevenhoven, R., Loeppert, R.H., Elsevier, 2007, p. 159-206Chapter in book (Refereed)
    Abstract [en]

    In natural environments, arsenic chemistry is dominated by the reactions of its two predominant soluble forms, arsenate and arsenite. To predict the fate of As in the environment, it is necessary to consider processes that act to restrict its mobility. The mobility of As is strongly influenced by adsorption reactions to particle surfaces. Arsenate and arsenite may form surface complexes with a number of different oxides, including Fe-, Al-, Mn- and Ti oxides. The focus of this chapter is on the adsorption of As(III) and As(V) to the surfaces of oxides, in particular Fe oxides. We have analysed the existing data for arsenite and arsenate adsorption to ferrihydrite and goethite. Spectroscopic results show that arsenate forms bidentate binuclear complexes under all conditions; for arsenite, evidence has been found both for a bidentate binuclear complex and for a weaker outer-sphere complex, which may be of some importance at low ionic strength. We optimized As adsorption parameters for two surface complexation models, the diffuse double-layer model (DLM) and the three-plane CD-MUSIC model (TPCD), taking into account the spectroscopic evidence. For arsenate adsorption to ferrihydrite, the new DLM constants imply stronger binding than the previous compilation by Dzombak and Morel (1990), whereas for arsenite the revised DLM constants are in reasonable agreement. The surface complexation models could not be optimized satisfactorily for data sets in which the dissolved arsenite concentration at equilibrium was larger than 10 mM; the reasons for this are discussed. Simulations of competition effects show that o-phosphate competes strongly with arsenate over the whole pH range. Silicic acid and carbonate are important competitors in the circumneutral pH range, while sulphate may have a small competitive effect at low pH. Humic substances are important competitors when a large part of the Fe oxides is covered with humic substances. By contrast, calcium promotes arsenate adsorption at alkaline pH because of surface charge effects.

  • 345.
    Gustafsson, Jon Petter
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Dässman, Ellinor
    Swedish University of Agricultural Sciences.
    Bäckström, Mattias
    Örebro University.
    Towards a consistent geochemical model for prediction of uranium(VI) removal from groundwater by ferrihydrite2009In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 24, no 3, p. 454-462Article in journal (Refereed)
    Abstract [en]

    Uranium(VI), which is often elevated in granitoidic groundwaters, is known to adsorb strongly to Fe (hydr)oxides under certain conditions. This process can be used in water treatment to remove U(VI). To develop a consistent geochemical model for U(VI) adsorption to ferrihydrite, batch experiments were performed and previous data sets reviewed to optimize a set of surface complexation constants using the 3-plane CD-MUSIC model. To consider the effect of dissolved organic matter (DOM) on U(VI) speciation, new parameters for the Stockholm Humic Model (SHM) were optimized using previously published data. The model, which was constrained from available X-ray absorption fine structure (EXAFS) spectroscopy evidence, fitted the data well when the surface sites were divided into low- and high-affinity binding sites. Application of the model concept to other published data sets revealed differences in the reactivity of different ferrihydrites towards U(VI). Use of the optimized SHM parameters for U(VI)-DOM complexation showed that this process is important for U(VI) speciation at low pH. However in neutral to alkaline waters with substantial carbonate present, Ca-U-CO3 complexes predominate. The calibrated geochemical model was used to simulate U(VI) adsorption to ferrihydrite for a hypothetical groundwater in the presence of several competitive ions. The results showed that U(VI) adsorption was strong between pH 5 and 8. Also near the calcite saturation limit, where U(VI) adsorption was weakest according to the model, the adsorption percentage was predicted to be >80%. Hence U(VI) adsorption to ferrihydrite-containing sorbents may be used as a method to bring down U(VI) concentrations to acceptable levels in groundwater.

  • 346.
    Gustafsson, Jon Petter
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Kleja, D. B.
    Modeling salt-dependent proton binding by organic soils with the MICA-Donnan and Stockholm Humic models2005In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 39, no 14, p. 5372-5377Article in journal (Refereed)
    Abstract [en]

    Models are available for simulations of proton dissociation and cation binding by natural organic matter; two examples are the NICA-Donnan and Stockholm Humic (SHM) models. To model proton and metal binding, it is necessary to properly account for the ionic strength dependence of proton dissociation. In previous applications of the models for soils it was assumed that the electrostatic interactions for solid-phase humic substances were the same as in solution;this assumption was recently challenged. Therefore, we reanalyzed previously published acid-base titrations of acid-washed Sphagnum peat, and we produced additional data sets for two Sphagnum peats and two Spodosol Oe horizons. For the soil suspensions, the original NICA-Donnan and SHM models, which were developed for dissolved humic substances, underestimated the observed salt dependence considerably. When a fixed Donnan volume of 1 L kg(-1) for humic substances in the solid phase was used, the NICA-Donnan model fits were much improved. Also for SHM, slight changes produced improved model fits. The models also produced acceptable simulations of the dissolved Ca, Mg, and Cd concentrations, provided that cation selectivity was introduced. In conclusion, the proposed extensions to the NICA-Donnan and SHM models were shown to predict the salt dependence of solid-phase humic substances more satisfactorily than earlier model versions.

  • 347.
    Gustafsson, Jon Petter
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    Mwamila, Luhuvilo B.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    Kergoat, Kevin
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    The pH dependence of phosphate sorption and desorption in Swedish agricultural soils2012In: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 189, p. 304-311Article in journal (Refereed)
    Abstract [en]

    A number of previous studies have reported the existence of a minimum in phosphate solubility between pH 5.5 and 7 in non-calcareous soils. Different hypotheses have been forwarded to explain this phenomenon. In this study, ten soil samples with varying textures and phosphorus status were subjected to batch experiments in which dissolved phosphate was measured as a function of pH and phosphate load. Soil samples with more than 20% clay all had a minimum phosphate solubility between pH 6 and 7, whereas for samples with <10% clay, no such minimum was observed. Further experiments involving additions of phosphate and arsenate showed an increasing adsorption of these anions with decreasing pH also below pH 6 in clay soils, suggesting that the pH dependence on adsorption and desorption in short-term experiments was not the same. Kinetic experiments showed that the increased phosphate desorption at lower pH values in non-calcareous clay soils was a quick process, which is consistent with adsorption/desorption being the most important mechanism governing the retention and release of inorganic P. Moreover, by comparing extraction results with batch experiment results for samples from a long-term fertility experiment, it was concluded that more than 60% of the accumulated phosphate was occluded, i.e. not reactive within 6 days. Additional evidence for an important role of occluded phosphate comes from an analysis of the Freundlich sorption isotherms for the studied soils. It is hypothesized that interlayered hydroxy-Al and hydroxy-Fe polymers in clay minerals may be important for P dynamics in clay soils by trapping some of the P in an occluded form. The results also suggest that improved knowledge on the speciation and dynamics of phosphorus in soils is required for consistent mechanistically based modeling of phosphate sorption/desorption reactions.

  • 348.
    Gustafsson, Jon Petter
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Persson, Ingmar
    Kleja, Dan Berggren
    Van Schaik, Joris W. J.
    Binding of iron(III) to organic soils: EXAFS spectroscopy and chemical equilibrium modeling2007In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 41, no 4, p. 1232-1237Article in journal (Refereed)
    Abstract [en]

    The complexation of iron(III) to soil organic matter is important for the binding of trace metals in natural environments because of competition effects. In this study, we used extended X-ray absorption fine structure (EXAFS) spectroscopy to characterize the binding mode for iron(III) in two soil samples from organic mor layers, one of which was also treated with iron(III). In most cases the EXAFS spectra had three significant contributions, inner-core Fe-O/N interactions at about 2.02(2) A, Fe-C interactions in the second scattering shell at 3.00(4) A, and a mean Fe-Fe distance at 3.37(3) A. One untreated sample showed features typical for iron (hydr)oxides; however, after treatment of iron(III) the EXAFS spectrum was dominated by organically complexed iron. The presence of a Fe-Fe distance in all samples showed that the major part of the organically complexed iron was hydrolyzed, most likely in a mixture of complexes with an inner core of (O5Fe)(2)O and (O5Fe)(3)O. These results were used to constrain a model for metal-humic complexation, the Stockholm Humic Model (SHM). The model was able to describe iron(III) binding very well at low pH considering only one dimeric iron(III)-humic complex. The competition effect on trace metals was also well described.

  • 349.
    Gustafsson, Jon Petter
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Renman, Agnieszka
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    Renman, Gunno
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    Poll, Katarina
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    Phosphate removal by mineral-based sorbents used in filters for small-scale wastewater treatment2008In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 42, no 1-2, p. 189-197Article in journal (Refereed)
    Abstract [en]

    The mineral-based sorbents Filtra P, Polonite (R), natural wollastonite and water-cooled blast furnace slag (WCBFS) were studied in terms of their PO4 removal performance. Results from a long-term column experiment showed that both Filtra P and Polonite (R) removed > 95% of PO4 from the applied synthetic solution, and that the used filter materials had accumulated several (1.9-19) g kg(-1) P. Phosphorus was removed also by natural wollastonite and WCBFS, but these materials were less efficient. Batch experiments on the used materials showed that the solubility PO4 was considerably larger than the one expected for crystalline Ca phosphates such as hydroxyapatite, and results from investigations with attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) on the Filtra P material showed that the formed P phase was not crystalline. These evidence suggest that a soluble amorphous tricalcium phosphate (ATCP) was formed in the mineral-based sorbents; the apparent solubility constant on dissolution was estimated to log K-s = -27.94 ( 0.31) at 21 degrees C. However, since only up to 18% of the accumulated PO4 was readily dissolved in the experiments, it cannot be excluded that part of the phosphorus had crystallized to slightly less soluble phases. In conclusion, Filtra P and Polonite are two promising mineral-based sorbents for phosphorus removal, and at least part of the accumulated phosphorus is present in a soluble form, readily available to plants.

  • 350.
    Gustafsson, Jon Petter
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Tiberg, Charlotta
    Swedish University of Agricultural Sciences.
    Edkymish, Abubaker
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    Kleja, Dan Berggren
    Swedish Geotechnical Institute.
    Modelling lead(II) sorption to ferrihydrite and soil organic matter2011In: Environmental Chemistry, ISSN 1448-2517, E-ISSN 1449-8979, Vol. 8, no 5, p. 485-492Article in journal (Refereed)
    Abstract [en]

    Lead(II) adsorption to soil organic matter and iron (hydr)oxides is strong, and may control the geochemical behaviour of this metal. Here, we report the adsorption of Pb(2+) (i) to 2-line ferrihydrite, and (ii) to a mor layer. The results showed that ferrihydrite has heterogeneous Pb(2+) binding. Use of a surface complexation model indicated that similar to 1% of the surface sites adsorbed Pb(2+) more strongly than the remaining 99 %. Although only one surface complexation reaction was used (a bidentate complex of the composition (equivalent to FeOH)(2)Pb(+)), three classes of sites with different affinity for Pb(2+) were needed to simulate Pb(2+) binding correctly over all Pb/Fe ratios analysed. For the mor layer, Pb(2+) sorption was much stronger than current models for organic complexation suggest. The results could be described by the Stockholm Humic Model when the binding heterogeneity was increased, and when it was assumed that 0.2% of the binding sites were specific for Pb. Use of revised model parameters for nine Vietnamese soils suggest that lead(II) binding was more correctly simulated than before. Thus, underestimation of lead(II) sorption to both (hydr) oxide surfaces and organic matter may explain the failure of previous geochemical modelling attempts for lead(II).

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