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  • 1.
    Galfi, Helen
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Haapala, Jenny
    Vatten Östersund, Water Engineering, Water Department Östersund, Östersund Municipality.
    Nordqvist, Kerstin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Westerlund, Camilla
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Marsalek, Jiri
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Inter-Event and Intra-Event Variations of Indicator Bacteria Concentrations in the Storm Sewer System of the City of Östersund, Sweden2016In: Journal of environmental engineering, ISSN 0733-9372, E-ISSN 1943-7870, Vol. 142, no 7, article id 6016003Article in journal (Refereed)
    Abstract [en]

    An episode of microbiological contamination of the drinking water supply of the City of Östersund, Sweden (63°10′45″N; 14°38′09″E) prompted a study of fecal pollution in four storm drainage catchments discharging in the vicinity of the water treatment plant intake, with the overall aim of determining the presence and variation of standard fecal indicator bacteria strains and total suspended solids (TSS) in stormwater from urban catchments with specific land uses and sizes varying from 5 to 40 ha. Four bacteria strains used as indicators of fecal pollution in Sweden were studied: total coliforms, enterococci, Escherichia coli (E. coli) and Clostridium perfringens (C. perfringens). In dry weather, indicator bacteria concentrations in storm sewers conveying baseflow did not exceed 100  colony forming units (CFU)/100  mL 100  colony forming units (CFU)/100  mL, but during wet weather, total coliform and enterococci concentrations increased 10 2 102 to 10 3 103 times, compared to those in baseflow, and considerably less in the case of E. coli and C. perfringens. Bacteria concentrations differed significantly among the sampling sites and in the majority of events observed in the four catchments; higher bacteria concentrations were observed during the early phases of runoff. Only in one catchment, positive correlations were observed between TSS and total coliforms, E. coli, and enterococci, suggesting similar sources; in the remaining catchments, no such correlations were observed. The collected indicator bacteria data represent a useful addition to the available data on indicator bacteria in stormwater in cold-climate regions.

  • 2.
    Lundberg, Angela
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Feiccabrino, James
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Westerlund, Camilla
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Urban snow deposits versus snow cooling plants in northern Sweden: A quantitative analysis of snow melt pollutant releases2014In: Water quality research journal of Canada, ISSN 1201-3080, Vol. 49, no 1, p. 32-42Article in journal (Refereed)
    Abstract [en]

    High-velocity runoff from snow deposit transports suspended grain-attached contaminants while underground snow storages trapped these contaminants within the storage. The aim here is to quantify pollutant masses from an urban snow deposit and to investigate the conditions when pollutant control was increased by turning a snow deposit into a snow cooling plant with permeable underground snow storage. Pollutant masses in an urban snow deposit in northern Sweden were: Cu = 67, Pb = 17, Zn = 160, P = 170, SS = 620, 000, Cl = 1, 200, N = 380 kg. A theoretical analysis showed that the fraction of surface runoff from a surface deposit largely depends on the hydraulic conductivity (K, m s-1) of the soil. For a melt rate of 30 mm, day-1, surface runoff would be about 97% for a soil with K = 10-8, while nonexistent for K>10-6. Similar soil conductivities are needed to ensure that all snow melt could be transported as groundwater from an underground storage. The largest pollution-control advantage with underground snow storage compared to a surface deposit would thus be that piping and filters for operation of the plant could be used to filter surface snow melt runoff before rejection

  • 3.
    McCarthy, David T.
    et al.
    Environmental and Public Health Microbiology Laboratory (EPHM Lab), Department of Civil Engineering, Monash University.
    Zhang, Kefeng
    Monash Infrastructure Research Institute, Department of Civil Engineering, Monash University.
    Westerlund, Camilla
    Water Coordinator, Water Authority-bottenvikens Water District Lulea.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Bertrand-Krajewski, Jean-Luc
    Univ Lyon, INSA Lyon.
    Fletcher, Tim D.
    School of Ecosystem and Forest Sciences, Faculty of Science, The University of Melbourne.
    Deletic, Ana
    Monash Infrastructure Research Institute, Department of Civil Engineering, Monash University.
    Assessment of sampling strategies for estimation of site mean concentrations of stormwater pollutants2018In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 129, p. 297-304Article in journal (Refereed)
    Abstract [en]

    The estimation of stormwater pollutant concentrations is a primary requirement of integrated urban water management. In order to determine effective sampling strategies for estimating pollutant concentrations, data from extensive field measurements at seven different catchments was used. At all sites, 1-min resolution continuous flow measurements, as well as flow-weighted samples, were taken and analysed for total suspend solids (TSS), total nitrogen (TN) and Escherichia coli (E. coli). For each of these parameters, the data was used to calculate the Event Mean Concentrations (EMCs) for each event. The measured Site Mean Concentrations (SMCs) were taken as the volume-weighted average of these EMCs for each parameter, at each site. 17 different sampling strategies, including random and fixed strategies were tested to estimate SMCs, which were compared with the measured SMCs. The ratios of estimated/measured SMCs were further analysed to determine the most effective sampling strategies. Results indicate that the random sampling strategies were the most promising method in reproducing SMCs for TSS and TN, while some fixed sampling strategies were better for estimating the SMC of E. coli. The differences in taking one, two or three random samples were small (up to 20% for TSS, and 10% for TN and E. coli), indicating that there is little benefit in investing in collection of more than one sample per event if attempting to estimate the SMC through monitoring of multiple events. It was estimated that an average of 27 events across the studied catchments are needed for characterising SMCs of TSS with a 90% confidence interval (CI) width of 1.0, followed by E.coli (average 12 events) and TN (average 11 events). The coefficient of variation of pollutant concentrations was linearly and significantly correlated to the 90% confidence interval ratio of the estimated/measured SMCs (R2 = 0.49; P < 0.01) as well as the number of events required to achieve certain accuracy, and hence could be a promising surrogate for determining the sampling frequency needed to accurately estimate SMCs of pollutants

  • 4.
    Moghadas, Shahab
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Westerlund, Camilla
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Gustafsson, Anna-Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Snowmelt modeling in urban areas: sensitivity analysis of the energy and mass balance method2012Conference paper (Refereed)
    Abstract [en]

    Flooding is one of the main concerns in seeking safe and sustainable urban areas. In many cases the design criteria are based on intense rainfall. It is, therefore, assumed that the peak flow in cities’ drainage systems is due to heavy and fast rainfalls. However snowmelt pattern could be more important for places with cold climate; therefore the need of a better snowmelt and runoff simulation becomes more important particularly when the effects of climate change needs to be considered. Two main methods are basically used for urban snowmelt simulation i.e. temperature index and energy budged methods. Studies done previously show that the energy balance method gives a better estimation for volume and time compare to the temperature index. For urban areas though, it is argued that the data demanding of the energy balance method can be a disadvantage and it could affect the model precision. However, the advances in geographical information systems (GIS) and the requirement for better time resolution than daily have increased the tendency of applying it for urban snow melt. There are couples of studies during recent years e.g. (Ho& Valeo 2005) applying energy budget method in urban areas, even though the efforts basically focused on developing routines and comparing it with the degree day method. There is still a gap in parameter sensitivity analysis especially with two main features of urban snowmelt modeling; firstly, the importance of input data along with difficulties in providing them; and secondly the classification of snow in urban areas based on snow properties. These two concerns were the motives to go one step ahead and to conduct a sensitivity analysis. The aim of the study is therefore to investigate the dependency of the simulation results to the different model parameters as built-in parameters and input data. Such analysis eventually can be used for snow classification which along with GIS technology can provide a reliable platform to simulate snowmelt over an urban catchment more precisely than what the current models are capable of today. Here in this study, a model namely Utah Energy Balance Snow Model (UEB) is used. The model uses a complete energy and mass balance routine to simulate snow accumulation and melt at a point scale. Except using the measured climatic values to run the model, the routines in this model has the capability of producing (simulating) solar radiation and albedo if the measured values are not available. The model has simulated the snow accumulation and melts in rural area with reasonable accuracy in previous studies i.e. (Tarboton et al. 1995). For this research, three snow deposits from 1991 and 1992 are taken to calibrate the model with. The pilot snow packs are identical to municipal snow deposit with density more than natural snow, around 700 Kg/m3. The snowmelt runoff has been measure between March and Jun 1991 and 1992. The necessary input values are collected from Meteorological and Hydrological Institute (SMHI) for the same periods. All input parameters are available on hourly and 3 hourly periods. The method is to run the model with real values collected from SMHI and calibrate it versus the measured data. The model is run using modified parameters to investigate the possible change in the simulation result. Eventually an analysis is done on each parameter and the dependency of the model. An analysis also is done by running the model with different time resolution, i.e. hourly, 3-hourly, and 6-hourly and to investigate the effect of time span in modeling snowmelt and simulation precision.

  • 5.
    Nordqvist, Kerstin
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Galfi, Helen
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Österlund, Helene
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Marsalek, Jiri
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Westerlund, Camilla
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Measuring solid concentrations in urban stormwater and snowmelt: a new operational procedure2014In: Environmental Science: Processes & Impacts, ISSN 2050-7887, E-ISSN 2050-7895, Vol. 16, no 9, p. 2172-2183Article in journal (Refereed)
    Abstract [en]

    A comparative study of five methods measuring suspended sediment or solid concentrations in water–sediment mixtures indicated that, depending on the method used, broadly varying results can be obtained. For water–sediment mixtures containing sand size particles, the standard TSS method produced negatively biased results, accounting for 0 to 90% of the present solids; the negative bias directly depended on the magnitude of the sand fraction in the water–sediment mixture. The main reason for the differences between the TSS and the rest of the methods laid in the handling of samples; in the former methods, whole samples were analysed, whereas the TSS analysis was performed on sub-samples withdrawn from the water sample, the withdrawal process tending to exclude large particles. The methods using whole water–solid samples, rather than aliquots withdrawn from such samples, produced accurate estimates of solid concentrations, with a fairly good precision. Two whole-sample methods were studied in detail, a slightly modified standard SSC-B method and the newly proposed operational procedure referred to as the Multiple Filter Procedure (MFP), using three filters arranged in a series with decreasing pore sizes (25, 1.6 and 0.45 µm). Both methods assessed accurately concentrations of solids in a broad range of concentrations (200–8000 mg L−1) and particle sizes (0.063–4.0 mm). The newly introduced MFP was in good agreement with the SSC procedure, the differences between the two procedures not exceeding the standard bias defined for the SSC-B method. The precision of both SSC and MFP was generally better than ±10%. Consequently, these methods should be used when the total mass of transported solids is of interest.

  • 6.
    Nordqvist, Kerstin
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Westerlund, Camilla
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Marsalek, Jiri
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Measuring solids concentrations in urban runoff: methods of analysis2011Conference paper (Refereed)
    Abstract [en]

    Various types of solids conveyed with rainfall and snowmelt runoff into receiving waters cause numerous environmental impacts, including reduced sunlight penetration, blanketing of fish spawning substrates, and transport of pollutants contributing to aquatic pollution. For the assessment of such impacts, it is important to measure solids concentrations in both runoff and snowmelt. In this study, accuracies of three analytical methods used to measure solids were assessed: (a) A TSS (total suspended solids) method, (b) Suspended sediment method (SSC-B), and (c) a multiple filter method (MFM). For rainfall runoff samples containing 90% of particles smaller than 5 μm, the MFM measurements produced concentrations significantly higher than those obtained with SSC-B and TSS methods, at a 95% confidence level. In the case of snowmelt runoff, the SSC-B and MFM methods yielded similar concentrations, which were 10-20% higher than those measured by the TSS method, and the coefficient of variation of repeated TSS readings was up to three times higher than that of the former methods. The results indicate the importance of choosing the “best” analytical method for assessing the operational and environmental impacts of solids conveyed by urban runoff and snowmelt.

  • 7. Roja, Modaresi
    et al.
    Westerlund, Camilla
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Estimation of pollutant loads transported by runoff by using a GIS model case study: Luleå city centre2009In: The 11th Nordic Wastewater Conference: 10-12 November 2009, Odense, Denmark, 2009, p. 194-198Conference paper (Refereed)
  • 8.
    Westerlund, Camilla
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Particle transport during snowmelt: influence by road salt, temperature and surface slope2007Conference paper (Other academic)
  • 9.
    Westerlund, Camilla
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Road runoff quality in cold climates2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The main objective of the doctoral thesis was to investigate the complex processes and influencing factors affecting snowmelt-induced runoff and snowmelt quality in a cold climate under wintry conditions compared to non- winter conditions in areas with a warmer climate. In order to improve the understanding and knowledge of road-runoff quantity, quality and pollutant transport, snowmelt and rainfall runoff were studied and characterized in the laboratory and in the field, respectively. Measurements were carried out at a field site during 2000, 2001 and 2004. The field site was a small urban runoff plot (540 m2) in the central part of Luleå, in northern Sweden. The runoff plot consisted of a road with a traffic intensity of 7400 vehicles/day and a strip of grassed land on the road boulevard used to store ploughed snow. For the laboratory experiments during 2006, snow was collected from the same field site and melted under defined conditions in climate rooms at Luleå University of Technology. Runoff samples from snowmelt and rainfall were collected and analysed for concentrations of total suspended solids (TSS), total and dissolved heavy metals (Cd, Cu, Ni, Pb, and Zn), chloride, and particles (4-120 µm) as well as for pH and conductivity. The results from the field site investigation showed higher concentrations and loads of TSS, particles, and total heavy metals for the snowmelt runoff compared to the rainfall runoff, and the highest concentrations were found during the rain-on-snow events. On the contrary, dissolved heavy metal loads were higher during the rain period. The metal elements investigated during the snowmelt runoff were more particulate- bound compared to the rain period, which was characterised by a higher percentage of the dissolved fraction. During the snowmelt period, investigated particle sizes and TSS were highly correlated with total concentrations of Cd, Cu, Ni, Pb, and Zn. During the rain period, the correlations between total metal concentrations and the different particle sizes were not as significant. The transport of H+-ions, the load of TSS and the total and dissolved heavy metal loads from the runoff plot to the gully pot showed no tendencies of a first flush, but, instead, showed a uniform transport. On the contrary, the transport of chloride showed tendencies of a slight first flush. Lysimeter setups in a laboratory setting showed that the addition of road salt, the surface slope, and the temperature had a significant influence on the transported TSS load; between 1 to 11 % of the TSS load was transported with the snowmelt compared to the TSS load in the initial snow. The lysimeter with added NaCl had the largest transported load of TSS. The study of a small, medium, and large lysimeter showed that the transported load of TSS in the snowmelt from the initial snow was 3, 3.7, and 4.8 %, respectively. The analysis of TSS underestimates the actual particle load contained in snow and snowmelt runoff, making total particle mass balances difficult to perform. A model of the runoff plot showed that the equations in the model used for describing snowmelt and the build-up and wash-off of particles during wintry conditions did not perform satisfactorily. In regions with cold climate, road runoff processes become more complex, compared to those in temperate regions. The effects that runoff has on receiving waters seem to be particularly severe during snowmelt and rain-on-snow in cold climates. Therefore, the special requirements of cold-climate conditions should be considered in planning processes related to the applicability, operation and need to specially design best management practices, snow-handling strategies, and environmental management practices as well as improving models.

  • 10.
    Westerlund, Camilla
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Seasonal variation of road runoff in cold climate2005Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The main objective of this thesis was to characterize and study the behaviour and transport of pollutants, i.e., suspended solids, particles and heavy metals, in road runoff from a small urban catchment during snowmelt and rainfall. The result will constitute a basis for essential considerations concerning the selection and design of environmental management practices and techniques in a cold climate. In regions with cold climate the urban drainage and highway runoff processes become much more complex, compared to temperate regions. The effects that runoff has on receiving waters seem to be particularly severe during snowmelt and rain-on-snow in cold climates. Therefore, climatic conditions should be taken into account in planning and design of BMPs and snow handling strategies. To increase the knowledge of seasonal variations of road runoff quantity and quality, measurements were carried out at a field site during melt and rain periods, year 2000 and 2001. The field site was a road with 7400 vehicles/day, in the central parts of Luleå in northern Sweden. Runoff samples were analysed for suspended solids (SS), particle-size distribution, total and dissolved heavy metals (Pb, Cu, Cd, Ni and Zn), pH, and conductivity. The results showed higher concentrations of SS, particles, and heavy metals for the melt period, as compared to the rain period, and the highest concentrations were found during the rain-on-snow events. The results indicated a flow dependent increase in the concentration of suspended solids during the melt period. The mass load for suspended solids, particles, and heavy metals was higher for the melt period than for the rain period. On the contrary, dissolved heavy metal loads were higher during the rain period. Metal elements during the melt period were more particulate bound as compared to the rain period characterised by a higher percentage of the dissolved fraction. During the melt period, investigated particle sizes and TSS were highly correlated with total concentrations of Cd, Cu, Ni, Pb, and Zn. During the rain period, the correlations between total metal concentrations and the different particle sizes were not as significant. It was shown that the modified degree-day method is inadequate to describe the snowmelt dynamics well. The build-up and transport of fine and coarse suspended solids should be improved during snowmelt conditions. Despite a simple model concept, it was possible to describe the dynamics of road runoff and suspended solids rather well, based on the continuous course of events for the whole modelling period. However, if the model were used for simulating a snowmelt period or single events during snowmelt, the model approach would be too simple.

  • 11.
    Westerlund, Camilla
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Dynamics of urban snowmelt and runoff during different climatic conditions2006Conference paper (Other academic)
    Abstract [en]

    Within the European Union, and maybe especially in Scandinavia, access to clean water is taken for granted without a second thought. However, it is not often realized that many of the human activities put a great burden on water quality and quantity. All polluted water, whether polluted by households, industry, agriculture, or traffic returns back, in some way, to the environment and may cause damage to human health or the environment. The increasing demand for cleaner rivers and lakes, groundwater and coastal beaches was the driving force for the EU Water Framework Directive which overall aim is to obtain, and keep a "good status" for water within EU. The protection should include all waters, surface waters and groundwater and should be achieved before year 2015. With these increasing demands upon water quality, further research is required in terms of the quantity and quality of road runoff.Further research is required particularly in areas with a cold climate since special conditions occur - storage of precipitation and pollutants in snowpacks during extended time periods, processes in the snowpack influencing the availability of pollutants, and dissimilar surface and transport network due to snow and ice. As a result, the runoff quantity and quality will differ compared to snow and-ice free climates (Marsalek, 2003). Also, it is of importance to realise that areas with cold climate can be subdivided into smaller areas with different climatic zones. For example, when looked upon Sweden, the winter could be divided into two different types. One type of winter climate, which is found in the south of Sweden, has a temperature often fluctuating around zero. Snowfall is received occasionally when the temperature is below zero, however, the snow is melting instantaneously or shortly after the snowfall. The other type of winter climate is what could be found in the north of Sweden, having long periods with temperatures below zero degrees. During this time there is an accumulation of snow and pollutants until the spring time when the temperature is fluctuating around zero and the snowmelt begins. This melt period resemble the winter climate found in the south of Sweden and is critical when it comes to risks connected to both quality and quantity. The highest concentrations of pollutants and the highest flows are found during snowmelt and rain-on-snow events respectively. There are many differences between the two different winter climates. The usage of salt on roads as a slipperiness control measure is more common in the southern parts of Sweden. Since the temperature often is around zero during winter time, the build-up of ice layers on roads are common. In the north of Sweden, it is often too cold to have a build-up of ice and the de-icers do not work at these low temperatures. Another difference is that the build up of pollutants is more significant for the winter climates with long, cold periods since the freezing-thawing cycles are not as frequent. When this accumulated snow is starting to melt, we get large quantities of water and also high concentrations of pollutants. However, to decrease the impacts from road runoff in cold regions, it is critical to not only understand the dynamics of pollutants, but also to use this knowledge in models to predict and prevent environmental damage. In this article the winter season will be subdivided into three different climategroups, one group where the temperature stays below zero during the whole winter period, the second group where the temperature is fluctuating between plus and minus five degrees, and the third group where the temperature is above zero degrees during the whole winter period. Processes and influencing factors will be investigated for all three groups in terms of dynamics of snowmelt and runoff and the quality of stormwater during the different conditions, see Figure 1. Also, a selection of commonly used models of today will be investigated and compared to see what equations are describing these physical and chemical processes. Figure1. Factors affecting the stormwater quantity and quality. Marsalek, J. (2003). Road salts in urban stormwater: an emerging issue in stormwater management in cold climate. Water, Science and Technology, vol. 48, No.9, pp 61-70.

  • 12. Westerlund, Camilla
    et al.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Particles and associated metals in road runoff during snowmelt and rainfall2006In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 362, no 1-3, p. 143-156Article in journal (Refereed)
    Abstract [en]

    This study analysed road runoff in northern Sweden with respect to the concentrations of and the loads of particles in different size fractions (4-6, 6-9, 9-15, 15-25, 25-40, and 40-120 μm) between a snowmelt period and a rainfall period, as well as during events within each period. There are also comparisons of the transport of different particle sizes between the two periods and during events within the periods and discussions on how different metals are associated with the varying particle sizes. The results showed, on average, eight times higher concentrations and five times higher loads of particles during the snowmelt period compared to the rain period for all particle size intervals. Using a t-test with 14 degrees of freedom, at a 90% and 95% confidence level, the mean- and the event mean concentrations of all particle size intervals were higher during the melt period compared to the rain period. Also, the particle concentrations for both periods decrease as the particle size increases. During the snowmelt and rainfall period, important factors influencing the concentrations and loads were the availability of material, the intensity of the lateral flow for the transport of the particles, and, additionally, for the rain period, the length of dry weather in between events. During the melt period, investigated particle sizes and TSS were highly correlated with total concentrations of Cd, Cu, Ni, Pb, and Zn. During the rain period, the correlations between total metal concentrations and the different particle sizes were not as significant.

  • 13.
    Westerlund, Camilla
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Pollutant release from a disturbed urban snowpack in northern Sweden2011In: Water quality research journal of Canada, ISSN 1201-3080, Vol. 46, no 2, p. 98-109Article in journal (Refereed)
    Abstract [en]

    Water and pollutant release from a disturbed urban snowpack was studied in an experimental plot encompassing a road section and the adjacent grassed boulevard in the city of Lulea, in northern Sweden. Winter road maintenance in this area includes snow ploughing and applications of grit without any road salts. During the study period, 18 snowmelt events were observed. Compared to rural areas and urban areas with extensive use of chloride in winter road maintenance, in the former case, the observed snowmelt quality differed by relatively high and uniform pH (7.7-8.1) and, in the latter case, by low chloride event-mean-concentrations (EMCs) (5.7-123.4 mg/L) and conductivity (11.6-60.7 mS/m). Total suspended solids (TSS) EMCs greatly exceeded those reported for rural snowmelt and urban rainfall runoff and contributed to the high pH buffering capacity of deposited snow. Observed concentrations of total and dissolved heavy metals were compared to water quality guidelines that suggested a high likelihood of biological effects. Chloride was the only pollutant that indicated an early release and all other constituents showed a uniform release with snowmelt from the snowpack. The partitioning of heavy metals between total and dissolved phases indicated the highest dissolved fractions for Cu, followed by Cd, Ni and Zn, and the lowest values were observed for Pb. The urban snowmelt characteristics substantially differed from those reported for undisturbed sites with respect to higher pollutant loads, high pH buffering capacity and a general absence of early or delayed pollutant release from the snowpack

  • 14.
    Westerlund, Camilla
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Stormwater in cold climates2007In: DayWater: an Adaptive Desicion Support System for Urban Stormwater Management, London: IWA Publishing, 2007, p. 231-246Chapter in book (Other academic)
  • 15. Westerlund, Camilla
    et al.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Transport of total suspended solids during snowmelt: influence by road salt, temperature and surface slope2008In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 192, no 1-4, p. 3-10Article in journal (Refereed)
    Abstract [en]

    In the beginning of March 2006, polluted snow from a roadside in Luleå, in the north of Sweden, with a traffic intensity of approximately 7,400 vehicles per day, was collected. The snow was homogenously mixed and divided into samples of 30 litres. The initial volumes and densities of the snow samples were measured and calculated. The snow samples were melted in climate rooms, with four different experimental configurations, to investigate the influence of road salt, temperature, and surface slope upon the transport of total suspended solids (TSS) (three replicates for each experimental configuration). The total volume of snowmelt runoff was collected and analysed for pH, conductivity, and concentrations of TSS and chlorides. The results showed that measured concentrations, calculated mass loads, and performed statistical t-tests of TSS for the snowmelt of the four different configurations implied that the transported mass load of TSS was higher with the addition of road salt and at higher ambient temperatures. However, the results showed a lower mass load of transported TSS for the lower slope.

  • 16. Westerlund, Camilla
    et al.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Bäckström, Magnus
    Seasonal variations in road runoff quality in Lulea, Sweden2003In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 48, no 9, p. 93-101Article in journal (Refereed)
    Abstract [en]

    In regions with cold climate the urban drainage and highway runoff processes become much more complex, compared to temperate regions. Therefore, climatic conditions should be taken into account in planning and design of BMPs and snow handling strategies. In order to increase the knowledge of road runoff quality during melt and rain periods, respectively, measurements were carried out at a field site during a two-month period. The field site was situated at Sodra Hamnleden, a road with 7,400 vehicles/day, in the central part of Lulea. Runoff samples were analysed for suspended solids and heavy metals (Pb, Cu, Cd, Ni and Zn). The results showed that the concentrations of suspended solids, lead, copper and cadmium were higher for the melt period, compared to rain generated runoff on the catchment without snow, and the highest concentrations were found during the rain-on-snow events. The results indicate a flow dependent increase in the concentration of suspended solids during the melt period. A comparison of the total mass of suspended solids over a one-month period showed that the melt period produced about 3 times more suspended solids. Metal elements during melt period were more particulate bound as compared to the rain period characterised by a higher percentage of the dissolved fraction

  • 17. Westerlund, Camilla
    et al.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Hernebring, C.
    Modelling of snowmelt and rainfall runoff: dynamics of road runoff and suspended solid transport2005In: Urban drainage 2005: selected proceedings of the 10th International Conference on Urban Drainage, held in Copenhagen, Denmark, 21 - 26 August 2005 / [ed] Peter Steen Mikkelsen, London: IWA Publishing, 2005, article id 165Conference paper (Refereed)
    Abstract [en]

    In this paper, a simple model concept is presented to describe the dynamics of road runoff and suspended-solid transport from a small urban catchment in northern Sweden. The study period stretches from March 28 to May 28, 2000, including both snowmelt and rainfall. A modified degree-day method is used to describe the snowmelt and the transport of suspended solids is described by a linear build-up function and a wash-off model. The model was verified through measurements taken from March 22 to May 22, 2001. The results from the simulations showed that the simple model concept was capable of describing the dynamics of road runoff and suspended solids rather well, based on the continuous course of events for the whole modelling period. However, if the model was used for simulating a snowmelt period, or single events during snowmelt, the model approach would be too simple.

  • 18.
    Westerlund, Camilla
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Hernebring, Claes
    DHI Water & Environment, Gothenburg.
    Svensson, Gilbert
    Modelling sediment transport during snowmelt- and rainfall-induced road runoff2008In: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 39, no 2, p. 113-122Article in journal (Refereed)
    Abstract [en]

    In this paper, a simple conceptual model is presented to describe the dynamics of total suspended solid (TSS) transport during snowmelt- and rainfall-induced road runoff from a small urban runoff plot in northern Sweden. The study period (28 March to 28 May 2000) included both snowmelt and rainfall. A temperature-index method is used to describe snowmelt and the accumulation and transport of TSS is described by a linear build-up function and a wash-off model. The model was verified through measurements taken from 22 March to 22 May 2001. The simulation results showed that the simple model concept was capable of describing the dynamics of road runoff and TSS well, based on the continuous course of events for the whole modelling period. However, if the model was used for simulating a snowmelt period, or single events during snowmelt, the model approach would be too simple.

  • 19.
    Westerlund, Camilla
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Nordqvist, Kerstin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Galfi, Helen
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Marsalek, Jiri
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Particle pathways during urban snowmelt and mass balance of selected pollutants2011Conference paper (Refereed)
    Abstract [en]

    The pathways and mass balance of selected pollutants, released during the snowmelt process, were investigated for urban bulk snow placed in small, intermediate, and large-scale lysimeters. The results showed that low percentages of TSS (total suspended solids) and heavy metal (Cu, Zn, Pb) loads contained in snow were transported with snowmelt, the rest remained in situ with the particulate residue. The TSS loads transported with snowmelt were 3, 3.4, and 4.8% of the initial TSS mass in the small, intermediate and large lysimeters, respectively. Particulate heavy metal loads transported with snowmelt, during the whole melting process, were measured in the intermediate lysimeter for copper and zinc, and for lead in the large lysimeter. The measured mass loads in snowmelt leaving the intermediate lysimeter were 7.5 and 7.2% for copper and zinc, respectively, and 1.7% for lead leaving the large lysimeter. The remainder of the loads stayed in situ with the particulate residue. The loads transported with snowmelt were independent of the initial TSS and metal concentrations in bulk snow. These findings have implications for siting and operating snow disposal facilities; most of the initial TSS and particulate heavy metal loads can be retained on site, rather than released with snowmelt into the receiving environments.

1 - 19 of 19
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