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  • 1.
    Borris, Matthias
    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.
    Gustafsson, Anna-Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Marsalek, Jiri
    National Water Research Institute, Environment Canada.
    Modelling the effects of changes in rainfall event characteristics on TSS loads in urban runoff2014In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 28, no 4, p. 1787-1796Article in journal (Refereed)
    Abstract [en]

    The effect of changes in rainfall event characteristics on urban stormwater quality, which was described by total suspended solids (TSS), was studied by means of computer simulations conducted with the Storm Water Management Model for a climate change scenario for northern Sweden. The simulation results showed that TSS event loads depended mainly on rainfall depth and intensity, but not on antecedent conditions. Storms with low-to-intermediate depths and intensities showed the highest sensitivity to changes in rainfall input, both for percentage and absolute changes in TSS wash-off loads, which was explained by the contribution of pervious areas and supply limitations. This has significant implications for stormwater management, because those relatively frequent events generally carry a high percentage of the annual pollutant load

  • 2. Granlund, Nils
    et al.
    Lundberg, Angela
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Gustafson, David
    KTH Royal Institute of Technology, Land and Water Resources Engineering.
    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

  • 3.
    Lundberg, Angela
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Ala-Aho, Pertti
    Water Resources and Environmental Engineering Laboratory, Department of Process and Environmental Engineering, University of Oulu.
    Eklo, Ole-Martin
    Bioforsk, Norwegian Institute for Agricultural and Environmental Research, Ås.
    Kløve, Bjørn
    Water Resources and Environmental Engineering Laboratory, Department of Process and Environmental Engineering, University of Oulu, University of Oulu, Bioforsk, UOULU.
    Kværner, Jens
    Bioforsk, Norwegian Institute for Agricultural and Environmental Research, Ås.
    Stumpp, Christine
    Helmholtz Zentrum München, German Research Center for Environmental Health – Institute of Groundwater Ecology.
    Snow and frost: implications for spatiotemporal infiltration patterns - a review2016In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 30, no 8, p. 1230-1250Article in journal (Refereed)
    Abstract [sv]

    Vast regions of the northern hemisphere are exposed to snowfall and seasonal frost. This has large effects on spatiotemporal distribution of infiltration and groundwater recharge processes as well as on the fate of pollutants. Therefore, snow and frost need to be central inherent elements of risk assessment and management schemes. However, snow and frost are often neglected or treated summarily or in a simplistic way by groundwater modellers. Snow deposition is uneven, and the snow is likely to sublimate, be redistributed and partly melt during the winter influencing the mass and spatial distribution of snow storage available for infiltration, the presence of ice layers within and under the snowpack and, therefore, also the spatial distribution of depths and permeability of the soil frost. In steep terrain, snowmelt may travel downhill tens of metres in hours along snow layers. The permeability of frozen soil is mainly influenced by soil type, its water and organic matter content, and the timing of the first snow in relation to the timing of sub-zero temperatures. The aim with this paper is to review the literature on snow and frost processes, modelling approaches with the purpose to visualize and emphasize the need to include these processes when modelling, managing and predicting groundwater recharge for areas exposed to seasonal snow and frost

  • 4.
    Lundberg, Angela
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Granlund, Nils
    Gustafsson, David
    Division of Biogeophysics, The Royal Institute of Technology, KTH.
    Towards automated 'ground truth' snow measurements: a review of operational and new measurement methods for Sweden, Norway, and Finland2010In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 24, no 14, p. 1955-1970Article in journal (Refereed)
    Abstract [en]

    Manual snow measurements are becoming increasingly expensive and climate-change-imposed snow alterations are affecting run-off and frost patterns; snow observations are included in run-off modelling, making reliable snow observations of utmost importance. Multiple new and modified ground-based techniques for monitoring snow depth, density, snow water equivalent (SWE), wetness, and layering have been tested over the last decade, justifying a review of such methods. Techniques based on snow mass, electrical properties, attenuation of radioactivity, and other miscellaneous properties are reviewed. The following sensors seem suitable for registration of temporal variations: ultrasonic (depth) and terrestrial laser scanning (depth), several snow pillows at the same location (SWE), Cold Regions Research and Engineering Laboratory/Natural Resources Conservation Service weighing sensor (SWE), Snowpower (depth, density, SWE, and wetness), active and passive (cosmic) γ-ray attenuation (SWE), and adjusted time domain reflectometry probes (density and wetness). Ground-penetrating radar (GPR) is, depending on the design and operation modes, suitable for different purposes; when arrays of antennas are pulled by a snowmobile, the technique is suitable for monitoring of spatial variations in depth, density, and SWE for dry snow. Techniques are under development, which will hopefully improve the accuracy for wet snow measurements. Frequency-modulated continuous wave GPRs seem fit for measurement of snow layering. Some suggested techniques are not operational yet. Copyright

  • 5.
    Lundberg, Angela
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Koivusalo, Harri
    Laboratory of Water Resources, Helsinki University of Technology.
    Estimating winter evaporation in boreal forests with operational snow course data2003In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 17, no 8, p. 1479-1493Article in journal (Refereed)
    Abstract [en]

    Snow course measurements from 11 sites located in eastern and northern Finland were used to estimate the total interception evaporation of a winter season for different forest categories. We categorized the sites based on forest density and tree species. Results showed that interception loss from gross precipitation increased with forest density and approached 30% for a forest with the highest density class. Interception loss for the most common forest density class was 11%. Interception losses were slightly larger in spruce forests than in pine, deciduous, or mixed forests. We provide suggestions as to how to design snow surveys to estimate wintertime interception evaporation better. Rough terrain and transition zones between forest and open areas should be avoided. Since evaporation fraction was strongly dependent on tree crown characteristics, snow course data should include direct estimates of canopy closure. Qualitative observations made by different observers should be given a reference frame to ensure comparability of records from different sites.

  • 6.
    Lundberg, Angela
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Nakai, Yuichiro
    Hokkaido Research Centre, Forestry and Forest Products Research Institute, Sapporo.
    Thunehed, Hans
    Luleå tekniska universitet.
    Halldin, Sven
    Uppsala University.
    Snow accumulation in forests from ground and remote sensing data2004In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 18, no 10, p. 1941-1955Article in journal (Refereed)
    Abstract [en]

    Winter-forest processes affect global and local climates. The interception-sublimation fraction (F) of snowfall in forests is a substantial part of the winter water budget (up to 40%). Climate, weather-forecast and hydrological modellers incorporate increasingly realistic surface schemes into their models, and algorithms describing snow accumulation and snow-interception sublimation are now finding their way into these schemes. Spatially variable data for calibration and verification of wintertime dynamics therefore are needed for such modelling schemes. The value of F was determined from snow courses in open and forested areas in Hokkaido, Japan. The value of F was related to species and canopy-structure measures such as closure, sky-view fraction (SVF) and leaf-area index (LAI). Forest structure was deduced from fish-eye photographs. The value of F showed a strong linear correlation to structure: F = 0·44 - 0·6 × SVF for SVF < 0·72 and F = 0 for SVF > 0·72, and F = 0·11 LAI. These relationships seemed valid for evergreen conifers, larch trees, alder, birch and mixed deciduous stands. Forest snow accumulation (SF) could be estimated from snowfall in open fields (So) and to LAI according to SF = So (1 - 0·11 LAI) as well as from SVF according to SF = So (0·56 + 0·6 SVF) for SVF < 0·72. The value of SF was equal to So for SVF values above 0·72. The value of sky-view fraction was correlated to the normalized difference snow index (NDSI) using a Landsat-TM image for observation plots exceeding 1 ha. Variables F and SF were related to NDSI for these plots according to: F = -0·37NDSI + 0·29 and SF = So (0·81 + 0·37NDSI). These relationships are somewhat hypothetical because plot-size limitation only allowed one sparse-forest observation of NDSI to be used. There is, therefore, a need to confirm these relationships with further studies.

  • 7.
    Lundberg, Angela
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Richardson-Näslund, C.
    Stockholms Universitet.
    Andersson, C.
    Länsstyrelsen i Norrbotten.
    Snow density variations: consequences for ground-penetrating radar2006In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 20, no 7, p. 1483-1495Article in journal (Refereed)
    Abstract [en]

    Reliable hydrological forecasts of snowmelt runoff are of major importance for many areas. Ground-penetrating radar (GPR) measurements are used to assess snowpack water equivalent for planning of hydropower production in northern Sweden. The travel time of the radar pulse through the snow cover is recorded and converted to snow water equivalent (SWE) using a constant snowpack mean density from the drainage basin studied. In this paper we improve the method to estimate SWE by introducing a depth-dependent snowpack density. We used 6 years measurements of peak snow depth and snowpack mean density at 11 locations in the Swedish mountains. The original method systematically overestimates the SWE at shallow depths (+25% for 0·5 m) and underestimates the SWE at large depths (-35% for 2·0 m). A large improvement was obtained by introducing a depth-density relation based on average conditions for several years, whereas refining this by using separate relations for individual years yielded a smaller improvement. The SWE estimates were substantially improved for thick snow covers, reducing the average error from 162 ± 23 mm to 53 ± 10 mm for depth range 1·2-2·0 m. Consequently, the introduction of a depth-dependent snow density yields substantial improvements of the accuracy in SWE values calculated from GPR data.

  • 8.
    Moghadas, Shahab
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Perttu, Anna-Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Peter
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    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.
    Laboratory study of infiltration into two frozen engineered (sandy) soils recommended for bioretention2016In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 30, no 8, p. 1251-1264Article in journal (Refereed)
    Abstract [en]

    Infiltration of water into two frozen engineered soils of different gradation was studied in laboratory soil columns 1.2 m long and 0.1 m in diameter. Prior to testing, the soil moisture was adjusted to two levels, described by the gravimetric water content of 5 or 10%, soils were compacted to about 80-90% of the maximum dry density, and refrigerated to temperatures ranging from −8 to −2 °C. Water with temperatures 8-9 °C was thereafter fed on the top of columns at a constant head and the times of water break through the column and reaching a steady percolation rate, as well as the percolation rate, were recorded. The soil water content was a critical factor affecting the thawing process; during freezing, soil moisture was converted into ice, which blocked pores, and its melting required high amounts of energy supplied by infiltrating water. Hence, the thawing of soils with higher initial water content was much slower than in lower moisture soils, and water breakthrough and the attainment of steady percolation required much longer times in higher moisture soils. Heat transfer between infiltrating water, soil ice and frozen soil particles was well described by the energy budget equations, which constitute a parsimonious model of the observed processes. The finer grained soil and more compacted soil columns exhibited reduced porosity and required longer times for soil thawing. Practical implications of study results for design of bioretention facilities (BFs) in cold climate include the use of coarse engineered soils and fitting BFs with a drain facilitating soil drainage before the onset of freezing weather. This article is protected by copyright. All rights reserved.

  • 9.
    Muthanna, Tone M.
    et al.
    Norwegian University of Science and Technology (NTNU), Trondheim.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Thorolfsson, S. T.
    Norwegian University of Science and Technology (NTNU), Trondheim.
    Seasonal climatic effects on the hydrology of a rain garden2008In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 22, no 11, p. 1640-1649Article in journal (Refereed)
    Abstract [en]

    paper evaluates the performance and winter hydrology of two small-scale rain gardens in a cold climate coastal area in Trondheim, Norway. One rain garden received runoff from a small residential watershed over a 20 month study period while the second rain garden with a shorter study period of 7 months was used as a control. The objective of the study was to investigate the extent to which cold climatic conditions would influence the hydrology and performance of the rain gardens. The hydraulic detention, storm lag time and peak flow reduction were measured and compared seasonally. No significant difference between seasonal lag time could be found, but there was a clear decreasing trend in lag time between rain, rain-on-snow and snowmelt. The average peak flow reduction for 44 storms in the study period was 42% compared to 27% for the winter seasons, indicating that the performance of the rain garden is reduced in the cold season (below 0 °C). The average hydraulic detention time for the rain garden was 0·84 ( ± 0·73) with runoff inflow and 1·91 ( ± 3·1) with only precipitation. A strong positive correlation was found between the time since the last wetting event and lag time, and between air temperature and hydraulic detention. This indicates that the time between events and seasonal air temperatures are key parameters in the hydraulic performance of cold climate rain gardens. The rain gardens were not used for snow storage areas, and a volume requirement for this was not evaluated in the study.

  • 10.
    Rujner, Hendrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Leonhardt, Günther
    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.
    Perttu, Anna-Maria
    SENS Sustainable Energy Solutions, 12154 Nacka, Sweden.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    The effects of initial soil moisture conditions on swale flow hydrographs2018In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 32, no 5, p. 644-654Article in journal (Refereed)
    Abstract [en]

    The effects of soil water content (SWC) on the formation of run‐off in grass swales draining into astorm sewer system were studied in two 30‐m test swales with trapezoidal cross sections. Swale1 was built in a loamy fine‐sand soil, on a slope of 1.5%, and Swale 2 was built in a sandy loam soil,on a slope of 0.7%. In experimental runs, the swales were irrigated with 2 flow rates reproducing run‐off from block rainfalls with intensities approximately corresponding to 2‐month and 3‐year events. Run‐off experiments were conducted for initial SWC (SWCini) ranging from 0.18 to 0.43 m3/m3. For low SWCini, the run‐off volume was greatly reduced by up to 82%, but at highSWCini, the volume reduction was as low as 15%. The relative swale flow volume reductions decreased with increasing SWCini and, for the conditions studied, indicated a transition of the dominating swale functions from run‐off dissipation to conveyance. Run‐off flow peaks were reduced proportionally to the flow volume reductions, in the range from 4% to 55%. The swale outflow hydrograph lag times varied from 5 to 15 min, with the high values corresponding tolow SWCini. Analysis of swale inflow/outflow hydrographs for high SWCini allowed estimations of the saturated hydraulic conductivities as 3.27 and 4.84 cm/hr in Swales 1 and 2, respectively. Such estimates differed from averages (N = 9) of double‐ring infiltrometer measurements (9.41 and 1.78 cm/hr). Irregularities in swale bottom slopes created bottom surface depression storage of 0.35 and 0.61 m3 for Swales 1 and 2, respectively, and functioned similarly as check bermscontributing to run‐off attenuation. The experimental findings offer implications for drainage swale planning and design: (a) SWCini strongly affect swale functioning in run‐off dissipation and conveyance during the early phase of run‐off, which is particularly important for design storms and their antecedent moisture conditions, and (b) concerning the longevity of swale operation, Swale 1 remains fully functional even after almost 60 years of operation, as judged from its attractive appearance, good infiltration rates (3.27 cm/hr), and high flow capacity.

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  • 11.
    Singh, V.P.
    et al.
    Department of Civil and Environmental Engineering, Louisiana State University, Baton Rouge.
    Bengtsson, L.
    Department of Water Resources Engineering, Lund University.
    Westerström, Göran
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Kinematic wave modelling of saturated basal flow in a snowpack1997In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 11, no 2, p. 177-187Article in journal (Refereed)
    Abstract [en]

    Movement of snowmelt water through a thin saturated layer at the infiltrating base of a snowpack is modelled by applying the kinematic wave theory. Analytical solutions are obtained for flow depth, velocity and discharge assuming that the rate of input to the saturated layer due to vertical percolation is constant. This assumption results in a linear rise and recession of the snowmelt hydrograph. The solutions are extended to the case of time-varying input. An explicit consideration of infiltration leads to a free boundary problem

  • 12.
    Singh, V.P.
    et al.
    Department of Civil and Environmental Engineering, Louisiana State University, Baton Rouge.
    Bengtsson, L.
    Department of Water Resources Engineering, Lund University.
    Westerström, Göran
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Kinematic wave modelling of vertical movement of snowmelt water through a snowpack1997In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 11, no 2, p. 149-167Article in journal (Refereed)
    Abstract [en]

    Vertical movement of snowmelt water through snowpacks is modelled by applying the kinematic wave theory. Analytical solutions are obtained for moisture flux, particle velocity, time history and velocity of meltwater front and total moisture content for a single melt event assuming that the melt rate is constant. These solutions are extended to the case involving more than one event.

  • 13.
    Westerström, Göran
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Singh, Vijay
    Louisiana State University, Baton Rouge, LA.
    An investigation of snowmelt runoff on experimental plots in Lulea, Sweden2000In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 14, no 10, p. 1869-85Article in journal (Refereed)
    Abstract [en]

    Empirical characteristics of snowmelt runoff are derived from observations made during snowmelt in a six-year period from 1980 to 1985 on three experimental plots and three plates located on the campus of the Lulea University of Technology in Lulea, Sweden. The plots had asphalt, gravel and grass surfaces. The plates were of different designs with one having the bottom cut out so that it was more like a frame. With the assumption that the asphalt surface of the plots was impervious, infiltration of meltwater into gravel and grass surfaces was deduced. Unlike rainfall infiltration, the graph of snowmelt infiltration rate resembled a flow hydrograph, with a distinct rise, a peak and a distinct recession. A strong linear relationship between the snowmelt runoff hydrograph peak and the snowmelt amount was found, which explained more than 90% of the variability in the snowmelt peak. This is in contrast with rainfall runoff where the relationship between runoff peak and volume is decidedly nonlinear. Hourly snowmelt runoff peak and daily snowmelt amount were found to exhibit nearly constant skew and follow approximately a Gumbel frequency distribution.

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